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BUG#14940 "MySQL choose wrong index", v.2
- Make the range-et-al optimizer produce E(#table records after table
condition is applied),
- Make the join optimizer use this value,
- Add "filtered" column to EXPLAIN EXTENDED to show
fraction of records left after table condition is applied
- Adjust test results, add comments
mysql-test/r/archive_gis.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/auto_increment.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/bdb_gis.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/bench_count_distinct.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/binlog_stm_blackhole.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/case.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/cast.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/compress.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/ctype_collate.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/ctype_cp1250_ch.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/date_formats.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/distinct.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/fulltext.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/func_compress.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/func_crypt.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/func_default.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/func_encrypt.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/func_gconcat.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/func_group.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/func_if.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/func_in.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/func_like.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/func_math.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/func_op.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/func_regexp.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/func_set.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/func_str.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/func_system.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/func_test.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/func_time.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/gis.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/group_by.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/group_min_max.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/having.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/heap.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/heap_hash.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/index_merge.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/index_merge_innodb.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/index_merge_ror.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/innodb_gis.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/insert_update.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/join.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/join_nested.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/key_diff.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/myisam.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/ndb_gis.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/negation_elimination.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/null.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/olap.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/partition_pruning.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/query_cache.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/row.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/rpl_get_lock.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/rpl_master_pos_wait.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/select.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/ssl.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/ssl_compress.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/subselect.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/type_blob.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/union.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/varbinary.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/variables.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/r/view.result:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/t/ctype_cp1250_ch.test:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/t/func_like.test:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/t/group_min_max.test:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/t/index_merge_ror.test:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/t/index_merge_ror_cpk.test:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/t/join.test:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
mysql-test/t/partition_pruning.test:
BUG#14940: Adjust the test results: EXPLAIN EXTENDED now has extra "filtered" column
sql/opt_range.cc:
BUG#14940: Make range/index_merge/group-min-max optimizer produce TABLE::quick_condition_rows -
estimate of #records that will match the table condition.
sql/sql_class.cc:
BUG#14940: Add "filtered" column to output of EXPLAIN EXTENDED
sql/sql_select.cc:
BUG#14940:
- Make the join optimizer to use TABLE::quick_condition_rows=
= E(#table records after filtering with table condition)
- Add "filtered" column to output of EXPLAIN EXTENDED
sql/sql_select.h:
BUG#14940: Added comments
sql/table.h:
BUG#14940: Added comments
This commit is contained in:
unknown
100
sql/opt_range.cc
100
sql/opt_range.cc
@ -478,7 +478,8 @@ static SEL_ARG *get_mm_leaf(RANGE_OPT_PARAM *param,COND *cond_func,Field *field,
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static SEL_TREE *get_mm_tree(RANGE_OPT_PARAM *param,COND *cond);
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static bool is_key_scan_ror(PARAM *param, uint keynr, uint8 nparts);
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static ha_rows check_quick_select(PARAM *param,uint index,SEL_ARG *key_tree);
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static ha_rows check_quick_select(PARAM *param,uint index,SEL_ARG *key_tree,
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bool update_tbl_stats);
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static ha_rows check_quick_keys(PARAM *param,uint index,SEL_ARG *key_tree,
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char *min_key,uint min_key_flag,
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char *max_key, uint max_key_flag);
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@ -488,6 +489,7 @@ QUICK_RANGE_SELECT *get_quick_select(PARAM *param,uint index,
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MEM_ROOT *alloc = NULL);
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static TRP_RANGE *get_key_scans_params(PARAM *param, SEL_TREE *tree,
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bool index_read_must_be_used,
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bool update_tbl_stats,
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double read_time);
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static
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TRP_ROR_INTERSECT *get_best_ror_intersect(const PARAM *param, SEL_TREE *tree,
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@ -1854,16 +1856,43 @@ static int fill_used_fields_bitmap(PARAM *param)
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quick - Parameter to use when reading records.
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In the table struct the following information is updated:
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quick_keys - Which keys can be used
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quick_rows - How many rows the key matches
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quick_keys - Which keys can be used
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quick_rows - How many rows the key matches
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quick_condition_rows - E(# rows that will satisfy the table condition)
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IMPLEMENTATION
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quick_condition_rows value is obtained as follows:
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It is a minimum of E(#output rows) for all considered table access
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methods (range and index_merge accesses over various indexes).
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The obtained value is not a true E(#rows that satisfy table condition)
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but rather a pessimistic estimate. To obtain a true E(#...) one would
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need to combine estimates of various access methods, taking into account
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correlations between sets of rows they will return.
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For example, if values of tbl.key1 and tbl.key2 are independent (a right
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assumption if we have no infromation about their correlation) then the
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correct estimate will be:
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E(#rows("tbl.key1 < c1 AND tbl.key2 < c2")) =
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= E(#rows(tbl.key1 < c1)) / total_rows(tbl) * E(#rows(tbl.key2 < c2) /
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total_rows(tbl).
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which is smaller than MIN(rows(tbl.key1 < c1), rows(tbl.key2 < c2)).
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TODO
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Check if this function really needs to modify keys_to_use, and change the
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code to pass it by reference if it doesn't.
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* Change the value returned in quick_condition_rows from a pessimistic
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estimate to true E(#rows that satisfy table condition).
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(we can re-use some of E(#rows) calcuation code from index_merge/intersection
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for this)
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* Check if this function really needs to modify keys_to_use, and change the
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code to pass it by reference if it doesn't.
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In addition to force_quick_range other means can be (an usually are) used
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to make this function prefer range over full table scan. Figure out if
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force_quick_range is really needed.
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* In addition to force_quick_range other means can be (an usually are) used
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to make this function prefer range over full table scan. Figure out if
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force_quick_range is really needed.
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RETURN
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-1 if impossible select (i.e. certainly no rows will be selected)
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@ -2015,10 +2044,15 @@ int SQL_SELECT::test_quick_select(THD *thd, key_map keys_to_use,
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Notice that it can be constructed no matter if there is a range tree.
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*/
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group_trp= get_best_group_min_max(¶m, tree);
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if (group_trp && group_trp->read_cost < best_read_time)
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if (group_trp)
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{
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best_trp= group_trp;
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best_read_time= best_trp->read_cost;
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param.table->quick_condition_rows= min(group_trp->records,
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head->file->stats.records);
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if (group_trp->read_cost < best_read_time)
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{
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best_trp= group_trp;
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best_read_time= best_trp->read_cost;
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}
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}
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if (tree)
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@ -2034,7 +2068,7 @@ int SQL_SELECT::test_quick_select(THD *thd, key_map keys_to_use,
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bool can_build_covering= FALSE;
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/* Get best 'range' plan and prepare data for making other plans */
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if ((range_trp= get_key_scans_params(¶m, tree, FALSE,
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if ((range_trp= get_key_scans_params(¶m, tree, FALSE, TRUE,
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best_read_time)))
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{
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best_trp= range_trp;
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@ -2077,13 +2111,15 @@ int SQL_SELECT::test_quick_select(THD *thd, key_map keys_to_use,
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SEL_IMERGE *imerge;
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TABLE_READ_PLAN *best_conj_trp= NULL, *new_conj_trp;
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LINT_INIT(new_conj_trp); /* no empty index_merge lists possible */
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DBUG_PRINT("info",("No range reads possible,"
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" trying to construct index_merge"));
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List_iterator_fast<SEL_IMERGE> it(tree->merges);
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while ((imerge= it++))
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{
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new_conj_trp= get_best_disjunct_quick(¶m, imerge, best_read_time);
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if (new_conj_trp)
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set_if_smaller(param.table->quick_condition_rows,
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new_conj_trp->records);
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if (!best_conj_trp || (new_conj_trp && new_conj_trp->read_cost <
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best_conj_trp->read_cost))
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best_conj_trp= new_conj_trp;
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@ -3381,7 +3417,7 @@ TABLE_READ_PLAN *get_best_disjunct_quick(PARAM *param, SEL_IMERGE *imerge,
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{
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DBUG_EXECUTE("info", print_sel_tree(param, *ptree, &(*ptree)->keys_map,
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"tree in SEL_IMERGE"););
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if (!(*cur_child= get_key_scans_params(param, *ptree, TRUE, read_time)))
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if (!(*cur_child= get_key_scans_params(param, *ptree, TRUE, FALSE, read_time)))
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{
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/*
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One of index scans in this index_merge is more expensive than entire
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@ -4282,6 +4318,7 @@ TRP_ROR_INTERSECT *get_best_ror_intersect(const PARAM *param, SEL_TREE *tree,
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ha_rows best_rows = double2rows(intersect_best->out_rows);
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if (!best_rows)
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best_rows= 1;
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set_if_smaller(param->table->quick_condition_rows, best_rows);
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trp->records= best_rows;
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trp->index_scan_costs= intersect_best->index_scan_costs;
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trp->cpk_scan= cpk_scan_used? cpk_scan: NULL;
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@ -4432,6 +4469,8 @@ TRP_ROR_INTERSECT *get_best_covering_ror_intersect(PARAM *param,
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trp->read_cost= total_cost;
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trp->records= records;
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trp->cpk_scan= NULL;
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if (records < param->table->quick_condition_rows)
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param->table->quick_condition_rows= records;
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DBUG_PRINT("info",
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("Returning covering ROR-intersect plan: cost %g, records %lu",
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@ -4456,7 +4495,8 @@ TRP_ROR_INTERSECT *get_best_covering_ror_intersect(PARAM *param,
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*/
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static TRP_RANGE *get_key_scans_params(PARAM *param, SEL_TREE *tree,
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bool index_read_must_be_used,
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bool index_read_must_be_used,
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bool update_tbl_stats,
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double read_time)
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{
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int idx;
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@ -4491,7 +4531,7 @@ static TRP_RANGE *get_key_scans_params(PARAM *param, SEL_TREE *tree,
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bool read_index_only= index_read_must_be_used ? TRUE :
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(bool) param->table->used_keys.is_set(keynr);
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found_records= check_quick_select(param, idx, *key);
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found_records= check_quick_select(param, idx, *key, update_tbl_stats);
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if (param->is_ror_scan)
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{
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tree->n_ror_scans++;
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@ -6637,9 +6677,12 @@ void SEL_ARG::test_use_count(SEL_ARG *root)
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SYNOPSIS
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check_quick_select
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param Parameter from test_quick_select
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idx Number of index to use in PARAM::key SEL_TREE::key
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tree Transformed selection condition, tree->key[idx] holds intervals
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tree to be used for scanning.
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idx Number of index to use in tree->keys
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tree Transformed selection condition, tree->keys[idx]
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holds the range tree to be used for scanning.
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update_tbl_stats If true, update table->quick_keys with information
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about range scan we've evaluated.
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NOTES
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param->is_ror_scan is set to reflect if the key scan is a ROR (see
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is_key_scan_ror function for more info)
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@ -6653,7 +6696,7 @@ void SEL_ARG::test_use_count(SEL_ARG *root)
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*/
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static ha_rows
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check_quick_select(PARAM *param,uint idx,SEL_ARG *tree)
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check_quick_select(PARAM *param,uint idx,SEL_ARG *tree, bool update_tbl_stats)
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{
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ha_rows records;
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bool cpk_scan;
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@ -6694,10 +6737,19 @@ check_quick_select(PARAM *param,uint idx,SEL_ARG *tree)
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records=check_quick_keys(param,idx,tree,param->min_key,0,param->max_key,0);
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if (records != HA_POS_ERROR)
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{
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param->table->quick_keys.set_bit(key);
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if (update_tbl_stats)
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{
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param->table->quick_keys.set_bit(key);
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param->table->quick_key_parts[key]=param->max_key_part+1;
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param->table->quick_n_ranges[key]= param->n_ranges;
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param->table->quick_condition_rows=
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min(param->table->quick_condition_rows, records);
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}
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/*
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Need to save quick_rows in any case as it is used when calculating
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cost of ROR intersection:
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*/
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param->table->quick_rows[key]=records;
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param->table->quick_key_parts[key]=param->max_key_part+1;
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param->table->quick_n_ranges[key]= param->n_ranges;
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if (cpk_scan)
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param->is_ror_scan= TRUE;
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}
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@ -8847,7 +8899,7 @@ get_best_group_min_max(PARAM *param, SEL_TREE *tree)
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&cur_param_idx);
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/* Check if this range tree can be used for prefix retrieval. */
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cur_quick_prefix_records= check_quick_select(param, cur_param_idx,
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cur_index_tree);
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cur_index_tree, TRUE);
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}
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cost_group_min_max(table, cur_index_info, used_key_parts,
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cur_group_key_parts, tree, cur_index_tree,
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