Re: [HACKERS] is 8.4 array_agg() supposed to work with array values?
Peter Eisentraut wrote: On Monday 19 January 2009 23:22:21 Todd A. Cook wrote: The docs at http://developer.postgresql.org/pgdocs/postgres/functions-aggregate.html don't prohibit using array values with array_arg(), so I assumed that it would work. test= select array_agg(v.a) from (values (array[1,2]), (array[3,4])) as v(a) ; ERROR: could not find array type for data type integer[] Yeah ... This is one of the weirdnesses of the PostgreSQL array implementation. integer[] and integer[][] etc. are actually the same type, just using a different number of dimensions internally. This would work much better if integer[][] where array of integer[], in the same way as integer[] is array of integer, in the way C deals with arrays. This is also a main reason why composite types and arrays don't mix orthogonally; there is no way to represent that in the system catalogs. To get back to your question, as far as array_agg() itself is concerned, it would probably work, but the rest of the sytem doesn't deal with it very well. You will probably be able to find a number of other places that break when trying to derive the array type from something that is already an array. Thanks for the clarification. -- todd -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] is 8.4 array_agg() supposed to work with array values?
On Tue, Jan 20, 2009 at 5:09 AM, Peter Eisentraut pete...@gmx.net wrote: This would work much better if integer[][] where array of integer[], in the same way as integer[] is array of integer, in the way C deals with arrays. Well the situation in C is substantially more complicated than you make out. I think the analogous situation in C is actually having an array of integer* pointing to separately allocated arrays. There are a number of places where Postgres has to special-case arrays and array references (think of update foo set bar[n] = baz for example) so I don't think it would work to just create the array type for integer[] either. -- greg -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] is 8.4 array_agg() supposed to work with array values?
On 1/20/09, Peter Eisentraut pete...@gmx.net wrote: integer[] is array of integer, in the way C deals with arrays. This is also a main reason why composite types and arrays don't mix orthogonally; there is no way to represent that in the system catalogs. What do you mean by this exactly? We've had arrays of composite types since 8.2. merlin -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] is 8.4 array_agg() supposed to work with array values?
On Tuesday 20 January 2009 18:09:51 Merlin Moncure wrote: On 1/20/09, Peter Eisentraut pete...@gmx.net wrote: integer[] is array of integer, in the way C deals with arrays. This is also a main reason why composite types and arrays don't mix orthogonally; there is no way to represent that in the system catalogs. What do you mean by this exactly? We've had arrays of composite types since 8.2. Yeah, the simple cases work. I meant it more in a general sense of structured and arbitrarily composed types. I'm also interested in multiset support, for example. Under the current arrangement, you couldn't really have array of multiset of array of something. -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] is 8.4 array_agg() supposed to work with array values?
On Monday 19 January 2009 23:22:21 Todd A. Cook wrote: The docs at http://developer.postgresql.org/pgdocs/postgres/functions-aggregate.html don't prohibit using array values with array_arg(), so I assumed that it would work. test= select array_agg(v.a) from (values (array[1,2]), (array[3,4])) as v(a) ; ERROR: could not find array type for data type integer[] Yeah ... This is one of the weirdnesses of the PostgreSQL array implementation. integer[] and integer[][] etc. are actually the same type, just using a different number of dimensions internally. This would work much better if integer[][] where array of integer[], in the same way as integer[] is array of integer, in the way C deals with arrays. This is also a main reason why composite types and arrays don't mix orthogonally; there is no way to represent that in the system catalogs. To get back to your question, as far as array_agg() itself is concerned, it would probably work, but the rest of the sytem doesn't deal with it very well. You will probably be able to find a number of other places that break when trying to derive the array type from something that is already an array. -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
