From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Jaime Casanova <systemguards(at)gmail(dot)com> |
Cc: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: get_rel_* functions in lsyscache.c |
Date: | 2005-06-25 14:40:02 |
Message-ID: | 21246.1119710402@sss.pgh.pa.us |
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Lists: | pgsql-hackers |
Jaime Casanova <systemguards(at)gmail(dot)com> writes:
> Hi, i have a doubt...
> it seems to me that the get_rel_* functions in lsyscache do the same as doing
> heap_open();
> Calling the appropiate macro Relation*
> heap_close();
> is there any difference between them? in wich situation is one better
> than the other?
The lsyscache functions are just notational convenience --- they're
shorter to write and easier to read than accessing the underlying
catalog entries for yourself. However, I'd usually only use them
to pull one or two items from a given catalog entries; if I need
several fields from the same catalog entry, I'd open the catalog
entry just once and grab the fields directly, to avoid multiple
cache searches.
regards, tom lane
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