mariadb/mysql-test/main/show_explain_json.test
2024-05-21 19:38:51 +02:00

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#
# Tests for SHOW EXPLAIN FORMAT=JSON FOR functionality.
# FORMAT=JSON is essential here, tests for traditional SHOW EXPLAIN FOR
# can be found at show_explain.test
#
--source include/have_debug.inc
--source include/have_debug_sync.inc
--source include/have_innodb.inc
--source include/have_perfschema.inc
# Using valgrind can cause 'reap' to fail. See comment below
--source include/not_valgrind.inc
--disable_warnings
drop table if exists t0, t1, t2, t3, t4;
drop view if exists v1;
--enable_warnings
SET @old_debug= @@session.debug_dbug;
#
# Testcases in this file do not work with embedded server. The reason for this
# is that we use the following commands for synchronization:
#
# set @show_explain_probe_select_id=1;
# SET debug_dbug='d,show_explain_probe_join_exec_start';
# send select count(*) from t1 where a < 100000;
#
# When ran with mysqltest_embedded, this translates into:
#
# Thread1> DBUG_PUSH("d,show_explain_probe_join_exec_start");
# Thread1> create another thread for doing "send ... reap"
# Thread2> mysql_parse("select count(*) from t1 where a < 100000");
#
# That is, "select count(*) ..." is ran in a thread for which DBUG_PUSH(...)
# has not been called. As a result, show_explain_probe_join_exec_start does not fire, and
# "select count(*) ..." does not wait till its SHOW EXPLAIN command, and the
# test fails.
#
-- source include/not_embedded.inc
set debug_sync='RESET';
create table t0 (a int);
insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
create table t1 (a int);
insert into t1 select A.a + 10*B.a + 100*C.a from t0 A, t0 B, t0 C;
alter table t1 add b int, add c int, add filler char(32);
update t1 set b=a, c=a, filler='fooo';
alter table t1 add key(a), add key(b);
#
# Try to call SHOW EXPLAIN with a missing thread ID
#
--error ER_PARSE_ERROR
show explain format=JSON for;
#
# Also test MySQL-compatible syntax EXPLAIN FOR CONNECTION which was introduced for MDEV-10000
#
--error ER_PARSE_ERROR
explain format=JSON for connection;
#
# Try to call SHOW EXPLAIN/EXPLAIN FOR CONNECTION for a non-existent thread
#
--error ER_NO_SUCH_THREAD
show explain FORMAT=json for 123456789;
--error ER_NO_SUCH_THREAD
explain FORMAT=json for connection 123456789;
--error ER_SET_CONSTANTS_ONLY
show explain FORMAT=json for (select max(a) from t0);
--error ER_SET_CONSTANTS_ONLY
explain FORMAT=json for connection (select max(a) from t0);
#
# Setup two threads and their ids
#
let $thr1=`select connection_id()`;
connect (con1, localhost, root,,);
connection con1;
let $thr2=`select connection_id()`;
SET @old_debug= @@session.debug_dbug;
connection default;
# SHOW EXPLAIN FOR <idle thread>
--error ER_TARGET_NOT_EXPLAINABLE
evalp show explain format=JSON for $thr2;
--error ER_TARGET_NOT_EXPLAINABLE
evalp explain format=json for connection $thr2;
# SHOW EXPLAIN FOR <ourselves>
--error ER_TARGET_NOT_EXPLAINABLE
evalp show explain format=json for $thr1;
--error ER_TARGET_NOT_EXPLAINABLE
evalp explain FORMAT=JSON for connection $thr1;
# Not supported format of output
--error ER_UNKNOWN_EXPLAIN_FORMAT
evalp show explain FORMAT=HTML for $thr1;
--error ER_UNKNOWN_EXPLAIN_FORMAT
evalp explain FORMAT=XML for connection $thr1;
let $wait_condition= select State='show_explain_trap' from information_schema.processlist where id=$thr2;
#
# Test SHOW EXPLAIN/EXPLAIN FOR CONNECTION for simple queries
#
connection con1;
set @show_explain_probe_select_id=1;
SET debug_dbug='+d,show_explain_probe_join_exec_start';
send select count(*) from t1 where a < 100000;
connection default;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp show explain FORMAT=JSON for $thr2;
connection con1;
reap;
send select max(c) from t1 where a < 10;
connection default;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp explain FORMAT=JSON for connection $thr2;
connection con1;
reap;
send select max(c) from t1 where a < 10;
connection default;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp explain format=JSON for connection $thr2;
connection con1;
reap;
--echo # We can catch EXPLAIN, too.
set @show_expl_tmp= @@optimizer_switch;
set optimizer_switch='index_condition_pushdown=on,mrr=on,mrr_sort_keys=on';
send explain select max(c) from t1 where a < 10;
connection default;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp show explain format=json for $thr2;
connection con1;
reap;
--echo # Same for EXPLAIN FOR CONNECTION
send explain select max(c) from t1 where a < 10;
connection default;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp explain format=JSON for connection $thr2;
connection con1;
reap;
set optimizer_switch= @show_expl_tmp;
SET debug_dbug=@old_debug;
--echo # UNION, first branch
set @show_explain_probe_select_id=1;
SET debug_dbug='+d,show_explain_probe_join_exec_start';
send explain select a from t0 A union select a+1 from t0 B;
connection default;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp show explain format = JSON for $thr2;
connection con1;
reap;
SET debug_dbug=@old_debug;
--echo # UNION, second branch
set @show_explain_probe_select_id=2;
SET debug_dbug='+d,show_explain_probe_join_exec_start';
send explain select a from t0 A union select a+1 from t0 B;
connection default;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp show explain format=JSON for $thr2;
connection con1;
reap;
SET debug_dbug=@old_debug;
--echo # Uncorrelated subquery, select
set @show_explain_probe_select_id=1;
SET debug_dbug='+d,show_explain_probe_join_exec_start';
send select a, (select max(a) from t0 B) from t0 A where a<1;
connection default;
--source include/wait_condition.inc
evalp show explain for $thr2;
connection con1;
reap;
SET debug_dbug=@old_debug;
--echo # Uncorrelated subquery, explain
set @show_explain_probe_select_id=1;
SET debug_dbug='+d,show_explain_probe_join_exec_start';
send explain select a, (select max(a) from t0 B) from t0 A where a<1;
connection default;
--source include/wait_condition.inc
evalp show explain for $thr2;
connection con1;
reap;
SET debug_dbug=@old_debug;
--echo # correlated subquery, select
set @show_explain_probe_select_id=1;
SET debug_dbug='+d,show_explain_probe_join_exec_start';
send select a, (select max(a) from t0 b where b.a+a.a<10) from t0 a where a<1;
connection default;
--source include/wait_condition.inc
evalp show explain for $thr2;
connection con1;
reap;
SET debug_dbug=@old_debug;
--echo # correlated subquery, explain
set @show_explain_probe_select_id=1;
SET debug_dbug='+d,show_explain_probe_join_exec_start';
send explain select a, (select max(a) from t0 b where b.a+a.a<10) from t0 a where a<1;
connection default;
--source include/wait_condition.inc
evalp show explain for $thr2;
connection con1;
reap;
SET debug_dbug=@old_debug;
--echo # correlated subquery, select, while inside the subquery
set @show_explain_probe_select_id=2; # <---
SET debug_dbug='+d,show_explain_probe_join_exec_start';
send select a, (select max(a) from t0 b where b.a+a.a<10) from t0 a where a<1;
connection default;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp show explain format=JSON for $thr2;
connection con1;
reap;
SET debug_dbug=@old_debug;
--echo # correlated subquery, explain, while inside the subquery
set @show_explain_probe_select_id=2;
SET debug_dbug='+d,show_explain_probe_join_exec_start';
send select a, (select max(a) from t0 b where b.a+a.a<10) from t0 a where a<1;
connection default;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp show explain format=JSON for $thr2;
connection con1;
reap;
SET debug_dbug=@old_debug;
--echo # correlated subquery, explain, while inside the subquery
set @show_explain_probe_select_id=1;
SET debug_dbug='+d,show_explain_probe_join_exec_end';
send select a, (select max(a) from t0 b where b.a+a.a<10) from t0 a where a<1;
connection default;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp show explain format=JSON for $thr2;
connection con1;
reap;
SET debug_dbug=@old_debug;
# TODO: explain in the parent subuqery when the un-correlated child has been
# run (and have done irreversible cleanups)
# ^^ Is this at all possible after 5.3?
# Maybe, for 5.3 try this:
# - run before/after the parent has invoked child's optimization
# - run after materialization
--echo # Try to do SHOW EXPLAIN for a query that runs a SET command:
--echo # I've found experimentally that select_id==2 here...
--echo #
create table t2 (a int);
insert into t2 values (1),(2);
set @show_explain_probe_select_id=3; # Stop in the subquery.
SET debug_dbug='+d,show_explain_probe_join_exec_start';
# t2 has 2 rows so we will stop in the subquery twice:
# - first one to serve the SHOW ANALYZE request
# - second one when waiting to be KILLed.
send set @foo= (select max(a) from t2
where a + (select max(a) from t0 where t0.a>t2.a) < 10000);
connection default;
--source include/wait_condition.inc
--error ER_TARGET_NOT_EXPLAINABLE
evalp show explain format=JSON for $thr2;
evalp kill query $thr2;
connection con1;
--error ER_QUERY_INTERRUPTED
reap;
SET debug_dbug=@old_debug;
drop table t2;
--echo #
--echo # Attempt SHOW EXPLAIN for an UPDATE
--echo #
create table t2 as select a as a, a as dummy from t0 limit 2;
set @show_explain_probe_select_id=2;
SET debug_dbug='+d,show_explain_probe_join_exec_start';
send update t2 set dummy=0 where (select max(a) from t0 where t2.a + t0.a <3) >3 ;
connection default;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp show explain format=JSON for $thr2;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp show explain format=JSON for $thr2;
connection con1;
reap;
--echo #
--echo # EXPLAIN FOR CONNECTION for an UPDATE
--echo #
set @show_explain_probe_select_id=2;
SET debug_dbug='+d,show_explain_probe_join_exec_start';
send update t2 set dummy=0 where (select max(a) from t0 where t2.a + t0.a <3) >3 ;
connection default;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp explain format=JSON for connection $thr2;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp explain format=JSON for connection $thr2;
connection con1;
reap;
drop table t2;
SET debug_dbug=@old_debug;
--echo #
--echo # Attempt SHOW EXPLAIN for a DELETE
--echo #
create table t2 as select a as a, a as dummy from t0 limit 2;
set @show_explain_probe_select_id=2;
SET debug_dbug='+d,show_explain_probe_join_exec_start';
send delete from t2 where (select max(a) from t0 where t2.a + t0.a <3) >3 ;
connection default;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp show explain format=JSON for $thr2;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp show explain format=JSON for $thr2;
connection con1;
reap;
drop table t2;
SET debug_dbug=@old_debug;
--echo #
--echo # Attempt EXPLAIN FOR CONNECTION for a DELETE
--echo #
create table t2 as select a as a, a as dummy from t0 limit 2;
set @show_explain_probe_select_id=2;
SET debug_dbug='+d,show_explain_probe_join_exec_start';
send delete from t2 where (select max(a) from t0 where t2.a + t0.a <3) >3 ;
connection default;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp explain format=JSON for connection $thr2;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp explain format=JSON for connection $thr2;
connection con1;
reap;
drop table t2;
SET debug_dbug=@old_debug;
--echo #
--echo # Multiple SHOW EXPLAIN calls for one select
--echo #
create table t2 as select a as a, a as dummy from t0 limit 3;
set @show_explain_probe_select_id=2;
SET debug_dbug='+d,show_explain_probe_join_exec_start';
send select t2.a, ((select max(a) from t0 where t2.a + t0.a <3) >3) as SUBQ from t2;
connection default;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp show explain format=json for $thr2;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp show explain format=json for $thr2;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp show explain format=json for $thr2;
connection con1;
reap;
drop table t2;
SET debug_dbug=@old_debug;
--echo #
--echo # Multiple EXPLAIN FOR CONNECTION calls for one select
--echo #
create table t2 as select a as a, a as dummy from t0 limit 3;
set @show_explain_probe_select_id=2;
SET debug_dbug='+d,show_explain_probe_join_exec_start';
send select t2.a, ((select max(a) from t0 where t2.a + t0.a <3) >3) as SUBQ from t2;
connection default;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp explain format=JSON for connection $thr2;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp explain format=JSON for connection $thr2;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp explain format=JSON for connection $thr2;
connection con1;
reap;
drop table t2;
SET debug_dbug=@old_debug;
--echo #
--echo # SHOW EXPLAIN for SELECT ... ORDER BY with "Using filesort"
--echo #
explain select * from t0 order by a;
SET debug_dbug='+d,show_explain_probe_join_exec_start';
set @show_explain_probe_select_id=1;
send select * from t0 order by a;
connection default;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp show explain format=json for $thr2;
connection con1;
reap;
SET debug_dbug=@old_debug;
--echo #
--echo # SHOW EXPLAIN for SELECT ... with "Using temporary"
--echo #
connection default;
explain select distinct a from t0;
connection con1;
SET debug_dbug='+d,show_explain_probe_join_exec_start';
set @show_explain_probe_select_id=1;
send select distinct a from t0;
connection default;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp show explain format=json for $thr2;
connection con1;
reap;
SET debug_dbug=@old_debug;
--echo #
--echo # SHOW EXPLAIN for SELECT ... with "Using temporary; Using filesort"
--echo #
connection default;
explain select distinct a from t0;
connection con1;
SET debug_dbug='+d,show_explain_probe_join_exec_start';
set @show_explain_probe_select_id=1;
send select distinct a from t0;
connection default;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp show explain format=json for $thr2;
connection con1;
reap;
SET debug_dbug=@old_debug;
--echo #
--echo # Check if queries in non-default charsets work.
--echo #
--disable_service_connection
set names cp1251;
# The below are two Russian letters with codes E3FB in cp1251 encoding.
select charset('<27><>');
select hex('<27><>');
set @show_explain_probe_select_id=1;
SET debug_dbug='+d,show_explain_probe_join_exec_start';
send
select * from t0 where length('<27><>') = a;
connection default;
set names utf8;
--source include/wait_condition.inc
--source include/explain-no-costs.inc
evalp show explain format=JSON for $thr2;
set names default;
connection con1;
# The constant should be two letters, the last looking like 'bl'
reap;
SET debug_dbug=@old_debug;
set names default;
drop table if exists t0,t1,t2;
--enable_service_connection
--echo #
--echo # MDEV-28124: Server crashes in Explain_aggr_filesort::print_json_members
--echo # upon SHOW ANALYZE/EXPLAIN FORMAT=JSON
--echo #
let $wait_condition= select State='show_explain_trap' from information_schema.processlist where id=$thr2;
connection con1;
set @show_explain_probe_query= 'SELECT count(*) - count(*) FROM sys.waits_by_user_by_latency';
set debug_dbug='+d,explain_notify_tables_are_closed';
# Statement guarantees to produce 0 on every run
send SELECT count(*) - count(*) FROM sys.waits_by_user_by_latency;
connection default;
--source include/wait_condition.inc
--error ER_TARGET_NOT_EXPLAINABLE
evalp SHOW EXPLAIN FORMAT=JSON FOR $thr2;
connection con1;
reap;
--echo # End
connection default;
disconnect con1;
set debug_sync='RESET';