Why is MySQL UPDATE, INSERT and delete so slow?

Why is MySQL UPDATE, INSERT and delete so slow?

Top 20 queries in my slow_query_log are update, insert and delete queries and I cannot understand why they are so slow (up to 120 seconds sometimes!)

How can I speed up a MySQL update?

A super-simple way to increase your throughput would be to write updated values only if they differ from previous one by at least an hour (or a day) – that would guarantee every user will basically get one write per browsing session, cutting your writes 10-100 times depending on your site usage patterns.

How to get rid of a hung MySQL transaction?

In this case, with the default isolation level REPEATABLE-READ, InnoDB can’t purge the undo records (transaction history) for other transactions until these “hung” transactions are finished. The quick solution is simple: kill those connections and InnoDB will roll back those transactions and purge transaction history.

Why is MySQL so slow in Hyper-V?

It is probably due to slow disk writes. In our case it was because Debian GNU/Linux running mysqld was virtualised in Hyper-V, and even if it was given SSD storage hdparm -t was giving terrible results (10-20MB/s instead of 600MB/s that it gets on raw hardware) Thanks for contributing an answer to Stack Overflow!

How long does simple update take in MySQL?

We are having trouble with simple updates on a single table taking a long time. The table contains ~5 Million rows. This query updates ~80k rows and takes around 60 seconds to complete, and the more rows updated the longer it takes which results in timeouts.

Why is InnoDB in MySQL so slow?

Sound like a design flaw. InnoDB in MySQL is really not well adapted to this type of data volume. Also I suggest you, if it’s possible and if your DB doesn’t have foreign keys to swith to the MyISAM engine. Meanwhile, you should be able to improve performance by creating BTREE and/or UNIQUE indexes on your sourceId and parentKey columns.

Why is MY SQL Server query suddenly slow?

Sometimes query performance problems sneak into SQL Server after a software release that involves database schema or code changes, and you must hunt down the offending query and tune it. Other times, however, the performance changes for less immediately explicable reasons.

Why does MySQL take so long to update the cache?

What is basically happening is that the cache needs to be updated following any query that modifies data (INSERT, UPDATE, DELETE). With a large cache it is taking a long time to do this, if the cache is smaller then its faster. So the work-around until the engine is fixed is to decrease the cache size.

Which is better delete or insert in SQL Server?

Ie. person=123 has 200 rows to delete, but only 199 to insert. Update would not be able to handle this. Your best approach should be to use a MERGE statement and a table valued parameter with the new values. Of course, no ORM can handle this, but you mention ‘performance’, and the terms ‘performance’ and ‘ORM’ cannot be used in the same sentence…

What’s the default size for MySQL in Windows?

The default value is 128MB, increased from a historical default of 8MB. The maximum value depends on the CPU architecture, 32-bit or 64-bit. For 32-bit systems, the CPU architecture and operating system sometimes impose a lower practical maximum size. The larger you set this value, the less disk I/O is needed to access data in tables.