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Synchronized Scan

From: Jeff Davis <pgsql(at)j-davis(dot)com>
To: pgsql-patches(at)postgresql(dot)org
Cc: Heikki Linnakangas <heikki(at)enterprisedb(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com>
Subject: Synchronized Scan
Date: 2007-05-20 22:01:32
Message-ID: 1179698492.2771.114.camel@jdavis (view raw or flat)
Thread:
Lists: pgsql-patches
Here is the latest version of my patch that's revised according to my
discussions with Heikki and Simon:

Changes:
  * uses LWLocks when accessing shared memory
  * removes the "sync_seqscan_offset" feature
  * uses the relfilenode as a key rather than relation OID
  * fixes regression test failure
  * uses a simple LRU (that stays in fixed-size shared memory) to track
the locations of other concurrent scans

For the LRU I used a doubly-linked list, which isn't strictly necessary.
However, we may decide to use a hash table for the lookup, in which case
the extra pointers will be useful. 

Regards,
	Jeff Davis

Attachment: syncscan20.patch
Description: text/x-patch (19.2 KB)

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