path: root/mysql-test/main/show_explain_json.test

#
# 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;

#
# 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;
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
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
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
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
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
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
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
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
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
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
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 #
set @show_explain_probe_select_id=2;
SET debug_dbug='+d,show_explain_probe_join_exec_start';
send set @foo= (select max(a) from t0 where sin(a) >0);
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;

--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
evalp show explain format=JSON for $thr2;
--source include/wait_condition.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
evalp explain format=JSON for connection $thr2;
--source include/wait_condition.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
evalp show explain format=JSON for $thr2;
--source include/wait_condition.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
evalp explain format=JSON for connection $thr2;
--source include/wait_condition.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
evalp show explain format=json for $thr2;
--source include/wait_condition.inc
evalp show explain format=json for $thr2;
--source include/wait_condition.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
evalp explain format=JSON for connection $thr2;
--source include/wait_condition.inc
evalp explain format=JSON for connection $thr2;
--source include/wait_condition.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
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
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
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('��');
select hex('��');

set @show_explain_probe_select_id=1;
SET debug_dbug='+d,show_explain_probe_join_exec_start';

send
select * from t0 where length('��') = a;

connection default;
set names utf8;
--source include/wait_condition.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';