Re: bad estimates - Mailing list pgsql-performance

From Christopher Kings-Lynne
Subject Re: bad estimates
Date
Msg-id 0bf301c36e05$a72f90b0$2800a8c0@mars
Whole thread Raw
In response to bad estimates / non-scanning aggregates  (Ken Geis <kgeis@speakeasy.org>)
List pgsql-performance
> > I went through the code (7.4 beta2) that estimates the cost of an index
> > scan path.  What I need to be sure of is that when running a query in
> > pgsql that uses only the columns that are in an index, the underlying
> > table need not be accessed.  I know that Oracle does this.

PostgreSQL absolutely does not do this.  It is also not possible to do this
due to MVCC.

Chris


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