On Feb 19, 2008, at 9:32 PM, Postgres User wrote:
I'm running a simple query on 8.2. With this syntax, Explain indicate
that the index is scanned:
select * from eod where name = 'AA'
However, when I change the query to use simple regex:
select * from eod where name ~ 'AA'
now Explain indicates a seq scan:
Index Scan using equity_eod_symbol_idx on equity_eod (cost=0.00..8.27
rows=1 width=149)
Index Cond: ((symbol)::text = 'AA'::text)
Is there any way to 'encourage' Postgres to hit the index when using
regex? Do I need to create a functional index or something?
Without the index in play, I really can't use regex on any of my
larger tables.
You need it to be anchored:
select * from eod where name ~ '^AA';
If you're looking to be able to use indexes for searches within a
string then, for 8.2, you'll need to check out tsearch2.
Erik Jones
DBA | Emma®
erik@xxxxxxxxxx
800.595.4401 or 615.292.5888
615.292.0777 (fax)
Emma helps organizations everywhere communicate & market in style.
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---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
