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Re: DELETE FROM t WHERE EXISTS

From: Dmitry Tkach <dmitry(at)openratings(dot)com>
To: Dan Langille <dan(at)langille(dot)org>
Subject: Re: DELETE FROM t WHERE EXISTS
Date: 2003-02-28 22:47:04
Message-ID: 3E5FE6E8.9020200@openratings.com (view raw or flat)
Thread:
Lists: pgsql-sql
What about

select * into temp rows_to_keep from clp order by commit_date limit 100;
truncate clp;
insert into clp select * from rows_to_keep;

Dima.



Dan Langille wrote:
> Hi folks,
> 
> I wanted to delete "old" rows from a table.  These are the rows I 
> want to keep:
> 
> SELECT * 
> FROM clp 
> ORDER BY commit_date 
> LIMIT 100
> 
> So I tried this:
> 
> DELETE FROM clp 
> WHERE NOT EXISTS (
> SELECT * 
> FROM clp 
> ORDER BY commit_date 
> LIMIT 100);
> 
> Uhh uhh, nothing deleted.  I don't understand why.
> 
> OK, I can do this instead:
> 
> DELETE from clp 
> where commit_log_id NOT in (
> SELECT commit_log_id 
> FROM clp 
> ORDER BY commit_date 
> LIMIT 100);
> 
> Can you think of a better way?


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Subject: Re: Optimizing
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Subject: Re: disable constraints

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