/******************************************************* Select (c) 1997 Innobase Oy Created 12/19/1997 Heikki Tuuri *******************************************************/ #include "row0sel.h" #ifdef UNIV_NONINL #include "row0sel.ic" #endif #include "dict0dict.h" #include "dict0boot.h" #include "trx0undo.h" #include "trx0trx.h" #include "btr0btr.h" #include "btr0cur.h" #include "btr0sea.h" #include "mach0data.h" #include "que0que.h" #include "row0upd.h" #include "row0row.h" #include "row0vers.h" #include "rem0cmp.h" #include "lock0lock.h" #include "eval0eval.h" #include "pars0sym.h" #include "pars0pars.h" #include "row0mysql.h" #include "read0read.h" #include "buf0lru.h" /* Maximum number of rows to prefetch; MySQL interface has another parameter */ #define SEL_MAX_N_PREFETCH 16 /* Number of rows fetched, after which to start prefetching; MySQL interface has another parameter */ #define SEL_PREFETCH_LIMIT 1 /* When a select has accessed about this many pages, it returns control back to que_run_threads: this is to allow canceling runaway queries */ #define SEL_COST_LIMIT 100 /* Flags for search shortcut */ #define SEL_FOUND 0 #define SEL_EXHAUSTED 1 #define SEL_RETRY 2 /************************************************************************ Returns TRUE if the user-defined column values in a secondary index record are alphabetically the same as the corresponding columns in the clustered index record. NOTE: the comparison is NOT done as a binary comparison, but character fields are compared with collation! */ static ibool row_sel_sec_rec_is_for_clust_rec( /*=============================*/ /* out: TRUE if the secondary record is equal to the corresponding fields in the clustered record, when compared with collation */ rec_t* sec_rec, /* in: secondary index record */ dict_index_t* sec_index, /* in: secondary index */ rec_t* clust_rec, /* in: clustered index record */ dict_index_t* clust_index) /* in: clustered index */ { dict_field_t* ifield; dict_col_t* col; byte* sec_field; ulint sec_len; byte* clust_field; ulint clust_len; ulint n; ulint i; dtype_t* cur_type; UT_NOT_USED(clust_index); n = dict_index_get_n_ordering_defined_by_user(sec_index); for (i = 0; i < n; i++) { ifield = dict_index_get_nth_field(sec_index, i); col = dict_field_get_col(ifield); clust_field = rec_get_nth_field(clust_rec, dict_col_get_clust_pos(col), &clust_len); sec_field = rec_get_nth_field(sec_rec, i, &sec_len); if (ifield->prefix_len > 0 && clust_len != UNIV_SQL_NULL) { cur_type = dict_col_get_type( dict_field_get_col(ifield)); clust_len = dtype_get_at_most_n_mbchars( cur_type, ifield->prefix_len, clust_len, clust_field); } if (0 != cmp_data_data(dict_col_get_type(col), clust_field, clust_len, sec_field, sec_len)) { return(FALSE); } } return(TRUE); } /************************************************************************* Creates a select node struct. */ sel_node_t* sel_node_create( /*============*/ /* out, own: select node struct */ mem_heap_t* heap) /* in: memory heap where created */ { sel_node_t* node; node = mem_heap_alloc(heap, sizeof(sel_node_t)); node->common.type = QUE_NODE_SELECT; node->state = SEL_NODE_OPEN; node->select_will_do_update = FALSE; node->latch_mode = BTR_SEARCH_LEAF; node->plans = NULL; return(node); } /************************************************************************* Frees the memory private to a select node when a query graph is freed, does not free the heap where the node was originally created. */ void sel_node_free_private( /*==================*/ sel_node_t* node) /* in: select node struct */ { ulint i; plan_t* plan; if (node->plans != NULL) { for (i = 0; i < node->n_tables; i++) { plan = sel_node_get_nth_plan(node, i); btr_pcur_close(&(plan->pcur)); btr_pcur_close(&(plan->clust_pcur)); if (plan->old_vers_heap) { mem_heap_free(plan->old_vers_heap); } } } } /************************************************************************* Evaluates the values in a select list. If there are aggregate functions, their argument value is added to the aggregate total. */ UNIV_INLINE void sel_eval_select_list( /*=================*/ sel_node_t* node) /* in: select node */ { que_node_t* exp; exp = node->select_list; while (exp) { eval_exp(exp); exp = que_node_get_next(exp); } } /************************************************************************* Assigns the values in the select list to the possible into-variables in SELECT ... INTO ... */ UNIV_INLINE void sel_assign_into_var_values( /*=======================*/ sym_node_t* var, /* in: first variable in a list of variables */ sel_node_t* node) /* in: select node */ { que_node_t* exp; if (var == NULL) { return; } exp = node->select_list; while (var) { ut_ad(exp); eval_node_copy_val(var->alias, exp); exp = que_node_get_next(exp); var = que_node_get_next(var); } } /************************************************************************* Resets the aggregate value totals in the select list of an aggregate type query. */ UNIV_INLINE void sel_reset_aggregate_vals( /*=====================*/ sel_node_t* node) /* in: select node */ { func_node_t* func_node; ut_ad(node->is_aggregate); func_node = node->select_list; while (func_node) { eval_node_set_int_val(func_node, 0); func_node = que_node_get_next(func_node); } node->aggregate_already_fetched = FALSE; } /************************************************************************* Copies the input variable values when an explicit cursor is opened. */ UNIV_INLINE void row_sel_copy_input_variable_vals( /*=============================*/ sel_node_t* node) /* in: select node */ { sym_node_t* var; var = UT_LIST_GET_FIRST(node->copy_variables); while (var) { eval_node_copy_val(var, var->alias); var->indirection = NULL; var = UT_LIST_GET_NEXT(col_var_list, var); } } /************************************************************************* Fetches the column values from a record. */ static void row_sel_fetch_columns( /*==================*/ dict_index_t* index, /* in: record index */ rec_t* rec, /* in: record in a clustered or non-clustered index */ sym_node_t* column) /* in: first column in a column list, or NULL */ { dfield_t* val; ulint index_type; ulint field_no; byte* data; ulint len; if (index->type & DICT_CLUSTERED) { index_type = SYM_CLUST_FIELD_NO; } else { index_type = SYM_SEC_FIELD_NO; } while (column) { field_no = column->field_nos[index_type]; if (field_no != ULINT_UNDEFINED) { data = rec_get_nth_field(rec, field_no, &len); if (column->copy_val) { eval_node_copy_and_alloc_val(column, data, len); } else { val = que_node_get_val(column); dfield_set_data(val, data, len); } } column = UT_LIST_GET_NEXT(col_var_list, column); } } /************************************************************************* Allocates a prefetch buffer for a column when prefetch is first time done. */ static void sel_col_prefetch_buf_alloc( /*=======================*/ sym_node_t* column) /* in: symbol table node for a column */ { sel_buf_t* sel_buf; ulint i; ut_ad(que_node_get_type(column) == QUE_NODE_SYMBOL); column->prefetch_buf = mem_alloc(SEL_MAX_N_PREFETCH * sizeof(sel_buf_t)); for (i = 0; i < SEL_MAX_N_PREFETCH; i++) { sel_buf = column->prefetch_buf + i; sel_buf->data = NULL; sel_buf->val_buf_size = 0; } } /************************************************************************* Frees a prefetch buffer for a column, including the dynamically allocated memory for data stored there. */ void sel_col_prefetch_buf_free( /*======================*/ sel_buf_t* prefetch_buf) /* in, own: prefetch buffer */ { sel_buf_t* sel_buf; ulint i; for (i = 0; i < SEL_MAX_N_PREFETCH; i++) { sel_buf = prefetch_buf + i; if (sel_buf->val_buf_size > 0) { mem_free(sel_buf->data); } } } /************************************************************************* Pops the column values for a prefetched, cached row from the column prefetch buffers and places them to the val fields in the column nodes. */ static void sel_pop_prefetched_row( /*===================*/ plan_t* plan) /* in: plan node for a table */ { sym_node_t* column; sel_buf_t* sel_buf; dfield_t* val; byte* data; ulint len; ulint val_buf_size; ut_ad(plan->n_rows_prefetched > 0); column = UT_LIST_GET_FIRST(plan->columns); while (column) { val = que_node_get_val(column); if (!column->copy_val) { /* We did not really push any value for the column */ ut_ad(!column->prefetch_buf); ut_ad(que_node_get_val_buf_size(column) == 0); #ifdef UNIV_DEBUG dfield_set_data(val, NULL, 0); #endif goto next_col; } ut_ad(column->prefetch_buf); sel_buf = column->prefetch_buf + plan->first_prefetched; data = sel_buf->data; len = sel_buf->len; val_buf_size = sel_buf->val_buf_size; /* We must keep track of the allocated memory for column values to be able to free it later: therefore we swap the values for sel_buf and val */ sel_buf->data = dfield_get_data(val); sel_buf->len = dfield_get_len(val); sel_buf->val_buf_size = que_node_get_val_buf_size(column); dfield_set_data(val, data, len); que_node_set_val_buf_size(column, val_buf_size); next_col: column = UT_LIST_GET_NEXT(col_var_list, column); } plan->n_rows_prefetched--; plan->first_prefetched++; } /************************************************************************* Pushes the column values for a prefetched, cached row to the column prefetch buffers from the val fields in the column nodes. */ UNIV_INLINE void sel_push_prefetched_row( /*====================*/ plan_t* plan) /* in: plan node for a table */ { sym_node_t* column; sel_buf_t* sel_buf; dfield_t* val; byte* data; ulint len; ulint pos; ulint val_buf_size; if (plan->n_rows_prefetched == 0) { pos = 0; plan->first_prefetched = 0; } else { pos = plan->n_rows_prefetched; /* We have the convention that pushing new rows starts only after the prefetch stack has been emptied: */ ut_ad(plan->first_prefetched == 0); } plan->n_rows_prefetched++; ut_ad(pos < SEL_MAX_N_PREFETCH); column = UT_LIST_GET_FIRST(plan->columns); while (column) { if (!column->copy_val) { /* There is no sense to push pointers to database page fields when we do not keep latch on the page! */ goto next_col; } if (!column->prefetch_buf) { /* Allocate a new prefetch buffer */ sel_col_prefetch_buf_alloc(column); } sel_buf = column->prefetch_buf + pos; val = que_node_get_val(column); data = dfield_get_data(val); len = dfield_get_len(val); val_buf_size = que_node_get_val_buf_size(column); /* We must keep track of the allocated memory for column values to be able to free it later: therefore we swap the values for sel_buf and val */ dfield_set_data(val, sel_buf->data, sel_buf->len); que_node_set_val_buf_size(column, sel_buf->val_buf_size); sel_buf->data = data; sel_buf->len = len; sel_buf->val_buf_size = val_buf_size; next_col: column = UT_LIST_GET_NEXT(col_var_list, column); } } /************************************************************************* Builds a previous version of a clustered index record for a consistent read */ static ulint row_sel_build_prev_vers( /*====================*/ /* out: DB_SUCCESS or error code */ read_view_t* read_view, /* in: read view */ plan_t* plan, /* in: plan node for table */ rec_t* rec, /* in: record in a clustered index */ rec_t** old_vers, /* out: old version, or NULL if the record does not exist in the view: i.e., it was freshly inserted afterwards */ mtr_t* mtr) /* in: mtr */ { ulint err; if (plan->old_vers_heap) { mem_heap_empty(plan->old_vers_heap); } else { plan->old_vers_heap = mem_heap_create(512); } err = row_vers_build_for_consistent_read(rec, mtr, plan->index, read_view, plan->old_vers_heap, old_vers); return(err); } /************************************************************************* Tests the conditions which determine when the index segment we are searching through has been exhausted. */ UNIV_INLINE ibool row_sel_test_end_conds( /*===================*/ /* out: TRUE if row passed the tests */ plan_t* plan) /* in: plan for the table; the column values must already have been retrieved and the right sides of comparisons evaluated */ { func_node_t* cond; /* All conditions in end_conds are comparisons of a column to an expression */ cond = UT_LIST_GET_FIRST(plan->end_conds); while (cond) { /* Evaluate the left side of the comparison, i.e., get the column value if there is an indirection */ eval_sym(cond->args); /* Do the comparison */ if (!eval_cmp(cond)) { return(FALSE); } cond = UT_LIST_GET_NEXT(cond_list, cond); } return(TRUE); } /************************************************************************* Tests the other conditions. */ UNIV_INLINE ibool row_sel_test_other_conds( /*=====================*/ /* out: TRUE if row passed the tests */ plan_t* plan) /* in: plan for the table; the column values must already have been retrieved */ { func_node_t* cond; cond = UT_LIST_GET_FIRST(plan->other_conds); while (cond) { eval_exp(cond); if (!eval_node_get_ibool_val(cond)) { return(FALSE); } cond = UT_LIST_GET_NEXT(cond_list, cond); } return(TRUE); } /************************************************************************* Retrieves the clustered index record corresponding to a record in a non-clustered index. Does the necessary locking. */ static ulint row_sel_get_clust_rec( /*==================*/ /* out: DB_SUCCESS or error code */ sel_node_t* node, /* in: select_node */ plan_t* plan, /* in: plan node for table */ rec_t* rec, /* in: record in a non-clustered index */ que_thr_t* thr, /* in: query thread */ rec_t** out_rec,/* out: clustered record or an old version of it, NULL if the old version did not exist in the read view, i.e., it was a fresh inserted version */ mtr_t* mtr) /* in: mtr used to get access to the non-clustered record; the same mtr is used to access the clustered index */ { dict_index_t* index; rec_t* clust_rec; rec_t* old_vers; ulint err; row_build_row_ref_fast(plan->clust_ref, plan->clust_map, rec); index = dict_table_get_first_index(plan->table); btr_pcur_open_with_no_init(index, plan->clust_ref, PAGE_CUR_LE, node->latch_mode, &(plan->clust_pcur), 0, mtr); clust_rec = btr_pcur_get_rec(&(plan->clust_pcur)); /* Note: only if the search ends up on a non-infimum record is the low_match value the real match to the search tuple */ if (!page_rec_is_user_rec(clust_rec) || btr_pcur_get_low_match(&(plan->clust_pcur)) < dict_index_get_n_unique(index)) { ut_a(rec_get_deleted_flag(rec)); ut_a(node->read_view); /* In a rare case it is possible that no clust rec is found for a delete-marked secondary index record: if in row0umod.c in row_undo_mod_remove_clust_low() we have already removed the clust rec, while purge is still cleaning and removing secondary index records associated with earlier versions of the clustered index record. In that case we know that the clustered index record did not exist in the read view of trx. */ clust_rec = NULL; goto func_exit; } if (!node->read_view) { /* Try to place a lock on the index record */ /* If innodb_locks_unsafe_for_binlog option is used, we lock only the record, i.e. next-key locking is not used. */ if (srv_locks_unsafe_for_binlog) { err = lock_clust_rec_read_check_and_lock(0, clust_rec, index, node->row_lock_mode, LOCK_REC_NOT_GAP, thr); } else { err = lock_clust_rec_read_check_and_lock(0, clust_rec, index, node->row_lock_mode, LOCK_ORDINARY, thr); } if (err != DB_SUCCESS) { return(err); } } else { /* This is a non-locking consistent read: if necessary, fetch a previous version of the record */ old_vers = NULL; if (!lock_clust_rec_cons_read_sees(clust_rec, index, node->read_view)) { err = row_sel_build_prev_vers(node->read_view, plan, clust_rec, &old_vers, mtr); if (err != DB_SUCCESS) { return(err); } clust_rec = old_vers; if (clust_rec == NULL) { *out_rec = clust_rec; return(DB_SUCCESS); } } /* If we had to go to an earlier version of row or the secondary index record is delete marked, then it may be that the secondary index record corresponding to clust_rec (or old_vers) is not rec; in that case we must ignore such row because in our snapshot rec would not have existed. Remember that from rec we cannot see directly which transaction id corresponds to it: we have to go to the clustered index record. A query where we want to fetch all rows where the secondary index value is in some interval would return a wrong result if we would not drop rows which we come to visit through secondary index records that would not really exist in our snapshot. */ if ((old_vers || rec_get_deleted_flag(rec)) && !row_sel_sec_rec_is_for_clust_rec(rec, plan->index, clust_rec, index)) { clust_rec = NULL; *out_rec = clust_rec; return(DB_SUCCESS); } } /* Fetch the columns needed in test conditions */ row_sel_fetch_columns(index, clust_rec, UT_LIST_GET_FIRST(plan->columns)); func_exit: *out_rec = clust_rec; return(DB_SUCCESS); } /************************************************************************* Sets a lock on a record. */ UNIV_INLINE ulint sel_set_rec_lock( /*=============*/ /* out: DB_SUCCESS or error code */ rec_t* rec, /* in: record */ dict_index_t* index, /* in: index */ ulint mode, /* in: lock mode */ ulint type, /* in: LOCK_ORDINARY, LOCK_GAP, or LOC_REC_NOT_GAP */ que_thr_t* thr) /* in: query thread */ { trx_t* trx; ulint err; trx = thr_get_trx(thr); if (UT_LIST_GET_LEN(trx->trx_locks) > 10000) { if (buf_LRU_buf_pool_running_out()) { return(DB_LOCK_TABLE_FULL); } } if (index->type & DICT_CLUSTERED) { err = lock_clust_rec_read_check_and_lock(0, rec, index, mode, type, thr); } else { err = lock_sec_rec_read_check_and_lock(0, rec, index, mode, type, thr); } return(err); } /************************************************************************* Opens a pcur to a table index. */ static void row_sel_open_pcur( /*==============*/ sel_node_t* node, /* in: select node */ plan_t* plan, /* in: table plan */ ibool search_latch_locked, /* in: TRUE if the thread currently has the search latch locked in s-mode */ mtr_t* mtr) /* in: mtr */ { dict_index_t* index; func_node_t* cond; que_node_t* exp; ulint n_fields; ulint has_search_latch = 0; /* RW_S_LATCH or 0 */ ulint i; if (search_latch_locked) { has_search_latch = RW_S_LATCH; } index = plan->index; /* Calculate the value of the search tuple: the exact match columns get their expressions evaluated when we evaluate the right sides of end_conds */ cond = UT_LIST_GET_FIRST(plan->end_conds); while (cond) { eval_exp(que_node_get_next(cond->args)); cond = UT_LIST_GET_NEXT(cond_list, cond); } if (plan->tuple) { n_fields = dtuple_get_n_fields(plan->tuple); if (plan->n_exact_match < n_fields) { /* There is a non-exact match field which must be evaluated separately */ eval_exp(plan->tuple_exps[n_fields - 1]); } for (i = 0; i < n_fields; i++) { exp = plan->tuple_exps[i]; dfield_copy_data(dtuple_get_nth_field(plan->tuple, i), que_node_get_val(exp)); } /* Open pcur to the index */ btr_pcur_open_with_no_init(index, plan->tuple, plan->mode, node->latch_mode, &(plan->pcur), has_search_latch, mtr); } else { /* Open the cursor to the start or the end of the index (FALSE: no init) */ btr_pcur_open_at_index_side(plan->asc, index, node->latch_mode, &(plan->pcur), FALSE, mtr); } ut_ad(plan->n_rows_prefetched == 0); ut_ad(plan->n_rows_fetched == 0); ut_ad(plan->cursor_at_end == FALSE); plan->pcur_is_open = TRUE; } /************************************************************************* Restores a stored pcur position to a table index. */ static ibool row_sel_restore_pcur_pos( /*=====================*/ /* out: TRUE if the cursor should be moved to the next record after we return from this function (moved to the previous, in the case of a descending cursor) without processing again the current cursor record */ sel_node_t* node, /* in: select node */ plan_t* plan, /* in: table plan */ mtr_t* mtr) /* in: mtr */ { ibool equal_position; ulint relative_position; ut_ad(!plan->cursor_at_end); relative_position = btr_pcur_get_rel_pos(&(plan->pcur)); equal_position = btr_pcur_restore_position(node->latch_mode, &(plan->pcur), mtr); /* If the cursor is traveling upwards, and relative_position is (1) BTR_PCUR_BEFORE: this is not allowed, as we did not have a lock yet on the successor of the page infimum; (2) BTR_PCUR_AFTER: btr_pcur_restore_position placed the cursor on the first record GREATER than the predecessor of a page supremum; we have not yet processed the cursor record: no need to move the cursor to the next record; (3) BTR_PCUR_ON: btr_pcur_restore_position placed the cursor on the last record LESS or EQUAL to the old stored user record; (a) if equal_position is FALSE, this means that the cursor is now on a record less than the old user record, and we must move to the next record; (b) if equal_position is TRUE, then if plan->stored_cursor_rec_processed is TRUE, we must move to the next record, else there is no need to move the cursor. */ if (plan->asc) { if (relative_position == BTR_PCUR_ON) { if (equal_position) { return(plan->stored_cursor_rec_processed); } return(TRUE); } ut_ad(relative_position == BTR_PCUR_AFTER || relative_position == BTR_PCUR_AFTER_LAST_IN_TREE); return(FALSE); } /* If the cursor is traveling downwards, and relative_position is (1) BTR_PCUR_BEFORE: btr_pcur_restore_position placed the cursor on the last record LESS than the successor of a page infimum; we have not processed the cursor record: no need to move the cursor; (2) BTR_PCUR_AFTER: btr_pcur_restore_position placed the cursor on the first record GREATER than the predecessor of a page supremum; we have processed the cursor record: we should move the cursor to the previous record; (3) BTR_PCUR_ON: btr_pcur_restore_position placed the cursor on the last record LESS or EQUAL to the old stored user record; (a) if equal_position is FALSE, this means that the cursor is now on a record less than the old user record, and we need not move to the previous record; (b) if equal_position is TRUE, then if plan->stored_cursor_rec_processed is TRUE, we must move to the previous record, else there is no need to move the cursor. */ if (relative_position == BTR_PCUR_BEFORE || relative_position == BTR_PCUR_BEFORE_FIRST_IN_TREE) { return(FALSE); } if (relative_position == BTR_PCUR_ON) { if (equal_position) { return(plan->stored_cursor_rec_processed); } return(FALSE); } ut_ad(relative_position == BTR_PCUR_AFTER || relative_position == BTR_PCUR_AFTER_LAST_IN_TREE); return(TRUE); } /************************************************************************* Resets a plan cursor to a closed state. */ UNIV_INLINE void plan_reset_cursor( /*==============*/ plan_t* plan) /* in: plan */ { plan->pcur_is_open = FALSE; plan->cursor_at_end = FALSE; plan->n_rows_fetched = 0; plan->n_rows_prefetched = 0; } /************************************************************************* Tries to do a shortcut to fetch a clustered index record with a unique key, using the hash index if possible (not always). */ static ulint row_sel_try_search_shortcut( /*========================*/ /* out: SEL_FOUND, SEL_EXHAUSTED, SEL_RETRY */ sel_node_t* node, /* in: select node for a consistent read */ plan_t* plan, /* in: plan for a unique search in clustered index */ mtr_t* mtr) /* in: mtr */ { dict_index_t* index; rec_t* rec; index = plan->index; ut_ad(node->read_view); ut_ad(plan->unique_search); ut_ad(!plan->must_get_clust); #ifdef UNIV_SYNC_DEBUG ut_ad(rw_lock_own(&btr_search_latch, RW_LOCK_SHARED)); #endif /* UNIV_SYNC_DEBUG */ row_sel_open_pcur(node, plan, TRUE, mtr); rec = btr_pcur_get_rec(&(plan->pcur)); if (!page_rec_is_user_rec(rec)) { return(SEL_RETRY); } ut_ad(plan->mode == PAGE_CUR_GE); /* As the cursor is now placed on a user record after a search with the mode PAGE_CUR_GE, the up_match field in the cursor tells how many fields in the user record matched to the search tuple */ if (btr_pcur_get_up_match(&(plan->pcur)) < plan->n_exact_match) { return(SEL_EXHAUSTED); } /* This is a non-locking consistent read: if necessary, fetch a previous version of the record */ if (index->type & DICT_CLUSTERED) { if (!lock_clust_rec_cons_read_sees(rec, index, node->read_view)) { return(SEL_RETRY); } } else if (!lock_sec_rec_cons_read_sees(rec, index, node->read_view)) { return(SEL_RETRY); } /* Test deleted flag. Fetch the columns needed in test conditions. */ row_sel_fetch_columns(index, rec, UT_LIST_GET_FIRST(plan->columns)); if (rec_get_deleted_flag(rec)) { return(SEL_EXHAUSTED); } /* Test the rest of search conditions */ if (!row_sel_test_other_conds(plan)) { return(SEL_EXHAUSTED); } ut_ad(plan->pcur.latch_mode == node->latch_mode); plan->n_rows_fetched++; return(SEL_FOUND); } /************************************************************************* Performs a select step. */ static ulint row_sel( /*====*/ /* out: DB_SUCCESS or error code */ sel_node_t* node, /* in: select node */ que_thr_t* thr) /* in: query thread */ { dict_index_t* index; plan_t* plan; mtr_t mtr; ibool moved; rec_t* rec; rec_t* old_vers; rec_t* clust_rec; ibool search_latch_locked; ibool consistent_read; /* The following flag becomes TRUE when we are doing a consistent read from a non-clustered index and we must look at the clustered index to find out the previous delete mark state of the non-clustered record: */ ibool cons_read_requires_clust_rec = FALSE; ulint cost_counter = 0; ibool cursor_just_opened; ibool must_go_to_next; ibool leaf_contains_updates = FALSE; /* TRUE if select_will_do_update is TRUE and the current clustered index leaf page has been updated during the current mtr: mtr must be committed at the same time as the leaf x-latch is released */ ibool mtr_has_extra_clust_latch = FALSE; /* TRUE if the search was made using a non-clustered index, and we had to access the clustered record: now &mtr contains a clustered index latch, and &mtr must be committed before we move to the next non-clustered record */ ulint found_flag; ulint err; ut_ad(thr->run_node == node); search_latch_locked = FALSE; if (node->read_view) { /* In consistent reads, we try to do with the hash index and not to use the buffer page get. This is to reduce memory bus load resulting from semaphore operations. The search latch will be s-locked when we access an index with a unique search condition, but not locked when we access an index with a less selective search condition. */ consistent_read = TRUE; } else { consistent_read = FALSE; } table_loop: /* TABLE LOOP ---------- This is the outer major loop in calculating a join. We come here when node->fetch_table changes, and after adding a row to aggregate totals and, of course, when this function is called. */ ut_ad(leaf_contains_updates == FALSE); ut_ad(mtr_has_extra_clust_latch == FALSE); plan = sel_node_get_nth_plan(node, node->fetch_table); index = plan->index; if (plan->n_rows_prefetched > 0) { sel_pop_prefetched_row(plan); goto next_table_no_mtr; } if (plan->cursor_at_end) { /* The cursor has already reached the result set end: no more rows to process for this table cursor, as also the prefetch stack was empty */ ut_ad(plan->pcur_is_open); goto table_exhausted_no_mtr; } /* Open a cursor to index, or restore an open cursor position */ mtr_start(&mtr); if (consistent_read && plan->unique_search && !plan->pcur_is_open && !plan->must_get_clust) { if (!search_latch_locked) { rw_lock_s_lock(&btr_search_latch); search_latch_locked = TRUE; } else if (btr_search_latch.writer_is_wait_ex) { /* There is an x-latch request waiting: release the s-latch for a moment; as an s-latch here is often kept for some 10 searches before being released, a waiting x-latch request would block other threads from acquiring an s-latch for a long time, lowering performance significantly in multiprocessors. */ rw_lock_s_unlock(&btr_search_latch); rw_lock_s_lock(&btr_search_latch); } found_flag = row_sel_try_search_shortcut(node, plan, &mtr); if (found_flag == SEL_FOUND) { goto next_table; } else if (found_flag == SEL_EXHAUSTED) { goto table_exhausted; } ut_ad(found_flag == SEL_RETRY); plan_reset_cursor(plan); mtr_commit(&mtr); mtr_start(&mtr); } if (search_latch_locked) { rw_lock_s_unlock(&btr_search_latch); search_latch_locked = FALSE; } if (!plan->pcur_is_open) { /* Evaluate the expressions to build the search tuple and open the cursor */ row_sel_open_pcur(node, plan, search_latch_locked, &mtr); cursor_just_opened = TRUE; /* A new search was made: increment the cost counter */ cost_counter++; } else { /* Restore pcur position to the index */ must_go_to_next = row_sel_restore_pcur_pos(node, plan, &mtr); cursor_just_opened = FALSE; if (must_go_to_next) { /* We have already processed the cursor record: move to the next */ goto next_rec; } } rec_loop: /* RECORD LOOP ----------- In this loop we use pcur and try to fetch a qualifying row, and also fill the prefetch buffer for this table if n_rows_fetched has exceeded a threshold. While we are inside this loop, the following holds: (1) &mtr is started, (2) pcur is positioned and open. NOTE that if cursor_just_opened is TRUE here, it means that we came to this point right after row_sel_open_pcur. */ ut_ad(mtr_has_extra_clust_latch == FALSE); rec = btr_pcur_get_rec(&(plan->pcur)); /* PHASE 1: Set a lock if specified */ if (!node->asc && cursor_just_opened && (rec != page_get_supremum_rec(buf_frame_align(rec)))) { /* When we open a cursor for a descending search, we must set a next-key lock on the successor record: otherwise it would be possible to insert new records next to the cursor position, and it might be that these new records should appear in the search result set, resulting in the phantom problem. */ if (!consistent_read) { /* If innodb_locks_unsafe_for_binlog option is used, we lock only the record, i.e. next-key locking is not used. */ if (srv_locks_unsafe_for_binlog) { err = sel_set_rec_lock(page_rec_get_next(rec), index, node->row_lock_mode, LOCK_REC_NOT_GAP, thr); } else { err = sel_set_rec_lock(page_rec_get_next(rec), index, node->row_lock_mode, LOCK_ORDINARY, thr); } if (err != DB_SUCCESS) { /* Note that in this case we will store in pcur the PREDECESSOR of the record we are waiting the lock for */ goto lock_wait_or_error; } } } if (rec == page_get_infimum_rec(buf_frame_align(rec))) { /* The infimum record on a page cannot be in the result set, and neither can a record lock be placed on it: we skip such a record. We also increment the cost counter as we may have processed yet another page of index. */ cost_counter++; goto next_rec; } if (!consistent_read) { /* Try to place a lock on the index record */ /* If innodb_locks_unsafe_for_binlog option is used, we lock only the record, i.e. next-key locking is not used. */ if (srv_locks_unsafe_for_binlog) { err = sel_set_rec_lock(rec, index, node->row_lock_mode, LOCK_REC_NOT_GAP, thr); } else { err = sel_set_rec_lock(rec, index, node->row_lock_mode, LOCK_ORDINARY, thr); } if (err != DB_SUCCESS) { goto lock_wait_or_error; } } if (rec == page_get_supremum_rec(buf_frame_align(rec))) { /* A page supremum record cannot be in the result set: skip it now when we have placed a possible lock on it */ goto next_rec; } ut_ad(page_rec_is_user_rec(rec)); if (cost_counter > SEL_COST_LIMIT) { /* Now that we have placed the necessary locks, we can stop for a while and store the cursor position; NOTE that if we would store the cursor position BEFORE placing a record lock, it might happen that the cursor would jump over some records that another transaction could meanwhile insert adjacent to the cursor: this would result in the phantom problem. */ goto stop_for_a_while; } /* PHASE 2: Check a mixed index mix id if needed */ if (plan->unique_search && cursor_just_opened) { ut_ad(plan->mode == PAGE_CUR_GE); /* As the cursor is now placed on a user record after a search with the mode PAGE_CUR_GE, the up_match field in the cursor tells how many fields in the user record matched to the search tuple */ if (btr_pcur_get_up_match(&(plan->pcur)) < plan->n_exact_match) { goto table_exhausted; } /* Ok, no need to test end_conds or mix id */ } else if (plan->mixed_index) { /* We have to check if the record in a mixed cluster belongs to this table */ if (!dict_is_mixed_table_rec(plan->table, rec)) { goto next_rec; } } /* We are ready to look at a possible new index entry in the result set: the cursor is now placed on a user record */ /* PHASE 3: Get previous version in a consistent read */ cons_read_requires_clust_rec = FALSE; if (consistent_read) { /* This is a non-locking consistent read: if necessary, fetch a previous version of the record */ if (index->type & DICT_CLUSTERED) { if (!lock_clust_rec_cons_read_sees(rec, index, node->read_view)) { err = row_sel_build_prev_vers(node->read_view, plan, rec, &old_vers, &mtr); if (err != DB_SUCCESS) { goto lock_wait_or_error; } if (old_vers == NULL) { row_sel_fetch_columns(index, rec, UT_LIST_GET_FIRST(plan->columns)); if (!row_sel_test_end_conds(plan)) { goto table_exhausted; } goto next_rec; } rec = old_vers; } } else if (!lock_sec_rec_cons_read_sees(rec, index, node->read_view)) { cons_read_requires_clust_rec = TRUE; } } /* PHASE 4: Test search end conditions and deleted flag */ /* Fetch the columns needed in test conditions */ row_sel_fetch_columns(index, rec, UT_LIST_GET_FIRST(plan->columns)); /* Test the selection end conditions: these can only contain columns which already are found in the index, even though the index might be non-clustered */ if (plan->unique_search && cursor_just_opened) { /* No test necessary: the test was already made above */ } else if (!row_sel_test_end_conds(plan)) { goto table_exhausted; } if (rec_get_deleted_flag(rec) && !cons_read_requires_clust_rec) { /* The record is delete marked: we can skip it if this is not a consistent read which might see an earlier version of a non-clustered index record */ if (plan->unique_search) { goto table_exhausted; } goto next_rec; } /* PHASE 5: Get the clustered index record, if needed and if we did not do the search using the clustered index */ if (plan->must_get_clust || cons_read_requires_clust_rec) { /* It was a non-clustered index and we must fetch also the clustered index record */ err = row_sel_get_clust_rec(node, plan, rec, thr, &clust_rec, &mtr); mtr_has_extra_clust_latch = TRUE; if (err != DB_SUCCESS) { goto lock_wait_or_error; } /* Retrieving the clustered record required a search: increment the cost counter */ cost_counter++; if (clust_rec == NULL) { /* The record did not exist in the read view */ ut_ad(consistent_read); goto next_rec; } if (rec_get_deleted_flag(clust_rec)) { /* The record is delete marked: we can skip it */ goto next_rec; } if (node->can_get_updated) { btr_pcur_store_position(&(plan->clust_pcur), &mtr); } } /* PHASE 6: Test the rest of search conditions */ if (!row_sel_test_other_conds(plan)) { if (plan->unique_search) { goto table_exhausted; } goto next_rec; } /* PHASE 7: We found a new qualifying row for the current table; push the row if prefetch is on, or move to the next table in the join */ plan->n_rows_fetched++; ut_ad(plan->pcur.latch_mode == node->latch_mode); if (node->select_will_do_update) { /* This is a searched update and we can do the update in-place, saving CPU time */ row_upd_in_place_in_select(node, thr, &mtr); leaf_contains_updates = TRUE; /* When the database is in the online backup mode, the number of log records for a single mtr should be small: increment the cost counter to ensure it */ cost_counter += 1 + (SEL_COST_LIMIT / 8); if (plan->unique_search) { goto table_exhausted; } goto next_rec; } if ((plan->n_rows_fetched <= SEL_PREFETCH_LIMIT) || plan->unique_search || plan->no_prefetch) { /* No prefetch in operation: go to the next table */ goto next_table; } sel_push_prefetched_row(plan); if (plan->n_rows_prefetched == SEL_MAX_N_PREFETCH) { /* The prefetch buffer is now full */ sel_pop_prefetched_row(plan); goto next_table; } next_rec: ut_ad(!search_latch_locked); if (mtr_has_extra_clust_latch) { /* We must commit &mtr if we are moving to the next non-clustered index record, because we could break the latching order if we would access a different clustered index page right away without releasing the previous. */ goto commit_mtr_for_a_while; } if (leaf_contains_updates && btr_pcur_is_after_last_on_page(&(plan->pcur), &mtr)) { /* We must commit &mtr if we are moving to a different page, because we have done updates to the x-latched leaf page, and the latch would be released in btr_pcur_move_to_next, without &mtr getting committed there */ ut_ad(node->asc); goto commit_mtr_for_a_while; } if (node->asc) { moved = btr_pcur_move_to_next(&(plan->pcur), &mtr); } else { moved = btr_pcur_move_to_prev(&(plan->pcur), &mtr); } if (!moved) { goto table_exhausted; } cursor_just_opened = FALSE; /* END OF RECORD LOOP ------------------ */ goto rec_loop; next_table: /* We found a record which satisfies the conditions: we can move to the next table or return a row in the result set */ ut_ad(btr_pcur_is_on_user_rec(&(plan->pcur), &mtr)); if (plan->unique_search && !node->can_get_updated) { plan->cursor_at_end = TRUE; } else { ut_ad(!search_latch_locked); plan->stored_cursor_rec_processed = TRUE; btr_pcur_store_position(&(plan->pcur), &mtr); } mtr_commit(&mtr); leaf_contains_updates = FALSE; mtr_has_extra_clust_latch = FALSE; next_table_no_mtr: /* If we use 'goto' to this label, it means that the row was popped from the prefetched rows stack, and &mtr is already committed */ if (node->fetch_table + 1 == node->n_tables) { sel_eval_select_list(node); if (node->is_aggregate) { goto table_loop; } sel_assign_into_var_values(node->into_list, node); thr->run_node = que_node_get_parent(node); if (search_latch_locked) { rw_lock_s_unlock(&btr_search_latch); } return(DB_SUCCESS); } node->fetch_table++; /* When we move to the next table, we first reset the plan cursor: we do not care about resetting it when we backtrack from a table */ plan_reset_cursor(sel_node_get_nth_plan(node, node->fetch_table)); goto table_loop; table_exhausted: /* The table cursor pcur reached the result set end: backtrack to the previous table in the join if we do not have cached prefetched rows */ plan->cursor_at_end = TRUE; mtr_commit(&mtr); leaf_contains_updates = FALSE; mtr_has_extra_clust_latch = FALSE; if (plan->n_rows_prefetched > 0) { /* The table became exhausted during a prefetch */ sel_pop_prefetched_row(plan); goto next_table_no_mtr; } table_exhausted_no_mtr: if (node->fetch_table == 0) { if (node->is_aggregate && !node->aggregate_already_fetched) { node->aggregate_already_fetched = TRUE; sel_assign_into_var_values(node->into_list, node); thr->run_node = que_node_get_parent(node); if (search_latch_locked) { rw_lock_s_unlock(&btr_search_latch); } return(DB_SUCCESS); } node->state = SEL_NODE_NO_MORE_ROWS; thr->run_node = que_node_get_parent(node); if (search_latch_locked) { rw_lock_s_unlock(&btr_search_latch); } return(DB_SUCCESS); } node->fetch_table--; goto table_loop; stop_for_a_while: /* Return control for a while to que_run_threads, so that runaway queries can be canceled. NOTE that when we come here, we must, in a locking read, have placed the necessary (possibly waiting request) record lock on the cursor record or its successor: when we reposition the cursor, this record lock guarantees that nobody can meanwhile have inserted new records which should have appeared in the result set, which would result in the phantom problem. */ ut_ad(!search_latch_locked); plan->stored_cursor_rec_processed = FALSE; btr_pcur_store_position(&(plan->pcur), &mtr); mtr_commit(&mtr); ut_ad(sync_thread_levels_empty_gen(TRUE)); return(DB_SUCCESS); commit_mtr_for_a_while: /* Stores the cursor position and commits &mtr; this is used if &mtr may contain latches which would break the latching order if &mtr would not be committed and the latches released. */ plan->stored_cursor_rec_processed = TRUE; ut_ad(!search_latch_locked); btr_pcur_store_position(&(plan->pcur), &mtr); mtr_commit(&mtr); leaf_contains_updates = FALSE; mtr_has_extra_clust_latch = FALSE; ut_ad(sync_thread_levels_empty_gen(TRUE)); goto table_loop; lock_wait_or_error: /* See the note at stop_for_a_while: the same holds for this case */ ut_ad(!btr_pcur_is_before_first_on_page(&(plan->pcur), &mtr) || !node->asc); ut_ad(!search_latch_locked); plan->stored_cursor_rec_processed = FALSE; btr_pcur_store_position(&(plan->pcur), &mtr); mtr_commit(&mtr); ut_ad(sync_thread_levels_empty_gen(TRUE)); return(err); } /************************************************************************** Performs a select step. This is a high-level function used in SQL execution graphs. */ que_thr_t* row_sel_step( /*=========*/ /* out: query thread to run next or NULL */ que_thr_t* thr) /* in: query thread */ { ulint i_lock_mode; sym_node_t* table_node; sel_node_t* node; ulint err; ut_ad(thr); node = thr->run_node; ut_ad(que_node_get_type(node) == QUE_NODE_SELECT); /* If this is a new time this node is executed (or when execution resumes after wait for a table intention lock), set intention locks on the tables, or assign a read view */ if (node->into_list && (thr->prev_node == que_node_get_parent(node))) { node->state = SEL_NODE_OPEN; } if (node->state == SEL_NODE_OPEN) { /* It may be that the current session has not yet started its transaction, or it has been committed: */ trx_start_if_not_started(thr_get_trx(thr)); plan_reset_cursor(sel_node_get_nth_plan(node, 0)); if (node->consistent_read) { /* Assign a read view for the query */ node->read_view = trx_assign_read_view( thr_get_trx(thr)); } else { if (node->set_x_locks) { i_lock_mode = LOCK_IX; } else { i_lock_mode = LOCK_IS; } table_node = node->table_list; while (table_node) { err = lock_table(0, table_node->table, i_lock_mode, thr); if (err != DB_SUCCESS) { que_thr_handle_error(thr, DB_ERROR, NULL, 0); return(NULL); } table_node = que_node_get_next(table_node); } } /* If this is an explicit cursor, copy stored procedure variable values, so that the values cannot change between fetches (currently, we copy them also for non-explicit cursors) */ if (node->explicit_cursor && UT_LIST_GET_FIRST(node->copy_variables)) { row_sel_copy_input_variable_vals(node); } node->state = SEL_NODE_FETCH; node->fetch_table = 0; if (node->is_aggregate) { /* Reset the aggregate total values */ sel_reset_aggregate_vals(node); } } err = row_sel(node, thr); /* NOTE! if queries are parallelized, the following assignment may have problems; the assignment should be made only if thr is the only top-level thr in the graph: */ thr->graph->last_sel_node = node; if (err == DB_SUCCESS) { /* Ok: do nothing */ } else if (err == DB_LOCK_WAIT) { return(NULL); } else { /* SQL error detected */ fprintf(stderr, "SQL error %lu\n", (ulong) err); que_thr_handle_error(thr, DB_ERROR, NULL, 0); return(NULL); } return(thr); } /************************************************************************** Performs a fetch for a cursor. */ que_thr_t* fetch_step( /*=======*/ /* out: query thread to run next or NULL */ que_thr_t* thr) /* in: query thread */ { sel_node_t* sel_node; fetch_node_t* node; ut_ad(thr); node = thr->run_node; sel_node = node->cursor_def; ut_ad(que_node_get_type(node) == QUE_NODE_FETCH); if (thr->prev_node != que_node_get_parent(node)) { if (sel_node->state != SEL_NODE_NO_MORE_ROWS) { sel_assign_into_var_values(node->into_list, sel_node); } thr->run_node = que_node_get_parent(node); return(thr); } /* Make the fetch node the parent of the cursor definition for the time of the fetch, so that execution knows to return to this fetch node after a row has been selected or we know that there is no row left */ sel_node->common.parent = node; if (sel_node->state == SEL_NODE_CLOSED) { /* SQL error detected */ fprintf(stderr, "SQL error %lu\n", (ulong)DB_ERROR); que_thr_handle_error(thr, DB_ERROR, NULL, 0); return(NULL); } thr->run_node = sel_node; return(thr); } /*************************************************************** Prints a row in a select result. */ que_thr_t* row_printf_step( /*============*/ /* out: query thread to run next or NULL */ que_thr_t* thr) /* in: query thread */ { row_printf_node_t* node; sel_node_t* sel_node; que_node_t* arg; ut_ad(thr); node = thr->run_node; sel_node = node->sel_node; ut_ad(que_node_get_type(node) == QUE_NODE_ROW_PRINTF); if (thr->prev_node == que_node_get_parent(node)) { /* Reset the cursor */ sel_node->state = SEL_NODE_OPEN; /* Fetch next row to print */ thr->run_node = sel_node; return(thr); } if (sel_node->state != SEL_NODE_FETCH) { ut_ad(sel_node->state == SEL_NODE_NO_MORE_ROWS); /* No more rows to print */ thr->run_node = que_node_get_parent(node); return(thr); } arg = sel_node->select_list; while (arg) { dfield_print_also_hex(que_node_get_val(arg)); fputs(" ::: ", stderr); arg = que_node_get_next(arg); } putc('\n', stderr); /* Fetch next row to print */ thr->run_node = sel_node; return(thr); } /******************************************************************** Converts a key value stored in MySQL format to an Innobase dtuple. The last field of the key value may be just a prefix of a fixed length field: hence the parameter key_len. But currently we do not allow search keys where the last field is only a prefix of the full key field len and print a warning if such appears. */ void row_sel_convert_mysql_key_to_innobase( /*==================================*/ dtuple_t* tuple, /* in: tuple where to build; NOTE: we assume that the type info in the tuple is already according to index! */ byte* buf, /* in: buffer to use in field conversions */ ulint buf_len, /* in: buffer length */ dict_index_t* index, /* in: index of the key value */ byte* key_ptr, /* in: MySQL key value */ ulint key_len, /* in: MySQL key value length */ trx_t* trx) /* in: transaction */ { byte* original_buf = buf; byte* original_key_ptr = key_ptr; dict_field_t* field; dfield_t* dfield; ulint data_offset; ulint data_len; ulint data_field_len; ibool is_null; byte* key_end; ulint n_fields = 0; ulint type; /* For documentation of the key value storage format in MySQL, see ha_innobase::store_key_val_for_row() in ha_innodb.cc. */ key_end = key_ptr + key_len; /* Permit us to access any field in the tuple (ULINT_MAX): */ dtuple_set_n_fields(tuple, ULINT_MAX); dfield = dtuple_get_nth_field(tuple, 0); field = dict_index_get_nth_field(index, 0); if (dfield_get_type(dfield)->mtype == DATA_SYS) { /* A special case: we are looking for a position in the generated clustered index which InnoDB automatically added to a table with no primary key: the first and the only ordering column is ROW_ID which InnoDB stored to the key_ptr buffer. */ ut_a(key_len == DATA_ROW_ID_LEN); dfield_set_data(dfield, key_ptr, DATA_ROW_ID_LEN); dtuple_set_n_fields(tuple, 1); return; } while (key_ptr < key_end) { ut_a(dict_col_get_type(field->col)->mtype == dfield_get_type(dfield)->mtype); data_offset = 0; is_null = FALSE; if (!(dfield_get_type(dfield)->prtype & DATA_NOT_NULL)) { /* The first byte in the field tells if this is an SQL NULL value */ data_offset = 1; if (*key_ptr != 0) { dfield_set_data(dfield, NULL, UNIV_SQL_NULL); is_null = TRUE; } } type = dfield_get_type(dfield)->mtype; /* Calculate data length and data field total length */ if (type == DATA_BLOB) { /* The key field is a column prefix of a BLOB or TEXT type column */ ut_a(field->prefix_len > 0); /* MySQL stores the actual data length to the first 2 bytes after the optional SQL NULL marker byte. The storage format is little-endian, that is, the most significant byte at a higher address. In UTF-8, MySQL seems to reserve field->prefix_len bytes for storing this field in the key value buffer, even though the actual value only takes data_len bytes from the start. */ data_len = key_ptr[data_offset] + 256 * key_ptr[data_offset + 1]; data_field_len = data_offset + 2 + field->prefix_len; data_offset += 2; type = DATA_CHAR; /* now that we know the length, we store the column value like it would be a fixed char field */ } else if (field->prefix_len > 0) { /* Looks like MySQL pads unused end bytes in the prefix with space. Therefore, also in UTF-8, it is ok to compare with a prefix containing full prefix_len bytes, and no need to take at most prefix_len / 3 UTF-8 characters from the start. If the prefix is used as the upper end of a LIKE 'abc%' query, then MySQL pads the end with chars 0xff. TODO: in that case does it any harm to compare with the full prefix_len bytes. How do characters 0xff in UTF-8 behave? */ data_len = field->prefix_len; data_field_len = data_offset + data_len; } else { data_len = dfield_get_type(dfield)->len; data_field_len = data_offset + data_len; } /* Storing may use at most data_len bytes of buf */ if (!is_null) { row_mysql_store_col_in_innobase_format( dfield, buf, key_ptr + data_offset, data_len, type, dfield_get_type(dfield)->prtype & DATA_UNSIGNED); buf += data_len; } key_ptr += data_field_len; if (key_ptr > key_end) { /* The last field in key was not a complete key field but a prefix of it. Print a warning about this! HA_READ_PREFIX_LAST does not currently work in InnoDB with partial-field key value prefixes. Since MySQL currently uses a padding trick to calculate LIKE 'abc%' type queries there should never be partial-field prefixes in searches. */ ut_print_timestamp(stderr); fputs( " InnoDB: Warning: using a partial-field key prefix in search.\n" "InnoDB: ", stderr); dict_index_name_print(stderr, trx, index); fprintf(stderr, ". Last data field length %lu bytes,\n" "InnoDB: key ptr now exceeds key end by %lu bytes.\n" "InnoDB: Key value in the MySQL format:\n", (ulong) data_field_len, (ulong) (key_ptr - key_end)); fflush(stderr); ut_print_buf(stderr, original_key_ptr, key_len); fprintf(stderr, "\n"); if (!is_null) { dfield->len -= (ulint)(key_ptr - key_end); } } n_fields++; field++; dfield++; } ut_a(buf <= original_buf + buf_len); /* We set the length of tuple to n_fields: we assume that the memory area allocated for it is big enough (usually bigger than n_fields). */ dtuple_set_n_fields(tuple, n_fields); } /****************************************************************** Stores the row id to the prebuilt struct. */ static void row_sel_store_row_id_to_prebuilt( /*=============================*/ row_prebuilt_t* prebuilt, /* in: prebuilt */ rec_t* index_rec, /* in: record */ dict_index_t* index) /* in: index of the record */ { byte* data; ulint len; data = rec_get_nth_field(index_rec, dict_index_get_sys_col_pos(index, DATA_ROW_ID), &len); if (len != DATA_ROW_ID_LEN) { fprintf(stderr, "InnoDB: Error: Row id field is wrong length %lu in ", (ulong) len); dict_index_name_print(stderr, prebuilt->trx, index); fprintf(stderr, "\n" "InnoDB: Field number %lu, record:\n", (ulong) dict_index_get_sys_col_pos(index, DATA_ROW_ID)); rec_print(stderr, index_rec); putc('\n', stderr); ut_error; } ut_memcpy(prebuilt->row_id, data, len); } /****************************************************************** Stores a non-SQL-NULL field in the MySQL format. */ UNIV_INLINE void row_sel_field_store_in_mysql_format( /*================================*/ byte* dest, /* in/out: buffer where to store; NOTE that BLOBs are not in themselves stored here: the caller must allocate and copy the BLOB into buffer before, and pass the pointer to the BLOB in 'data' */ ulint col_len,/* in: MySQL column length */ byte* data, /* in: data to store */ ulint len, /* in: length of the data */ ulint type, /* in: data type */ ulint is_unsigned)/* in: != 0 if an unsigned integer type */ { byte* ptr; ut_ad(len != UNIV_SQL_NULL); if (type == DATA_INT) { /* Convert integer data from Innobase to a little-endian format, sign bit restored to normal */ ptr = dest + len; for (;;) { ptr--; *ptr = *data; if (ptr == dest) { break; } data++; } if (!is_unsigned) { dest[len - 1] = (byte) (dest[len - 1] ^ 128); } ut_ad(col_len == len); } else if (type == DATA_VARCHAR || type == DATA_VARMYSQL || type == DATA_BINARY) { /* Store the length of the data to the first two bytes of dest; does not do anything yet because MySQL has no real vars! */ dest = row_mysql_store_var_len(dest, len); ut_memcpy(dest, data, len); /* ut_ad(col_len >= len + 2); No real var implemented in MySQL yet! */ } else if (type == DATA_BLOB) { /* Store a pointer to the BLOB buffer to dest: the BLOB was already copied to the buffer in row_sel_store_mysql_rec */ row_mysql_store_blob_ref(dest, col_len, data, len); } else { ut_memcpy(dest, data, len); ut_ad(col_len == len); } } /****************************************************************** Convert a row in the Innobase format to a row in the MySQL format. Note that the template in prebuilt may advise us to copy only a few columns to mysql_rec, other columns are left blank. All columns may not be needed in the query. */ static ibool row_sel_store_mysql_rec( /*====================*/ /* out: TRUE if success, FALSE if could not allocate memory for a BLOB (though we may also assert in that case) */ byte* mysql_rec, /* out: row in the MySQL format */ row_prebuilt_t* prebuilt, /* in: prebuilt struct */ rec_t* rec) /* in: Innobase record in the index which was described in prebuilt's template */ { mysql_row_templ_t* templ; mem_heap_t* extern_field_heap = NULL; byte* data; ulint len; byte* blob_buf; int pad_char; ulint i; ut_ad(prebuilt->mysql_template); if (prebuilt->blob_heap != NULL) { mem_heap_free(prebuilt->blob_heap); prebuilt->blob_heap = NULL; } /* MySQL assumes that all columns have the SQL NULL bit set unless it is a nullable column with a non-NULL value */ memset(mysql_rec, 0xFF, prebuilt->null_bitmap_len); for (i = 0; i < prebuilt->n_template; i++) { templ = prebuilt->mysql_template + i; data = rec_get_nth_field(rec, templ->rec_field_no, &len); if (rec_get_nth_field_extern_bit(rec, templ->rec_field_no)) { /* Copy an externally stored field to the temporary heap */ ut_a(!prebuilt->trx->has_search_latch); extern_field_heap = mem_heap_create(UNIV_PAGE_SIZE); /* NOTE: if we are retrieving a big BLOB, we may already run out of memory in the next call, which causes an assert */ data = btr_rec_copy_externally_stored_field(rec, templ->rec_field_no, &len, extern_field_heap); ut_a(len != UNIV_SQL_NULL); } if (len != UNIV_SQL_NULL) { if (templ->type == DATA_BLOB) { ut_a(prebuilt->templ_contains_blob); /* A heuristic test that we can allocate the memory for a big BLOB. We have a safety margin of 1000000 bytes. Since the test takes some CPU time, we do not use it for small BLOBs. */ if (len > 2000000 && !ut_test_malloc(len + 1000000)) { ut_print_timestamp(stderr); fprintf(stderr, " InnoDB: Warning: could not allocate %lu + 1000000 bytes to retrieve\n" "InnoDB: a big column. Table name ", (ulong) len); ut_print_name(stderr, prebuilt->trx, prebuilt->table->name); putc('\n', stderr); if (extern_field_heap) { mem_heap_free( extern_field_heap); } return(FALSE); } /* Copy the BLOB data to the BLOB heap of prebuilt */ if (prebuilt->blob_heap == NULL) { prebuilt->blob_heap = mem_heap_create(len); } blob_buf = mem_heap_alloc(prebuilt->blob_heap, len); ut_memcpy(blob_buf, data, len); data = blob_buf; } row_sel_field_store_in_mysql_format( mysql_rec + templ->mysql_col_offset, templ->mysql_col_len, data, len, templ->type, templ->is_unsigned); if (templ->type == DATA_VARCHAR || templ->type == DATA_VARMYSQL || templ->type == DATA_BINARY) { /* Pad with trailing spaces */ data = mysql_rec + templ->mysql_col_offset; /* Handle UCS2 strings differently. As no new collations will be introduced in 4.1, we hardcode the charset-collation codes here. 5.0 will use a different approach. */ if (templ->charset == 35 || templ->charset == 90 || (templ->charset >= 128 && templ->charset <= 144)) { /* space=0x0020 */ ulint col_len = templ->mysql_col_len; ut_a(!(col_len & 1)); if (len & 1) { /* A 0x20 has been stripped from the column. Pad it back. */ goto pad_0x20; } /* Pad the rest of the string with 0x0020 */ while (len < col_len) { data[len++] = 0x00; pad_0x20: data[len++] = 0x20; } } else { /* space=0x20 */ memset(data + len, 0x20, templ->mysql_col_len - len); } } /* Cleanup */ if (extern_field_heap) { mem_heap_free(extern_field_heap); extern_field_heap = NULL; } if (templ->mysql_null_bit_mask) { /* It is a nullable column with a non-NULL value */ mysql_rec[templ->mysql_null_byte_offset] &= ~(byte) (templ->mysql_null_bit_mask); } } else { /* MySQL seems to assume the field for an SQL NULL value is set to zero or space. Not taking this into account caused seg faults with NULL BLOB fields, and bug number 154 in the MySQL bug database: GROUP BY and DISTINCT could treat NULL values inequal. */ if (templ->type == DATA_VARCHAR || templ->type == DATA_CHAR || templ->type == DATA_BINARY || templ->type == DATA_FIXBINARY || templ->type == DATA_MYSQL || templ->type == DATA_VARMYSQL) { /* MySQL pads all non-BLOB and non-TEXT string types with space ' ' */ pad_char = ' '; } else { pad_char = '\0'; } /* Handle UCS2 strings differently. As no new collations will be introduced in 4.1, we hardcode the charset-collation codes here. 5.0 will use a different approach. */ if (pad_char != '\0' && (templ->charset == 35 || templ->charset == 90 || (templ->charset >= 128 && templ->charset <= 144))) { /* There are two bytes per char, so the length has to be an even number. */ ut_a(!(templ->mysql_col_len & 1)); data = mysql_rec + templ->mysql_col_offset; len = templ->mysql_col_len; /* Pad with 0x0020. */ while (len >= 2) { *data++ = 0x00; *data++ = 0x20; len -= 2; } } else { memset(mysql_rec + templ->mysql_col_offset, pad_char, templ->mysql_col_len); } } } return(TRUE); } /************************************************************************* Builds a previous version of a clustered index record for a consistent read */ static ulint row_sel_build_prev_vers_for_mysql( /*==============================*/ /* out: DB_SUCCESS or error code */ read_view_t* read_view, /* in: read view */ dict_index_t* clust_index, /* in: clustered index */ row_prebuilt_t* prebuilt, /* in: prebuilt struct */ rec_t* rec, /* in: record in a clustered index */ rec_t** old_vers, /* out: old version, or NULL if the record does not exist in the view: i.e., it was freshly inserted afterwards */ mtr_t* mtr) /* in: mtr */ { ulint err; if (prebuilt->old_vers_heap) { mem_heap_empty(prebuilt->old_vers_heap); } else { prebuilt->old_vers_heap = mem_heap_create(200); } err = row_vers_build_for_consistent_read(rec, mtr, clust_index, read_view, prebuilt->old_vers_heap, old_vers); return(err); } /************************************************************************* Retrieves the clustered index record corresponding to a record in a non-clustered index. Does the necessary locking. Used in the MySQL interface. */ static ulint row_sel_get_clust_rec_for_mysql( /*============================*/ /* out: DB_SUCCESS or error code */ row_prebuilt_t* prebuilt,/* in: prebuilt struct in the handle */ dict_index_t* sec_index,/* in: secondary index where rec resides */ rec_t* rec, /* in: record in a non-clustered index; if this is a locking read, then rec is not allowed to be delete-marked, and that would not make sense either */ que_thr_t* thr, /* in: query thread */ rec_t** out_rec,/* out: clustered record or an old version of it, NULL if the old version did not exist in the read view, i.e., it was a fresh inserted version */ mtr_t* mtr) /* in: mtr used to get access to the non-clustered record; the same mtr is used to access the clustered index */ { dict_index_t* clust_index; rec_t* clust_rec; rec_t* old_vers; ulint err; trx_t* trx; *out_rec = NULL; trx = thr_get_trx(thr); row_build_row_ref_in_tuple(prebuilt->clust_ref, sec_index, rec, trx); clust_index = dict_table_get_first_index(sec_index->table); btr_pcur_open_with_no_init(clust_index, prebuilt->clust_ref, PAGE_CUR_LE, BTR_SEARCH_LEAF, prebuilt->clust_pcur, 0, mtr); clust_rec = btr_pcur_get_rec(prebuilt->clust_pcur); prebuilt->clust_pcur->trx_if_known = trx; /* Note: only if the search ends up on a non-infimum record is the low_match value the real match to the search tuple */ if (!page_rec_is_user_rec(clust_rec) || btr_pcur_get_low_match(prebuilt->clust_pcur) < dict_index_get_n_unique(clust_index)) { /* In a rare case it is possible that no clust rec is found for a delete-marked secondary index record: if in row0umod.c in row_undo_mod_remove_clust_low() we have already removed the clust rec, while purge is still cleaning and removing secondary index records associated with earlier versions of the clustered index record. In that case we know that the clustered index record did not exist in the read view of trx. */ if (!rec_get_deleted_flag(rec) || prebuilt->select_lock_type != LOCK_NONE) { ut_print_timestamp(stderr); fputs(" InnoDB: error clustered record" " for sec rec not found\n" "InnoDB: ", stderr); dict_index_name_print(stderr, trx, sec_index); fputs("\n" "InnoDB: sec index record ", stderr); rec_print(stderr, rec); fputs("\n" "InnoDB: clust index record ", stderr); rec_print(stderr, clust_rec); putc('\n', stderr); trx_print(stderr, trx); fputs("\n" "InnoDB: Submit a detailed bug report to http://bugs.mysql.com\n", stderr); } clust_rec = NULL; goto func_exit; } if (prebuilt->select_lock_type != LOCK_NONE) { /* Try to place a lock on the index record; we are searching the clust rec with a unique condition, hence we set a LOCK_REC_NOT_GAP type lock */ err = lock_clust_rec_read_check_and_lock(0, clust_rec, clust_index, prebuilt->select_lock_type, LOCK_REC_NOT_GAP, thr); if (err != DB_SUCCESS) { return(err); } } else { /* This is a non-locking consistent read: if necessary, fetch a previous version of the record */ old_vers = NULL; /* If the isolation level allows reading of uncommitted data, then we never look for an earlier version */ if (trx->isolation_level > TRX_ISO_READ_UNCOMMITTED && !lock_clust_rec_cons_read_sees(clust_rec, clust_index, trx->read_view)) { err = row_sel_build_prev_vers_for_mysql( trx->read_view, clust_index, prebuilt, clust_rec, &old_vers, mtr); if (err != DB_SUCCESS) { return(err); } clust_rec = old_vers; } /* If we had to go to an earlier version of row or the secondary index record is delete marked, then it may be that the secondary index record corresponding to clust_rec (or old_vers) is not rec; in that case we must ignore such row because in our snapshot rec would not have existed. Remember that from rec we cannot see directly which transaction id corresponds to it: we have to go to the clustered index record. A query where we want to fetch all rows where the secondary index value is in some interval would return a wrong result if we would not drop rows which we come to visit through secondary index records that would not really exist in our snapshot. */ if (clust_rec && (old_vers || rec_get_deleted_flag(rec)) && !row_sel_sec_rec_is_for_clust_rec(rec, sec_index, clust_rec, clust_index)) { clust_rec = NULL; } else { #ifdef UNIV_SEARCH_DEBUG ut_a(clust_rec == NULL || row_sel_sec_rec_is_for_clust_rec(rec, sec_index, clust_rec, clust_index)); #endif } } func_exit: *out_rec = clust_rec; if (prebuilt->select_lock_type == LOCK_X) { /* We may use the cursor in update: store its position */ btr_pcur_store_position(prebuilt->clust_pcur, mtr); } return(DB_SUCCESS); } /************************************************************************ Restores cursor position after it has been stored. We have to take into account that the record cursor was positioned on may have been deleted. Then we may have to move the cursor one step up or down. */ static ibool sel_restore_position_for_mysql( /*===========================*/ /* out: TRUE if we may need to process the record the cursor is now positioned on (i.e. we should not go to the next record yet) */ ulint latch_mode, /* in: latch mode wished in restoration */ btr_pcur_t* pcur, /* in: cursor whose position has been stored */ ibool moves_up, /* in: TRUE if the cursor moves up in the index */ mtr_t* mtr) /* in: mtr; CAUTION: may commit mtr temporarily! */ { ibool success; ulint relative_position; relative_position = pcur->rel_pos; success = btr_pcur_restore_position(latch_mode, pcur, mtr); if (relative_position == BTR_PCUR_ON) { if (success) { return(FALSE); } if (moves_up) { btr_pcur_move_to_next(pcur, mtr); } return(TRUE); } if (relative_position == BTR_PCUR_AFTER || relative_position == BTR_PCUR_AFTER_LAST_IN_TREE) { if (moves_up) { return(TRUE); } if (btr_pcur_is_on_user_rec(pcur, mtr)) { btr_pcur_move_to_prev(pcur, mtr); } return(TRUE); } ut_ad(relative_position == BTR_PCUR_BEFORE || relative_position == BTR_PCUR_BEFORE_FIRST_IN_TREE); if (moves_up && btr_pcur_is_on_user_rec(pcur, mtr)) { btr_pcur_move_to_next(pcur, mtr); } return(TRUE); } /************************************************************************ Pops a cached row for MySQL from the fetch cache. */ UNIV_INLINE void row_sel_pop_cached_row_for_mysql( /*=============================*/ byte* buf, /* in/out: buffer where to copy the row */ row_prebuilt_t* prebuilt) /* in: prebuilt struct */ { ut_ad(prebuilt->n_fetch_cached > 0); ut_memcpy(buf, prebuilt->fetch_cache[prebuilt->fetch_cache_first], prebuilt->mysql_row_len); prebuilt->n_fetch_cached--; prebuilt->fetch_cache_first++; if (prebuilt->n_fetch_cached == 0) { prebuilt->fetch_cache_first = 0; } } /************************************************************************ Pushes a row for MySQL to the fetch cache. */ UNIV_INLINE void row_sel_push_cache_row_for_mysql( /*=============================*/ row_prebuilt_t* prebuilt, /* in: prebuilt struct */ rec_t* rec) /* in: record to push */ { byte* buf; ulint i; ut_ad(prebuilt->n_fetch_cached < MYSQL_FETCH_CACHE_SIZE); ut_a(!prebuilt->templ_contains_blob); if (prebuilt->fetch_cache[0] == NULL) { /* Allocate memory for the fetch cache */ for (i = 0; i < MYSQL_FETCH_CACHE_SIZE; i++) { /* A user has reported memory corruption in these buffers in Linux. Put magic numbers there to help to track a possible bug. */ buf = mem_alloc(prebuilt->mysql_row_len + 8); prebuilt->fetch_cache[i] = buf + 4; mach_write_to_4(buf, ROW_PREBUILT_FETCH_MAGIC_N); mach_write_to_4(buf + 4 + prebuilt->mysql_row_len, ROW_PREBUILT_FETCH_MAGIC_N); } } ut_ad(prebuilt->fetch_cache_first == 0); ut_a(row_sel_store_mysql_rec( prebuilt->fetch_cache[prebuilt->n_fetch_cached], prebuilt, rec)); prebuilt->n_fetch_cached++; } /************************************************************************* Tries to do a shortcut to fetch a clustered index record with a unique key, using the hash index if possible (not always). We assume that the search mode is PAGE_CUR_GE, it is a consistent read, there is a read view in trx, btr search latch has been locked in S-mode. */ static ulint row_sel_try_search_shortcut_for_mysql( /*==================================*/ /* out: SEL_FOUND, SEL_EXHAUSTED, SEL_RETRY */ rec_t** out_rec,/* out: record if found */ row_prebuilt_t* prebuilt,/* in: prebuilt struct */ mtr_t* mtr) /* in: started mtr */ { dict_index_t* index = prebuilt->index; dtuple_t* search_tuple = prebuilt->search_tuple; btr_pcur_t* pcur = prebuilt->pcur; trx_t* trx = prebuilt->trx; rec_t* rec; ut_ad(index->type & DICT_CLUSTERED); ut_ad(!prebuilt->templ_contains_blob); btr_pcur_open_with_no_init(index, search_tuple, PAGE_CUR_GE, BTR_SEARCH_LEAF, pcur, #ifndef UNIV_SEARCH_DEBUG RW_S_LATCH, #else 0, #endif mtr); rec = btr_pcur_get_rec(pcur); if (!page_rec_is_user_rec(rec)) { return(SEL_RETRY); } /* As the cursor is now placed on a user record after a search with the mode PAGE_CUR_GE, the up_match field in the cursor tells how many fields in the user record matched to the search tuple */ if (btr_pcur_get_up_match(pcur) < dtuple_get_n_fields(search_tuple)) { return(SEL_EXHAUSTED); } /* This is a non-locking consistent read: if necessary, fetch a previous version of the record */ if (!lock_clust_rec_cons_read_sees(rec, index, trx->read_view)) { return(SEL_RETRY); } if (rec_get_deleted_flag(rec)) { return(SEL_EXHAUSTED); } *out_rec = rec; return(SEL_FOUND); } /************************************************************************ Searches for rows in the database. This is used in the interface to MySQL. This function opens a cursor, and also implements fetch next and fetch prev. NOTE that if we do a search with a full key value from a unique index (ROW_SEL_EXACT), then we will not store the cursor position and fetch next or fetch prev must not be tried to the cursor! */ ulint row_search_for_mysql( /*=================*/ /* out: DB_SUCCESS, DB_RECORD_NOT_FOUND, DB_END_OF_INDEX, DB_DEADLOCK, DB_LOCK_TABLE_FULL, DB_CORRUPTION, or DB_TOO_BIG_RECORD */ byte* buf, /* in/out: buffer for the fetched row in the MySQL format */ ulint mode, /* in: search mode PAGE_CUR_L, ... */ row_prebuilt_t* prebuilt, /* in: prebuilt struct for the table handle; this contains the info of search_tuple, index; if search tuple contains 0 fields then we position the cursor at the start or the end of the index, depending on 'mode' */ ulint match_mode, /* in: 0 or ROW_SEL_EXACT or ROW_SEL_EXACT_PREFIX */ ulint direction) /* in: 0 or ROW_SEL_NEXT or ROW_SEL_PREV; NOTE: if this is != 0, then prebuilt must have a pcur with stored position! In opening of a cursor 'direction' should be 0. */ { dict_index_t* index = prebuilt->index; dtuple_t* search_tuple = prebuilt->search_tuple; btr_pcur_t* pcur = prebuilt->pcur; trx_t* trx = prebuilt->trx; dict_index_t* clust_index; que_thr_t* thr; rec_t* rec; rec_t* index_rec; rec_t* clust_rec; rec_t* old_vers; ulint err = DB_SUCCESS; ibool moved; ibool cons_read_requires_clust_rec; ibool was_lock_wait; ulint ret; ulint shortcut; ibool unique_search = FALSE; ibool unique_search_from_clust_index = FALSE; ibool mtr_has_extra_clust_latch = FALSE; ibool moves_up = FALSE; ibool set_also_gap_locks = TRUE; /* if the query is a plain locking SELECT, and the isolation level is <= TRX_ISO_READ_COMMITTED, then this is set to FALSE */ ibool success; ulint cnt = 0; ulint next_offs; mtr_t mtr; ut_ad(index && pcur && search_tuple); ut_ad(trx->mysql_thread_id == os_thread_get_curr_id()); if (prebuilt->table->ibd_file_missing) { ut_print_timestamp(stderr); fprintf(stderr, " InnoDB: Error:\n" "InnoDB: MySQL is trying to use a table handle but the .ibd file for\n" "InnoDB: table %s does not exist.\n" "InnoDB: Have you deleted the .ibd file from the database directory under\n" "InnoDB: the MySQL datadir, or have you used DISCARD TABLESPACE?\n" "InnoDB: Look from\n" "http://dev.mysql.com/doc/mysql/en/InnoDB_troubleshooting_datadict.html\n" "InnoDB: how you can resolve the problem.\n", prebuilt->table->name); return(DB_ERROR); } if (prebuilt->magic_n != ROW_PREBUILT_ALLOCATED) { fprintf(stderr, "InnoDB: Error: trying to free a corrupt\n" "InnoDB: table handle. Magic n %lu, table name ", (ulong) prebuilt->magic_n); ut_print_name(stderr, trx, prebuilt->table->name); putc('\n', stderr); mem_analyze_corruption((byte*)prebuilt); ut_error; } if (trx->n_mysql_tables_in_use == 0 && prebuilt->select_lock_type == LOCK_NONE) { /* Note that if MySQL uses an InnoDB temp table that it created inside LOCK TABLES, then n_mysql_tables_in_use can be zero; in that case select_lock_type is set to LOCK_X in ::start_stmt. */ fputs( "InnoDB: Error: MySQL is trying to perform a SELECT\n" "InnoDB: but it has not locked any tables in ::external_lock()!\n", stderr); trx_print(stderr, trx); fputc('\n', stderr); } /* fprintf(stderr, "Match mode %lu\n search tuple ", (ulong) match_mode); dtuple_print(search_tuple); fprintf(stderr, "N tables locked %lu\n", trx->mysql_n_tables_locked); */ /*-------------------------------------------------------------*/ /* PHASE 0: Release a possible s-latch we are holding on the adaptive hash index latch if there is someone waiting behind */ if (trx->has_search_latch && btr_search_latch.writer != RW_LOCK_NOT_LOCKED) { /* There is an x-latch request on the adaptive hash index: release the s-latch to reduce starvation and wait for BTR_SEA_TIMEOUT rounds before trying to keep it again over calls from MySQL */ rw_lock_s_unlock(&btr_search_latch); trx->has_search_latch = FALSE; trx->search_latch_timeout = BTR_SEA_TIMEOUT; } /*-------------------------------------------------------------*/ /* PHASE 1: Try to pop the row from the prefetch cache */ if (direction == 0) { trx->op_info = "starting index read"; prebuilt->n_rows_fetched = 0; prebuilt->n_fetch_cached = 0; prebuilt->fetch_cache_first = 0; if (prebuilt->sel_graph == NULL) { /* Build a dummy select query graph */ row_prebuild_sel_graph(prebuilt); } } else { trx->op_info = "fetching rows"; if (prebuilt->n_rows_fetched == 0) { prebuilt->fetch_direction = direction; } if (direction != prebuilt->fetch_direction) { if (prebuilt->n_fetch_cached > 0) { ut_error; /* TODO: scrollable cursor: restore cursor to the place of the latest returned row, or better: prevent caching for a scroll cursor! */ } prebuilt->n_rows_fetched = 0; prebuilt->n_fetch_cached = 0; prebuilt->fetch_cache_first = 0; } else if (prebuilt->n_fetch_cached > 0) { row_sel_pop_cached_row_for_mysql(buf, prebuilt); prebuilt->n_rows_fetched++; srv_n_rows_read++; trx->op_info = ""; return(DB_SUCCESS); } if (prebuilt->fetch_cache_first > 0 && prebuilt->fetch_cache_first < MYSQL_FETCH_CACHE_SIZE) { /* The previous returned row was popped from the fetch cache, but the cache was not full at the time of the popping: no more rows can exist in the result set */ trx->op_info = ""; return(DB_RECORD_NOT_FOUND); } prebuilt->n_rows_fetched++; if (prebuilt->n_rows_fetched > 1000000000) { /* Prevent wrap-over */ prebuilt->n_rows_fetched = 500000000; } mode = pcur->search_mode; } /* In a search where at most one record in the index may match, we can use a LOCK_REC_NOT_GAP type record lock when locking a non-delete- marked matching record. Note that in a unique secondary index there may be different delete- marked versions of a record where only the primary key values differ: thus in a secondary index we must use next-key locks when locking delete-marked records. */ if (match_mode == ROW_SEL_EXACT && index->type & DICT_UNIQUE && dtuple_get_n_fields(search_tuple) == dict_index_get_n_unique(index) && (index->type & DICT_CLUSTERED || !dtuple_contains_null(search_tuple))) { /* Note above that a UNIQUE secondary index can contain many rows with the same key value if one of the columns is the SQL null. A clustered index under MySQL can never contain null columns because we demand that all the columns in primary key are non-null. */ unique_search = TRUE; /* Even if the condition is unique, MySQL seems to try to retrieve also a second row if a primary key contains more than 1 column. Return immediately if this is not a HANDLER command. */ if (direction != 0 && !prebuilt->used_in_HANDLER) { trx->op_info = ""; return(DB_RECORD_NOT_FOUND); } } mtr_start(&mtr); /*-------------------------------------------------------------*/ /* PHASE 2: Try fast adaptive hash index search if possible */ /* Next test if this is the special case where we can use the fast adaptive hash index to try the search. Since we must release the search system latch when we retrieve an externally stored field, we cannot use the adaptive hash index in a search in the case the row may be long and there may be externally stored fields */ if (unique_search && index->type & DICT_CLUSTERED && direction == 0 && !prebuilt->templ_contains_blob && !prebuilt->used_in_HANDLER && (prebuilt->mysql_row_len < UNIV_PAGE_SIZE / 8)) { mode = PAGE_CUR_GE; unique_search_from_clust_index = TRUE; if (trx->mysql_n_tables_locked == 0 && prebuilt->select_lock_type == LOCK_NONE && trx->isolation_level > TRX_ISO_READ_UNCOMMITTED && trx->read_view) { /* This is a SELECT query done as a consistent read, and the read view has already been allocated: let us try a search shortcut through the hash index. NOTE that we must also test that mysql_n_tables_locked == 0, because this might also be INSERT INTO ... SELECT ... or CREATE TABLE ... SELECT ... . Our algorithm is NOT prepared to inserts interleaved with the SELECT, and if we try that, we can deadlock on the adaptive hash index semaphore! */ #ifndef UNIV_SEARCH_DEBUG if (!trx->has_search_latch) { rw_lock_s_lock(&btr_search_latch); trx->has_search_latch = TRUE; } #endif shortcut = row_sel_try_search_shortcut_for_mysql(&rec, prebuilt, &mtr); if (shortcut == SEL_FOUND) { #ifdef UNIV_SEARCH_DEBUG ut_a(0 == cmp_dtuple_rec(search_tuple, rec)); #endif if (!row_sel_store_mysql_rec(buf, prebuilt, rec)) { err = DB_TOO_BIG_RECORD; /* We let the main loop to do the error handling */ goto shortcut_fails_too_big_rec; } mtr_commit(&mtr); /* ut_print_name(stderr, index->name); fputs(" shortcut\n", stderr); */ srv_n_rows_read++; if (trx->search_latch_timeout > 0 && trx->has_search_latch) { trx->search_latch_timeout--; rw_lock_s_unlock(&btr_search_latch); trx->has_search_latch = FALSE; } trx->op_info = ""; /* NOTE that we do NOT store the cursor position */ return(DB_SUCCESS); } else if (shortcut == SEL_EXHAUSTED) { mtr_commit(&mtr); /* ut_print_name(stderr, index->name); fputs(" record not found 2\n", stderr); */ if (trx->search_latch_timeout > 0 && trx->has_search_latch) { trx->search_latch_timeout--; rw_lock_s_unlock(&btr_search_latch); trx->has_search_latch = FALSE; } trx->op_info = ""; /* NOTE that we do NOT store the cursor position */ return(DB_RECORD_NOT_FOUND); } shortcut_fails_too_big_rec: mtr_commit(&mtr); mtr_start(&mtr); } } /*-------------------------------------------------------------*/ /* PHASE 3: Open or restore index cursor position */ if (trx->has_search_latch) { rw_lock_s_unlock(&btr_search_latch); trx->has_search_latch = FALSE; } trx_start_if_not_started(trx); if (trx->isolation_level <= TRX_ISO_READ_COMMITTED && prebuilt->select_lock_type != LOCK_NONE && trx->mysql_query_str) { /* Scan the MySQL query string; check if SELECT is the first word there */ dict_accept(*trx->mysql_query_str, "SELECT", &success); if (success) { /* It is a plain locking SELECT and the isolation level is low: do not lock gaps */ set_also_gap_locks = FALSE; } } /* Note that if the search mode was GE or G, then the cursor naturally moves upward (in fetch next) in alphabetical order, otherwise downward */ if (direction == 0) { if (mode == PAGE_CUR_GE || mode == PAGE_CUR_G) { moves_up = TRUE; } } else if (direction == ROW_SEL_NEXT) { moves_up = TRUE; } thr = que_fork_get_first_thr(prebuilt->sel_graph); que_thr_move_to_run_state_for_mysql(thr, trx); clust_index = dict_table_get_first_index(index->table); if (direction != 0) { moved = sel_restore_position_for_mysql(BTR_SEARCH_LEAF, pcur, moves_up, &mtr); if (!moved) { goto next_rec; } } else if (dtuple_get_n_fields(search_tuple) > 0) { btr_pcur_open_with_no_init(index, search_tuple, mode, BTR_SEARCH_LEAF, pcur, 0, &mtr); pcur->trx_if_known = trx; } else { if (mode == PAGE_CUR_G) { btr_pcur_open_at_index_side(TRUE, index, BTR_SEARCH_LEAF, pcur, FALSE, &mtr); } else if (mode == PAGE_CUR_L) { btr_pcur_open_at_index_side(FALSE, index, BTR_SEARCH_LEAF, pcur, FALSE, &mtr); } } if (!prebuilt->sql_stat_start) { /* No need to set an intention lock or assign a read view */ if (trx->read_view == NULL && prebuilt->select_lock_type == LOCK_NONE) { fputs( "InnoDB: Error: MySQL is trying to perform a consistent read\n" "InnoDB: but the read view is not assigned!\n", stderr); trx_print(stderr, trx); fputc('\n', stderr); ut_a(0); } } else if (prebuilt->select_lock_type == LOCK_NONE) { /* This is a consistent read */ /* Assign a read view for the query */ trx_assign_read_view(trx); prebuilt->sql_stat_start = FALSE; } else { if (prebuilt->select_lock_type == LOCK_S) { err = lock_table(0, index->table, LOCK_IS, thr); } else { err = lock_table(0, index->table, LOCK_IX, thr); } if (err != DB_SUCCESS) { goto lock_wait_or_error; } prebuilt->sql_stat_start = FALSE; } rec_loop: /*-------------------------------------------------------------*/ /* PHASE 4: Look for matching records in a loop */ rec = btr_pcur_get_rec(pcur); /* fputs("Using ", stderr); dict_index_name_print(stderr, index); fprintf(stderr, " cnt %lu ; Page no %lu\n", cnt, buf_frame_get_page_no(buf_frame_align(rec))); rec_print(rec); */ if (rec == page_get_infimum_rec(buf_frame_align(rec))) { /* The infimum record on a page cannot be in the result set, and neither can a record lock be placed on it: we skip such a record. */ goto next_rec; } if (rec == page_get_supremum_rec(buf_frame_align(rec))) { if (prebuilt->select_lock_type != LOCK_NONE && set_also_gap_locks) { /* Try to place a lock on the index record */ /* If innodb_locks_unsafe_for_binlog option is used, we do not lock gaps. Supremum record is really a gap and therefore we do not set locks there. */ if (srv_locks_unsafe_for_binlog == FALSE) { err = sel_set_rec_lock(rec, index, prebuilt->select_lock_type, LOCK_ORDINARY, thr); if (err != DB_SUCCESS) { goto lock_wait_or_error; } } } /* A page supremum record cannot be in the result set: skip it now that we have placed a possible lock on it */ goto next_rec; } /*-------------------------------------------------------------*/ /* Do sanity checks in case our cursor has bumped into page corruption */ next_offs = rec_get_next_offs(rec); if (next_offs >= UNIV_PAGE_SIZE || next_offs < PAGE_SUPREMUM) { if (srv_force_recovery == 0 || moves_up == FALSE) { ut_print_timestamp(stderr); buf_page_print(buf_frame_align(rec)); fprintf(stderr, "\nInnoDB: rec address %p, first buffer frame %p\n" "InnoDB: buffer pool high end %p, buf block fix count %lu\n", rec, buf_pool->frame_zero, buf_pool->high_end, (ulong)buf_block_align(rec)->buf_fix_count); fprintf(stderr, "InnoDB: Index corruption: rec offs %lu next offs %lu, page no %lu,\n" "InnoDB: ", (ulong) (rec - buf_frame_align(rec)), (ulong) next_offs, (ulong) buf_frame_get_page_no(rec)); dict_index_name_print(stderr, trx, index); fputs(". Run CHECK TABLE. You may need to\n" "InnoDB: restore from a backup, or dump + drop + reimport the table.\n", stderr); err = DB_CORRUPTION; goto lock_wait_or_error; } else { /* The user may be dumping a corrupt table. Jump over the corruption to recover as much as possible. */ fprintf(stderr, "InnoDB: Index corruption: rec offs %lu next offs %lu, page no %lu,\n" "InnoDB: ", (ulong) (rec - buf_frame_align(rec)), (ulong) next_offs, (ulong) buf_frame_get_page_no(rec)); dict_index_name_print(stderr, trx, index); fputs(". We try to skip the rest of the page.\n", stderr); btr_pcur_move_to_last_on_page(pcur, &mtr); goto next_rec; } } if (srv_force_recovery > 0) { if (!rec_validate(rec) || !btr_index_rec_validate(rec, index, FALSE)) { fprintf(stderr, "InnoDB: Index corruption: rec offs %lu next offs %lu, page no %lu,\n" "InnoDB: ", (ulong) (rec - buf_frame_align(rec)), (ulong) next_offs, (ulong) buf_frame_get_page_no(rec)); dict_index_name_print(stderr, trx, index); fputs(". We try to skip the record.\n", stderr); goto next_rec; } } /*-------------------------------------------------------------*/ /* Note that we cannot trust the up_match value in the cursor at this place because we can arrive here after moving the cursor! Thus we have to recompare rec and search_tuple to determine if they match enough. */ if (match_mode == ROW_SEL_EXACT) { /* Test if the index record matches completely to search_tuple in prebuilt: if not, then we return with DB_RECORD_NOT_FOUND */ /* fputs("Comparing rec and search tuple\n", stderr); */ if (0 != cmp_dtuple_rec(search_tuple, rec)) { if (prebuilt->select_lock_type != LOCK_NONE && set_also_gap_locks) { /* Try to place a gap lock on the index record only if innodb_locks_unsafe_for_binlog option is not set */ if (srv_locks_unsafe_for_binlog == FALSE) { err = sel_set_rec_lock(rec, index, prebuilt->select_lock_type, LOCK_GAP, thr); if (err != DB_SUCCESS) { goto lock_wait_or_error; } } } btr_pcur_store_position(pcur, &mtr); ret = DB_RECORD_NOT_FOUND; /* ut_print_name(stderr, index->name); fputs(" record not found 3\n", stderr); */ goto normal_return; } } else if (match_mode == ROW_SEL_EXACT_PREFIX) { if (!cmp_dtuple_is_prefix_of_rec(search_tuple, rec)) { if (prebuilt->select_lock_type != LOCK_NONE && set_also_gap_locks) { /* Try to place a gap lock on the index record only if innodb_locks_unsafe_for_binlog option is not set */ if (srv_locks_unsafe_for_binlog == FALSE) { err = sel_set_rec_lock(rec, index, prebuilt->select_lock_type, LOCK_GAP, thr); if (err != DB_SUCCESS) { goto lock_wait_or_error; } } } btr_pcur_store_position(pcur, &mtr); ret = DB_RECORD_NOT_FOUND; /* ut_print_name(stderr, index->name); fputs(" record not found 4\n", stderr); */ goto normal_return; } } /* We are ready to look at a possible new index entry in the result set: the cursor is now placed on a user record */ cons_read_requires_clust_rec = FALSE; if (prebuilt->select_lock_type != LOCK_NONE) { /* Try to place a lock on the index record; note that delete marked records are a special case in a unique search. If there is a non-delete marked record, then it is enough to lock its existence with LOCK_REC_NOT_GAP. */ if (!set_also_gap_locks || (unique_search && !rec_get_deleted_flag(rec))) { err = sel_set_rec_lock(rec, index, prebuilt->select_lock_type, LOCK_REC_NOT_GAP, thr); } else { /* If innodb_locks_unsafe_for_binlog option is used, we lock only the record, i.e. next-key locking is not used. */ if (srv_locks_unsafe_for_binlog) { err = sel_set_rec_lock(rec, index, prebuilt->select_lock_type, LOCK_REC_NOT_GAP, thr); } else { err = sel_set_rec_lock(rec, index, prebuilt->select_lock_type, LOCK_ORDINARY, thr); } } if (err != DB_SUCCESS) { goto lock_wait_or_error; } } else { /* This is a non-locking consistent read: if necessary, fetch a previous version of the record */ if (trx->isolation_level == TRX_ISO_READ_UNCOMMITTED) { /* Do nothing: we let a non-locking SELECT read the latest version of the record */ } else if (index == clust_index) { /* Fetch a previous version of the row if the current one is not visible in the snapshot; if we have a very high force recovery level set, we try to avoid crashes by skipping this lookup */ if (srv_force_recovery < 5 && !lock_clust_rec_cons_read_sees(rec, index, trx->read_view)) { err = row_sel_build_prev_vers_for_mysql( trx->read_view, clust_index, prebuilt, rec, &old_vers, &mtr); if (err != DB_SUCCESS) { goto lock_wait_or_error; } if (old_vers == NULL) { /* The row did not exist yet in the read view */ goto next_rec; } rec = old_vers; } } else if (!lock_sec_rec_cons_read_sees(rec, index, trx->read_view)) { /* We are looking into a non-clustered index, and to get the right version of the record we have to look also into the clustered index: this is necessary, because we can only get the undo information via the clustered index record. */ cons_read_requires_clust_rec = TRUE; } } if (rec_get_deleted_flag(rec) && !cons_read_requires_clust_rec) { /* The record is delete-marked: we can skip it if this is not a consistent read which might see an earlier version of a non-clustered index record */ goto next_rec; } /* Get the clustered index record if needed and if we did not do the search using the clustered index */ index_rec = rec; if (index != clust_index && (cons_read_requires_clust_rec || prebuilt->need_to_access_clustered)) { /* It was a non-clustered index and we must fetch also the clustered index record */ mtr_has_extra_clust_latch = TRUE; err = row_sel_get_clust_rec_for_mysql(prebuilt, index, rec, thr, &clust_rec, &mtr); if (err != DB_SUCCESS) { goto lock_wait_or_error; } if (clust_rec == NULL) { /* The record did not exist in the read view */ ut_ad(prebuilt->select_lock_type == LOCK_NONE); goto next_rec; } if (rec_get_deleted_flag(clust_rec)) { /* The record is delete marked: we can skip it */ goto next_rec; } if (prebuilt->need_to_access_clustered) { rec = clust_rec; } } /* We found a qualifying row */ if (prebuilt->n_rows_fetched >= MYSQL_FETCH_CACHE_THRESHOLD && prebuilt->select_lock_type == LOCK_NONE && !prebuilt->templ_contains_blob && !prebuilt->clust_index_was_generated && !prebuilt->used_in_HANDLER && prebuilt->template_type != ROW_MYSQL_DUMMY_TEMPLATE) { /* Inside an update, for example, we do not cache rows, since we may use the cursor position to do the actual update, that is why we require ...lock_type == LOCK_NONE. Since we keep space in prebuilt only for the BLOBs of a single row, we cannot cache rows in the case there are BLOBs in the fields to be fetched. In HANDLER we do not cache rows because there the cursor is a scrollable cursor. */ row_sel_push_cache_row_for_mysql(prebuilt, rec); if (prebuilt->n_fetch_cached == MYSQL_FETCH_CACHE_SIZE) { goto got_row; } goto next_rec; } else { if (prebuilt->template_type == ROW_MYSQL_DUMMY_TEMPLATE) { ut_memcpy(buf + 4, rec - rec_get_extra_size(rec), rec_get_size(rec)); mach_write_to_4(buf, rec_get_extra_size(rec) + 4); } else { if (!row_sel_store_mysql_rec(buf, prebuilt, rec)) { err = DB_TOO_BIG_RECORD; goto lock_wait_or_error; } } if (prebuilt->clust_index_was_generated) { row_sel_store_row_id_to_prebuilt(prebuilt, index_rec, index); } } got_row: /* We have an optimization to save CPU time: if this is a consistent read on a unique condition on the clustered index, then we do not store the pcur position, because any fetch next or prev will anyway return 'end of file'. An exception is the MySQL HANDLER command where the user can move the cursor with PREV or NEXT even after a unique search. */ if (!unique_search_from_clust_index || prebuilt->select_lock_type == LOCK_X || prebuilt->used_in_HANDLER) { /* Inside an update always store the cursor position */ btr_pcur_store_position(pcur, &mtr); } ret = DB_SUCCESS; goto normal_return; next_rec: /*-------------------------------------------------------------*/ /* PHASE 5: Move the cursor to the next index record */ if (mtr_has_extra_clust_latch) { /* We must commit mtr if we are moving to the next non-clustered index record, because we could break the latching order if we would access a different clustered index page right away without releasing the previous. */ btr_pcur_store_position(pcur, &mtr); mtr_commit(&mtr); mtr_has_extra_clust_latch = FALSE; mtr_start(&mtr); moved = sel_restore_position_for_mysql(BTR_SEARCH_LEAF, pcur, moves_up, &mtr); if (moved) { cnt++; goto rec_loop; } } if (moves_up) { moved = btr_pcur_move_to_next(pcur, &mtr); } else { moved = btr_pcur_move_to_prev(pcur, &mtr); } if (!moved) { btr_pcur_store_position(pcur, &mtr); if (match_mode != 0) { ret = DB_RECORD_NOT_FOUND; } else { ret = DB_END_OF_INDEX; } goto normal_return; } cnt++; goto rec_loop; lock_wait_or_error: /*-------------------------------------------------------------*/ btr_pcur_store_position(pcur, &mtr); mtr_commit(&mtr); mtr_has_extra_clust_latch = FALSE; trx->error_state = err; /* The following is a patch for MySQL */ que_thr_stop_for_mysql(thr); was_lock_wait = row_mysql_handle_errors(&err, trx, thr, NULL); if (was_lock_wait) { mtr_start(&mtr); sel_restore_position_for_mysql(BTR_SEARCH_LEAF, pcur, moves_up, &mtr); mode = pcur->search_mode; goto rec_loop; } /* fputs("Using ", stderr); dict_index_name_print(stderr, index); fprintf(stderr, " cnt %lu ret value %lu err\n", cnt, err); */ trx->op_info = ""; return(err); normal_return: /*-------------------------------------------------------------*/ que_thr_stop_for_mysql_no_error(thr, trx); mtr_commit(&mtr); if (prebuilt->n_fetch_cached > 0) { row_sel_pop_cached_row_for_mysql(buf, prebuilt); ret = DB_SUCCESS; } /* fputs("Using ", stderr); dict_index_name_print(stderr, index); fprintf(stderr, " cnt %lu ret value %lu err\n", cnt, err); */ if (ret == DB_SUCCESS) { srv_n_rows_read++; } trx->op_info = ""; return(ret); } /*********************************************************************** Checks if MySQL at the moment is allowed for this table to retrieve a consistent read result, or store it to the query cache. */ ibool row_search_check_if_query_cache_permitted( /*======================================*/ /* out: TRUE if storing or retrieving from the query cache is permitted */ trx_t* trx, /* in: transaction object */ const char* norm_name) /* in: concatenation of database name, '/' char, table name */ { dict_table_t* table; ibool ret = FALSE; table = dict_table_get(norm_name, trx); if (table == NULL) { return(FALSE); } mutex_enter(&kernel_mutex); /* Start the transaction if it is not started yet */ trx_start_if_not_started_low(trx); /* If there are locks on the table or some trx has invalidated the cache up to our trx id, then ret = FALSE. We do not check what type locks there are on the table, though only IX type locks actually would require ret = FALSE. */ if (UT_LIST_GET_LEN(table->locks) == 0 && ut_dulint_cmp(trx->id, table->query_cache_inv_trx_id) >= 0) { ret = TRUE; /* If the isolation level is high, assign a read view for the transaction if it does not yet have one */ if (trx->isolation_level >= TRX_ISO_REPEATABLE_READ && !trx->read_view) { trx->read_view = read_view_open_now(trx, trx->read_view_heap); } } mutex_exit(&kernel_mutex); return(ret); }