Re: [HACKERS] SELECT * FROM LIMIT 1; is really slow

Wed, 26 May 2004 21:07:06 -0700

Tom Lane wrote:

of dead tuples followed by a lot of pages worth of live tuples.  Plain
VACUUM cannot do much to fix this since it doesn't move rows around.
VACUUM FULL will fix it, but its index-update overhead is high enough
that CLUSTER is a better deal.

Tom: I was interested in performance improvements from cluster, so I tried to cluster a table on a spatial index:


dra_working=# \d geomtest
        Table "public.geomtest"
     Column     |   Type   | Modifiers
----------------+----------+-----------
 rd_segment_id  | integer  |
 admit_date     | date     |
 retire_date    | date     |
 most_recent    | boolean  |
 lineargeometry | geometry |
Indexes: geomtest_idx gist (lineargeometry)

dra_working=# cluster geomtest_idx on geomtest;
ERROR: CLUSTER: cannot cluster when index access method does not handle nulls
You may be able to work around this by marking column "lineargeometry" NOT NULL
dra_working=# select version();
version
---------------------------------------
PostgreSQL 7.3.6 on i686-pc-linux-gnu



As of quite a while ago (7.2?) the GiST access method was made null-safe by Teodor and Oleg, I think. Is this a safety wrapper left over from before the upgrade to GiST?



-- __ / | Paul Ramsey | Refractions Research | Email: [EMAIL PROTECTED] | Phone: (250) 885-0632 \_

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