MDEV-14585 Automatically remove #sql- tables in InnoDB dictionary during recovery

This is a backport of the following commits:
commit b4165985c97a4133e19dd99b459dea27f87fbb1b
commit 69e88de0fe6dc5312f5d6e7a179a5ab73d60dc43
commit 40f4525f43aba5d579cf55bae2df504001cd04f4
commit 656f66def27b7a2cf42a28f873f1eeef0416aa71

Now that MDEV-14717 made RENAME TABLE crash-safe within InnoDB,
it should be safe to drop the #sql- tables within InnoDB during
crash recovery. These tables can be one of two things:

(1) #sql-ib related to deferred DROP TABLE (follow-up to MDEV-13407)
or to table-rebuilding ALTER TABLE...ALGORITHM=INPLACE
(since MDEV-14378, only related to the intermediate copy of a table),

(2) #sql- related to the intermediate copy of a table during
ALTER TABLE...ALGORITHM=COPY

We will not drop tables whose name starts with #sql2, because
the server can be killed during an ALGORITHM=COPY operation at
a point where the original table was renamed to #sql2 but the
finished intermediate copy was not yet renamed from #sql-
to the original table name.

If an old version of MariaDB Server before 10.2.13 (MDEV-11415)
was killed while ALTER TABLE...ALGORITHM=COPY was in progress,
after recovery there could be undo log records for some records that were
inserted into an intermediate copy of the table. Due to these undo log
records, InnoDB would resurrect locks at recovery, and the intermediate
table would be locked while we are trying to drop it. This would cause
a call to row_rename_table_for_mysql(), either from
row_mysql_drop_garbage_tables() or from the rollback of a RENAME
operation that was part of the ALTER TABLE.

row_rename_table_for_mysql(): Do not attempt to parse FOREIGN KEY
constraints when renaming from #sql-something to #sql-something-else,
because it does not make any sense.

row_drop_table_for_mysql(): When deferring DROP TABLE due to locks,
do not rename the table if its name already starts with the #sql-
prefix, which is what row_mysql_drop_garbage_tables() uses.
Previously, the too strict prefix #sql-ib was used, and some
tables were renamed unnecessarily.

1 files changed, 1 insertions, 5 deletions

diff --git a/storage/innobase/handler/ha_innodb.cc b/storage/innobase/handler/ha_innodb.cc
index 7bb84b41a11..e29e1b0ed4b 100644
--- a/storage/innobase/handler/ha_innodb.cc
+++ b/storage/innobase/handler/ha_innodb.cc
@@ -13509,11 +13509,7 @@ int ha_innobase::truncate()
 
 	if (!err) {
 		/* Reopen the newly created table, and drop the
-		original table that was renamed to temp_name.
-
-		Note: In MariaDB 10.2 (before MDEV-14585), if the
-		server is killed and restarted before the original
-		table is dropped, the table will remain orphaned. */
+		original table that was renamed to temp_name. */
 		close();
 		err = open(name, 0, 0);
 		if (!err) {