Bugfixing for mysql_fdw #239
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added 3 commits
March 29, 2022 15:14
**Describe the bug**
mysql_fdw deparse the Subscripting Array to be the same as postgres_fdw.
However, MySQL have no type as ARRAY in Postgresql, so we don't pushdown Array Subscripting.
**To Reproduce**
1. Create table on MySQL server
mysql -h $MYSQL_HOST -u $MYSQL_USER_NAME -D $MYSQL_PORT -D mysql_fdw_regress -e "CREATE TABLE s6(id int PRIMARY KEY, c1 int, c2 int, c3 text);"
2. Execute SQL
CREATE FOREIGN TABLE ft5 (id int, c1 int, c2 int, c3 text)
SERVER mysql_svr OPTIONS (dbname 'mysql_fdw_regress', table_name 's6');
INSERT INTO ft5
SELECT id,
id,
id % 5,
to_char(id, 'FM00000')
FROM generate_series(1, 10) id;
3. Result before fixing
EXPLAIN VERBOSE
SELECT * FROM ft5 t1 WHERE c1 = (ARRAY[c1,c2,3])[2];
ERROR: failed to prepare the MySQL query:
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '[`c1`, `c2`, 3])[2])))' at line 1
**Result after fixing**
EXPLAIN VERBOSE
SELECT * FROM ft5 t1 WHERE c1 = (ARRAY[c1,c2,3])[2];
QUERY PLAN
--------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft5 t1 (cost=100.00..125.17 rows=6 width=44)
Output: id, c1, c2, c3
Local server startup cost: 10
Remote query: SELECT `id`, `c1`, `c2`, `c3` FROM `mysql_fdw_regress`.`s6` WHERE ((`c1` = ELT(2, `c1`, `c2`, 3)))
(4 rows)
**Additional context**
Use Mysql ELT(N,str1,str2,str3,...) function to support array subscripting function:
+ Support 1D array subscription.
+ Do not support multiple dimension array
+ Do not support slice function
+ Do not support Var subscription.
**Describe the bug**
Because MySQL does not support tableoid, ctid,...
So not pushdown system column instead of raise error.
**To Reproduce**
1. Execute SQL
CREATE FOREIGN TABLE ft1 (
c0 int,
c1 int NOT NULL,
c2 int NOT NULL,
c3 text,
c4 timestamptz,
c5 timestamp,
c6 varchar(10),
c7 char(10) default 'ft1',
c8 user_enum
) SERVER mysql_svr OPTIONS (dbname 'mysql_fdw_post');
EXPLAIN (VERBOSE, COSTS OFF) SELECT * FROM ft1 t1 ORDER BY t1.c3, t1.c1, t1.tableoid OFFSET 100 LIMIT 10;
2.Result before fixing
EXPLAIN (VERBOSE, COSTS OFF) SELECT * FROM ft1 t1 ORDER BY t1.c3, t1.c1, t1.tableoid OFFSET 100 LIMIT 10;
ERROR: system attribute tableoid can't be fetched from remote relation
**Result after fixing**
QUERY PLAN
----------------------------------------------------------------------------------------------------------------
Limit
Output: c1, c2, c3, c4, c5, c6, c7, c8, tableoid
-> Sort
Output: c1, c2, c3, c4, c5, c6, c7, c8, tableoid
Sort Key: t1.c3, t1.c1, t1.tableoid
-> Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8, tableoid
Remote query: SELECT `C 1`, `c2`, `c3`, `c4`, `c5`, `c6`, `c7`, `c8` FROM `mysql_fdw_post`.`T 1`
(8 rows)
**Describe the bug** Failed to bind the MySQL query when foreign scan will select NULL from an inner join. **To Reproduce** 1. On MySQL server DROP DATABASE IF EXISTS join_limit; CREATE DATABASE join_limit; USE join_limit; CREATE TABLE J1_TBL ( i integer, j integer, t text); CREATE TABLE J2_TBL ( i integer, k integer); CREATE TABLE J3_TBL ( i integer, t text); INSERT INTO J1_TBL VALUES (1, 4, 'one'); INSERT INTO J1_TBL VALUES (2, 3, 'two'); INSERT INTO J1_TBL VALUES (3, 2, 'three'); INSERT INTO J1_TBL VALUES (4, 1, 'four'); INSERT INTO J1_TBL VALUES (5, 0, 'five'); INSERT INTO J1_TBL VALUES (6, 6, 'six'); INSERT INTO J1_TBL VALUES (7, 7, 'seven'); INSERT INTO J1_TBL VALUES (8, 8, 'eight'); INSERT INTO J1_TBL VALUES (0, NULL, 'zero'); INSERT INTO J1_TBL VALUES (NULL, NULL, 'null'); INSERT INTO J1_TBL VALUES (NULL, 0, 'zero'); INSERT INTO J2_TBL VALUES (1, -1); INSERT INTO J2_TBL VALUES (2, 2); INSERT INTO J2_TBL VALUES (3, -3); INSERT INTO J2_TBL VALUES (2, 4); INSERT INTO J2_TBL VALUES (5, -5); INSERT INTO J2_TBL VALUES (5, -5); INSERT INTO J2_TBL VALUES (0, NULL); INSERT INTO J2_TBL VALUES (NULL, NULL); INSERT INTO J2_TBL VALUES (NULL, 0); INSERT INTO J3_TBL VALUES (1, 'first'); INSERT INTO J3_TBL VALUES (2, NULL); INSERT INTO J3_TBL VALUES (2, 'second'); INSERT INTO J3_TBL VALUES (3, 'third'); INSERT INTO J3_TBL VALUES (4, 'forth'); INSERT INTO J3_TBL VALUES (5, 'five'); 2. Execute SQL CREATE FOREIGN TABLE J1_TBL__mysql_svr__0 ( i integer, j integer, t text) SERVER mysql_svr OPTIONS (dbname 'join_limit', table_name 'J1_TBL'); CREATE FOREIGN TABLE J2_TBL__mysql_svr__0 ( i integer, k integer) SERVER mysql_svr OPTIONS (dbname 'join_limit', table_name 'J2_TBL'); CREATE FOREIGN TABLE J3_TBL__mysql_svr__0 ( i integer, t text) SERVER mysql_svr OPTIONS (dbname 'join_limit', table_name 'J3_TBL'); SELECT * FROM j2_tbl__mysql_svr__0 where exists (select t3.i, t from j3_tbl__mysql_svr__0 t3 join j2_tbl__mysql_svr__0 t2 on t2.i = t3.i); 3. Result before fixing SELECT * FROM j2_tbl__mysql_svr__0 where exists (select t3.i, t from j3_tbl__mysql_svr__0 t3 join j2_tbl__mysql_svr__0 t2 on t2.i = t3.i); ERROR: failed to bind the MySQL query **Result after fixing** i | k ---+---- 1 | -1 2 | 2 3 | -3 2 | 4 5 | -5 5 | -5 0 | | | 0 (9 rows) **Additional context** Because with tupleDescriptor->natts = 0 is used to palloc for table->mysql_bind. But it will return invalid memory like address: 0x7f7f7f7f7f7f7f7f. With this allocated memory, the binding will fail and it causes error "failed to bind the MySQL query". When natts is 0, it means the PostgreSQL/PGSpider core does not need any result in tuple slot. Therefore, no need to allocate memory for festate->table in this case.
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Support Subscripting Array syntax
Please check describe in commmit:
(MinhLA1410@1152ff0)
Not pushdown system column instead of raise error
Please check describe in commmit:
(MinhLA1410@e4cc9ff)
Do not allocate when natts is 0
Please check describe in commmit:
MinhLA1410@4d42bba