On Tue, 18 Jun 2002, Josh Berkus wrote:
> Wei,
>
> > Is there any disadvantage of using TEXT datatype as opposed to a VARCHAR
> > datatype with a maximum length, especially when I do searches on them?
>
> Yes. You can't index TEXT because it's of potentially unlimited length.
Well indexing text works fine for me.
Table "repdat" Column | Type | Modifiers
-----------------+-----------------------------+-----------vslid | integer |vslname
| character varying(15) |orderno | integer | not nulldate_in | timestamp
withouttime zone |port_landed | character varying(15) |subject | text |catid
| integer |
dynacom=# EXPLAIN ANALYZE SELECT subject from repdat where subject='UTM
FOR SPECIAL SURVEY JUNE2000';
NOTICE: QUERY PLAN:
Index Scan using repdat_subject_idx on repdat (cost=0.00..7.40 rows=1
width=28) (actual time=0.05..0.06 rows=1 loops=1)
Total runtime: 0.10 msec
EXPLAIN
dynacom=#
dynacom=# SET enable_indexscan = off;
SET VARIABLE
dynacom=# EXPLAIN ANALYZE SELECT subject from repdat where subject='UTM
FOR SPECIAL SURVEY JUNE2000';
NOTICE: QUERY PLAN:
Seq Scan on repdat (cost=0.00..388.59 rows=1 width=28) (actual
time=0.03..8.14
rows=1 loops=1)
Total runtime: 8.19 msec
EXPLAIN
dynacom=#
>
>
--
Achilleus Mantzios
S/W Engineer
IT dept
Dynacom Tankers Mngmt
tel: +30-10-8981112
fax: +30-10-8981877
email: achill@matrix.gatewaynet.com mantzios@softlab.ece.ntua.gr