[jira] [Updated] (DERBY-6096) OutOfMemoryError with Clob or Blob hash join: DataTypeDescriptor.estimatedMemoryUsage() has no case for BLOB or CLOB so would underestimate memory usage for those types at zero

["Rick Hillegas (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/DERBY-6096?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Rick Hillegas updated DERBY-6096:
---------------------------------

    Attachment: releaseNote.html

Correct some typos in the detailed release note.

> OutOfMemoryError with Clob or Blob hash join: DataTypeDescriptor.estimatedMemoryUsage()  has no case for BLOB or CLOB so would underestimate memory usage for those types at zero
> ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: DERBY-6096
>                 URL: https://issues.apache.org/jira/browse/DERBY-6096
>             Project: Derby
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 10.1.3.1, 10.2.2.0, 10.3.3.0, 10.4.2.0, 10.5.3.0, 10.6.2.1, 10.7.1.1, 10.8.3.0, 10.9.1.0, 10.10.1.1
>            Reporter: Kathey Marsden
>            Assignee: Kathey Marsden
>              Labels: derby_backport_reject_10_10
>             Fix For: 10.11.0.0
>
>         Attachments: D6096.java, derby-6096_code_diff.txt, derby-6096_diff.txt, derby-6096_diff2.txt, less-gc.diff, releaseNote.html, releaseNote.html
>
>
> In discussion on derby-dev regarding how much memory is used for hash joins, Knut noted:
> I haven't verified, but I think HashJoinStrategy uses
> DataTypeDescriptor.estimatedMemoryUsage() to estimate how much memory
> the hash table will consume. That method has no case for BLOB or CLOB,
> so it looks as if it will return zero for LOB columns. If that's so, it
> will definitely overestimate how many rows fits in maxMemoryPerTable
> kilobytes if the rows contain LOBs.
> DataTypeDescriptor.estimatedMemoryUsage() should be updated to include BLOB and CLOB and we should try verify if this theory is correct with a reproduction.



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