helpers to convert C types to postgres types (Array)
in [PgSql]
|
Prev: [HACKERS] [CFReview] Red-Black Tree
Next: [HACKERS] ordered aggregates using WITHIN GROUP (was Re: can somebodyexecute this query on Oracle 11.2g and send result?)
From: Merlin Moncure on 29 Jan 2010 09:19 On Fri, Jan 29, 2010 at 7:34 AM, Ivan Sergio Borgonovo <mail(a)webthatworks.it> wrote: > I'm still trying to collect all the bits to be able to read and > return several types of data in C functions. > > I'm looking for quick ways to deal with ArrayType. > > I'd expect some helper because these kind of operation should be > frequent and without any helper (function/macro) they really make > the code awful. > > Generally you work with C types that later you've to "convert" to > Postgres types. > > So for example you may have an array of int2 that then you've to > place into an ArrayType. > > I think there are 3 kinds of operation you may have to do: > > 1 You may have an already "formed" C array type and you'd just copy > it into an ArrayType > 2 You may know the # of elements of the C array type but you're > filling it an element at a time > 3 You don't know the number of elements in the array in advance so > you'd like to append to the ArrayType one element at a time > > 1 seems to require > - creating an array of Datum > - looping over the C array > - assign to each Datum element the "converted" C value > - construct_array the Postgres array > That's a pain. Any other way? macro? > > 2 Seems the easiest > > 3 ??? > Is there any function in postgres that let you append elements to > an ArrayType? well, you have the entire backend array api available. you can always call array_cat or array_push depending on how you want to do it. if you are worried about performance though the fastest way is going to be to collect your element datums in a vector and calling construct_array however. merlin -- Sent via pgsql-hackers mailing list (pgsql-hackers(a)postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers |