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From: aoki@postgres.Berkeley.EDU (Paul M. Aoki)
To: shlam@ie.cuhk.hk
Cc: postgres@postgres.Berkeley.EDU
Subject: Re: how to clean up pg_log, pg_time and pg_variable? 
Reply-To: aoki@postgres.Berkeley.EDU (Paul M. Aoki)
In-reply-to: Your message of Mon, 06 Jun 94 17:39:03 +0800 
	     <9406060939.AA14430@eng.ie.cuhk.hk> 
Date: Mon, 06 Jun 94 02:57:46 -0700
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shlam@ie.cuhk.hk writes:
> I discover that the size of $postgres/data/pg_log, pg_time and
> pg_variable grow very large.

pg_variable should never grow beyond one disk page (8k).

with respect to the other two, pg_log grows at 2 bits (.25 bytes) per
transaction and pg_time grows at 4 bytes per transaction.

> Is there any command to clean up or reset these files ?

what pg_log and pg_time store are the commit status and commit time of
each transaction.  in theory, this could be compressed by something
like run-length encoding (since most transactions commit) or truncated
after vacuuming (if you could somehow arrange to vacuum the entire
installation..).  in fact, they just grow.

it would be a bad idea to remove them or truncate them.
--
  Paul M. Aoki  |  CS Div., Dept. of EECS, UCB  |  aoki@postgres.Berkeley.EDU
                |  Berkeley, CA 94720           |  ...!uunet!ucbvax!aoki

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