Details
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Type:
Bug
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Status: Stalled
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Priority:
Minor
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Resolution: Unresolved
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Affects Version/s: 10.0.10
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Fix Version/s: 10.0
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Component/s: None
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Labels:None
Description
Some administrative commands report corruption for CONNECT tables:
- CHECK TABLE
- REPAIR TABLE
- ANALYZE TABLE
- others?
For example:
MariaDB [test]> CHECK TABLE tc;
+---------+-------+----------+------------------------------------------------------------------------+
| Table | Op | Msg_type | Msg_text |
+---------+-------+----------+------------------------------------------------------------------------+
| test.tc | check | Error | CONNECT Unsupported command |
| test.tc | check | Error | Can't lock file (errno: 122 "Internal (unspecified) error in handler") |
| test.tc | check | error | Corrupt |
+---------+-------+----------+------------------------------------------------------------------------+
3 rows in set (0.00 sec)
I understand that they are not supported. The problem is with the last row. If you want a program to verify whether a table is corrupted, you issue CHECK TABLE and look if the last returned row has Msg_type='error' and Msg_text='Corrupt'. You do the same if you want the program to try a REPAIR and check if it succeeds.
It would be nice if CONNECT could avoid returning that row.
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CHECKSUM returns the first two, but not 'Corrupt'.
Interestingly, OPTIMIZE behaves nice:
+---------+----------+----------+-----------------------------+ | Table | Op | Msg_type | Msg_text | +---------+----------+----------+-----------------------------+ | test.t1 | optimize | Warning | CONNECT Unsupported command | | test.t1 | optimize | status | OK | +---------+----------+----------+-----------------------------+
Here is what I get with the last version of CONNECT:
MariaDB [connect]> CHECK TABLE employe; +-----------------+-------+----------+------------------------------------------------------------------------+ | Table | Op | Msg_type | Msg_text | +-----------------+-------+----------+------------------------------------------------------------------------+ | connect.employe | check | Error | CONNECT Unsupported command | | connect.employe | check | Error | Can't lock file (errno: 122 "Internal (unspecified) error in handler") | | connect.employe | check | error | Corrupt | +-----------------+-------+----------+------------------------------------------------------------------------+ 3 rows in set (0.08 sec) MariaDB [connect]> REPAIR TABLE employe; +-----------------+--------+----------+------------------------------------------------------------------------+ | Table | Op | Msg_type | Msg_text | +-----------------+--------+----------+------------------------------------------------------------------------+ | connect.employe | repair | Error | CONNECT Unsupported command | | connect.employe | repair | Error | Can't lock file (errno: 122 "Internal (unspecified) error in handler") | | connect.employe | repair | error | Corrupt | +-----------------+--------+----------+------------------------------------------------------------------------+ 3 rows in set (0.00 sec) MariaDB [connect]> ANALYZE TABLE employe; +-----------------+---------+----------+------------------------------------------------------------------------+ | Table | Op | Msg_type | Msg_text | +-----------------+---------+----------+------------------------------------------------------------------------+ | connect.employe | analyze | Error | CONNECT Unsupported command | | connect.employe | analyze | Error | Can't lock file (errno: 122 "Internal (unspecified) error in handler") | | connect.employe | analyze | error | Corrupt | +-----------------+---------+----------+------------------------------------------------------------------------+ 3 rows in set (0.00 sec) MariaDB [connect]> OPTIMIZE TABLE employe; +-----------------+----------+----------+----------+ | Table | Op | Msg_type | Msg_text | +-----------------+----------+----------+----------+ | connect.employe | optimize | status | OK | +-----------------+----------+----------+----------+ 1 row in set (0.05 sec) MariaDB [connect]> CHECKSUM TABLE employe; +-----------------+----------+ | Table | Checksum | +-----------------+----------+ | connect.employe | NULL | +-----------------+----------+ 1 row in set, 2 warnings (0.08 sec)
The problem is complex. CONNECT works by treating each query as a separate entity. For this, it needs to know when a new query begins. There are two functions that mark the start of new query for a table:
1 - external_lock: called when the table is not locked
2 - start_stmt: called when the table is locked
Therefore CONNECT does all query initialization and termination work in external_lock (most of the time) in particular checks whether the command is supported or not supported. When a command is not supported CONNECT prepares the message "CONNECT Unsupported command" and returns HA_ERR_INTERNAL_ERROR.
What happens next is MariaDB processing. The message "Can't lock file" comes from CONNECT doing things in external_lock that are not related to locking. I don't know where the "Corrupt" message comes from.
This shows that some plugins, in particular CONNECT, need a true function call at the beginning of each new query. The start_stmt function would be all right if unconditionally called.
For example, if it could do something like this (InnoDB), it would be perfect: