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https://issues.apache.org/jira/browse/DERBY-2604?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12499316
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V.Narayanan commented on DERBY-2604:
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There are a few more issues I haven't addressed in v4 that need to be addressed
1) Add buffering for InputStreams by wrapping ClobLocatorInputStream in
a BufferedInputStream and ClobLocatorReader in a BufferedReader.
2) I noticed that in BlobLocatorInputStream, maxPos is used to store the size
of the Blob. This is initialized in the constructor of
BlobLocatorInputStream.
This I observed serves the following purpose.
a) If the locator associated with the Blob object becomes invalid(e.g.
due to
a transaction commit) and the getBinaryStream is called to retrieve
an InputStream the sqlLength() call in the constructor of
BlobInputStream
would throw an SQLException saying the locator associated with this
Blob is invalid.
On the other hand if this method call were not there we would
get a stream from the Blob and would be informed of the locator
invalidation
only during the first call to any method on this InputStream.
I observed this when I ran BlobClob4BlobTest after enabling locators.
In testClobAfterCommit() clob.getAsciiStream was not failing as
expected
because the current ClobLocatorInputStream does not call
clob.sqlLength()
in its constructor.
3) I also think using maxPos to return a CharacterStream subset requested by
getCharacterStream(long, long) is better than the length() method
implemented
by.
Pls accept my apologies for this last moment change. I will be submitting a new
v5 patch addressing the above.
pls ignore v4.
If anyone has reviewed v4 and find this addition inconvinient I will submit
these changes as a
follow up to v4.
> Implement Clob support for locators
> -----------------------------------
>
> Key: DERBY-2604
> URL: https://issues.apache.org/jira/browse/DERBY-2604
> Project: Derby
> Issue Type: Sub-task
> Components: Network Server
> Reporter: V.Narayanan
> Assigned To: V.Narayanan
> Attachments: ClobLocatorWork_v1.diff, ClobLocatorWork_v1.stat,
> ClobLocatorWork_v2.diff, ClobLocatorWork_v2.stat, ClobLocatorWork_v3.diff,
> ClobLocatorWork_v3.stat, ClobLocatorWork_v4.diff, ClobLocatorWork_v4.stat,
> ConnectionLocatorWork_v2.diff, ConnectionLocatorWork_v4.diff
>
>
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