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From "A B (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-2499) Update Tuning Guide documentation to reflect the new static IN list transformation that occurs as a result of DERBY-47.
Date Mon, 23 Apr 2007 22:12:15 GMT

    [ https://issues.apache.org/jira/browse/DERBY-2499?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12491083
] 

A B commented on DERBY-2499:
----------------------------

> Typically all examples start flush left. Then we indent for different parts
> of the command and SQL statement. For the smaller examples, I did indent. but
> for the JDBC and SQL examples I kept them as is.  

Okay, works for me.  Thanks for clarifying the norm here.

Just a couple of more knits on the _v2 patch:

1) Missing an "s" on "transform" in the following sentence under "Examples":

    The Derby optimizer transform this query internally into:

2) I missed this the first time, but I think it would be better to replace "query" with "predicate"
in the following two sentences:

     At a higher level, the approach by Derby to use index probing for IN lists is
     an internal way of evaluating the transformed query multiple times. The query
     is evaluated one time for each value in the IN list.

   I think from a technical standpoint "predicate" is a more correct high-level depiction
of what Derby is doing internally.

3) I think we need to remove the "s" from "statements" in the following:

     From an SQL perspective, Derby is logically (but not actually) performing the
     following statements:

   The SQL statment shown is actually a single statement composed of several subqueries, hence
no "s" is required.

Thanks for the great (and fast) work, Laura!

> Update Tuning Guide documentation to reflect the new static IN list transformation that
occurs as a result of DERBY-47.
> -----------------------------------------------------------------------------------------------------------------------
>
>                 Key: DERBY-2499
>                 URL: https://issues.apache.org/jira/browse/DERBY-2499
>             Project: Derby
>          Issue Type: Sub-task
>          Components: Documentation
>    Affects Versions: 10.3.0.0
>            Reporter: A B
>         Assigned To: Laura Stewart
>            Priority: Minor
>         Attachments: derby2499_1.diff, derby2499_2.diff, rtuntransform582.html, rtuntransform582.html
>
>
> DERBY-47 changed the static rewrite logic for IN lists.  Whereas we used to create a
BETWEEN predicate for IN-lists that contain all constants and then use that predicate to limit
the scan, we now create a "probe predicate" for IN-lists that contain all constants *and/or*
parameter nodes and then use that new predicate to perform execution-time probing.
> The documentation in the Tuning Guide needs to be updated to reflect this change in behavior.

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