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The crash happened with an indexed virtual column whose value is evaluated using a function that has a different meaning in sql_mode='' vs sql_mode=ORACLE: - DECODE() - LTRIM() - RTRIM() - LPAD() - RPAD() - REPLACE() - SUBSTR() For example: CREATE TABLE t1 ( b VARCHAR(1), g CHAR(1) GENERATED ALWAYS AS (SUBSTR(b,0,0)) VIRTUAL, KEY g(g) ); So far we had replacement XXX_ORACLE() functions for all mentioned function, e.g. SUBSTR_ORACLE() for SUBSTR(). So it was possible to correctly re-parse SUBSTR_ORACLE() even in sql_mode=''. But it was not possible to re-parse the MariaDB version of SUBSTR() after switching to sql_mode=ORACLE. It was erroneously mis-interpreted as SUBSTR_ORACLE(). As a result, this combination worked fine: SET sql_mode=ORACLE; CREATE TABLE t1 ... g CHAR(1) GENERATED ALWAYS AS (SUBSTR(b,0,0)) VIRTUAL, ...; INSERT ... FLUSH TABLES; SET sql_mode=''; INSERT ... But the other way around it crashed: SET sql_mode=''; CREATE TABLE t1 ... g CHAR(1) GENERATED ALWAYS AS (SUBSTR(b,0,0)) VIRTUAL, ...; INSERT ... FLUSH TABLES; SET sql_mode=ORACLE; INSERT ... At CREATE time, SUBSTR was instantiated as Item_func_substr and printed in the FRM file as substr(). At re-open time with sql_mode=ORACLE, "substr()" was erroneously instantiated as Item_func_substr_oracle. Fix: The fix proposes a symmetric solution. It provides a way to re-parse reliably all sql_mode dependent functions to their original CREATE TABLE time meaning, no matter what the open-time sql_mode is. We take advantage of the same idea we previously used to resolve sql_mode dependent data types. Now all sql_mode dependent functions are printed by SHOW using a schema qualifier when the current sql_mode differs from the function sql_mode: SET sql_mode=''; CREATE TABLE t1 ... SUBSTR(a,b,c) ..; SET sql_mode=ORACLE; SHOW CREATE TABLE t1; -> mariadb_schema.substr(a,b,c) SET sql_mode=ORACLE; CREATE TABLE t2 ... SUBSTR(a,b,c) ..; SET sql_mode=''; SHOW CREATE TABLE t1; -> oracle_schema.substr(a,b,c) Old replacement names like substr_oracle() are still understood for backward compatibility and used in FRM files (for downgrade compatibility), but they are not printed by SHOW any more.
87 lines
2.8 KiB
Text
87 lines
2.8 KiB
Text
#
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# MDEV-14012 - sql_mode=Oracle: substr(): treat position 0 as position 1
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# MDEV-10574 - sql_mode=Oracle: return null instead of empty string
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#
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SET sql_mode=ORACLE;
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SELECT SUBSTR('abc',2,1),SUBSTR('abc',1,1), SUBSTR('abc',0,1) FROM dual;
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SUBSTR('abc',2,1) SUBSTR('abc',1,1) SUBSTR('abc',0,1)
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b a a
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SELECT SUBSTR('abc',2),SUBSTR('abc',1), SUBSTR('abc',0) FROM dual;
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SUBSTR('abc',2) SUBSTR('abc',1) SUBSTR('abc',0)
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bc abc abc
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SELECT SUBSTR(null,2,1),SUBSTR(null,1), SUBSTR(null,0) FROM dual;
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SUBSTR(null,2,1) SUBSTR(null,1) SUBSTR(null,0)
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NULL NULL NULL
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SELECT SUBSTR('abc',-2),SUBSTR('abc',-1), SUBSTR('abc',-0) FROM dual;
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SUBSTR('abc',-2) SUBSTR('abc',-1) SUBSTR('abc',-0)
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bc c abc
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SELECT SUBSTR('abc',-2,1),SUBSTR('abc',-1,1), SUBSTR('abc',-0,1) FROM dual;
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SUBSTR('abc',-2,1) SUBSTR('abc',-1,1) SUBSTR('abc',-0,1)
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b c a
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SELECT SUBSTR('abc',null) FROM dual;
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SUBSTR('abc',null)
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NULL
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SELECT SUBSTR('abc',2,null),SUBSTR('abc',1,null), SUBSTR('abc',0,null) FROM dual;
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SUBSTR('abc',2,null) SUBSTR('abc',1,null) SUBSTR('abc',0,null)
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NULL NULL NULL
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SELECT SUBSTR('abc',2,0),SUBSTR('abc',1,0), SUBSTR('abc',0,0) FROM dual;
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SUBSTR('abc',2,0) SUBSTR('abc',1,0) SUBSTR('abc',0,0)
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NULL NULL NULL
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SELECT SUBSTR('abc',2,-1),SUBSTR('abc',1,-1), SUBSTR('abc',0,-1) FROM dual;
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SUBSTR('abc',2,-1) SUBSTR('abc',1,-1) SUBSTR('abc',0,-1)
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NULL NULL NULL
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SELECT SUBSTR(SPACE(0),1) FROM DUAL;
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SUBSTR(SPACE(0),1)
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NULL
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CREATE TABLE t1 (c1 VARCHAR(10),start INTEGER, length INTEGER);
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INSERT INTO t1 VALUES ('abc', 1, 1);
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INSERT INTO t1 VALUES ('abc', 0, 1);
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INSERT INTO t1 VALUES (null, 1, 1);
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INSERT INTO t1 VALUES (null, 0, 1);
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INSERT INTO t1 VALUES ('abc', 1, 0);
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INSERT INTO t1 VALUES ('abc', 0, 0);
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INSERT INTO t1 VALUES (null, 1, 0);
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INSERT INTO t1 VALUES (null, 0, 0);
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INSERT INTO t1 VALUES ('abc', 1, -1);
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INSERT INTO t1 VALUES ('abc', 0, -1);
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INSERT INTO t1 VALUES (null, 1, -1);
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INSERT INTO t1 VALUES (null, 0, -1);
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INSERT INTO t1 VALUES (SPACE(0), 0, 1);
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SELECT SUBSTR(c1,start,length) FROM t1;
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SUBSTR(c1,start,length)
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a
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a
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NULL
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NULL
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NULL
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NULL
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NULL
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NULL
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NULL
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NULL
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NULL
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NULL
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NULL
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DROP TABLE t1;
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CREATE TABLE t1 (c1 VARCHAR(10) NOT NULL);
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CREATE TABLE t2 AS SELECT SUBSTR(C1,1,1) AS C1 from t1;
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SHOW CREATE TABLE t2;
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Table Create Table
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t2 CREATE TABLE "t2" (
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"C1" varchar(1) DEFAULT NULL
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)
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DROP TABLE t2;
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DROP TABLE t1;
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EXPLAIN EXTENDED SELECT SUBSTR('abc',2,1) ;
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 SIMPLE NULL NULL NULL NULL NULL NULL NULL NULL No tables used
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Warnings:
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Note 1003 select substr('abc',2,1) AS "SUBSTR('abc',2,1)"
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CREATE VIEW v1 AS SELECT SUBSTR('abc',2,1) ;
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SHOW CREATE VIEW v1;
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View Create View character_set_client collation_connection
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v1 CREATE VIEW "v1" AS select substr('abc',2,1) AS "SUBSTR('abc',2,1)" latin1 latin1_swedish_ci
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SELECT * FROM v1;
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SUBSTR('abc',2,1)
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b
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DROP VIEW v1;
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