On 4/23/15 11:06 AM, Petr Jelinek wrote:
On 23/04/15 17:45, Bruce Momjian wrote:
On Thu, Apr 23, 2015 at 09:45:38AM -0400, Robert Haas wrote:
Agreed, no extra file, and the same write volume as currently. It would
also match pg_clog, which uses two bits per transaction --- maybe we can
reuse some of that code.
Yeah, this approach seems promising. We probably can't reuse code from
clog because the usage pattern is different (key for clog is xid, while
for visibility/freeze map ctid is used). But visibility map storage
layer is pretty simple so it should be easy to extend it for this use.
Actually, there may be some bit manipulation functions we could reuse;
things like efficiently counting how many things in a byte are set.
Probably doesn't make sense to fully refactor it, but at least CLOG is a
good source for cut/paste/whack.
--
Jim Nasby, Data Architect, Blue Treble Consulting
Data in Trouble? Get it in Treble! http://BlueTreble.com
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