From: Keith Gray <keith@heart.com.au>
To: Ludwig Lim <lud_nowhere_man@yahoo.com>
Cc: PostgreSQL Mailing List <pgsql-sql@postgresql.org>
Subject: Re: Slow performance on MAX(primary_key)
Date: Tue, 15 Oct 2002 17:47:13 +1000
Message-ID: <3DABC801.8060902@heart.com.au> (raw)
References: <20021015071628.57518.qmail@web80304.mail.yahoo.com>
Ludwig Lim wrote:
>>I have just been comparing some large table
>>performance under 7.1 using the
>>
>> select max(primary key)from table;
>>
>
> Try using the following as alternative :
>
> SELECT primary_key
> FROM table
> ORDER BY primary_key desc
> LIMIT 1;
>
> This should work if primary_key is indexes.
>
> As of now, Max() doesn't utilizes the indices hence
> it always do a sequential scan.
Thanks Ludwig,
That does help performance, but I was using a "standard"
SQL command wrapped in a VB6 ADO ODBC program.
Is this likely to be sorted in 7.2 ?
Is anyone looking at this?
--
Keith Gray
Technical Services Manager
Heart Consulting Services
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To: pgsql-sql@postgresql.org
Cc: keith@heart.com.au, lud_nowhere_man@yahoo.com
Subject: Re: Slow performance on MAX(primary_key)
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