On 8/1/2012 1:13 PM, Rick James wrote:
That leads to another question...
Does this 'separate cache' contain an extra copy (vs the 'only' copy) of the
non-transacted events?
I would expect that it must be an extra copy.
No. The non-transacted events are applied to the tables they belong to
as they are executed. We track them in this cache for replication
purposes. Are you worried about a race between a crash and the time
where the cache is applied to the main binary logs?
This is a very unlikely event for two reasons:
1) the non-transacted change must occur within a transaction
2) most users that use transactions only use transaction-enabled storage
engines (InnoDB).
So in order to lose non-transacted changes from a crash that happens
before the cache is appended to the binary log, you must
a) have a sequence of statements (or ROW-based changes) that is smaller
than --binlog-cache-size limit
b) have a mixed-mode transaction.
If this is a valid concern for your usage pattern set
--binlog-cache-size to a smaller value.
http://dev.mysql.com/doc/refman/5.5/en/replication-options-binary-log.html#sysvar_binlog_cache_size
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Shawn Green
MySQL Principal Technical Support Engineer
Oracle USA, Inc. - Hardware and Software, Engineered to Work Together.
Office: Blountville, TN
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