Re: Deprecating Hash Indexes

On Monday, October 15, 2012 08:14:51 PM Josh Berkus wrote:
> > * Put WARNINGs in the docs against the use of hash indexes, backpatch
> > to 8.3. CREATE INDEX gives no warning currently, though Index Types
> > does mention a caution.
>
> I'd be in favor of a warning on create index.
>
> Also, are hash indexes replicated?

No. As they aren't WAL logged they can't be transported via wal based
replication (PITR/HS/SR). Which rather quickly results in a very broken setup,
there has been at least one bug on -bugs because of this and there have been
several people in the irc channel experiencing this.

> > * Mention in the current docs that hash indexes are likely to be
> > deprecated completely in future releases. Should anybody ever make
> > them work, we can change that advice quickly but I don't think we're
> > going to.
>
> I'm not sure that's true, necessarily. The nice thing about work on
> hash indexes is that it's potentially rather self-contained, i.e. a good
> GSOC project. However ...

While self contained I fear you still need quite a bit more knowledge than
usual students have.

Greetings,

Andres
--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services