KuroiNeko wrote:
> > I wonder if there couldn't borrowed some code from Interbase which has
> > full featured stored procedures - at least it was told to me that it has
> > ...
>
> Well, I have some hands-on experience with IB, don't know whether this is
> perfectly relevant, but here goes....
> Indeed, stored procedures in IB can do what's called `returning record
> sets' in this thread. This is helpfull when tuples restriction is based
> upon condition that is not easy/possible to formulate in SQL (where
> clause). On the other hand, IB has two different ways to call an SP:
> execute procedure for `singleton' SPs and select for those returning
> multiple tuples.
> However, IB supports only its own SP language. It's pretty much complete
> and well thought and implemented, but if you want an SP in PERL, you're out
> of luck.
> What I'd really like to see is `pre-compiled' SPs in PGSQL. IB has this
> feature (SPs are converted to BLR when DDL statement is executed), not sure
> about PGSQL. I've noticed that language-specific errors in SPs are only
> reported by PGSQL when SP is executed, so I suggest that interpreter (eg
> for PL/PGSQL) is called each time.
Not entirely true.
PL/Tcl has "spi_exec" as well as "spi_prepare/spi_execp". A
function is only sourced into the interpreter once per
session (backend lifetime) and has a global upvar called GB
where it could store prepared plans at it's first call. Since
version 8.0 Tcl uses a bytecode compiler and will not
interpret the real source text again and again.
PL/pgSQL parses the entire function body at first call (per
backend). But the SPI querystrings for all the statements
aren't parsed at that time. It uses SPI_prepare() only for
expressions and queries that actually get executed, so that a
huge function that is called only once in a backend, erroring
out at the first IF, will not parse most of it's queries.
This is surely a win for performance, but it makes it
difficult to develop. This will change a little in the
future, but I do delay those changes because I think the
changes when tuple sets get supported will be huge anyway and
complicating the code now wouldn't help.
Jan
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