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Thread: array_to_set functions

array_to_set functions

From
Decibel!
Date:
David Fetter and I just came up with these, perhaps others will find
them useful:

CREATE OR REPLACE FUNCTION array_to_set(anyarray, int) RETURNS SETOF anyelement LANGUAGE SQL AS $$
    SELECT $1[i] from generate_series(array_lower($1, $2), array_upper($1, $2)) i
$$;
CREATE OR REPLACE FUNCTION array_to_set(anyarray) RETURNS SETOF anyelement LANGUAGE SQL AS $$
    SELECT array_to_set($1, 1)
$$;
--
Decibel!, aka Jim Nasby                        decibel@decibel.org
EnterpriseDB      http://enterprisedb.com      512.569.9461 (cell)
Attachment

Re: array_to_set functions

From
"Merlin Moncure"
Date:
On 8/1/07, Decibel! <decibel@decibel.org> wrote:
> David Fetter and I just came up with these, perhaps others will find
> them useful:
>
> CREATE OR REPLACE FUNCTION array_to_set(anyarray, int) RETURNS SETOF anyelement LANGUAGE SQL AS $$
>     SELECT $1[i] from generate_series(array_lower($1, $2), array_upper($1, $2)) i
> $$;
> CREATE OR REPLACE FUNCTION array_to_set(anyarray) RETURNS SETOF anyelement LANGUAGE SQL AS $$
>     SELECT array_to_set($1, 1)
> $$;

very nice, although IMO there is a strong justification for these
functions to be in core and written in C for efficiency (along with
array_accum, which I have hand burn from copying and pasting out of
the documentation).

merlin

Re: array_to_set functions

From
Guy Fraser
Date:
On Wed, 2007-08-01 at 07:14 +0530, Merlin Moncure wrote:
> On 8/1/07, Decibel! <decibel@decibel.org> wrote:
> > David Fetter and I just came up with these, perhaps others will find
> > them useful:
> >
> > CREATE OR REPLACE FUNCTION array_to_set(anyarray, int) RETURNS SETOF anyelement LANGUAGE SQL AS $$
> >     SELECT $1[i] from generate_series(array_lower($1, $2), array_upper($1, $2)) i
> > $$;
> > CREATE OR REPLACE FUNCTION array_to_set(anyarray) RETURNS SETOF anyelement LANGUAGE SQL AS $$
> >     SELECT array_to_set($1, 1)
> > $$;
>
> very nice, although IMO there is a strong justification for these
> functions to be in core and written in C for efficiency (along with
> array_accum, which I have hand burn from copying and pasting out of
> the documentation).
>
> merlin
>
Excellent timing guys. :^)

I was trying to build a function to list the items of an array, but
ran into problems and was going to post what I had been working on.

Your functions work great.

In case you don't have the function to generate an array from a set
here is one I have been using :


CREATE AGGREGATE array_accum (
    BASETYPE = anyelement,
    SFUNC = array_append,
    STYPE = anyarray,
    INITCOND = '{}'
);


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--
Guy Fraser
Network Administrator
The Internet Centre
1-888-450-6787
(780)450-6787

Re: array_to_set functions

From
"Merlin Moncure"
Date:
On 8/3/07, Guy Fraser <guy@incentre.net> wrote:
> On Wed, 2007-08-01 at 07:14 +0530, Merlin Moncure wrote:
> > On 8/1/07, Decibel! <decibel@decibel.org> wrote:
> > > David Fetter and I just came up with these, perhaps others will find
> > > them useful:
> > >
> > > CREATE OR REPLACE FUNCTION array_to_set(anyarray, int) RETURNS SETOF anyelement LANGUAGE SQL AS $$
> > >     SELECT $1[i] from generate_series(array_lower($1, $2), array_upper($1, $2)) i
> > > $$;
> > > CREATE OR REPLACE FUNCTION array_to_set(anyarray) RETURNS SETOF anyelement LANGUAGE SQL AS $$
> > >     SELECT array_to_set($1, 1)
> > > $$;
> >
> > very nice, although IMO there is a strong justification for these
> > functions to be in core and written in C for efficiency (along with
> > array_accum, which I have hand burn from copying and pasting out of
> > the documentation).
> >
> > merlin
> >
> Excellent timing guys. :^)
>
> I was trying to build a function to list the items of an array, but
> ran into problems and was going to post what I had been working on.
>
> Your functions work great.
>
> In case you don't have the function to generate an array from a set
> here is one I have been using :
>
>
> CREATE AGGREGATE array_accum (
>     BASETYPE = anyelement,
>     SFUNC = array_append,
>     STYPE = anyarray,
>     INITCOND = '{}'
> );

I think that's what just about everyone uses.  Unfortunately the
reverse of the function (array_to_set above) AFAIK does not map
directly to the C array API.

merlin

Re: array_to_set functions

From
Decibel!
Date:
On Sun, Aug 05, 2007 at 08:18:08PM +0530, Merlin Moncure wrote:
> On 8/3/07, Guy Fraser <guy@incentre.net> wrote:
> > On Wed, 2007-08-01 at 07:14 +0530, Merlin Moncure wrote:
> > > On 8/1/07, Decibel! <decibel@decibel.org> wrote:
> > > > David Fetter and I just came up with these, perhaps others will find
> > > > them useful:
> > > >
> > > > CREATE OR REPLACE FUNCTION array_to_set(anyarray, int) RETURNS SETOF anyelement LANGUAGE SQL AS $$
> > > >     SELECT $1[i] from generate_series(array_lower($1, $2), array_upper($1, $2)) i
> > > > $$;
> > > > CREATE OR REPLACE FUNCTION array_to_set(anyarray) RETURNS SETOF anyelement LANGUAGE SQL AS $$
> > > >     SELECT array_to_set($1, 1)
> > > > $$;
> > >
> > > very nice, although IMO there is a strong justification for these
> > > functions to be in core and written in C for efficiency (along with
> > > array_accum, which I have hand burn from copying and pasting out of
> > > the documentation).
> > >
> > > merlin
> > >
> > Excellent timing guys. :^)
> >
> > I was trying to build a function to list the items of an array, but
> > ran into problems and was going to post what I had been working on.
> >
> > Your functions work great.
> >
> > In case you don't have the function to generate an array from a set
> > here is one I have been using :
> >
> >
> > CREATE AGGREGATE array_accum (
> >     BASETYPE = anyelement,
> >     SFUNC = array_append,
> >     STYPE = anyarray,
> >     INITCOND = '{}'
> > );
>
> I think that's what just about everyone uses.  Unfortunately the
> reverse of the function (array_to_set above) AFAIK does not map
> directly to the C array API.

Oh, cool, hadn't thought about using an aggregate to do this. That's
probably faster than what I came up with.
--
Decibel!, aka Jim Nasby                        decibel@decibel.org
EnterpriseDB      http://enterprisedb.com      512.569.9461 (cell)
Attachment

Re: array_to_set functions

From
Guy Fraser
Date:
On Tue, 2007-08-07 at 17:46 -0500, Decibel! wrote:
> On Sun, Aug 05, 2007 at 08:18:08PM +0530, Merlin Moncure wrote:
> > On 8/3/07, Guy Fraser <guy@incentre.net> wrote:
> > > On Wed, 2007-08-01 at 07:14 +0530, Merlin Moncure wrote:
> > > > On 8/1/07, Decibel! <decibel@decibel.org> wrote:
> > > > > David Fetter and I just came up with these, perhaps others will find
> > > > > them useful:
> > > > >
> > > > > CREATE OR REPLACE FUNCTION array_to_set(anyarray, int) RETURNS SETOF anyelement LANGUAGE SQL AS $$
> > > > >     SELECT $1[i] from generate_series(array_lower($1, $2), array_upper($1, $2)) i
> > > > > $$;
> > > > > CREATE OR REPLACE FUNCTION array_to_set(anyarray) RETURNS SETOF anyelement LANGUAGE SQL AS $$
> > > > >     SELECT array_to_set($1, 1)
> > > > > $$;
> > > >
> > > > very nice, although IMO there is a strong justification for these
> > > > functions to be in core and written in C for efficiency (along with
> > > > array_accum, which I have hand burn from copying and pasting out of
> > > > the documentation).
> > > >
> > > > merlin
> > > >
> > > Excellent timing guys. :^)
> > >
> > > I was trying to build a function to list the items of an array, but
> > > ran into problems and was going to post what I had been working on.
> > >
> > > Your functions work great.
> > >
> > > In case you don't have the function to generate an array from a set
> > > here is one I have been using :
> > >
> > >
> > > CREATE AGGREGATE array_accum (
> > >     BASETYPE = anyelement,
> > >     SFUNC = array_append,
> > >     STYPE = anyarray,
> > >     INITCOND = '{}'
> > > );
> >
> > I think that's what just about everyone uses.  Unfortunately the
> > reverse of the function (array_to_set above) AFAIK does not map
> > directly to the C array API.
>
> Oh, cool, hadn't thought about using an aggregate to do this. That's
> probably faster than what I came up with.
You are welcome. I am glad someone appreciated my gesture.