On Wed, 21 Apr 2004 vinayj@ncst.ernet.in wrote:
> Hi
> I am working on a project in postgres..in which i designed customized data type
> and operations on it.it requires a look up table..
> I have three options regarding this table...
> 1. Every time a query is executed it creates table assigns values and after
> execution destroys it...which is overhead..
>
> 2. store table on disk in database and access it whenever required but it
> degrades the performance
>
> 3. whenever psql starts it can load the table in memory from database which is
> efficient way to do
PostgreSQL has no facility to put tables into memory.
Assuming this lookup table will be hit quite often, it WILL be in memory
for selects. updates / deletes / inserts will have to get flushed out to
disk of course.
the Linux and BSD kernels are both quite good at keeping commonly used
data in memory. I think you are mistaken in assuming that an "on disk"
table will be significantly slower than if it was fixed in memory due to
the very efficient cachine of the most common unix kernels.