MDEV-23499 Assertion c.same_type(*o) failed

dict_col_t::same_encoding(), dict_col_t::same_format(): Allow an instantaneous change of a column to a compatible encoding, just like ha_innobase::can_convert_string() and similar functions do.
MariaDB · Aug 18, 2020 · 064bfba · 064bfba
1 parent 5c8a124
commit 064bfba
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Showing 4 changed files with 15 additions and 2 deletions.
diff --git a/mysql-test/suite/innodb/r/instant_alter_bugs.result b/mysql-test/suite/innodb/r/instant_alter_bugs.result
@@ -407,4 +407,10 @@ CREATE TABLE t (i INT PRIMARY KEY) ENGINE=InnoDB;
 INSERT INTO t SET i=1;
 ALTER TABLE t ADD e CHAR(255) CHARACTER SET UTF32 FIRST, ALGORITHM=INSTANT;
 DROP TABLE t;
+#
+# MDEV-23499 Assertion c.same_type(*o) failed
+#
+CREATE TABLE t (pk SERIAL, b TEXT CHARACTER SET utf8) ENGINE=InnoDB;
+ALTER TABLE t MODIFY b TEXT CHARACTER SET utf8mb4 FIRST;
+DROP TABLE t;
 SET GLOBAL innodb_purge_rseg_truncate_frequency=@save_frequency;
diff --git a/mysql-test/suite/innodb/t/instant_alter_bugs.test b/mysql-test/suite/innodb/t/instant_alter_bugs.test
@@ -429,4 +429,11 @@ INSERT INTO t SET i=1;
 ALTER TABLE t ADD e CHAR(255) CHARACTER SET UTF32 FIRST, ALGORITHM=INSTANT;
 DROP TABLE t;
 
+--echo #
+--echo # MDEV-23499 Assertion c.same_type(*o) failed
+--echo #
+CREATE TABLE t (pk SERIAL, b TEXT CHARACTER SET utf8) ENGINE=InnoDB;
+ALTER TABLE t MODIFY b TEXT CHARACTER SET utf8mb4 FIRST;
+DROP TABLE t;
+
 SET GLOBAL innodb_purge_rseg_truncate_frequency=@save_frequency;
diff --git a/storage/innobase/dict/dict0mem.cc b/storage/innobase/dict/dict0mem.cc
@@ -120,7 +120,7 @@ bool dict_col_t::same_encoding(uint16_t a, uint16_t b)
 {
   if (const CHARSET_INFO *acs= get_charset(a, MYF(MY_WME)))
     if (const CHARSET_INFO *bcs= get_charset(b, MYF(MY_WME)))
-      return Charset(acs).same_encoding(bcs);
+      return Charset(bcs).encoding_allows_reinterpret_as(acs);
   return false;
 }
 

diff --git a/storage/innobase/include/dict0mem.h b/storage/innobase/include/dict0mem.h
@@ -728,7 +728,7 @@ struct dict_col_t{
   bool same_format(const dict_col_t &other) const
   {
     return same_type(other) && len >= other.len &&
-      mbminlen == other.mbminlen && mbmaxlen == other.mbmaxlen &&
+      mbminlen == other.mbminlen && mbmaxlen >= other.mbmaxlen &&
       !((prtype ^ other.prtype) & ~(DATA_NOT_NULL | DATA_VERSIONED |
                                     CHAR_COLL_MASK << 16 |
                                     DATA_LONG_TRUE_VARCHAR));