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https://issues.apache.org/jira/browse/DERBY-4587?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12854044#action_12854044
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C.S. Nirmal J. Fernando commented on DERBY-4587:
------------------------------------------------
Rather than print them out, I used derby.language.logQueryPlan = true (to get
the more accurate statistics), and following is the derby.log file:
----------------------------------------------------------------
2010-04-06 16:04:06.112 GMT:
Booting Derby version The Apache Software Foundation - Apache Derby - 10.6.0.0
alpha - (exported): instance a816c00e-0127-d3dd-438c-0000003f3a18
on database directory C:\OtherNirmal\GSoC\Code\jars\sane\nirmal
Database Class Loader started - derby.database.classpath=''
2010-04-06 16:04:06.906 GMT Thread[main,5,main] (XID = 1430), (SESSIONID = 0),
(DATABASE = nirmal), (DRDAID = null), Committing
2010-04-06 16:04:06.907 GMT Thread[main,5,main] (XID = 1430), (SESSIONID = 0),
(DATABASE = nirmal), (DRDAID = null), Rolling backan
2010-04-06 16:04:06.909 GMT Thread[main,5,main] (XID = 1431), (SESSIONID = 1),
(DATABASE = nirmal), (DRDAID = null), Committing
2010-04-06 16:04:08.753 GMT Thread[main,5,main] (XID = 1432), (SESSIONID = 1),
(DATABASE = nirmal), (DRDAID = null), Begin compiling prepared statement:
select * from myTable where i=1 :End prepared statement
2010-04-06 16:04:09.493 GMT Thread[main,5,main] (XID = 1432), (SESSIONID = 1),
(DATABASE = nirmal), (DRDAID = null), End compiling prepared statement: select
* from myTable where i=1 :End prepared statement
2010-04-06 16:04:09.671 GMT Thread[main,5,main] (XID = 1432), (SESSIONID = 1),
(DATABASE = nirmal), (DRDAID = null), Executing prepared statement: select *
from myTable where i=1 :End prepared statement
2010-04-06 16:04:09.796 GMT Thread[main,5,main] (XID = 1432), (SESSIONID = 1),
(DATABASE = nirmal), (DRDAID = null), Committing
2010-04-06 16:04:09.989 GMT Thread[main,5,main] (XID = 1432), (SESSIONID = 1),
select * from myTable where i=1 ******* Table Scan ResultSet for MYTABLE at
read committed isolation level using instantaneous share row locking chosen by
the optimizer
Number of opens = 1
Rows seen = 3
Rows filtered = 0
Fetch Size = 16
constructor time (milliseconds) = 0
open time (milliseconds) = 0
next time (milliseconds) = 0
close time (milliseconds) = 0
next time in milliseconds/row = 0
scan information:
Bit set of columns fetched=All
Number of columns fetched=2
Number of pages visited=1
Number of rows qualified=3
Number of rows visited=7
Scan type=heap
start position:
null
stop position:
null
qualifiers:
Column[0][0] Id: 0
Operator: =
Ordered nulls: false
Unknown return value: false
Negate comparison result: false
optimizer estimated row count: 1.30
optimizer estimated cost: 29.56
2010-04-06 16:04:09.990 GMT Thread[main,5,main] (XID = 1432), (SESSIONID = 1),
(DATABASE = nirmal), (DRDAID = null), Committing
2010-04-06 16:10:07.514 GMT Thread[main,5,main] (XID = 1432), (SESSIONID = 1),
(DATABASE = nirmal), (DRDAID = null), Rolling back
2010-04-06 16:10:07.537 GMT:
Shutting down instance a816c00e-0127-d3dd-438c-0000003f3a18
----------------------------------------------------------------
I'm looking to retrieve XPlainTable values now.
> Add tools for improved analysis and understanding of query plans and
> execution statistics
> -----------------------------------------------------------------------------------------
>
> Key: DERBY-4587
> URL: https://issues.apache.org/jira/browse/DERBY-4587
> Project: Derby
> Issue Type: Improvement
> Components: SQL, Tools
> Reporter: Bryan Pendleton
> Assignee: Bryan Pendleton
> Attachments: PostgreSQL license.jpg
>
>
> I think it would be great to see some work in the area of tools for helping
> with the analysis of complex query execution. Quite frequently, users of
> Derby have trouble comprehending (a) how their query is being translated
> into a query plan by the optimizer, and (b) what the execution-time resource
> usage of the various parts of the query is.
> There are low-level features in Derby which capture this information and
> record it, such as logQueryPlan, and the XPLAIN tables, but there is a lot
> of opportunity for designing higher-level tools which can process the query
> plan and execution statistics information and present it in a more
> comprehensible fashion.
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