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https://issues.apache.org/jira/browse/DERBY-2642?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12495524
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Knut Anders Hatlen commented on DERBY-2642:
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This test contains one call to SYSCS_GET_RUNTIMESTATISTICS with the following
comment:
-- verify that like optimization being performed
execute p2 using 'values ''%'' ';
values SYSCS_UTIL.SYSCS_GET_RUNTIMESTATISTICS();
Does anyone know which part of the query plan that shows that like optimization
has been performed?
This is what the query plan in question looks like:
Statement Name:
null
Statement Text:
select id from test where vc10 like ?
Parse Time: 0
Bind Time: 0
Optimize Time: 0
Generate Time: 0
Compile Time: 0
Execute Time: 0
Begin Compilation Timestamp : null
End Compilation Timestamp : null
Begin Execution Timestamp : null
End Execution Timestamp : null
Statement Execution Plan Text:
Project-Restrict ResultSet (3):
Number of opens = 1
Rows seen = 7
Rows filtered = 0
restriction = false
projection = true
constructor time (milliseconds) = 0
open time (milliseconds) = 0
next time (milliseconds) = 0
close time (milliseconds) = 0
restriction time (milliseconds) = 0
projection time (milliseconds) = 0
Source result set:
Project-Restrict ResultSet (2):
Number of opens = 1
Rows seen = 7
Rows filtered = 0
restriction = true
projection = false
constructor time (milliseconds) = 0
open time (milliseconds) = 0
next time (milliseconds) = 0
close time (milliseconds) = 0
restriction time (milliseconds) = 0
projection time (milliseconds) = 0
Source result set:
Table Scan ResultSet for TEST at read committed isolation level
using instantaneous share row locking chosen by the optimizer
Number of opens = 1
Rows seen = 7
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={0, 2}
Number of columns fetched=2
Number of pages visited=1
Number of rows qualified=7
Number of rows visited=8
Scan type=heap
start position:
null stop position:
null qualifiers:
Column[0][0] Id: 2
Operator: <
Ordered nulls: false
Unknown return value: true
Negate comparison result: true
Column[0][1] Id: 2
Operator: <
Order&
> Convert lang/dynamicLikeOptimization.sql to JUnit
> -------------------------------------------------
>
> Key: DERBY-2642
> URL: https://issues.apache.org/jira/browse/DERBY-2642
> Project: Derby
> Issue Type: Improvement
> Components: Test
> Affects Versions: 10.3.0.0
> Reporter: Knut Anders Hatlen
> Priority: Minor
>
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