revision-id: 9f8c928a939e5b92aaf5e64aab468f01d656af68 (mariadb-10.5.4-837-g9f8c928a939) parent(s): 4ba4c06038165726dad6a18d85c2b54446ea5ef8 author: Sergei Petrunia committer: Sergei Petrunia timestamp: 2021-08-08 19:41:35 +0300 message: MDEV-26301: LATERAL DERIVED refills the temp. table too many times --- mysql-test/main/derived_split_innodb.result | 220 ++++++++++++++++++++++++++++ mysql-test/main/derived_split_innodb.test | 153 +++++++++++++++++++ mysql-test/main/mysqld--help.result | 3 +- mysql-test/main/opt_trace.result | 2 +- sql/opt_split.cc | 192 +++++++++++++++++++++++- sql/sql_derived.cc | 9 ++ sql/sql_lex.cc | 1 + sql/sql_lex.h | 3 + sql/sql_priv.h | 1 + sql/sql_select.cc | 5 +- sql/sql_select.h | 28 +++- sql/sql_union.cc | 1 + sql/sys_vars.cc | 1 + 13 files changed, 609 insertions(+), 10 deletions(-) diff --git a/mysql-test/main/derived_split_innodb.result b/mysql-test/main/derived_split_innodb.result index 9edf9a1f2ae..d37339b8393 100644 --- a/mysql-test/main/derived_split_innodb.result +++ b/mysql-test/main/derived_split_innodb.result @@ -241,3 +241,223 @@ set optimizer_switch='split_materialized=default'; set use_stat_tables=default; set optimizer_use_condition_selectivity=default; # End of 10.3 tests +# +# MDEV-26301: LATERAL DERIVED refills the temp. table too many times +# +create table t1(a int, b int); +insert into t1 select seq,seq from seq_1_to_5; +create table t2(a int, b int, key(a)); +insert into t2 +select A.seq,B.seq from seq_1_to_25 A, seq_1_to_2 B; +create table t3(a int, b int, key(a)); +insert into t3 +select A.seq,B.seq from seq_1_to_5 A, seq_1_to_3 B; +analyze table t1,t2,t3 persistent for all; +Table Op Msg_type Msg_text +test.t1 analyze status Engine-independent statistics collected +test.t1 analyze status OK +test.t2 analyze status Engine-independent statistics collected +test.t2 analyze status Table is already up to date +test.t3 analyze status Engine-independent statistics collected +test.t3 analyze status Table is already up to date +explain +select * from +(t1 left join t2 on t2.a=t1.b) left join t3 on t3.a=t1.b; +id select_type table type possible_keys key key_len ref rows Extra +1 SIMPLE t1 ALL NULL NULL NULL NULL 5 +1 SIMPLE t2 ref a a 5 test.t1.b 2 Using where +1 SIMPLE t3 ref a a 5 test.t1.b 3 Using where +create table t10 ( +grp_id int, +col1 int, +key(grp_id) +); +insert into t10 +select +A.seq, +B.seq +from +seq_1_to_100 A, +seq_1_to_100 B; +create table t11 ( +col1 int, +col2 int +); +insert into t11 +select A.seq, A.seq from seq_1_to_10 A; +analyze table t10,t11 persistent for all; +Table Op Msg_type Msg_text +test.t10 analyze status Engine-independent statistics collected +test.t10 analyze status Table is already up to date +test.t11 analyze status Engine-independent statistics collected +test.t11 analyze status OK +set optimizer_trace=1; +explain +select * from +( +(t1 left join t2 on t2.a=t1.b) +left join t3 on t3.a=t1.b +) left join (select grp_id, count(*) +from t10 left join t11 on t11.col1=t10.col1 +group by grp_id) T on T.grp_id=t1.b; +id select_type table type possible_keys key key_len ref rows Extra +1 PRIMARY t1 ALL NULL NULL NULL NULL 5 +1 PRIMARY t2 ref a a 5 test.t1.b 2 Using where +1 PRIMARY t3 ref a a 5 test.t1.b 3 Using where +1 PRIMARY <derived2> ref key0 key0 5 test.t1.b 10 Using where +2 LATERAL DERIVED t10 ref grp_id grp_id 5 test.t1.b 100 +2 LATERAL DERIVED t11 ALL NULL NULL NULL NULL 10 Using where; Using join buffer (flat, BNL join) +select +json_detailed(json_extract(trace, '$**.split_plan_choice')) +from +information_schema.optimizer_trace; +json_detailed(json_extract(trace, '$**.split_plan_choice')) +[ + + { + "unsplit_cost": 253440.0075, + "split_cost": 2535.968504, + "record_count_for_split": 30, + "split_chosen": true + } +] +set @tmp_26301=@@optimizer_switch; +set optimizer_switch='split_materialized_is_lazy=on'; +explain +select * from +( +(t1 left join t2 on t2.a=t1.b) +left join t3 on t3.a=t1.b +) left join (select grp_id, count(*) +from t10 left join t11 on t11.col1=t10.col1 +group by grp_id) T on T.grp_id=t1.b; +id select_type table type possible_keys key key_len ref rows Extra +1 PRIMARY t1 ALL NULL NULL NULL NULL 5 +1 PRIMARY t2 ref a a 5 test.t1.b 2 Using where +1 PRIMARY t3 ref a a 5 test.t1.b 3 Using where +1 PRIMARY <derived2> ref key0 key0 5 test.t1.b 10 Using where +2 LATERAL DERIVED t10 ref grp_id grp_id 5 test.t1.b 100 +2 LATERAL DERIVED t11 ALL NULL NULL NULL NULL 10 Using where; Using join buffer (flat, BNL join) +select +json_detailed(json_extract(trace, '$**.split_plan_choice')) +from +information_schema.optimizer_trace; +json_detailed(json_extract(trace, '$**.split_plan_choice')) +[ + + { + "unsplit_cost": 253440.0075, + "split_cost": 2535.968504, + "record_count_for_split": 30, + "join_prefix_fanout_for_split": 5, + "split_chosen": true + } +] +create table t21 (pk int primary key); +insert into t21 values (1),(2),(3); +create table t22 (pk int primary key); +insert into t22 values (1),(2),(3); +explain +select * from +t21, t22, +( +(t1 left join t2 on t2.a=t1.b) +left join t3 on t3.a=t1.b +) left join (select grp_id, count(*) +from t10 left join t11 on t11.col1=t10.col1 +group by grp_id) T on T.grp_id=t1.b +where +t21.pk=1 and t22.pk=2; +id select_type table type possible_keys key key_len ref rows Extra +1 PRIMARY t21 const PRIMARY PRIMARY 4 const 1 Using index +1 PRIMARY t22 const PRIMARY PRIMARY 4 const 1 Using index +1 PRIMARY t1 ALL NULL NULL NULL NULL 5 +1 PRIMARY t2 ref a a 5 test.t1.b 2 Using where +1 PRIMARY t3 ref a a 5 test.t1.b 3 Using where +1 PRIMARY <derived2> ref key0 key0 5 test.t1.b 10 Using where +2 LATERAL DERIVED t10 ref grp_id grp_id 5 test.t1.b 100 +2 LATERAL DERIVED t11 ALL NULL NULL NULL NULL 10 Using where; Using join buffer (flat, BNL join) +select +json_detailed(json_extract(trace, '$**.split_plan_choice')) +from +information_schema.optimizer_trace; +json_detailed(json_extract(trace, '$**.split_plan_choice')) +[ + + { + "unsplit_cost": 253440.0075, + "split_cost": 2535.968504, + "record_count_for_split": 30, + "join_prefix_fanout_for_split": 5, + "split_chosen": true + } +] +explain +select * from +t21, +( +(t1 left join t2 on t2.a=t1.b) +left join t3 on t3.a=t1.b +) left join (select grp_id, count(*) +from +t22 join t10 left join t11 on t11.col1=t10.col1 +where +t22.pk=1 +group by grp_id) T on T.grp_id=t1.b +where +t21.pk=1; +id select_type table type possible_keys key key_len ref rows Extra +1 PRIMARY t21 const PRIMARY PRIMARY 4 const 1 Using index +1 PRIMARY t1 ALL NULL NULL NULL NULL 5 +1 PRIMARY t2 ref a a 5 test.t1.b 2 Using where +1 PRIMARY t3 ref a a 5 test.t1.b 3 Using where +1 PRIMARY <derived2> ref key0 key0 5 test.t1.b 10 Using where +2 LATERAL DERIVED t22 const PRIMARY PRIMARY 4 const 1 Using index +2 LATERAL DERIVED t10 ref grp_id grp_id 5 test.t1.b 100 +2 LATERAL DERIVED t11 ALL NULL NULL NULL NULL 10 Using where; Using join buffer (flat, BNL join) +select +json_detailed(json_extract(trace, '$**.split_plan_choice')) +from +information_schema.optimizer_trace; +json_detailed(json_extract(trace, '$**.split_plan_choice')) +[ + + { + "unsplit_cost": 253440.0075, + "split_cost": 2535.968504, + "record_count_for_split": 30, + "join_prefix_fanout_for_split": 5, + "split_chosen": true + } +] +create table t5 ( +pk int primary key +); +insert into t5 select seq from seq_1_to_1000; +explain +select * from +t21, +( +(((t1 join t5 on t5.pk=t1.b)) left join t2 on t2.a=t1.b) +left join t3 on t3.a=t1.b +) left join (select grp_id, count(*) +from +t22 join t10 left join t11 on t11.col1=t10.col1 +where +t22.pk=1 +group by grp_id) T on T.grp_id=t1.b +where +t21.pk=1; +id select_type table type possible_keys key key_len ref rows Extra +1 PRIMARY t21 const PRIMARY PRIMARY 4 const 1 Using index +1 PRIMARY t1 ALL NULL NULL NULL NULL 5 Using where +1 PRIMARY t5 eq_ref PRIMARY PRIMARY 4 test.t1.b 1 Using index +1 PRIMARY t2 ref a a 5 test.t1.b 2 +1 PRIMARY t3 ref a a 5 test.t1.b 3 +1 PRIMARY <derived2> ref key0 key0 5 test.t1.b 10 Using where +2 LATERAL DERIVED t22 const PRIMARY PRIMARY 4 const 1 Using index +2 LATERAL DERIVED t10 ref grp_id grp_id 5 test.t5.pk 100 +2 LATERAL DERIVED t11 ALL NULL NULL NULL NULL 10 Using where; Using join buffer (flat, BNL join) +set optimizer_trace=0; +set optimizer_switch=@tmp_26301; +drop table t1,t2,t3,t5, t10, t11, t21, t22; diff --git a/mysql-test/main/derived_split_innodb.test b/mysql-test/main/derived_split_innodb.test index bee9ef497b6..1369018f532 100644 --- a/mysql-test/main/derived_split_innodb.test +++ b/mysql-test/main/derived_split_innodb.test @@ -193,3 +193,156 @@ set use_stat_tables=default; set optimizer_use_condition_selectivity=default; --echo # End of 10.3 tests + +--echo # +--echo # MDEV-26301: LATERAL DERIVED refills the temp. table too many times +--echo # + +# 5 values +create table t1(a int, b int); +insert into t1 select seq,seq from seq_1_to_5; + +# 5 value groups of size 2 each +create table t2(a int, b int, key(a)); +insert into t2 +select A.seq,B.seq from seq_1_to_25 A, seq_1_to_2 B; + +# 5 value groups of size 3 each +create table t3(a int, b int, key(a)); +insert into t3 +select A.seq,B.seq from seq_1_to_5 A, seq_1_to_3 B; + +analyze table t1,t2,t3 persistent for all; + +explain +select * from + (t1 left join t2 on t2.a=t1.b) left join t3 on t3.a=t1.b; + +# Now, create tables for Groups. + +create table t10 ( + grp_id int, + col1 int, + key(grp_id) +); + +# 100 groups of 100 values each +insert into t10 +select + A.seq, + B.seq +from + seq_1_to_100 A, + seq_1_to_100 B; + +# and X10 multiplier + +create table t11 ( + col1 int, + col2 int +); +insert into t11 +select A.seq, A.seq from seq_1_to_10 A; + + +analyze table t10,t11 persistent for all; +set optimizer_trace=1; + +explain +select * from + ( + (t1 left join t2 on t2.a=t1.b) + left join t3 on t3.a=t1.b + ) left join (select grp_id, count(*) + from t10 left join t11 on t11.col1=t10.col1 + group by grp_id) T on T.grp_id=t1.b; +select + json_detailed(json_extract(trace, '$**.split_plan_choice')) +from + information_schema.optimizer_trace; + +set @tmp_26301=@@optimizer_switch; +set optimizer_switch='split_materialized_is_lazy=on'; + +explain +select * from + ( + (t1 left join t2 on t2.a=t1.b) + left join t3 on t3.a=t1.b + ) left join (select grp_id, count(*) + from t10 left join t11 on t11.col1=t10.col1 + group by grp_id) T on T.grp_id=t1.b; +select + json_detailed(json_extract(trace, '$**.split_plan_choice')) +from + information_schema.optimizer_trace; + +create table t21 (pk int primary key); +insert into t21 values (1),(2),(3); + +create table t22 (pk int primary key); +insert into t22 values (1),(2),(3); + +# Same as above but throw in a couple of const tables. +explain +select * from + t21, t22, + ( + (t1 left join t2 on t2.a=t1.b) + left join t3 on t3.a=t1.b + ) left join (select grp_id, count(*) + from t10 left join t11 on t11.col1=t10.col1 + group by grp_id) T on T.grp_id=t1.b +where + t21.pk=1 and t22.pk=2; + +select + json_detailed(json_extract(trace, '$**.split_plan_choice')) +from + information_schema.optimizer_trace; + +explain +select * from + t21, + ( + (t1 left join t2 on t2.a=t1.b) + left join t3 on t3.a=t1.b + ) left join (select grp_id, count(*) + from + t22 join t10 left join t11 on t11.col1=t10.col1 + where + t22.pk=1 + group by grp_id) T on T.grp_id=t1.b +where + t21.pk=1; + +select + json_detailed(json_extract(trace, '$**.split_plan_choice')) +from + information_schema.optimizer_trace; + +# And also add a non-const table + +create table t5 ( + pk int primary key + ); +insert into t5 select seq from seq_1_to_1000; + +explain +select * from + t21, + ( + (((t1 join t5 on t5.pk=t1.b)) left join t2 on t2.a=t1.b) + left join t3 on t3.a=t1.b + ) left join (select grp_id, count(*) + from + t22 join t10 left join t11 on t11.col1=t10.col1 + where + t22.pk=1 + group by grp_id) T on T.grp_id=t1.b +where + t21.pk=1; + +set optimizer_trace=0; +set optimizer_switch=@tmp_26301; +drop table t1,t2,t3,t5, t10, t11, t21, t22; diff --git a/mysql-test/main/mysqld--help.result b/mysql-test/main/mysqld--help.result index 78616ae7c9d..6a38d720493 100644 --- a/mysql-test/main/mysqld--help.result +++ b/mysql-test/main/mysqld--help.result @@ -718,7 +718,8 @@ The following specify which files/extra groups are read (specified before remain extended_keys, exists_to_in, orderby_uses_equalities, condition_pushdown_for_derived, split_materialized, condition_pushdown_for_subquery, rowid_filter, - condition_pushdown_from_having, not_null_range_scan + condition_pushdown_from_having, not_null_range_scan, + split_materialized_is_lazy --optimizer-trace=name Controls tracing of the Optimizer: optimizer_trace=option=val[,option=val...], where option diff --git a/mysql-test/main/opt_trace.result b/mysql-test/main/opt_trace.result index d4ba8eccb91..97d3b48ee85 100644 --- a/mysql-test/main/opt_trace.result +++ b/mysql-test/main/opt_trace.result @@ -8954,9 +8954,9 @@ json_detailed(json_extract(trace, '$**.lateral_derived_choice')) ], "split_plan_choice": { + "unsplit_cost": 25.72361682, "split_cost": 2.488945919, "record_count_for_split": 4, - "unsplit_cost": 25.72361682, "split_chosen": true }, "chosen_lateral_derived": diff --git a/sql/opt_split.cc b/sql/opt_split.cc index d482c2de2a4..7157caa248e 100644 --- a/sql/opt_split.cc +++ b/sql/opt_split.cc @@ -876,11 +876,92 @@ void reset_validity_vars_for_keyuses(KEYUSE_EXT *key_keyuse_ext_start, } + +/* + @brief + Find shortest join order sub-prefix that covers the specified table_map. + + @detail + Given a join prefix and a bitmap of table(s) in table_map, find the + shortest prefix of the prefix that covers the tables in the table_map. +*/ + +uint get_prefix_size(const POSITION *positions, uint max_pos, table_map map) +{ + map= map & ~PSEUDO_TABLE_BITS; // remove OUTER_REF_TABLE_BIT + table_map covered= 0; + uint i; + + for (i=0; i < max_pos; i++) + { + covered |= positions[i].table->table->map; + if (!(map & ~covered)) + break; + } + return i; +} + + +/* + @brief + Find the shortest join prefix that has a KEYUSE_EXT for a given key_part. + + @detail + Given an array of KEYUSE objects for access to {table, key, key_part}, + and a join order prefix (specified by array of POSITION structs), + find the shortest prefix for which there is a KEYUSE_EXT object describin + the access to they table.key.key_part + + @note + KEYUSE_EXT objects are from inside the derived table, while the join + prefix is from the parent JOIN, so we need to use + KEYUSE_EXT::needed_in_prefix +*/ + +uint get_min_prefix_for_key_part(const POSITION *positions, uint max_prefix_size, + KEYUSE_EXT *keyuse) +{ + TABLE *table= keyuse->table; + uint key= keyuse->key; + uint keypart= keyuse->keypart; + uint prefix_size= max_prefix_size; + + while (keyuse->table == table && keyuse->key == key && + keyuse->keypart == keypart) + { + uint cur_size= get_prefix_size(positions, max_prefix_size, + keyuse->needed_in_prefix); + if (cur_size < prefix_size) + prefix_size= cur_size; + keyuse++; + } + return prefix_size; +} + + +/* + Get fanout of of a join prefix +*/ +double get_join_prefix_fanout(const POSITION *positions, uint prefix_size) +{ + double fanout = 1.0; + for (uint i=0; i <= prefix_size; i++) + { + if (positions[i].records_read > 1e-30) + fanout *= positions[i].records_read; + if (positions[i].cond_selectivity > 1e-30) + fanout *= positions[i].cond_selectivity; + } + return fanout; +} + /** @brief Choose the best splitting to extend the evaluated partial join @param + join_prefix Join order prefix built so far + prefix_size Length of the join prefix record_count estimated cardinality of the extended partial join remaining_tables tables not joined yet @@ -906,7 +987,9 @@ void reset_validity_vars_for_keyuses(KEYUSE_EXT *key_keyuse_ext_start, if the plan has been chosen, NULL - otherwise. */ -SplM_plan_info * JOIN_TAB::choose_best_splitting(double record_count, +SplM_plan_info * JOIN_TAB::choose_best_splitting(const POSITION *join_prefix, + uint prefix_size, + double record_count, table_map remaining_tables) { SplM_opt_info *spl_opt_info= table->spl_opt_info; @@ -922,6 +1005,7 @@ SplM_plan_info * JOIN_TAB::choose_best_splitting(double record_count, SplM_plan_info *spl_plan= 0; uint best_key= 0; uint best_key_parts= 0; + uint best_min_prefix_size; Json_writer_object spl_trace(thd, "lateral_derived_choice"); Json_writer_array trace_indexes(thd, "indexes_for_splitting"); @@ -942,6 +1026,7 @@ SplM_plan_info * JOIN_TAB::choose_best_splitting(double record_count, uint key= keyuse_ext->key; KEYUSE_EXT *key_keyuse_ext_start= keyuse_ext; key_part_map found_parts= 0; + uint prefix_len= 0; do { if (keyuse_ext->needed_in_prefix & remaining_tables) @@ -951,11 +1036,40 @@ SplM_plan_info * JOIN_TAB::choose_best_splitting(double record_count, } if (!(keyuse_ext->keypart_map & found_parts)) { + /* + Check for + 1. found_parts is empty and this is the first key part we've found + 2. or, we are looking at the first keyuse object for this keypart, + and found_parts has a bit set for the previous key part. + */ if ((!found_parts && !keyuse_ext->keypart) || (found_parts && ((keyuse_ext->keypart_map >> 1) & found_parts))) + { + if (optimizer_flag(thd, OPTIMIZER_SWITCH_SPLIT_MATERIALIZED_IS_LAZY)) + { + /* + Find the shortest join prefix we'll need to get a lookup value + for this keypart read this key part + */ + uint min_for_kp= get_min_prefix_for_key_part(join_prefix, + prefix_size, + keyuse_ext); + /* + The join prefix needed to read all keyparts is the longest + prefix of all key parts. + */ + if (min_for_kp > prefix_len) + prefix_len= min_for_kp; + } + found_parts|= keyuse_ext->keypart_map; + } else { + /* + This is a new key part but it doesn't form a continuous index + prefix. Skip all KEYUSEs for this index. + */ do { keyuse_ext++; @@ -981,6 +1095,11 @@ SplM_plan_info * JOIN_TAB::choose_best_splitting(double record_count, best_key_parts= keyuse_ext->keypart + 1; best_rec_per_key= rec_per_key; best_key_keyuse_ext_start= key_keyuse_ext_start; + if (optimizer_flag(thd, OPTIMIZER_SWITCH_SPLIT_MATERIALIZED_IS_LAZY)) + { + best_min_prefix_size= prefix_len; + trace.add("min_prefix_len", (longlong)prefix_len); + } } keyuse_ext++; } @@ -1069,10 +1188,29 @@ SplM_plan_info * JOIN_TAB::choose_best_splitting(double record_count, if (spl_plan) { Json_writer_object choice(thd, "split_plan_choice"); + choice.add("unsplit_cost", spl_opt_info->unsplit_cost); + choice.add("split_cost", spl_plan->cost); choice.add("record_count_for_split", record_count); - choice.add("unsplit_cost", spl_opt_info->unsplit_cost); - if(record_count * spl_plan->cost < spl_opt_info->unsplit_cost - 0.01) + + double fanout= record_count; + if (optimizer_flag(thd, OPTIMIZER_SWITCH_SPLIT_MATERIALIZED_IS_LAZY)) + { + /* + The LATERAL DERIVED table will only be refilled if the values it + refers to change. + The values refer only to the prefix of the join prefix so far. + Adjust the number of LATERAL DERIVED refills accordingly. + */ + double prefix_fanout= get_join_prefix_fanout(join_prefix, + best_min_prefix_size); + if (prefix_fanout < fanout) + fanout= prefix_fanout; + + choice.add("join_prefix_fanout_for_split", fanout); + } + + if (fanout * spl_plan->cost < spl_opt_info->unsplit_cost - 0.01) { /* The best plan that employs splitting is cheaper than @@ -1112,6 +1250,10 @@ SplM_plan_info * JOIN_TAB::choose_best_splitting(double record_count, @param remaining_tables used to filter out the equalities that cannot be pushed. + lparams if non-NULL, call lparams->add() to collect a list + of the "parameter" items for the lateral subquery. + The list will be used to reduce the number of times + the lateral derived table is refilled. @details This function is called by JOIN_TAB::fix_splitting that is used @@ -1128,18 +1270,23 @@ SplM_plan_info * JOIN_TAB::choose_best_splitting(double record_count, true on failure */ -bool JOIN::inject_best_splitting_cond(table_map remaining_tables) +bool JOIN::inject_best_splitting_cond(table_map remaining_tables, + Lateral_derived_parameters *lparams) { Item *inj_cond= 0; List<Item> *inj_cond_list= &spl_opt_info->inj_cond_list; List_iterator<KEY_FIELD> li(spl_opt_info->added_key_fields); KEY_FIELD *added_key_field; + table_map needed_tables= 0; while ((added_key_field= li++)) { if (remaining_tables & added_key_field->val->used_tables()) continue; + if (lparams && lparams->add_param(added_key_field->val)) + return true; if (inj_cond_list->push_back(added_key_field->cond, thd->mem_root)) return true; + needed_tables |= added_key_field->val->used_tables(); } DBUG_ASSERT(inj_cond_list->elements); switch (inj_cond_list->elements) { @@ -1230,8 +1377,15 @@ bool JOIN_TAB::fix_splitting(SplM_plan_info *spl_plan, memcpy((char *) md_join->best_positions, (char *) spl_plan->best_positions, sizeof(POSITION) * md_join->table_count); - if (md_join->inject_best_splitting_cond(remaining_tables)) + + Lateral_derived_parameters *lparams= NULL; + if (optimizer_flag(join->thd, OPTIMIZER_SWITCH_SPLIT_MATERIALIZED_IS_LAZY)) + lparams= new Lateral_derived_parameters; + + if (md_join->inject_best_splitting_cond(remaining_tables, lparams)) return true; + + table->pos_in_table_list->get_unit()->lateral_derived_params= lparams; /* This is called for a proper work of JOIN::get_best_combination() called for the join that materializes T @@ -1283,3 +1437,31 @@ bool JOIN::fix_all_splittings_in_plan() } return false; } + + +bool Lateral_derived_parameters::add_param(Item *item) +{ + Cached_item *tmp; + if (!(tmp= new_Cached_item(current_thd, item, FALSE)) || + list.push_back(tmp)) + return true; + + return false; +} + + +/* + @brief + Test if LATERAL DERIVED table's parameters changed since last invocation + + @return + false Parameter values have not changed since last invocation + true Parameter values have changed since last invocation. Current values + of the parameters are now saved. +*/ +bool Lateral_derived_parameters::need_refill() +{ + if (test_if_group_changed(list) == -1) + return false; // not changed + return true; +} diff --git a/sql/sql_derived.cc b/sql/sql_derived.cc index f8ee3475af8..25524c90da5 100644 --- a/sql/sql_derived.cc +++ b/sql/sql_derived.cc @@ -1233,6 +1233,15 @@ bool mysql_derived_fill(THD *thd, LEX *lex, TABLE_LIST *derived) DBUG_RETURN(res); } + /* + For LATERAL DERIVED tables, check if we actually need to refill it. If its + "parameters" (i.e. items it refers to) have the same values, we don't need + to refill. + */ + if (unit->lateral_derived_params && + !unit->lateral_derived_params->need_refill()) + DBUG_RETURN(false); + if (unit->executed && !derived_is_recursive && (unit->uncacheable & UNCACHEABLE_DEPENDENT)) { diff --git a/sql/sql_lex.cc b/sql/sql_lex.cc index b9ca67182cf..5b3897b28fa 100644 --- a/sql/sql_lex.cc +++ b/sql/sql_lex.cc @@ -2915,6 +2915,7 @@ void st_select_lex_unit::init_query() columns_are_renamed= false; with_wrapped_tvc= false; have_except_all_or_intersect_all= false; + lateral_derived_params= NULL; } void st_select_lex::init_query() diff --git a/sql/sql_lex.h b/sql/sql_lex.h index 45a3bf72fa4..278ee7d5276 100644 --- a/sql/sql_lex.h +++ b/sql/sql_lex.h @@ -845,6 +845,7 @@ class JOIN; class select_unit; class Procedure; class Explain_query; +class Lateral_derived_parameters; void delete_explain_query(LEX *lex); void create_explain_query(LEX *lex, MEM_ROOT *mem_root); @@ -964,6 +965,8 @@ class st_select_lex_unit: public st_select_lex_node { bool columns_are_renamed; + Lateral_derived_parameters *lateral_derived_params; + void init_query(); st_select_lex* outer_select(); const st_select_lex* first_select() const diff --git a/sql/sql_priv.h b/sql/sql_priv.h index 07f07a7150f..7cdb6a62d08 100644 --- a/sql/sql_priv.h +++ b/sql/sql_priv.h @@ -234,6 +234,7 @@ #define OPTIMIZER_SWITCH_USE_ROWID_FILTER (1ULL << 33) #define OPTIMIZER_SWITCH_COND_PUSHDOWN_FROM_HAVING (1ULL << 34) #define OPTIMIZER_SWITCH_NOT_NULL_RANGE_SCAN (1ULL << 35) +#define OPTIMIZER_SWITCH_SPLIT_MATERIALIZED_IS_LAZY (1ULL << 36) #define OPTIMIZER_SWITCH_DEFAULT (OPTIMIZER_SWITCH_INDEX_MERGE | \ OPTIMIZER_SWITCH_INDEX_MERGE_UNION | \ diff --git a/sql/sql_select.cc b/sql/sql_select.cc index 39e224ab024..85c3355cf08 100644 --- a/sql/sql_select.cc +++ b/sql/sql_select.cc @@ -7460,7 +7460,10 @@ best_access_path(JOIN *join, loose_scan_opt.init(join, s, remaining_tables); if (s->table->is_splittable()) - spl_plan= s->choose_best_splitting(record_count, remaining_tables); + { + spl_plan= s->choose_best_splitting(join_positions, idx, record_count, + remaining_tables); + } Json_writer_array trace_paths(thd, "considered_access_paths"); if (s->keyuse) diff --git a/sql/sql_select.h b/sql/sql_select.h index 29e42ff8ef8..2a9cb5464e6 100644 --- a/sql/sql_select.h +++ b/sql/sql_select.h @@ -249,6 +249,7 @@ class AGGR_OP; class Filesort; struct SplM_plan_info; class SplM_opt_info; +class Lateral_derived_parameters; typedef struct st_join_table { TABLE *table; @@ -682,7 +683,9 @@ typedef struct st_join_table { void partial_cleanup(); void add_keyuses_for_splitting(); - SplM_plan_info *choose_best_splitting(double record_count, + SplM_plan_info *choose_best_splitting(const POSITION *join_prefix, + uint top_prefix_size, + double record_count, table_map remaining_tables); bool fix_splitting(SplM_plan_info *spl_plan, table_map remaining_tables, bool is_const_table); @@ -1795,7 +1798,8 @@ class JOIN :public Sql_alloc bool inject_cond_into_where(Item *injected_cond); bool check_for_splittable_materialized(); void add_keyuses_for_splitting(); - bool inject_best_splitting_cond(table_map remaining_tables); + bool inject_best_splitting_cond(table_map remaining_tables, + Lateral_derived_parameters *params); bool fix_all_splittings_in_plan(); void make_notnull_conds_for_range_scans(); @@ -2532,4 +2536,24 @@ void propagate_new_equalities(THD *thd, Item *cond, COND_EQUAL *inherited, bool *is_simplifiable_cond); +/* + A list of parameters for a derived table that uses LATERAL DERIVED + optimization. + + The last values of the parameters are saved, which one can use to check + whether + - they've changed and one needs to refill the LATERAL DERIVED table + - they are not changed and refill is not needed. +*/ +class Lateral_derived_parameters : public Sql_alloc +{ + List<Cached_item> list; +public: + // Construction interface + bool add_param(Item *item); + + // Execution interface + bool need_refill(); +}; + #endif /* SQL_SELECT_INCLUDED */ diff --git a/sql/sql_union.cc b/sql/sql_union.cc index b88d78c0db3..a0a89b1e401 100644 --- a/sql/sql_union.cc +++ b/sql/sql_union.cc @@ -2588,6 +2588,7 @@ bool st_select_lex_unit::cleanup() } columns_are_renamed= false; cleaned= 1; + lateral_derived_params= NULL; for (SELECT_LEX *sl= first_select(); sl; sl= sl->next_select()) error|= sl->cleanup(); diff --git a/sql/sys_vars.cc b/sql/sys_vars.cc index 2f7cf290dcd..725f407fc3b 100644 --- a/sql/sys_vars.cc +++ b/sql/sys_vars.cc @@ -2717,6 +2717,7 @@ export const char *optimizer_switch_names[]= "rowid_filter", "condition_pushdown_from_having", "not_null_range_scan", + "split_materialized_is_lazy", "default", NullS };