I'm trying to call MAX() on the first value of a multi-column index of a partitioned table and the planner is choosing to do a sequential scan instead of an index scan. Is there something I can do to fix this?
Here's a simplified version of our schema: CREATE TABLE data ( tutci DOUBLE PRECISION, tutcf DOUBLE PRECISION, value INTEGER ); CREATE TABLE data1 ( CHECK ( tutci >= 1000 AND tutci < 2000 ) ) INHERITS (data); CREATE TABLE data2 ( CHECK ( tutci >= 2000 AND tutci < 3000 ) ) INHERITS (data);
With the following indexes: CREATE INDEX data_tutc_index ON data(tutci, tutcf); CREATE INDEX data1_tutc_index ON data1(tutci, tutcf); CREATE INDEX data2_tutc_index ON data2(tutci, tutcf);
No data is stored in the parent table (only in the partitions) and the explain is as follows after doing a CLUSTER on the index and a VACUUM ANALYZE after populating with simple test data: EXPLAIN SELECT MAX(tutci) FROM data; QUERY PLAN ---------------------------------------------------------------------------- Aggregate (cost=408.53..408.54 rows=1 width=8) -> Append (cost=0.00..354.42 rows=21642 width=8) -> Seq Scan on data (cost=0.00..26.30 rows=1630 width=8) -> Seq Scan on data1 data (cost=0.00..164.11 rows=10011 width=8) -> Seq Scan on data2 data (cost=0.00..164.01 rows=10001 width=8)
