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From "Anurag Shekhar (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-3354) Select from large lob table with embedded gives OutOfMemoryError
Date Tue, 01 Apr 2008 11:22:40 GMT

    [ https://issues.apache.org/jira/browse/DERBY-3354?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12584108#action_12584108
] 

Anurag Shekhar commented on DERBY-3354:
---------------------------------------

LobMapping and locater is used by the stored procedures (on behalf of 
network driver) to get hold of a particular lob object. LobMapping is additionally 
used to clear the lob object during commit/rollback and connection close. 

Separating these two functionality in two different collections may solve OOM problem.

We can continue to have LobMapping only if the LOB is created through client driver (entry
will 
be made in LOBMapiing in getLocator)

Create methods will make an entry to a new collection holding week references of the LOBs.


This will ensure that LOB will get garbage collected if they unreferenced in Embedded 
mode but in case of client server mode the references will be protected from being garbage

collected unless free is called by the stored procedure. 

> Select from large lob table with embedded gives OutOfMemoryError
> ----------------------------------------------------------------
>
>                 Key: DERBY-3354
>                 URL: https://issues.apache.org/jira/browse/DERBY-3354
>             Project: Derby
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 10.3.1.4, 10.3.2.1, 10.4.0.0
>            Reporter: Kathey Marsden
>            Assignee: Anurag Shekhar
>         Attachments: derby-3354.diff, LocLeak.java
>
>
> Retrieving from a large table with lobs gives an OutOfMemoryException, even if free()
is explictly called on the lob.   I believe this is because EmbedConnection.addLobMapping
is called for every lob creation but is never cleared until commit or rollback, even if the
lob is freed.

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