Re: How do I bulk insert to a table without affecting read performance on that table?

On Jan 26, 2008 5:42 AM, growse <nabble(at)growse(dot)com> wrote:
>
>
>
> Scott Marlowe-2 wrote:
> >
> > On Jan 25, 2008 5:27 PM, growse <nabble(at)growse(dot)com> wrote:
> >>
> >> Hi,
> >>
> >> I've got a pg database, and a batch process that generates some metadata
> >> to
> >> be inserted into one of the tables. Every 15 minutes or so, the batch
> >> script
> >> re-calculates the meta data (600,000 rows), dumps it to file, and then
> >> does
> >> a TRUNCATE table followed by a COPY to import that file into the table.
> >>
> >> The problem is, that whilst this process is happening, other queries
> >> against
> >> this table time out. I've tried to copy into a temp table before doing an
> >> "INSERT INTO table (SELECT * FROM temp)", but the second statement still
> >> takes a lot of time and causes a loss of performance.
> >
> > Can you import to another table then
> >
> > begin;
> > alter table realtable rename to garbage;
> > alter table loadtable rename to realtable;
> > commit;
> >
> > ?
>
> This is a possibility. My question on this is that would an ALTER TABLE real
> RENAME TO garbage be faster than a DROP TABLE real?

I don't know. They're both pretty fast. I'd do a test, with parallel
contention on the table and see.