| From: | Thom Brown <thom(at)linux(dot)com> |
|---|---|
| To: | Stefan Keller <sfkeller(at)gmail(dot)com> |
| Cc: | pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Index containing records instead of pointers to the data? |
| Date: | 2011-09-18 20:21:52 |
| Message-ID: | CAA-aLv5LnrkfUQV1djitxV2vrsiBK=fRinKPn5cxyUey1+4w1g@mail.gmail.com |
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| Lists: | pgsql-performance |
On 18 September 2011 21:18, Stefan Keller <sfkeller(at)gmail(dot)com> wrote:
> Hi,
>
> Sorry if this is an odd question:
> I assume that Postgres indexes don't store records but only pointers
> to the data.
> This means, that there is always an additional access needed (real table I/O).
> Would an index containing data records make sense?
Yes, it's called a covering index, where the data required to produce
results for the query are entirely contained in the index. That
should be hopefully coming in 9.2.
See http://wiki.postgresql.org/wiki/Index-only_scans
--
Thom Brown
Twitter: @darkixion
IRC (freenode): dark_ixion
Registered Linux user: #516935
EnterpriseDB UK: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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