Re: What is wrong with hashed index usage?

Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> <para>
> ! Because of the limited utility of hash indexes, a B-tree index
> ! should generally be preferred over a hash index. We do not have
> ! sufficient evidence that hash indexes are actually faster than
> ! B-trees even for <literal>=</literal> comparisons. Moreover,
> ! hash indexes require coarser locks; see <xref
> ! linkend="locking-indexes">.
> </para>
> </note>
> </para>
> --- 181,189 ----
> </synopsis>
> <note>
> <para>
> ! Testing has shown that hash indexes are slower than btree indexes,
> ! and the size and build time for hash indexes is much worse. For
> ! these reasons, hash index use is discouraged.

This change strikes me as a step backwards. The existing wording tells
the truth; the proposed revision removes the facts in favor of a blanket
assertion that is demonstrably false.

regards, tom lane