Re: Which indexes to drop

From: Ron Johnson <ron(dot)l(dot)johnson(at)cox(dot)net>
To: PgSQL Novice ML <pgsql-novice(at)postgresql(dot)org>
Subject: Re: Which indexes to drop
Date: 2002-06-19 10:35:38
Message-ID: 1024482938.13457.16.camel@rebel
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On Wed, 2002-06-19 at 03:24, John Taylor wrote:
> On Tuesday 18 June 2002 23:51, Ron Johnson wrote:
> > On Tue, 2002-06-18 at 10:36, Josh Berkus wrote:
> > > John,
> > >
> > > > I'm optimising my data load by dropping indexes.
> > > >
> > > > My question is, what do I do with the indexes created by postgres for
> > > > primary keys ?
> > > >
> > > > Is it OK to drop them ?
> > >
> > > No.
> >
> > I've done it many times...
> >
> > alter table t_lane_tx
> > add constraint c_lane_tx_pk primary key (lane_tx_id);
> >
> > > > How do I create them again afterwards, so that they are used
> > > > correctly for constraint checking ?
> >
> > In this instance, you can have speed or you can have correctness.
> > Pick one. Of course, if you know that your input data is good,
> > you have both...
> >
>
> I think I'm going to assume that my data is good, otherwise the load will take about 30 hours !
>
> So do I need to:
> remove the constraint

Creating a PK constraint implicitly creates an index with the
same name. So, drop the "same named" index and the PK constraint
will go away...

> load
> add the constraint
> or
> drop index

See above...

> load
> add the constraint
>
>
> ie:
> Will removing the constraint automatically drop the index
>
> Will dropping the index remove the constraint

The docs are pretty clear about it...

--
+-------------------------------------------------------------+
| Ron Johnson, Jr. Home: ron(dot)l(dot)johnson(at)cox(dot)net |
| Jefferson, LA USA http://ronandheather.dhs.org:81 |
| |
| "Object-oriented programming is an exceptionally bad idea |
| which could only have originated in California." |
| --Edsger Dijkstra |
+-------------------------------------------------------------+

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