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Re: Stopgap solution for table-size-estimate updatingproblem

From: "Zeugswetter Andreas DAZ SD" <ZeugswetterA(at)spardat(dot)at>
To: "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: "Simon Riggs" <simon(at)2ndquadrant(dot)com>,<pgsql-hackers(at)postgreSQL(dot)org>
Subject: Re: Stopgap solution for table-size-estimate updatingproblem
Date: 2004-11-29 16:30:18
Message-ID: 46C15C39FEB2C44BA555E356FBCD6FA40184D250@m0114.s-mxs.net (view raw or flat)
Thread:
Lists: pgsql-hackers
>> This is not true in my case, since I only "update statistics"/analyze
>> when the tables have representative content (i.e. not empty).
> 
> I'm unsure why you feel you need a knob to defeat this.  The only time
> when the plan would change from what you think of as the hand-tuned
> case is when the physical table size is greatly different from what it
> was when you analyzed.

Ok, understood. I just need to make sure I don't "vacuum full" in that case,
which is good anyway if I expect the table to soon grow to this size again.
I think that is good. 

I think I recall that lseek may have a negative effect on some OS's readahead 
calculations (probably only systems that cannot handle an lseek to the next page 
eighter) ? Do you think we should cache the last value to avoid the syscall ?

Andreas

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Subject: Re: Stopgap solution for table-size-estimate updatingproblem
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