[postgis-devel] CLUSTER in 8.3

Obe, Regina robe.dnd at cityofboston.gov
Fri Dec 5 12:05:33 PST 2008


So I guess its probably the fix to 8.3.5

#

Fix GiST index corruption due to marking the wrong index entry "dead" after a deletion (Teodor)

This would result in index searches failing to find rows they should have found. 

That introduced this seeming race condition.


-----Original Message-----
From: postgis-devel-bounces at postgis.refractions.net on behalf of Paul Ramsey
Sent: Fri 12/5/2008 3:01 PM
To: PostGIS Development Discussion
Subject: Re: [postgis-devel] CLUSTER in 8.3
 
Works with btree.

pramsey=# create table ttt as select * from counties;
SELECT
pramsey=# create index gid_bix on ttt (gid);
CREATE INDEX
pramsey=# select count(*) from ttt;
 count
-------
  3141
(1 row)

pramsey=# cluster ttt using gid_bix;
CLUSTER
pramsey=# select count(*) from ttt;
 count
-------
  3141
(1 row)


On Fri, Dec 5, 2008 at 11:49 AM, Chris Hodgson <chodgson at refractions.net> wrote:
> Kevin Neufeld wrote:
>>
>> Mark Cave-Ayland wrote:
>>  > I think the GiST part is a red herring - there is no way that a "SELECT
>>>
>>> COUNT(*) FROM foo" can use an index in PostgreSQL. My suspicion is that
>>> it's related to the use of ANALYZE/VACUUM/CLUSTER.
>>>
>>
>> Maybe.  You're right that "SELECT ..." doesn't use the index, but the
>> CLUSTER physically reorders the table based on the index.  If there is a
>> bizzare bug in our GiST implementation that produces an empty traversal list
>> some of the time, the table would be empty.
>>
>> Never mind, I just saw Paul's post.  This is good news for us in that it's
>> not related to our implementation of GiST ...  but it still could be related
>> to PostgreSQL's implementation, no?
>
> Well, can anyone replicate the problem by clustering on a non-gist index? If
> so, then we should really be able to just throw this problem at the Postgres
> Devs. I'd be surprised if this was the case though, I can't believe no-one
> else would have come across this yet...
>
> Chris
> _______________________________________________
> postgis-devel mailing list
> postgis-devel at postgis.refractions.net
> http://postgis.refractions.net/mailman/listinfo/postgis-devel
>
_______________________________________________
postgis-devel mailing list
postgis-devel at postgis.refractions.net
http://postgis.refractions.net/mailman/listinfo/postgis-devel



-----------------------------------------
The substance of this message, including any attachments, may be
confidential, legally privileged and/or exempt from disclosure
pursuant to Massachusetts law. It is intended
solely for the addressee. If you received this in error, please
contact the sender and delete the material from any computer.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/postgis-devel/attachments/20081205/8c30190d/attachment.html>


More information about the postgis-devel mailing list