memory dilemma

Hi,

I have dilemma with PG's memory. I'am finishing with to_char()
implementation and I try use internal cache buffer in this routines.
This cache is used if a to_char() format-picture (which going to the
internal to_char parser) is equal as previous and to_char's parser is
skiped. It is very good, because speed rise (20%).

A problem is how implement this cache:

via palloc - It is standard in PG, but it is problem, because
memory contents is not persisten across transactions. And
I don't know how check when memory is free (lose) and a routine
must reallocs memory again (if transaction finish PG memory
management not zeroizing (reset) memory and any "if( buffer )"
still affects as good memory).

via malloc - (Now used). It is good, because buffer is persistent.
This variant is (example) use in regexp utils in PG now.
But is it nice?

via a static buffer - but how long? Terrible. Or set any default
size for this buffer, and if format-picture will bigger - use
pallocated memory and not use cache buffer. (It is my favourite
variant.)

not use cache - hmm.. but I like fast routines (my current
to_char() implementation is faster (20-50%) than current
date_part()).

Any idea? Please.

Karel

PS. IMHO - add to PostgreSQL any *across transactions persistent*
memory managemet?

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Karel Zak <zakkr(at)zf(dot)jcu(dot)cz> http://home.zf.jcu.cz/~zakkr/

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