Michael Paquier wrote: > Hi all, > > Today while playing with some queries I bumped into the following thing: > =# with count_query as (select generate_series(0,1) as a) select b > from count_query, generate_series(1, count_query.a) as b; > b > --- > 1 > (1 row) > =# with count_query as (select generate_series(0,1) as a) select b > from generate_series(1, count_query.a) as b, count_query; > ERROR: 42P01: missing FROM-clause entry for table "count_query" > LINE 1: ...eries(0,1) as a) select b from generate_series(1, count_quer... > ^ > LOCATION: errorMissingRTE, parse_relation.c:2850 > > I have been a little bit surprised by the fact that different entry > ordering in the FROM clause of the main query had different effects. > Perhaps there is something I am missing?
This seems natural to me -- in your second example, by the time you reference count_query it hasn't yet been declared and thus it's not available in the namespace. This is how I expect a LATERAL reference to work: a RTE can reference previous entries, but not ones that come later. (SRFs in FROM become lateral references automatically, as I recall. Without LATERAL, you wouldn't have been able to refer to count_query at all.) -- Álvaro Herrera http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
