From: | Keith Gray <keith(at)heart(dot)com(dot)au> |
---|---|
To: | Ludwig Lim <lud_nowhere_man(at)yahoo(dot)com> |
Cc: | PostgreSQL Mailing List <pgsql-sql(at)postgresql(dot)org> |
Subject: | Re: Slow performance on MAX(primary_key) |
Date: | 2002-10-15 07:47:13 |
Message-ID: | 3DABC801.8060902@heart.com.au |
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Lists: | pgsql-sql |
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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