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4329ec5d3b
Introduce @@optimizer_switch flag: hash_join_cardinality When it is on, use EITS statistics to produce tighter bounds for hash join output cardinality. Amended by Monty. Reviewed by: Monty <monty@mariadb.org>
41 lines
1.4 KiB
Text
41 lines
1.4 KiB
Text
--source include/have_sequence.inc
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# Embedded doesn't have optimizer trace:
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--source include/not_embedded.inc
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create table t1 (a int, b int, c int);
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insert into t1 select seq,seq/2, seq/4 from seq_1_to_100;
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create table t2 (a int, b int, c int);
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insert into t2 select seq, seq/2, seq/4 from seq_1_to_200;
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analyze table t1,t2 persistent for all;
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set optimizer_trace=1;
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set join_cache_level=6;
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set optimizer_switch='hash_join_cardinality=on';
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explain select *
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from t1, t2
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where t1.a=t2.a and t1.a=t2.b and t1.c=t2.c;
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set @json= (select trace from information_schema.optimizer_trace);
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select json_detailed(json_extract(@json, '$**.hash_join_cardinality')) as JS;
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select json_detailed(json_extract(@json, '$**.rest_of_plan[*].rows_for_plan'))
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as ROWS_FOR_PLAN;
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explain select *
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from t1, t2 where t1.c=t2.c;
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set @json= (select trace from information_schema.optimizer_trace);
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select json_detailed(json_extract(@json, '$**.hash_join_cardinality')) as JS;
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select json_detailed(json_extract(@json, '$**.rest_of_plan[*].rows_for_plan'))
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as ROWS_FOR_PLAN;
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explain select *
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from t1 straight_join t2 where t1.c=t2.c and t2.a<30;
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set @json= (select trace from information_schema.optimizer_trace);
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--echo # Note that rows is the same:
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select json_detailed(json_extract(@json, '$**.hash_join_cardinality')) as JS;
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--echo # Despite available selectivity:
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select json_detailed(json_extract(@json, '$**.selectivity_for_columns')) as JS;
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drop table t1,t2;
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