Apologies, as usual I didn't read the docs carefully enough.
On Tue, May 17, 2016 at 7:13 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
Shay Rojansky <roji@roji.org> writes: > A user of mine just raised a strange issue... While it is possible to use a > parameter in a LIMIT clause, PostgreSQL does not seem to allow using one in > a FETCH NEXT clause. In other words, while the following works: > SELECT 1 LIMIT $1; > The following generates a syntax error: > SELECT 1 FETCH NEXT $1 ROWS ONLY; > Since LIMIT and FETCH NEXT are supposed to be equivalent this behavior is > odd.
Per the SELECT reference page:
SQL:2008 introduced a different syntax to achieve the same result, which PostgreSQL also supports. It is:
OFFSET start { ROW | ROWS } FETCH { FIRST | NEXT } [ count ] { ROW | ROWS } ONLY
In this syntax, to write anything except a simple integer constant for start or count, you must write parentheses around it.
The comments about this in gram.y are informative:
* Allowing full expressions without parentheses causes various parsing * problems with the trailing ROW/ROWS key words. SQL only calls for * constants, so we allow the rest only with parentheses. If omitted, * default to 1.
