[
https://issues.apache.org/jira/browse/DERBY-3130?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12534771
]
Kristian Waagan commented on DERBY-3130:
----------------------------------------
Hi Knut,
I think this is a good fix. I have gotten into trouble with larger databases
when pulling in lots of indexes (normally using a SELECT COUNT(*) ). The
problem for me has been that the page cache gets bigger when it is filled with
index pages than when it is filled with data pages.
In some cases, the only way around it has been to reduce the page cache size,
but then Derby is not allowed to utilize all the memory it could have during
normal processing.
I think there is a typo in your last comment, the default page cache size is
1000 pages, not 4000.
If a patch is created I can test it out in one of my runs that experience the
described problem.
> Reduce memory footprint of StoredRecordHeader
> ---------------------------------------------
>
> Key: DERBY-3130
> URL: https://issues.apache.org/jira/browse/DERBY-3130
> Project: Derby
> Issue Type: Improvement
> Components: Store
> Affects Versions: 10.4.0.0
> Reporter: Knut Anders Hatlen
> Priority: Minor
> Attachments: SmallRecordsTest.java
>
>
> Derby's page cache often has a memory footprint that is much larger than
> pageSize*pageCacheSize. One large contributor to the footprint is the array
> of StoredPageHeader objects in BasePage. The memory consumed by these objects
> can be as large as, and sometimes even larger than, the byte arrays
> containing the raw page data. (See for instance
> http://www.nabble.com/How-much-derby-need-memory--tf3307655.html.) Reducing
> the size of the StoredPageHeader objects could therefore reduce Derby's
> memory footprint significantly, especially if the page cache is large and
> contains many pages from tables with small records or from indices.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
