Re: WIP: preloading of ispell dictionary

From: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
To: Nicolas Barbier <nicolas(dot)barbier(at)gmail(dot)com>
Cc: PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: WIP: preloading of ispell dictionary
Date: 2010-03-23 08:04:50
Message-ID: 162867791003230104p6ff8d946yd6b97c47f660fc6c@mail.gmail.com
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2010/3/23 Nicolas Barbier <nicolas(dot)barbier(at)gmail(dot)com>:
> 2010/3/23 Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>:
>
>> 2010/3/23 Takahiro Itagaki <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp>:
>>
>>> The fundamental issue seems to be in the slow initialization of
>>> dictionaries. If so, how about adding a pre-complile tool to convert
>>> a dictionary into a binary file, and each backend simply mmap it?
>>
>> It means loading about 25MB from disc. for every first tsearch query -
>> sorry, I don't believe can be good.
>
> The operating system's VM subsystem should make that a non-problem.
> "Loading" is also not the word I would use to indicate what mmap does.

Maybe we can do some manipulation inside memory - I have not any
knowledges about mmap. With Simple Allocator we can have a dictionary
data as one block. Problems are a pointers, but I believe so can be
replaced by offsets.

Personally I dislike idea some dictionary precompiler - it is next
application for maintaining and maybe not necessary. And still you
need a next application for loading.

p.s. I able to serialise czech dictionary, because it use only simply regexp.

Pavel

>
> Nicolas
>

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