SQL help for efficient time handling..
От | Rajesh Kumar Mallah |
---|---|
Тема | SQL help for efficient time handling.. |
Дата | |
Msg-id | 200303221332.33121.mallah@trade-india.com обсуждение исходный текст |
Ответы |
Re: SQL help for efficient time handling..
(Stephan Szabo <sszabo@megazone23.bigpanda.com>)
|
Список | pgsql-sql |
Hi everyone, I have a table time_dimension loaded with 1440 records i record for each min in 24 hrs CREATE TABLE general.time_dimension ( time_id integer not null , sql_time time(0) without time zone not null, PRIMARY KEY (time_id), UNIQUE (sql_time) ); sample data is like, tradein_clients=# SELECT * from time_dimension limit 10; +---------+----------+ | time_id | sql_time | +---------+----------+ | 1 | 00:00:00 | | 2 | 00:01:00 | | 3 | 00:02:00 | | 4 | 00:03:00 | | 5 | 00:04:00 | | 6 | 00:05:00 | | 7 | 00:06:00 | | 8 | 00:07:00 | | 9 | 00:08:00 | | 10 | 00:09:00 | +---------+----------+ (10 rows) To get current_time_id i use a query like SELECT time_id from time_dimension where sql_time=date_trunc('minute' , cast(now() as time without time zone) ); it works but uses seq_scan Seq Scan on time_dimension (cost=0.00..35.00 rows=5 width=4) (actual time=4.75..8.16 rows=1 loops=1) Filter: ((sql_time)::interval= date_trunc('minute'::text, ((now())::time without time zone)::interval)) Total runtime: 8.20 msec whereas a query like explain analyze SELECT time_id from time_dimension where sql_time='13:13:13'; +------------------------------------------------------------------------------------------------------------------------------------------+ | QUERY PLAN | +------------------------------------------------------------------------------------------------------------------------------------------+ | Index Scan using time_dimension_sql_time_key on time_dimension (cost=0.00..4.82 rows=1 width=4) (actual time=0.03..0.03rows=0 loops=1) | | Index Cond: (sql_time = '13:13:13'::time without time zone) | | Total runtime: 0.06 msec -------------------------------------------------------------------------------------------------------------------------------------------- take much less. can anyone tell be the best way to get time_id from time_dimension for current_time. any help is appreciated. Regds Mallah. -- Rajesh Kumar Mallah, Project Manager (Development) Infocom Network Limited, New Delhi phone: +91(11)6152172 (221) (L) ,9811255597 (M) Visit http://www.trade-india.com , India's Leading B2B eMarketplace.
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