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https://issues.apache.org/jira/browse/DERBY-3926?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Mamta A. Satoor updated DERBY-3926:
-----------------------------------
Attachment: DERBY3926_notforcheckin_patch2_051109_diff.txt
I am reattaching the earlier patch with little more
comments(DERBY3926_notforcheckin_patch2_051109_diff.txt) to help understand
the code for someone who might be looking at the patch. My patch is adding sort
node for the query from the wisconsin test as shown below is
connect 'jdbc:derby:wombat';
select * from tenktup1, tenktup2
where tenktup1.unique1 = tenktup2.unique1
order by tenktup1.unique1;
I think the reason for the sort node might be the code below that I have added
in my patch
if (currentRowOrdering.orderingRequiredOnTable(optimizable.getTableNumber()))
With the if statement above, I was trying to see if the current optimizable is
covering some columns from the order by and if there are constant predicates on
those column. I am trying to do this by just looking at currentRowOrdering
object. I think the correct code should look at both requiredRowOrdering
provided by the user and current row ordering info for the current join order
as collected by the optimizer in the currentRowOrdering object. I will work on
fixing the if statement code above to see if it gets rid of the sort node for
the query above.
> Incorrect ORDER BY caused by index
> ----------------------------------
>
> Key: DERBY-3926
> URL: https://issues.apache.org/jira/browse/DERBY-3926
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Affects Versions: 10.1.3.3, 10.2.3.0, 10.3.3.1, 10.4.2.0
> Reporter: Tars Joris
> Assignee: Mamta A. Satoor
> Attachments: d3926_repro.sql, derby-reproduce.zip,
> DERBY3926_notforcheckin_patch1_051109_diff.txt,
> DERBY3926_notforcheckin_patch1_051109_stat.txt,
> DERBY3926_notforcheckin_patch2_051109_diff.txt, script3.sql,
> script3WithUserFriendlyIndexNames.sql, test-script.zip
>
>
> I think I found a bug in Derby that is triggered by an index on a large
> column: VARCHAR(1024). I know it is generally not a good idea to have an
> index on such a large column.
> I have a table (table2) with a column "value", my query orders on this column
> but the result is not sorted. It is sorted if I remove the index on that
> column.
> The output of the attached script is as follows (results should be ordered on
> the middle column):
> ID |VALUE |VALUE
> ----------------------------------------------
> 2147483653 |000002 |21857
> 2147483654 |000003 |21857
> 4294967297 |000001 |21857
> While I would expect:
> ID |VALUE |VALUE
> ----------------------------------------------
> 4294967297 |000001 |21857
> 2147483653 |000002 |21857
> 2147483654 |000003 |21857
> This is the definition:
> CREATE TABLE table1 (id BIGINT NOT NULL, PRIMARY KEY(id));
> CREATE INDEX key1 ON table1(id);
> CREATE TABLE table2 (id BIGINT NOT NULL, name VARCHAR(40) NOT NULL, value
> VARCHAR(1024), PRIMARY KEY(id, name));
> CREATE UNIQUE INDEX key2 ON table2(id, name);
> CREATE INDEX key3 ON table2(value);
> This is the query:
> SELECT table1.id, m0.value, m1.value
> FROM table1, table2 m0, table2 m1
> WHERE table1.id=m0.id
> AND m0.name='PageSequenceId'
> AND table1.id=m1.id
> AND m1.name='PostComponentId'
> AND m1.value='21857'
> ORDER BY m0.value;
> The bug can be reproduced by just executing the attached script with the
> ij-tool.
> Note that the result of the query becomes correct when enough data is
> changed. This prevented me from creating a smaller example.
> See the attached file "derby-reproduce.zip" for sysinfo, derby.log and
> script.sql.
> Michael Segel pointed out:
> "It looks like its hitting the index ordering on id,name from table 2 and is
> ignoring the order by clause."
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