Re: [HACKERS] Priorities for 6.6

>
> > In short, if you load a bunch of tuples into a table, the first select
> > after the load can run a lot slower than you might expect, because it'll
> > be writing back most or all of the pages it touches. But that penalty
> > doesn't affect every select, only the first one to scan a newly-written
> > tuple.
>
> I have removed this from the TODO list:
>
> * Prevent fsync in SELECT-only queries

I think this entry should stay.

In fact, there is a write on every transaction that
commits/aborts even if it's one that doesn't modify any data.
pg_log is written for SELECT only transactions too. I'm
nearly 99.5% sure that not fsync()'ing those transaction
would not hit reliability and we might have to work it out.

This might be one cause that surrounding a bunch of SELECT
statements by BEGIN/END speeds up PostgreSQL in non -F mode.

Jan

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