Re: Checkpoint question

Zitat von Tom Lane <tgl@sss.pgh.pa.us>:
> Probably insufficient disk bandwidth.  If you have two drives available,
> try putting the WAL files (pg_xlog directory) on a different drive from
> the data files.  Assuming you have adequate RAM, updates will be mainly
> limited by writes to WAL, while checkpoint doesn't touch WAL and is all
> about pushing data from RAM to the data files.  So with a proper drive
> split, checkpoint really shouldn't affect update rate at all.  (It could
> affect the time for SELECT queries, if they need to fetch data that
> isn't in RAM, but that didn't seem to be your complaint.)
>
>             regards, tom lane
>
> ---------------------------(end of broadcast)---------------------------
> TIP 9: the planner will ignore your desire to choose an index scan if your
>       joining column's datatypes do not match
>
>
Can you specify more exactly what you mean with update rate? I moslty perform
inserts on the database (is that what you mean?).
Also I do not understand, why checkpoint does not touch WAL, but RAM. I thought
that a checkpoint reads the information from the WAL-Files and pushes these
information to the data files.

Thanks Andreas

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