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 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