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From "Lars Hofhansl (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-5224) Iteratively executing the same SQL query will greatly damage the performance
Date Fri, 12 Apr 2019 21:32:00 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-5224?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16816673#comment-16816673
] 

Lars Hofhansl commented on PHOENIX-5224:
----------------------------------------

Is that theoretical based on general JDBC best practices, or do you have some numbers? How
much is the runtime of these tests actually improve?

I'm not opposed to the change, it's a nice improvement. Just wondering about the claim that
this "will greatly damage the performance" in Phoenix.


> Iteratively executing the same SQL query will greatly damage the performance
> ----------------------------------------------------------------------------
>
>                 Key: PHOENIX-5224
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-5224
>             Project: Phoenix
>          Issue Type: Bug
>            Reporter: bd2019us
>            Priority: Major
>              Labels: pull-request-available
>         Attachments: 1.patch
>
>          Time Spent: 1h 20m
>  Remaining Estimate: 0h
>
> Locations: 
> (1) phoenix-core/src/it/java/org/apache/phoenix/end2end/index/IndexRebuildIncrementDisableCountIT.java:170
> (2) phoenix-core/src/it/java/org/apache/phoenix/tx/TxCheckpointIT.java:108
> (3) phoenix-core/src/it/java/org/apache/phoenix/end2end/DeleteIT.java:794,858
> (4) phoenix-core/src/it/java/org/apache/phoenix/end2end/UpsertSelectAutoCommitIT.java:240
> (5) phoenix-core/src/it/java/org/apache/phoenix/end2end/DropTableIT.java:35
> At these locations, the java.sql.Statement is intensively used in a loop and executing
the same SQL query, which will highly damage the performance of database access. In such cases,
java.sql.PreparedStatement should be used to enable the database compiling the SQL command
ahead of time, which has a much better performance compared with Statement.



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