[jira] Created: (DERBY-1193) increase usage of "unfilled" pages after successful committed deleted purged rows.

["Mike Matrigali (JIRA)" <de...@db.apache.org>]

increase usage of "unfilled" pages after successful committed deleted purged rows.
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         Key: DERBY-1193
         URL: http://issues.apache.org/jira/browse/DERBY-1193
     Project: Derby
        Type: Improvement

  Components: Store  
    Versions: 10.1.2.3    
    Reporter: Mike Matrigali
    Priority: Minor


The current system is pretty pessimistic about setting the "unfilled" state on a page.  It seems like any time a row is purged from
a page the page state could be set to unfilled as it is likely another row in the same table may now fit on the page.  This may be
too simple, maybe some number greater than 1, or some comparison to the average row length of the rows in the table, or maybe
maximum row length.

The downside to setting unfilled optimistically is possible extra overhead on subsequent inserts.  It is a space vs. performance 
tradeoff.

Minimally purges done in the first phase of compress, should set unfilled so that defragment phase can have more opportunity to 
reclaim space.

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