diff options
Diffstat (limited to 'sql/opt_subselect.cc')
| -rw-r--r-- | sql/opt_subselect.cc | 104 |
1 files changed, 86 insertions, 18 deletions
diff --git a/sql/opt_subselect.cc b/sql/opt_subselect.cc index 88b1428f2b1..cb451c02a8b 100644 --- a/sql/opt_subselect.cc +++ b/sql/opt_subselect.cc @@ -180,7 +180,7 @@ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - optimize_semijoin_nests() does pre-optimization - during join optimization, the join has one JOIN_TAB (or is it POSITION?) - array, and suffix-based detection is used, see advance_sj_state() + array, and suffix-based detection is used, see optimize_semi_joins() - after join optimization is done, get_best_combination() switches the data-structure to prefix-based, multiple JOIN_TAB ranges format. @@ -2761,7 +2761,7 @@ bool find_eq_ref_candidate(TABLE *table, table_map sj_inner_tables) Do semi-join optimization step after we've added a new tab to join prefix SYNOPSIS - advance_sj_state() + optimize_semi_joins() join The join we're optimizing remaining_tables Tables not in the join prefix new_join_tab Join tab we've just added to the join prefix @@ -2821,9 +2821,9 @@ bool is_multiple_semi_joins(JOIN *join, POSITION *prefix, uint idx, table_map in } -void advance_sj_state(JOIN *join, table_map remaining_tables, uint idx, - double *current_record_count, double *current_read_time, - POSITION *loose_scan_pos) +void optimize_semi_joins(JOIN *join, table_map remaining_tables, uint idx, + double *current_record_count, + double *current_read_time, POSITION *loose_scan_pos) { POSITION *pos= join->positions + idx; const JOIN_TAB *new_join_tab= pos->table; @@ -3014,19 +3014,36 @@ void advance_sj_state(JOIN *join, table_map remaining_tables, uint idx, } } - if ((emb_sj_nest= new_join_tab->emb_sj_nest)) + update_sj_state(join, new_join_tab, idx, remaining_tables); + + pos->prefix_cost.convert_from_cost(*current_read_time); + pos->prefix_record_count= *current_record_count; + pos->dups_producing_tables= dups_producing_tables; +} + + +/* + Update JOIN's semi-join optimization state after the join tab new_tab + has been added into the join prefix. + + @seealso restore_prev_sj_state() does the reverse actoion +*/ + +void update_sj_state(JOIN *join, const JOIN_TAB *new_tab, + uint idx, table_map remaining_tables) +{ + if (TABLE_LIST *emb_sj_nest= new_tab->emb_sj_nest) { join->cur_sj_inner_tables |= emb_sj_nest->sj_inner_tables; /* Remove the sj_nest if all of its SJ-inner tables are in cur_table_map */ if (!(remaining_tables & - emb_sj_nest->sj_inner_tables & ~new_join_tab->table->map)) + emb_sj_nest->sj_inner_tables & ~new_tab->table->map)) join->cur_sj_inner_tables &= ~emb_sj_nest->sj_inner_tables; } - - pos->prefix_cost.convert_from_cost(*current_read_time); - pos->prefix_record_count= *current_record_count; - pos->dups_producing_tables= dups_producing_tables; +#ifndef DBUG_OFF + join->dbug_verify_sj_inner_tables(idx + 1); +#endif } @@ -3579,10 +3596,46 @@ bool Duplicate_weedout_picker::check_qep(JOIN *join, return FALSE; } +#ifndef DBUG_OFF +/* + Verify the value of JOIN::cur_sj_inner_tables by recomputing it +*/ +bool JOIN::dbug_verify_sj_inner_tables(uint prefix_size) const +{ + table_map cur_map= const_table_map; + table_map nests_entered= 0; + if (emb_sjm_nest) + { + DBUG_ASSERT(cur_sj_inner_tables == 0); + return (cur_sj_inner_tables == 0); + } + + for (uint i= const_tables; i < prefix_size; i++) + { + JOIN_TAB *tab= positions[i].table; + cur_map |= tab->table->map; + if (TABLE_LIST *sj_nest= tab->emb_sj_nest) + { + nests_entered |= sj_nest->sj_inner_tables; + if (!(sj_nest->sj_inner_tables & ~cur_map)) + { + // all nest tables are in the prefix already + nests_entered &= ~sj_nest->sj_inner_tables; + } + } + } + DBUG_ASSERT(nests_entered == cur_sj_inner_tables); + return (nests_entered == cur_sj_inner_tables); +} +#endif /* Remove the last join tab from from join->cur_sj_inner_tables bitmap - we assume remaining_tables doesnt contain @tab. + + @note + remaining_tables contains @tab. + + @seealso update_sj_state() does the reverse */ void restore_prev_sj_state(const table_map remaining_tables, @@ -3596,15 +3649,30 @@ void restore_prev_sj_state(const table_map remaining_tables, tab->join->sjm_lookup_tables &= ~subq_tables; } - if ((emb_sj_nest= tab->emb_sj_nest)) + if (!tab->join->emb_sjm_nest && (emb_sj_nest= tab->emb_sj_nest)) { + table_map subq_tables= emb_sj_nest->sj_inner_tables & + ~tab->join->const_table_map; /* If we're removing the last SJ-inner table, remove the sj-nest */ - if ((remaining_tables & emb_sj_nest->sj_inner_tables) == - (emb_sj_nest->sj_inner_tables & ~tab->table->map)) + if ((remaining_tables & subq_tables) == subq_tables) { + // All non-const tables of the SJ nest are in the remaining_tables. + // we are not in the nest anymore. tab->join->cur_sj_inner_tables &= ~emb_sj_nest->sj_inner_tables; } + else + { + // Semi-join nest has: + // - a table being removed (not in the prefix) + // - some tables in the prefix. + tab->join->cur_sj_inner_tables |= emb_sj_nest->sj_inner_tables; + } } + +#ifndef DBUG_OFF + /* positions[idx] has been removed. Verify the state for [0...idx-1] */ + tab->join->dbug_verify_sj_inner_tables(idx); +#endif } @@ -3831,8 +3899,8 @@ void fix_semijoin_strategies_for_picked_join_order(JOIN *join) join->best_positions[first].sj_strategy= SJ_OPT_MATERIALIZE_SCAN; join->best_positions[first].n_sj_tables= sjm->tables; /* - Do what advance_sj_state did: re-run best_access_path for every table - in the [last_inner_table + 1; pos..) range + Do what optimize_semi_joins did: re-run best_access_path for every + table in the [last_inner_table + 1; pos..) range */ double prefix_rec_count; /* Get the prefix record count */ @@ -5086,7 +5154,7 @@ int setup_semijoin_loosescan(JOIN *join) The choice between the strategies is made by the join optimizer (see - advance_sj_state() and fix_semijoin_strategies_for_picked_join_order()). + optimize_semi_joins() and fix_semijoin_strategies_for_picked_join_order()). This function sets up all fields/structures/etc needed for execution except for setup/initialization of semi-join materialization which is done in setup_sj_materialization() (todo: can't we move that to here also?) |