From: Popeanga Marian <pmarian@cnlo.ro>
To: Rajesh Kumar Mallah <mallah@trade-india.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: SQL help for efficient time handling..
Date: Sat, 22 Mar 2003 11:08:42 +0200
Message-ID: <3E7C281A.4050709@cnlo.ro> (raw)
References: <200303221332.33121.mallah@trade-india.com>
<3E7C22B8.70601@cnlo.ro>
<200303221425.02824.mallah@trade-india.com>
I don't see any other solution than creating differrent
columns for hours, minutes and index them.
Rajesh Kumar Mallah wrote:
>nopes!
>
>does not match any record..
>SELECT time_id from time_dimension where sql_time=cast( now() as time without time zone);
>+---------+
>| time_id |
>+---------+
>+---------+
>(0 rows)
>
>
>On Saturday 22 Mar 2003 2:15 pm, Popeanga Marian wrote:
>
>
>>Hello Mallah,
>>
>>Have you tryed this :
>>
>> SELECT time_id from time_dimension where sql_time=cast(now() as time without time zone);
>>
>>Your tabel is indexed for a time h:m:s and you should to have a where
>>clause with a time value like this index is defined. Other way you will
>>have a filter scan.
>>
>>Rajesh Kumar Mallah wrote:
>>
>>
>>
>>>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..0.03 rows=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.
>>>
>>>
>>>
>>>
>>>
>>>
>>--
>>Popeanga Marian
>>DBA Oracle
>>CNLO Romania
>>
>>
>>
>>
>>
>>
>>
>
>
>
--
Popeanga Marian
DBA Oracle
CNLO Romania
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To: pgsql-sql@postgresql.org
Cc: pmarian@cnlo.ro, mallah@trade-india.com
Subject: Re: SQL help for efficient time handling..
In-Reply-To: <3E7C281A.4050709@cnlo.ro>
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