Allow ALTER TABLE ... IMPORT TABLESPACE without creating the table
followed by discarding the tablespace.
That is, assuming we want to import table t1 to t2, instead of
CREATE TABLE t2 LIKE t1;
ALTER TABLE t2 DISCARD TABLESPACE;
FLUSH TABLES t1 FOR EXPORT;
--copy_file $MYSQLD_DATADIR/test/t1.cfg $MYSQLD_DATADIR/test/t2.cfg
--copy_file $MYSQLD_DATADIR/test/t1.ibd $MYSQLD_DATADIR/test/t2.ibd
UNLOCK TABLES;
ALTER TABLE t2 IMPORT TABLESPACE;
We can simply do
FLUSH TABLES t1 FOR EXPORT;
--copy_file $MYSQLD_DATADIR/test/t1.cfg $MYSQLD_DATADIR/test/t2.cfg
--copy_file $MYSQLD_DATADIR/test/t1.frm $MYSQLD_DATADIR/test/t2.frm
--copy_file $MYSQLD_DATADIR/test/t1.ibd $MYSQLD_DATADIR/test/t2.ibd
UNLOCK TABLES;
ALTER TABLE t2 IMPORT TABLESPACE;
We achieve this by creating a "stub" table in the second scenario
while opening the table, where t2 does not exist but needs to import
from t1. The "stub" table is similar to a table that is created but
then instructed to discard its tablespace.
We include tests with various row formats, encryption, with indexes
and auto-increment.
Import operation without .cfg file fails when there is mismatch of index
between metadata table and .ibd file. Moreover, MDEV-19022 shows
that InnoDB can end up with index tree where non-leaf page has only
one child page. So it is unsafe to find the secondary index root page.
This patch does the following when importing the table without .cfg file:
1) If the metadata contains more than one index then InnoDB stops
the import operation and report the user to drop all secondary
indexes before doing import operation.
2) When the metadata contain only clustered index then InnoDB finds the
index id by reading page 0 & page 3 instead of traversing the
whole tablespace.
