Re: Stopgap solution for table-size-estimate updatingproblem - Mailing list pgsql-hackers

From Zeugswetter Andreas DAZ SD
Subject Re: Stopgap solution for table-size-estimate updatingproblem
Date
Msg-id 46C15C39FEB2C44BA555E356FBCD6FA40184D250@m0114.s-mxs.net
Whole thread Raw
Responses Re: Stopgap solution for table-size-estimate updatingproblem
List 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


pgsql-hackers by date:

Previous
From: Andreas Pflug
Date:
Subject: Re: Error: column "nsptablespace" does not exist
Next
From: Tom Lane
Date:
Subject: Re: Stopgap solution for table-size-estimate updatingproblem