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https://issues.apache.org/jira/browse/DERBY-2836?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Laura Stewart reassigned DERBY-2836:
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Assignee: Laura Stewart
> Documentation of derby.storage.pageSize should mention that the default is
> dynamic
> ----------------------------------------------------------------------------------
>
> Key: DERBY-2836
> URL: https://issues.apache.org/jira/browse/DERBY-2836
> Project: Derby
> Issue Type: Improvement
> Components: Documentation
> Affects Versions: 10.2.2.0
> Reporter: Kurt Huwig
> Assignee: Laura Stewart
>
> The documention of derby.storage.pageSize at
> docs/html/tuning/rtunproper40688.html says:
> Default
> 4096 bytes.
> But this page docs/html/tuning/ctunperf816059.html hints, that this default
> is not necessarily the one to be used:
> "Derby autotunes the database pagesize. If you have long columns, the default
> pagesize for the table is set to 32K. Otherwise, the default is 4K."
> Also the documentation of derby.storage.pageCacheSize at
> docs/html/tuning/rtunproper81359.html does not mention this:
> "When increasing the size of the page cache, you typically have to allow more
> memory for the Java heap when starting the embedding application (taking into
> consideration, of course, the memory needs of the embedding application as
> well). For example, using the default page size of 4K, a page cache size of
> 2000 pages will require at least 8 MB of memory (and probably more, given the
> overhead)."
> We had one machine crashing, because we expected the page size to be the
> default of 4096. After 2 hours of testing, I found out that for my particular
> example, the page size is set to 32K. So having a note added would have at
> least saved me some time and hassle.
> I recommend to add the sentence
> "Derby autotunes the database pagesize. If you have long columns, the default
> pagesize for the table is set to 32K. Otherwise, the default is 4K."
> to both the documentation of derby.storage.pageSize and
> derby.storage.pageCacheSize
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