One major problem in terms of MySQL
performance that still stands in the way of InnoDB scalability is
the trx_list scan on consistent read view creation.
It was originally reported as a part of MySQL bug
#49169 and can be described as follows. Whenever a connection
wants to create a consistent read, it has to make a snapshot of
the transaction states to determine which transactions are seen
in the view later. To this end, InnoDB scans
trx_list (i.e. the list of currently open
transactions) and copies IDs of transactions that have not yet
been committed at the current point in time, and thus should not
be visible in the consistent read. For the
REPEATABLE_READ isolation level, the snapshot is
created on the first SELECT …
Showing entries 1 to 1
Apr
12
2013
Showing entries 1 to 1