Re: WIP: shared ispell dictionary

Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>

From: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
To: Pavel Stehule <pavel.stehule@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@postgresql.org>, Teodor Sigaev <teodor@sigaev.ru>
Date: 2010-03-18T11:45:55Z
Lists: pgsql-hackers
Pavel Stehule wrote:
> attached patch add possibility to share ispell dictionary between
> processes. The reason for this is the slowness of first tsearch query
> and size of allocated memory per process. When I tested loading of
> ispell dictionary (for Czech language) I got about 500 ms and 48MB.
> With simple allocator it uses only 25 MB. If we remove some check and
> tolower string transformation from loading stage it needs only 200 ms.
> But with broken dict or affix file it can put wrong results. This
> patch significantly reduce load on servers that use ispell
> dictionaries.
> 
> I know so Tom worries about using of share memory. I think so it
> unnecessarily. After loading data from dictionary are only read, never
> modified. Second idea - this dictionary template can be distributed as
> separate project (it needs a few changes in core - and simple
> allocator).

Fixed-size shared memory blocks are always problematic. Would it be
possible to do the preloading with shared_preload_libraries somehow?

-- 
  Heikki Linnakangas
  EnterpriseDB   http://www.enterprisedb.com