Tom Lane wrote:
It seemed reasonable to me that a select on the first element of an
array column could use an index on the column, but, as seen in this
example, I can't get it to do so:
Nope. The operators that go along with a btree index are equality,
less than, etc on the whole indexed column. btree knows nothing
about extracting array elements.
I guess I was working by analogy with queries like this:
select * from someTable where textColumn like 'foo%';
This will happily use an ordinary btree index on textColumn, right?
(Although I know it's only for the C locale with the default op
class.) Anyway, I guess this is a far more common case than matching
the prefix of an array. Like another poster suggested, I can have an
additional expression index on the first element of my array column.
- John Burger
MITRE
---------------------------(end of broadcast)---------------------------
TIP 4: Have you searched our list archives?
http://archives.postgresql.org/
