Clarified error messages related to unsafe statements:
- avoid the internal technical term "row injection"
- use 'binary log' instead of 'binlog'
- avoid the word 'unsafeness'
transaction
BUG#52616 Temp table prevents switch binlog format from STATEMENT to ROW
Before the WL#2687 and BUG#46364, every non-transactional change that happened
after a transactional change was written to trx-cache and flushed upon
committing the transaction. WL#2687 and BUG#46364 changed this behavior and
non-transactional changes are now written to the binary log upon committing
the statement.
A binary log event is identified as transactional or non-transactional through
a flag in the Log_event which is set taking into account the underlie storage
engine on what it is stems from. In the current bug, this flag was not being
set properly when the DROP TEMPORARY TABLE was executed.
However, while fixing this bug we figured out that changes to temporary tables
should be always written to the trx-cache if there is an on-going transaction.
Otherwise, binlog events in the reversed order would be produced.
Regarding concurrency, keeping changes to temporary tables in the trx-cache is
also safe as temporary tables are only visible to the owner connection.
In this patch, we classify the following statements as unsafe:
1 - INSERT INTO t_myisam SELECT * FROM t_myisam_temp
2 - INSERT INTO t_myisam_temp SELECT * FROM t_myisam
3 - CREATE TEMPORARY TABLE t_myisam_temp SELECT * FROM t_myisam
On the other hand, the following statements are classified as safe:
1 - INSERT INTO t_innodb SELECT * FROM t_myisam_temp
2 - INSERT INTO t_myisam_temp SELECT * FROM t_innodb
The patch also guarantees that transactions that have a DROP TEMPORARY are
always written to the binary log regardless of the mode and the outcome:
commit or rollback. In particular, the DROP TEMPORARY is extended with the
IF EXISTS clause when the current statement logging format is set to row.
Finally, the patch allows to switch from STATEMENT to MIXED/ROW when there
are temporary tables but the contrary is not possible.
The patch for WL 1563 added a new duplicate key error message so that the
key name could be provided instead of the key number. But the error code
for the new message was used even though that did not need to change.
This could cause unnecessary problems for applications that used the old
ER_DUP_ENTRY error code to detect duplicate key errors.
The following is an excerption from the WL.
1. Change so that MIXED is default format
1.1 to change the default for command line --binlog-format
1.2 to alter global_system_variables.binlog_format calculation
basing on command line --binlog-format parameter and
its default.
2. Change test suite so that more testing is done by MIXED format.
2.1 to check if there are test cases requiring --binlog-foramt=statement via
`source include/have_binlog_format_statement.inc' and affected by
altering the latter to be "mixed".
2.2 to check the content of such vulnerable cases to find if
extending to the mixed does not modify results. In that case simply
substitute source arguments as explained.
2.3 if a test in mixed mode deals with features triggering
row-binlogging then if necessary we can switch explicitly
to statement mode or create another test to run with
non-recommended STATEMENT mode
Particullarily, extracting INSERT DELAYED
binlogging subtest for statement mode is performed, and
the snippet is moved into a separate test file.
Note that since now all three modes verify this use case
through 3 different tests.
No changes in item 3 of HLD appeared to be needed.
The problem was that (for any storage engine), the created temporary table was not removed if CREATE SELECT failed (because
of a constraint violation for example). This was not consistent with the manual and with CREATE SELECT (no TEMPORARY).
