"Adam Pritchard" <vesper76@xxxxxxxxx> writes: > CREATE TABLE t ( c1 INT, c2 INT ); > CREATE INDEX c1_idx ON t(c2); > CREATE INDEX c2_idx ON t(c2); > EXPLAIN SELECT * FROM t ORDER BY c1, c2; > "Sort (cost=69.83..72.33 rows=1000 width=8)" > " Sort Key: c1, c2" > " -> Seq Scan on t (cost=0.00..20.00 rows=1000 width=8)" > If we instead use an index on c1, c2: > CREATE INDEX c1_c2_idx ON t(c1, c2); > "Index Scan using c1_c2_idx on t (cost=0.00..52.00 rows=1000 width=8)" The latter index matches the sort ordering requested by the query; no single-column index can do so. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
