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https://issues.apache.org/jira/browse/DERBY-4373?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12917553#action_12917553
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Knut Anders Hatlen commented on DERBY-4373:
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Thanks for analyzing this issue, Mamta.
>From you description, it sounds to me like what the network client does is not
>necessarily wrong, just different. Since the forward-only result set has been
>exhausted, the caller cannot actually use the result set anymore, and that's
>why the server thinks it's ok to close the cursor earlier.
The lifetime of a cursor may differ between client and embedded in both ends.
The client will start fetching rows from the cursor on executeQuery(), whereas
embedded won't do it until next() is called. And the client driver will release
the resources held by a forward-only result set when the last row has been
fetched, whereas the embedded driver waits until ResultSet.close() is called.
These differences cause some differences in when locks are obtained and
released, but they also make it possible to save two round-trips between the
client and the server for many SELECT statements.
I'm willing to accept that client and embedded behave differently on the
boundaries in this case. So I'd be satisfied with a solution that makes the
test expect a difference between client and embedded (with an explanation in a
comment), or one that makes the test use a result set that's not exhausted when
testing that an open held cursor prevents emptying the temporary table. But if
you still want to make the drivers behave the same way on the boundaries,
please make sure that you don't add extra client/server round-trips on close
for queries that don't access temporary tables.
> different results with network server vs. embedded on select from a temporary
> table with resultset cursor hold over commit
> --------------------------------------------------------------------------------------------------------------------------
>
> Key: DERBY-4373
> URL: https://issues.apache.org/jira/browse/DERBY-4373
> Project: Derby
> Issue Type: Bug
> Components: JDBC
> Affects Versions: 10.6.1.0
> Reporter: Myrna van Lunteren
> Attachments: repro_d4373.java
>
>
> Found this during review of conversion of declareGlobalTempTableJavaJDBC30 to
> junit (DERBY-2895) - when I tried to run the test with network server:
> We define a statement like so:
> Statement s1 = conn.createStatement(ResultSet.TYPE_FORWARD_ONLY,
> ResultSet.CONCUR_READ_ONLY,
> ResultSet.HOLD_CURSORS_OVER_COMMIT );
> and global temp table like so:
> s1.executeUpdate("declare global temporary table SESSION.t1(c11
> int, c12 int) on commit delete rows not logged");
> Then, we insert 2 rows, open a result set that selects *, then do commit.
> With a new resultset, we do another select, which with network server gives 0
> rows, but with embedded, 2.
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