How to lock reads and deletes in InnoDB?
For locking reads (SELECT with FOR UPDATE or LOCK IN SHARE MODE), UPDATE, and DELETE statements, locking depends on whether the statement uses a unique index with a unique search condition, or a range-type search condition. For a unique index with a unique search condition, InnoDB locks only the index record found, not the gap before it.
Is there a way to update InnoDB table statistics manually?
ANALYZE TABLE will not help, because it uses the same algorithm. Increasing the number of “stats” sample pages would help, but it has its own downside: the more pages you have to examine, the slower ANALYZE TABLE runs. While this command is not blocking, it still creates side effects as described in this blog post.
How to lock all rows in MySQL update statement?
FOR UPDATE statement locking all rows in a table MySQL Server version 5.1.41 with InnoDB plugin enabled. I have the following three tables for invoices: invoices, invoice_components and invoice_expenses. Table invoices has invoice_id primary key.
How does InnoDB calculate the cardinality of an index?
When InnoDB calculates the cardinality of an index, it does not scan the full table by default. Instead it looks at random pages, as determined by options innodb_stats_sample_pages, innodb_stats_transient_sample_pages and innodb_stats_persistent_sample_pages, or by the CREATE TABLE option STATS_SAMPLE_PAGES.
Why does MySQL select for update statement lock all?
I suspect it has to do with gap locks and next-key locks and the differences in the behaviour of REPEATABLE READ : For locking reads (SELECT with FOR UPDATE or LOCK IN SHARE MODE), UPDATE, and DELETE statements, locking depends on whether the statement uses a unique index with a unique search condition, or a range-type search condition.
Is there any way to select without causing locking in MySQL?
As we know MyISAM can cause table level locks, especially if you have an update pending which will get locked, and then other select queries behind this update get locked too. So this method won’t prevent a lock, but it will make a lot of tiny locks, so as not to hang a website for example which needs a response within a very short frame of time.
Is there a way to select without locking in MyISAM?
MyISAM uses table locks to achieve a very high read speed, but if you have an UPDATE statement waiting, then future SELECTS will queue up behind the UPDATE. InnoDB tables use row-level locking, and you won’t have the whole table lock up behind an UPDATE.