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Posted to derby-dev@db.apache.org by "Knut Anders Hatlen (JIRA)" <ji...@apache.org> on 2011/01/18 11:35:43 UTC
[jira] Created: (DERBY-4977) XPLAIN reports negative EXECUTE_TIME
for some parts of a join
XPLAIN reports negative EXECUTE_TIME for some parts of a join
-------------------------------------------------------------
Key: DERBY-4977
URL: https://issues.apache.org/jira/browse/DERBY-4977
Project: Derby
Issue Type: Bug
Components: SQL
Affects Versions: 10.7.1.1
Reporter: Knut Anders Hatlen
Priority: Minor
I see that if I execute a join against the system tables with XPLAIN and statistics timing enabled, some of the rows in SYSXPLAIN_RESULTSET_TIMINGS have negative values in the EXECUTE_TIME column.
Here are the contents of the SYSXPLAIN_RESULTSET_TIMINGS after two runs with the attached repro script:
ij> select execute_time from my_schema.sysxplain_resultset_timings;
EXECUTE_TIME
--------------------
-1
0
0
-6
9
16
6 rows selected
ij> select execute_time from my_schema.sysxplain_resultset_timings;
EXECUTE_TIME
--------------------
-1
1
0
-7
10
15
6 rows selected
Note the two rows with negative values in both of the examples.
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[jira] Updated: (DERBY-4977) XPLAIN reports negative EXECUTE_TIME
for some parts of a join
Posted by "Dag H. Wanvik (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/DERBY-4977?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Dag H. Wanvik updated DERBY-4977:
---------------------------------
Urgency: Low
Labels: derby_triage10_8 (was: )
> XPLAIN reports negative EXECUTE_TIME for some parts of a join
> -------------------------------------------------------------
>
> Key: DERBY-4977
> URL: https://issues.apache.org/jira/browse/DERBY-4977
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Affects Versions: 10.7.1.1
> Reporter: Knut Anders Hatlen
> Priority: Minor
> Labels: derby_triage10_8
> Attachments: timing.sql
>
>
> I see that if I execute a join against the system tables with XPLAIN and statistics timing enabled, some of the rows in SYSXPLAIN_RESULTSET_TIMINGS have negative values in the EXECUTE_TIME column.
> Here are the contents of the SYSXPLAIN_RESULTSET_TIMINGS after two runs with the attached repro script:
> ij> select execute_time from my_schema.sysxplain_resultset_timings;
> EXECUTE_TIME
> --------------------
> -1
> 0
> 0
> -6
> 9
> 16
> 6 rows selected
> ij> select execute_time from my_schema.sysxplain_resultset_timings;
> EXECUTE_TIME
> --------------------
> -1
> 1
> 0
> -7
> 10
> 15
> 6 rows selected
> Note the two rows with negative values in both of the examples.
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[jira] Updated: (DERBY-4977) XPLAIN reports negative EXECUTE_TIME
for some parts of a join
Posted by "Knut Anders Hatlen (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/DERBY-4977?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Knut Anders Hatlen updated DERBY-4977:
--------------------------------------
Attachment: timing.sql
> XPLAIN reports negative EXECUTE_TIME for some parts of a join
> -------------------------------------------------------------
>
> Key: DERBY-4977
> URL: https://issues.apache.org/jira/browse/DERBY-4977
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Affects Versions: 10.7.1.1
> Reporter: Knut Anders Hatlen
> Priority: Minor
> Attachments: timing.sql
>
>
> I see that if I execute a join against the system tables with XPLAIN and statistics timing enabled, some of the rows in SYSXPLAIN_RESULTSET_TIMINGS have negative values in the EXECUTE_TIME column.
> Here are the contents of the SYSXPLAIN_RESULTSET_TIMINGS after two runs with the attached repro script:
> ij> select execute_time from my_schema.sysxplain_resultset_timings;
> EXECUTE_TIME
> --------------------
> -1
> 0
> 0
> -6
> 9
> 16
> 6 rows selected
> ij> select execute_time from my_schema.sysxplain_resultset_timings;
> EXECUTE_TIME
> --------------------
> -1
> 1
> 0
> -7
> 10
> 15
> 6 rows selected
> Note the two rows with negative values in both of the examples.
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