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https://issues.apache.org/jira/browse/DERBY-4373?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12917126#action_12917126
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Mamta A. Satoor commented on DERBY-4373:
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It appears that the embedded behavior is correct. Following is the explanation
of the behavior of the embedded and network server(one thing to note is that
the Derby resultsets by default are held open over commit. In the repro, all
the resultsets are created with the default holdability).
The relevant part of the attached repro can be broken down to following steps
1)autocommit is set to false
2)declare global temp table with on commit delete rows
3)create resultset rs1tmp
4)rs1tmp.next
5)rs1tmp.close
6)create resultset rs1
7)rs1.next
8)commit
9)create resultset rs5tmp
As we can see in the above sequence of steps, the second resultset rs1 is
opened(step 6) before commit and the user never explicitly closes that
resultset before the commit(step 8).
In the embedded mode, during the commit(step 8), we check if there are any open
resultsets over a temporary table and if yes, then even though the temporary
table has been defined to delete the rows on commit, it will not delete the
rows because of that open resultset. Because of that, after the commit(step 8),
when a new resultset is created(step 9) on that temporary table, it still finds
all the rows intact in the temporary table.
Network server on the other hand tries to do optimization with the closing of
the resultset. For the steps above, when the first resultset rs1tmp is
created(step 3), network server reads all the data and since it is a forward
only resultset, it closes the resultset even before client requested close(step
5) of that resultset. Next, when the resultset rs1 is created(step 6), network
server reads all the data for that resultset and it closes this resultset too
(without the explicit request from the client to close it). Next when
commit(step 8) is issued by the client, we check if there are any open
resultsets over the temporary table and of course, in case of network server,
we don't find any because network server went ahead and closed them and hence
all the rows from the temporary table get deleted. It seems like that the
network server should not close the resultset implicitly if they are supposed
to be held open over commit. I will get that logic a try and see what happens.
I will highly appreciate if there is any feedback on my analysis or the
approach to fix the problem.
> 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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