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?

--
regards,
Jaime Casanova
(DBA: DataBase Aniquilator

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Jaime Casanova <systemguards@gmail.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

---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match