Re: text vs varchar

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 null
date_in | timestamp without time 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(at)matrix(dot)gatewaynet(dot)com
mantzios(at)softlab(dot)ece(dot)ntua(dot)gr