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Fix for MDEV-8321, MDEV-6223

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EXPLAIN INSERT ... SELECT tried to use SELECT's execution path. This
caused a collection of problems:
- SELECT_DESCRIBE flag was not put into select_lex->options, which
  means it was not in JOIN::select_options either (except for the first
  member of the UNION).
- This caused UNION members to be executed. They would attempt to write
  join output rows to the output.
- (Actual cause of the crash) second join sibling would call
  result->send_eof() when finished execution. Then,
  Explain_query::print_explain would attempt to write to query output
  again, and cause an assertion due to non-empty query output.
This commit is contained in:
Sergei Petrunia 2015-10-06 15:54:37 +03:00
parent a7dd24cdaa
commit 1289794799
4 changed files with 56 additions and 3 deletions
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26
mysql-test/r/explain_non_select.result
View File

@ -247,3 +247,29 @@ CHECK TABLE t1;
Table Op Msg_type Msg_text
test.t1 check status OK
DROP TABLE t1, t2;
#
# MDEV-8321: Assertion `! is_set()' failed in Diagnostics_area::set_eof_status on EXPLAIN INSERT ... UNION
#
CREATE TABLE t1 (a INT);
CREATE TABLE t2 (b INT);
CREATE TABLE t3 (c INT);
INSERT INTO t1 VALUES (1),(2);
INSERT INTO t2 VALUES (3),(4);
INSERT INTO t3 VALUES (5),(6);
EXPLAIN INSERT INTO t1 SELECT * FROM t2 UNION SELECT * FROM t3;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t2 ALL NULL NULL NULL NULL 2
2 UNION t3 ALL NULL NULL NULL NULL 2
NULL UNION RESULT <union1,2> ALL NULL NULL NULL NULL NULL
drop table t1,t2,t3;
#
# MDEV-6223: Assertion `! is_set()' fails in Diagnostics_area::set_eof_status on EXPLAIN INSERT executed as a PS
#
CREATE TABLE t1 (a INT) ENGINE = MyISAM;
CREATE TABLE t2 (b INT) ENGINE = MyISAM;
INSERT INTO t2 VALUES (1),(2);
PREPARE stmt FROM 'EXPLAIN INSERT INTO t1 SELECT * FROM t2';
EXECUTE stmt;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 2
drop table t1,t2;

26
mysql-test/t/explain_non_select.test
View File

@ -224,3 +224,29 @@ CHECK TABLE t1;
DROP TABLE t1, t2;
--echo #
--echo # MDEV-8321: Assertion `! is_set()' failed in Diagnostics_area::set_eof_status on EXPLAIN INSERT ... UNION
--echo #
CREATE TABLE t1 (a INT);
CREATE TABLE t2 (b INT);
CREATE TABLE t3 (c INT);
# Data is not necessary, tables can be empty as well
INSERT INTO t1 VALUES (1),(2);
INSERT INTO t2 VALUES (3),(4);
INSERT INTO t3 VALUES (5),(6);
EXPLAIN INSERT INTO t1 SELECT * FROM t2 UNION SELECT * FROM t3;
drop table t1,t2,t3;
--echo #
--echo # MDEV-6223: Assertion `! is_set()' fails in Diagnostics_area::set_eof_status on EXPLAIN INSERT executed as a PS
--echo #
CREATE TABLE t1 (a INT) ENGINE = MyISAM;
CREATE TABLE t2 (b INT) ENGINE = MyISAM;
INSERT INTO t2 VALUES (1),(2);
PREPARE stmt FROM 'EXPLAIN INSERT INTO t1 SELECT * FROM t2';
EXECUTE stmt;
drop table t1,t2;

3
sql/sql_parse.cc
View File

@ -3533,6 +3533,9 @@ end_with_restore_list:
lex->duplicates,
lex->ignore)))
{
if (explain)
res= mysql_explain_union(thd, &thd->lex->unit, sel_result);
else
res= handle_select(thd, lex, sel_result, OPTION_SETUP_TABLES_DONE);
/*
Invalidate the table in the query cache if something changed

2
sql/sql_union.cc
View File

@ -286,8 +286,6 @@ bool st_select_lex_unit::prepare(THD *thd_arg, select_result *sel_result,
{
if (!(tmp_result= union_result= new select_union))
goto err;
if (describe)
tmp_result= sel_result;
}
else
tmp_result= sel_result;