The Postgres 9 docs state:
38.5.3. Executing a Query with a Single-Row Result
SELECT select_expressions INTO [STRICT] target FROM
...; ....(doc'd othe details)...
then target will be set to the first row returned by the query.... Any result rows after the first row are discarded.
My question is: are the rows discarded or is there really an implicit
LIMIT 1 would not improve the performance of
SELECT INTO returning many rows, or would it?