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Displaying posts with tag: memory management (reset)

Making MySQL Better More Quickly
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With the upcoming release of MySQL 5.7 I begin to see a problem which I think needs attention at least for 5.8 or whatever comes next.

  • The GA release cycle is too long, being about 2 years and that means 3 years between upgrades in a production environment
  • More people use MySQL and the data it holds becomes more important. So playing with development versions while possible becomes harder.  This is bad for Oracle as they do not get the feedback they need to adjust the development of new features and have to best guess the right choices.
  • Production DBAs do want new features and crave them if it makes our life easier, if performance improves, but we also have to live in an environment which is sufficiently stable.  This is a hard mixture of requirements to work with.
  • In larger environments the transition from one major version to another, even when
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OPTIMIZE TABLE on Cluster (revisited)
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Jonas just wrote a patch to this bug on OPTIMIZE TABLE, and the issue that was also discussed in this blog post. Jonas also fixed this bug when he was at it.

Before, OPTIMIZE TABLE hardly freed up any pages and to defragment you had to do a rolling restart of the data nodes.

Now, there is only a 2% discrepancy between OPTIMIZE TABLE and doing a rolling restart. This is great stuff.
This will fix will make it into 6.3.26 and 7.0.7.

See below for details:

Creating two tables, t5 and t6:

CREATE TABLE `t5` (
`id` varchar(32) CHARACTER SET utf8 NOT NULL,
`name`












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Memory (de)allocation,(de)fragmentation, and chkfrag!
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(this blog post applies to MySQL Cluster 6.3 and MySQL Cluster 6.4/7.0)

A while ago I discussed Memory Allocation in MySQL Cluster. Here it comes again, but we also discuss fragmentation and a tool to help analyze if there is fragmentation.

The main problem I want to address here is that "I filled up 100% of my DataMemory, then deleted 40% and I cannot create a new table!!". Now this is not such a common problem, but can happen in systems with a lot of insert/deletes (especially on VAR* columns), and can be an issue if you need to create a new table. If the allocation patterns are always on the same set of tables, then this is less of an issue.

Allocation





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