Variable substitution with psql

Updated: Thanks @johto for s/:bar/:foo/. :)

A coworker asked about variable substitution with psql using \set, and so I looked into it a bit further.

You definitely can do things like this:

16:55 sdeckelmann@[local]:5432|postgres=> \set test 'select * from :foo limit 10;'
16:56 sdeckelmann@[local]:5432|postgres=> \set foo 'test'
16:56 sdeckelmann@[local]:5432|postgres=> :test
myint
-------
1
2
3
4
5
6
7
8
9
10
(10 rows)

But, what about something like this:


=> \set test 'select * from :var limit 10;'
=> :test mytable

Unfortunately, this isn’t supported.

The best you could do is something pathological like:

=> \set s 'select * from '
=> \set pr ' limit 10;'
=> :s mytable :pr
=> :s test :pr
myint
-------
1
2
3
4
5
6
7
8
9
10
(10 rows)