Hi all!
I have problems getting PG to use an index when sorting.
I have a simple table
create table person(
id serial primary key,
firstname varchar,
lastname varchar
);
I create an index:
CREATE INDEX person_lowerfullname_idx ON
person((lower(COALESCE(firstname, '')) || lower(COALESCE(lastname, '')))
varchar_pattern_ops);
And this query refuses to use that index:
select id from person order by (lower(COALESCE(firstname, '')) ||
lower(COALESCE(lastname, ''))) ASC limit 1;
If I add an index:
CREATE INDEX person_lowerfirstname_idx ON person(lower(firstname));
The following query will use that index for sorting and cut-off:
select id from person order by (lower(firstname) ) ASC limit 1;
Any hints or explaination on why the "concat-index" won't be used?
PS: I have tried to issue a "set enable_seqscan to off;" to ensure that it
will use an index if one appropriate exists
--
Andreas Joseph Krogh <[EMAIL PROTECTED]>
Senior Software Developer / Manager
------------------------+---------------------------------------------+
OfficeNet AS | The most difficult thing in the world is to |
Karenslyst Allé 11 | know how to do a thing and to watch |
PO. Box 529 Skøyen | somebody else doing it wrong, without |
0214 Oslo | comment. |
NORWAY | |
Tlf: +47 24 15 38 90 | |
Fax: +47 24 15 38 91 | |
Mobile: +47 909 56 963 | |
------------------------+---------------------------------------------+
---------------------------(end of broadcast)---------------------------
TIP 7: You can help support the PostgreSQL project by donating at
http://www.postgresql.org/about/donate
