[Xapian-discuss] xapian performance

[Olly Betts]

On Tue, Nov 14, 2006 at 02:55:27PM -0200, Fernando Nemec wrote:
> When I try to do a search with several phrased words like this:
> "ronaldo jogou somente trinta minutos ontem", the search time go very
> high. This example takes about 30 seconds in the first try. The very
> same search took < 700 ms on the first run and < 100 ms forth.

I'm not sure I understand the difference between "first try" and "first
run" here?

A phrase search where all the terms occur together in a lot of documents
but rarely as a phrase will be a slow case when searching from "cold"
(with none of the database in the cache).

30 seconds is worse than I'd expect though.  Even allowing for seeking
around, you can get a lot of data off a modern hard drive in 30 seconds!

There have been a couple of other reports of similar very slow search
times from cold in some cases, and I'm starting to wonder if there's a
bug which is causing us to read a lot more data than we need to or
something like that.  Let me take a look.

If it's phrase searching speed you're particularly trying to improve,
using flint should help, as should compacting the database before
searching it.

Cheers,
    Olly