Re: Sequence Scan vs. Index scan

Assuming you are joining on "Table 1".id = "Table 2".id - do you have indexes on both columns? Have you analyzed your tables + indexes (are there statistics available?) If not those criterias are met, it is unlikely that postgres will choose an index scan.

-----Original Message-----
From: pgsql-performance-owner(at)postgresql(dot)org
[mailto:pgsql-performance-owner(at)postgresql(dot)org]On Behalf Of Fernando
Lujan
Sent: den 21 mars 2006 19:08
To: pgsql-performance(at)postgresql(dot)org
Subject: [PERFORM] Sequence Scan vs. Index scan

Hi guys,

I'm trying to figure out when Sequence Scan is better than Index Scan. I
just want to know this because I disabled the sequence scan in
postgresql and receive a better result. :)

Two tables.

Table 1 (1 million rows )
-----------
id
text
table2_id

Table 2 (300 thousand rows)
----------
id
text 2

When I join these two tables I have a sequence_scan. :(

Thanks in advance.

Fernando Lujan

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