On Tue, Dec 10, 2013 at 5:57 PM, bricklen <bricklen@xxxxxxxxx> wrote:
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If you willing to install the pgstattuple[1] extension, what does the output say? Note, there is some overhead on larger tables (disk I/O primarily)
Yeah, this is a prod database that sees nontrivial traffic, so I'm not yet ready to install pgstattuple.
Also, check the output from bloat query at https://wiki.postgresql.org/wiki/Show_database_bloat
Interestingly, that does return results that include the tables which are exhibiting the zero dead tuple behavior. Thanks.
On Tue, Dec 10, 2013 at 6:05 PM, Tom Lane <tgl@xxxxxxxxxxxxx> wrote:
Dead tuples and empty space are not the same thing.
Can you elaborate on that?
What I'm trying to do is efficiently choose tables which are displaying significant space bloat to schedule them for a manual vacuum full.
My understanding was that percentage of dead tuples would be a reasonable metric, since dead tuples in the table would also be reflected in the indexes, and since vacuum and autovacuum attempt to return pages which are entirely empty of live tuples. Actually, I assumed that dead tuples were also the triggering metric for autovacuum and autoanalyze.
If that method is not feasible, can you suggest a different method for determining candidate tables to reclaim space from?
-john
John Melesky | Sr Database Administrator
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