Re: Craeteing sparse arrays

Peter Hunsberger <peter(dot)hunsberger(at)gmail(dot)com> writes:
> Is there any easy way to create sparse arrays with Postres?

Have you tried it?

regression=# create table foo (bar text[]);
CREATE TABLE
regression=# insert into foo (bar[3],bar[7]) values ( 'a', 'b');
INSERT 0 1
regression=# select * from foo;
bar
----------------------------
[3:7]={a,NULL,NULL,NULL,b}
(1 row)

In the last couple of releases, assigning to a nonexistent subscript
will fill nulls into positions between that and the existent ones,
so something like UPDATE foo SET bar[7] = 'b' will clearly do what
you want. The above syntax is less obvious but IIRC it's treated
as an assignment to bar[3] followed by an assignment to bar[7].

I wouldn't want to try working with very large arrays in PG, mind
you --- it's not terribly efficient with them.

regards, tom lane