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265 lines
6.2 KiB
Text
265 lines
6.2 KiB
Text
--echo #
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--echo # MDEV-34720: Poor plan choice for large JOIN with ORDER BY and small LIMIT
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--echo #
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--source include/have_sequence.inc
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# We need optimizer trace
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--source include/not_embedded.inc
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create table t1 (
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a int,
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b int,
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c int,
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col1 int,
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col2 int,
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index(a),
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index(b),
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index(col1)
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);
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insert into t1 select
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mod(seq, 100),
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mod(seq, 95),
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seq,
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seq,
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seq
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from
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seq_1_to_10000;
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create table t10 (
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a int,
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a_value char(10),
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key(a)
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);
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insert into t10 select seq, seq from seq_1_to_100;
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create table t11 (
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b int,
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b_value char(10),
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key(b)
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);
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insert into t11 select seq, seq from seq_1_to_150;
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set @tmp_os=@@optimizer_trace;
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set optimizer_trace=1;
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--echo #
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--echo # Query 1 - basic example.
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--echo #
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let $query= explain
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select
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*
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from
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t1
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join t10 on t1.a=t10.a
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join t11 on t1.b=t11.b
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order by
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t1.col1
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limit 10;
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--echo # Table t1 is not the first, have to use temporary+filesort:
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eval $query;
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set optimizer_join_limit_pref_ratio=10;
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--echo # t1 is first, key=col1 produces ordering, no filesort or temporary:
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eval $query;
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set @trace=(select trace from information_schema.optimizer_trace);
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--source include/optimizer_trace_no_costs.inc
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select json_detailed(json_extract(@trace, '$**.join_limit_shortcut_choice')) as JS;
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--echo #
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--echo # Query 2 - same as above but without a suitable index.
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--echo #
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let $query=
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explain
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select
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*
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from
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t1
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join t10 on t1.a=t10.a
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join t11 on t1.b=t11.b
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order by
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t1.col2
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limit 10;
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--echo # Table t1 is not the first, have to use temporary+filesort:
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set optimizer_join_limit_pref_ratio=0;
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eval $query;
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--echo # t1 is first but there's no suitable index,
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--echo # so we use filesort but using temporary:
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set optimizer_join_limit_pref_ratio=10;
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eval $query;
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set @trace=(select trace from information_schema.optimizer_trace);
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--source include/optimizer_trace_no_costs.inc
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select json_detailed(json_extract(@trace, '$**.join_limit_shortcut_choice')) as JS;
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--echo #
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--echo # Query 3: Counter example with large limit
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--echo #
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let $query= explain
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select
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*
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from
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t1
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join t10 on t1.a=t10.a
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join t11 on t1.b=t11.b
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order by
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t1.col1
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limit 5000;
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--echo # Table t1 is not the first, have to use temporary+filesort:
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set optimizer_join_limit_pref_ratio=0;
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eval $query;
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--echo # Same plan as above:
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--echo # Table t1 is not the first, have to use temporary+filesort:
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set optimizer_join_limit_pref_ratio=10;
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eval $query;
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set @trace=(select trace from information_schema.optimizer_trace);
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--source include/optimizer_trace_no_costs.inc
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select json_detailed(json_extract(@trace, '$**.join_limit_shortcut_choice')) as JS;
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--echo #
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--echo # Query 4: LEFT JOIN makes it impossible to put ORDER-BY-table first,
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--echo # however the optimizer still puts it as sort_by_table.
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--echo #
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set optimizer_join_limit_pref_ratio=10;
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explain
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select
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*
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from
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t10 left join (t1 join t11 on t1.b=t11.b ) on t1.a=t10.a
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order by
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t1.col2
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limit 10;
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set @trace=(select trace from information_schema.optimizer_trace);
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--echo # This will show nothing as limit shortcut code figures that
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--echo # it's not possible to use t1 to construct shortcuts:
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--source include/optimizer_trace_no_costs.inc
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select json_detailed(json_extract(@trace, '$**.join_limit_shortcut_choice')) as JS;
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--echo #
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--echo # Query 5: Same as Q1 but also with a semi-join
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--echo #
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set optimizer_join_limit_pref_ratio=default;
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let $query= explain
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select
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*
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from
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t1
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join t10 on t1.a=t10.a
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join t11 on t1.b=t11.b
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where
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t1.a in (select a from t10) and
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t1.b in (select b from t11)
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order by
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t1.col1
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limit 10;
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--echo # Table t1 is not the first, have to use temporary+filesort:
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eval $query;
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set optimizer_join_limit_pref_ratio=10;
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--echo # t1 is first, key=col1 produces ordering, no filesort or temporary:
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eval $query;
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set @trace=(select trace from information_schema.optimizer_trace);
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--source include/optimizer_trace_no_costs.inc
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select json_detailed(json_extract(@trace, '$**.join_limit_shortcut_choice')) as JS;
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--echo #
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--echo # Query 6: same as Query 1 but let's limit the search depth
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--echo #
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set @tmp_osd=@@optimizer_search_depth;
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set optimizer_search_depth=1;
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let $query= explain
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select
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*
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from
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t1
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join t10 on t1.a=t10.a
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join t11 on t1.b=t11.b
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order by
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t1.col1
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limit 10;
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set optimizer_join_limit_pref_ratio=default;
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--echo # Table t1 is not the first, have to use temporary+filesort:
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eval $query;
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set optimizer_join_limit_pref_ratio=10;
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--echo # t1 is first, key=col1 produces ordering, no filesort or temporary:
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eval $query;
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set @trace=(select trace from information_schema.optimizer_trace);
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--source include/optimizer_trace_no_costs.inc
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select json_detailed(json_extract(@trace, '$**.join_limit_shortcut_choice')) as JS;
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set optimizer_search_depth=@tmp_osd;
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set optimizer_trace=@tmp_os;
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--echo # An extra testcase for MDEV-35164 (its main testcase is below).
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alter table t1 add unique key(col2);
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insert into t10 select * from t10;
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insert into t10 select * from t10;
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analyze table t10;
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--echo # This will not crash and also show that sorting is not done when
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--echo # ORDER BY only refers to const table columns:
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explain
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select
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*
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from
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t1
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join t10 on t1.a=t10.a
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join t11 on t1.b=t11.b
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where
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t1.col2=3
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order by
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t1.col1
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limit 10;
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drop table t1, t10, t11;
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set optimizer_join_limit_pref_ratio=default;
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--echo #
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--echo # MDEV-35072: Assertion failure with optimizer_join_limit_pref_ratio and 1-table select
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--echo #
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SET optimizer_join_limit_pref_ratio=1;
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CREATE TABLE t1 (c1 INT, INDEX(c1));
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INSERT INTO t1 VALUES (1),(2);
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SELECT * FROM t1 ORDER BY c1 LIMIT 1;
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DROP TABLE t1;
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--echo #
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--echo # MDEV-35164: optimizer_join_limit_pref_ratio: assertion when the ORDER BY table becomes constant
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--echo # Original testcase:
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--echo #
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SET optimizer_join_limit_pref_ratio=1;
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CREATE TABLE t1 (a INT KEY,b INT, KEY(b)) ;
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INSERT INTO t1 VALUES (2,NULL);
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INSERT INTO t1 VALUES (5,NULL);
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SELECT * FROM t1 NATURAL JOIN t1 AS t2 WHERE t1.b=NULL ORDER BY t1.a LIMIT 1;
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DROP TABLE t1;
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set optimizer_join_limit_pref_ratio=default;
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--echo #
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--echo # MDEV-35072: Assertion failure with optimizer_join_limit_pref_ratio and 1-table select
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--echo #
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SET optimizer_join_limit_pref_ratio=1;
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CREATE TABLE t1 (c1 INT, INDEX(c1));
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INSERT INTO t1 VALUES (1),(2);
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SELECT * FROM t1 ORDER BY c1 LIMIT 1;
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DROP TABLE t1;
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set optimizer_join_limit_pref_ratio=default;
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