Re: WIP: shared ispell dictionary

2010/3/18 Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>:
> 2010/3/18 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
>> Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> writes:
>>> I know so Tom worries about using of share memory.
>>
>> You're right, and if I have any say in the matter no patch like this
>> will ever go in.
>>
>> What I would suggest looking into is some way of preprocessing the raw
>> text dictionary file into a format that can be slurped into memory
>> quickly.  The main problem compared to the way things are done now
>> is that the current internal format relies heavily on pointers.
>> Maybe you could replace those by offsets?
>
> You have to maintain a new application :( There can be a new kind of bugs.
>
> I playing with preload solution now. And I found a new issue.
>
> I don't know why, but when I preload library with large mem like
> ispell, then all next operations are ten times slower :(
>

this strange issue is from very large memory context. When I don't
join tseach cached context with working context, then this issue
doesn't exists.

Datum
dpreloaddict_init(PG_FUNCTION_ARGS)
{

<------>if (prepd == NULL)
<------><------>return dispell_init(fcinfo); // use without preloading
<------>else
<------>{
<------>
<------><------>//return PointerGetDatum(prepd);
<------><------>/*.
<------><------> * Add preload context to current conntext -- when
this code is active, then I have a issue
<------><------> */
<------><------>preload_ctx->parent = CurrentMemoryContext;
<------><------>preload_ctx->nextchild = CurrentMemoryContext->firstchild;
<------><------>CurrentMemoryContext->firstchild = preload_ctx;
<------><------>
<------><------>return PointerGetDatum(prepd);
<------>}
}

Pavel

>
> When I reduce memory with simple allocator, then this issue is
> removed, but it is strange.
>
> Pavel
>
>
>>
>>                        regards, tom lane
>>
>