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From "Daniel John Debrunner (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-2746) If table only has fixed sized fields then derby should automatically set reserved space to 0.
Date Fri, 01 Jun 2007 21:17:15 GMT

    [ https://issues.apache.org/jira/browse/DERBY-2746?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12500862
] 

Daniel John Debrunner commented on DERBY-2746:
----------------------------------------------

I'd actually looked at doing this before, thought I'd even entered an issue but I guess I
didn't.

One natural place to do it is where the code currently checks to see if the page size should
be increased for long rows,
somewhere in the create table logic, ie above the store.

It might be possible to get even smarter and figure out an optimal reserved space, rather
than just 0 or the default of 20%.
E.g. with only one nullable INT column in a table of 20 fixed length columns one could calculate
the amount of space
needed to change the all NULL values to non-NULL values. So it might come out at 3% reserved
space.

> If table only has fixed sized fields then derby should automatically set reserved space
to 0.
> ---------------------------------------------------------------------------------------------
>
>                 Key: DERBY-2746
>                 URL: https://issues.apache.org/jira/browse/DERBY-2746
>             Project: Derby
>          Issue Type: Improvement
>          Components: SQL
>            Reporter: Mike Matrigali
>            Priority: Minor
>
> At create table time the system should be able to tell if all the columns are fixed length,
and if the user has not set  reserved space it should be changed to 
> 0.  

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