Percona-specific extension comments

Registered by Alexey Kopytov

We often want to implement some server improvements by extending the syntax for a specific statement. On the other hand, it's always desirable to keep syntax compatibility with the upstream server or other server flavors.

Examples:
https://bugs.launchpad.net/percona-server/+bug/671227
https://bugs.launchpad.net/percona-server/+bug/712591

We should look into adding support for Percona-specific extension comments, in a similar way to MySQL-specific comments /*! ... */. For example, comments of the form /*? ... */ can be interpreted and executed by Percona Server, but are ignored by the upstream server. We can also support version-specific extensions too, i.e. /*?50510 ... */

Examples:

SELECT /*? TIMEOUT=60 */ col1, col2 FROM tbl1;

CREATE TABLE t1 (a INT )ENGINE=InnoDB /*?50160 TABLESPACE 'system' */;

Blueprint information

Status:
Not started
Approver:
None
Priority:
High
Drafter:
Alexey Kopytov
Direction:
Approved
Assignee:
None
Definition:
New
Series goal:
None
Implementation:
Unknown
Milestone target:
None

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See also MariaDB-specific executable comment syntax: http://kb.askmonty.org/en/comment-syntax

Column compression should use this instead of the current version markers, which match upstream server lacking the feature too.

(?)

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