Re: possible TODO: read-only tables, select from indexes only. - Mailing list pgsql-hackers

From Tom Lane
Subject Re: possible TODO: read-only tables, select from indexes only.
Date
Msg-id 23818.1114299231@sss.pgh.pa.us
Whole thread Raw
In response to Re: possible TODO: read-only tables, select from indexes only.  (Alvaro Herrera <alvherre@dcc.uchile.cl>)
List pgsql-hackers
Alvaro Herrera <alvherre@dcc.uchile.cl> writes:
> One idea that may be closer to reality might be implementing heaps that
> behave as indexes (or indexes that behave as heaps), or clustered
> indexes as some other database call them; the main idea being that at
> the leaf nodes of the index, the whole heap tuple resides instead of
> only a CTID.

The main problem with this is that you'd not have a stable TID for a
given tuple, since it might be forced to move by operations such as
index page splits.  It might be impractical to support any secondary
indexes on such a table --- but I can definitely see that there are
applications that wouldn't care.

> One problem I see with that approach is the maximum tuple size ... our
> current btree index code can't handle tuples bigger than (BLCKSZ/3)
> IIRC, some 2 kB.

So you toast 'em ... I don't see this as a fatal drawback.
        regards, tom lane


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