Date: Fri, 7 Mar 2003 11:26:39 +0100
From: Andre Schubert <andre@km3.de>
To: pgsql-sql@postgresql.org
Subject: Help on indexing timestamps
Message-Id: <20030307112639.395720be.andre@km3.de>
Organization: km3 teledienst GmbH
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Hi all,

i have a little problem on indexing a table which contains
about 4 millions of traffic-data.
My problem is, that a want to select all data from
a specific month from a specific ip and this select should use the index.
I use the following select:

db_nmkm3aue=# explain analyze select sum(inet_up+inet_down) from tbl_traffic where date_trunc('month',tbl_traffic.time_stamp)::timestamptz = date_trunc('month',now() - timespan('1 months')) and ip = '80.243.38.57';
NOTICE:  QUERY PLAN:

Aggregate  (cost=116.30..116.30 rows=1 width=16) (actual time=1620.79..1620.79 rows=1 loops=1)
  ->  Index Scan using idx_ip_time_stamp on tbl_traffic  (cost=0.00..116.30 rows=1 width=16) (actual time=1216.79..1579.89 rows=5232 loops=1)
Total runtime: 1620.94 msec

But it takes a long time to select the traffic for all Ips.
Is there a way to select these data with using the index correctly ?

Thanks in advance

BTW: Table-schema as follows

db_test=# \d tbl_traffic
                Table "tbl_traffic"
   Column   |           Type           | Modifiers 
------------+--------------------------+-----------
 time_stamp | timestamp with time zone | not null
 ip         | inet                     | 
 local_up   | bigint                   | not null
 local_down | bigint                   | not null
 inet_up    | bigint                   | not null
 inet_down  | bigint                   | not null
Indexes: idx_ip_time_stamp

db_test=# \d idx_ip_time_stamp
       Index "idx_ip_time_stamp"
   Column   |           Type           
------------+--------------------------
 ip         | inet
 time_stamp | timestamp with time zone