CREATE TABLE parent(ts timestamptz, i int, n numeric, s text) PARTITION BY RANGE (ts); -- row partitions CREATE TABLE p0 PARTITION OF parent FOR VALUES FROM ('2020-01-01') TO ('2020-02-01'); CREATE TABLE p1 PARTITION OF parent FOR VALUES FROM ('2020-02-01') TO ('2020-03-01'); CREATE TABLE p2 PARTITION OF parent FOR VALUES FROM ('2020-03-01') TO ('2020-04-01'); CREATE TABLE p3 PARTITION OF parent FOR VALUES FROM ('2020-04-01') TO ('2020-05-01'); INSERT INTO parent SELECT '2020-01-15', 10, 100, 'one thousand' FROM generate_series(1,100000); INSERT INTO parent SELECT '2020-02-15', 20, 200, 'two thousand' FROM generate_series(1,100000); INSERT INTO parent SELECT '2020-03-15', 30, 300, 'three thousand' FROM generate_series(1,100000); INSERT INTO parent SELECT '2020-04-15', 30, 300, 'three thousand' FROM generate_series(1,100000); -- run parallel plans SET force_parallel_mode = regress; SET min_parallel_table_scan_size = 1; SET parallel_tuple_cost = 0; SET max_parallel_workers = 4; SET max_parallel_workers_per_gather = 4; EXPLAIN (costs off) SELECT count(*), sum(i), min(i), max(i) FROM parent; QUERY PLAN --------------------------------------------------------------------- Finalize Aggregate -> Gather Workers Planned: 4 -> Partial Aggregate -> Parallel Append -> Parallel Seq Scan on p0 -> Parallel Seq Scan on p1 -> Parallel Seq Scan on p2 -> Parallel Seq Scan on p3 (9 rows) SELECT count(*), sum(i), min(i), max(i) FROM parent; count | sum | min | max --------------------------------------------------------------------- 400000 | 9000000 | 10 | 30 (1 row) -- set older partitions as columnar SELECT alter_table_set_access_method('p0','columnar'); NOTICE: creating a new table for public.p0 NOTICE: Moving the data of public.p0 NOTICE: Dropping the old public.p0 NOTICE: Renaming the new table to public.p0 alter_table_set_access_method --------------------------------------------------------------------- (1 row) SELECT alter_table_set_access_method('p1','columnar'); NOTICE: creating a new table for public.p1 NOTICE: Moving the data of public.p1 NOTICE: Dropping the old public.p1 NOTICE: Renaming the new table to public.p1 alter_table_set_access_method --------------------------------------------------------------------- (1 row) SELECT alter_table_set_access_method('p3','columnar'); NOTICE: creating a new table for public.p3 NOTICE: Moving the data of public.p3 NOTICE: Dropping the old public.p3 NOTICE: Renaming the new table to public.p3 alter_table_set_access_method --------------------------------------------------------------------- (1 row) -- should also be parallel plan EXPLAIN (costs off) SELECT count(*), sum(i), min(i), max(i) FROM parent; QUERY PLAN --------------------------------------------------------------------- Finalize Aggregate -> Gather Workers Planned: 4 -> Partial Aggregate -> Parallel Append -> Custom Scan (ColumnarScan) on p3 -> Custom Scan (ColumnarScan) on p0 -> Custom Scan (ColumnarScan) on p1 -> Parallel Seq Scan on p2 (9 rows) SELECT count(*), sum(i), min(i), max(i) FROM parent; count | sum | min | max --------------------------------------------------------------------- 400000 | 9000000 | 10 | 30 (1 row) -- and also parallel without custom scan SET columnar.enable_custom_scan = FALSE; EXPLAIN (costs off) SELECT count(*), sum(i), min(i), max(i) FROM parent; QUERY PLAN --------------------------------------------------------------------- Finalize Aggregate -> Gather Workers Planned: 4 -> Partial Aggregate -> Parallel Append -> Seq Scan on p0 -> Seq Scan on p1 -> Seq Scan on p3 -> Parallel Seq Scan on p2 (9 rows) SELECT count(*), sum(i), min(i), max(i) FROM parent; count | sum | min | max --------------------------------------------------------------------- 400000 | 9000000 | 10 | 30 (1 row) SET columnar.enable_custom_scan TO DEFAULT; SET force_parallel_mode TO DEFAULT; SET min_parallel_table_scan_size TO DEFAULT; SET parallel_tuple_cost TO DEFAULT; SET max_parallel_workers TO DEFAULT; SET max_parallel_workers_per_gather TO DEFAULT; DROP TABLE parent; -- -- Test inheritance -- CREATE TABLE i_row(i int); INSERT INTO i_row VALUES(100); CREATE TABLE i_col(i int) USING columnar; INSERT INTO i_col VALUES(200); CREATE TABLE ij_row_row(j int) INHERITS(i_row); INSERT INTO ij_row_row VALUES(300, 1000); CREATE TABLE ij_row_col(j int) INHERITS(i_row) USING columnar; INSERT INTO ij_row_col VALUES(400, 2000); CREATE TABLE ij_col_row(j int) INHERITS(i_col); INSERT INTO ij_col_row VALUES(500, 3000); CREATE TABLE ij_col_col(j int) INHERITS(i_col) USING columnar; INSERT INTO ij_col_col VALUES(600, 4000); EXPLAIN (costs off) SELECT * FROM i_row; QUERY PLAN --------------------------------------------------------------------- Append -> Seq Scan on i_row -> Seq Scan on ij_row_row -> Custom Scan (ColumnarScan) on ij_row_col (4 rows) SELECT * FROM i_row; i --------------------------------------------------------------------- 100 300 400 (3 rows) EXPLAIN (costs off) SELECT * FROM ONLY i_row; QUERY PLAN --------------------------------------------------------------------- Seq Scan on i_row (1 row) SELECT * FROM ONLY i_row; i --------------------------------------------------------------------- 100 (1 row) EXPLAIN (costs off) SELECT * FROM i_col; QUERY PLAN --------------------------------------------------------------------- Append -> Custom Scan (ColumnarScan) on i_col -> Seq Scan on ij_col_row -> Custom Scan (ColumnarScan) on ij_col_col (4 rows) SELECT * FROM i_col; i --------------------------------------------------------------------- 200 500 600 (3 rows) EXPLAIN (costs off) SELECT * FROM ONLY i_col; QUERY PLAN --------------------------------------------------------------------- Custom Scan (ColumnarScan) on i_col (1 row) SELECT * FROM ONLY i_col; i --------------------------------------------------------------------- 200 (1 row) EXPLAIN (costs off) SELECT * FROM ij_row_row; QUERY PLAN --------------------------------------------------------------------- Seq Scan on ij_row_row (1 row) SELECT * FROM ij_row_row; i | j --------------------------------------------------------------------- 300 | 1000 (1 row) EXPLAIN (costs off) SELECT * FROM ij_row_col; QUERY PLAN --------------------------------------------------------------------- Custom Scan (ColumnarScan) on ij_row_col (1 row) SELECT * FROM ij_row_col; i | j --------------------------------------------------------------------- 400 | 2000 (1 row) EXPLAIN (costs off) SELECT * FROM ij_col_row; QUERY PLAN --------------------------------------------------------------------- Seq Scan on ij_col_row (1 row) SELECT * FROM ij_col_row; i | j --------------------------------------------------------------------- 500 | 3000 (1 row) EXPLAIN (costs off) SELECT * FROM ij_col_col; QUERY PLAN --------------------------------------------------------------------- Custom Scan (ColumnarScan) on ij_col_col (1 row) SELECT * FROM ij_col_col; i | j --------------------------------------------------------------------- 600 | 4000 (1 row) SET columnar.enable_custom_scan = FALSE; EXPLAIN (costs off) SELECT * FROM i_row; QUERY PLAN --------------------------------------------------------------------- Append -> Seq Scan on i_row -> Seq Scan on ij_row_row -> Seq Scan on ij_row_col (4 rows) SELECT * FROM i_row; i --------------------------------------------------------------------- 100 300 400 (3 rows) EXPLAIN (costs off) SELECT * FROM ONLY i_row; QUERY PLAN --------------------------------------------------------------------- Seq Scan on i_row (1 row) SELECT * FROM ONLY i_row; i --------------------------------------------------------------------- 100 (1 row) EXPLAIN (costs off) SELECT * FROM i_col; QUERY PLAN --------------------------------------------------------------------- Append -> Seq Scan on i_col -> Seq Scan on ij_col_row -> Seq Scan on ij_col_col (4 rows) SELECT * FROM i_col; i --------------------------------------------------------------------- 200 500 600 (3 rows) EXPLAIN (costs off) SELECT * FROM ONLY i_col; QUERY PLAN --------------------------------------------------------------------- Seq Scan on i_col (1 row) SELECT * FROM ONLY i_col; i --------------------------------------------------------------------- 200 (1 row) EXPLAIN (costs off) SELECT * FROM ij_row_row; QUERY PLAN --------------------------------------------------------------------- Seq Scan on ij_row_row (1 row) SELECT * FROM ij_row_row; i | j --------------------------------------------------------------------- 300 | 1000 (1 row) EXPLAIN (costs off) SELECT * FROM ij_row_col; QUERY PLAN --------------------------------------------------------------------- Seq Scan on ij_row_col (1 row) SELECT * FROM ij_row_col; i | j --------------------------------------------------------------------- 400 | 2000 (1 row) EXPLAIN (costs off) SELECT * FROM ij_col_row; QUERY PLAN --------------------------------------------------------------------- Seq Scan on ij_col_row (1 row) SELECT * FROM ij_col_row; i | j --------------------------------------------------------------------- 500 | 3000 (1 row) EXPLAIN (costs off) SELECT * FROM ij_col_col; QUERY PLAN --------------------------------------------------------------------- Seq Scan on ij_col_col (1 row) SELECT * FROM ij_col_col; i | j --------------------------------------------------------------------- 600 | 4000 (1 row) SET columnar.enable_custom_scan TO DEFAULT; DROP TABLE i_row CASCADE; NOTICE: drop cascades to 2 other objects DETAIL: drop cascades to table ij_row_row drop cascades to table ij_row_col DROP TABLE i_col CASCADE; NOTICE: drop cascades to 2 other objects DETAIL: drop cascades to table ij_col_row drop cascades to table ij_col_col