Comments on: A review of SecoBackup Amazon S3 backups for MySQL

By: review32

review32 — Fri, 02 Oct 2009 04:07:14 +0000

UI is half broken. Overall, it’s not ready for shrinkwrapping.

By: Xaprb

Xaprb — Sun, 08 Mar 2009 13:24:15 +0000

There’s no LOCK TABLES. –opt sets a bunch of flags including –lock-tables, but –single-transaction sets that one off and leaves others on. This is why I looked at the mysql general log to make sure. I would guess the authors of the software don’t know these subtleties.

By: Dipin

Dipin — Sun, 08 Mar 2009 07:08:20 +0000

@Shlomi – Thanks for the pointer. I had completely missed that little detail. My only question is that although it states in the manual that the two are mutually exclusive, it doesn’t state which one wins out when both are used or which rules are used to determine which one wins out (i.e. the last one specified wins or the single-transaction always wins) and that seems kind of scary to me.

-Dipin

By: Shlomi Noach

Shlomi Noach — Sun, 08 Mar 2009 06:37:22 +0000

@Dipin -
–lock-tables and –single-transaction are mutually exclusive (that’s also on the docs), and since –single-transaction is second, it should override the –lock-tables.

But this adds to the question of how professional the product is: it’s a bit funny to add these two fields together.
–opt is better used with MyISAM (adds locks, disables keys), while –single-transaction plays well with InnoDB.

A smart backup tool should be able to detect if there is a single engine type throughout the db (disregarding the mysql schema itself) and set the flags accordingly.

Shlomi

By: Dipin

Dipin — Sun, 08 Mar 2009 01:55:00 +0000

According to the mysql documentation (http://dev.mysql.com/doc/refman/5.1/en/mysqldump.html#option_mysqldump_opt), it seems that the –opt parameter includes a –lock-tables to lock the tables during the dump. So the answer to 4 should be that it uses LOCK TABLES and interrupts processing.

-Dipin