Re: WIP: preloading of ispell dictionary

2010/3/24 Craig Ringer <craig@postnewspapers.com.au>:
> Pavel Stehule wrote:
>
>> Personally I dislike idea some dictionary precompiler - it is next
>> application for maintaining and maybe not necessary.
>
> That's the sort of thing that can be done when first required by any
> backend and the results saved in a file for other backends to mmap().
> It'd probably want to be opened r/w access-exclusive initially, then
> re-opened read-only access-shared when ready for use.
>
> My only concern would be that the cache would want to be forcibly
> cleared at postmaster start, so that "restart the postmaster" fixes any
> messsed-up-cache issues that might arise (not that they should) without
> people having to go rm'ing in the datadir. Even if Pg never has any bugs
> that result in bad cache files, the file system / bad memory / cosmic
> rays / etc can still mangle a cache file.
>
> BTW, mmap() isn't an issue on Windows:
>  http://msdn.microsoft.com/en-us/library/aa366556%28VS.85%29.aspx
> It's spelled CreateFileMapping, but otherwise is fairly similar, and is
> perfect for this sort of use.
>
> A shared read-only mapping of processed-and-cached tsearch2 dictionaries
> would save a HUGE amount of memory if many backends were using tsearch2
> at the same time. I'd make a big difference here.
>

If you know this area well, please, enhance my first patch. I am not
able to oppose to Tom, who has a clean opinion on this patch :(

Pavel


> --
> Craig Ringer
>