mirror of
https://github.com/timescale/timescaledb.git
synced 2025-05-16 02:23:49 +08:00
cf009cc584
Hash partitioning previously relied on coercing (casting) values to strings before calculating a hash value, including creating CHECK constraints with casts. This approach is fairly suboptimal from a performance perspective and might have issues related to different character encodings depending on system. Hash partitioning now instead uses a partitioning function that takes an anyelement type that calls type-dependent hash functions internal to PostgreSQL. This should provide more efficient hashing both by avoiding unnecessary string conversions and by using more optimal type-specific hash functions. Support for the previous hash partitioning function is preserved for backwards compatibility. Hypertables created with the previous function will continue to use to old hashing strategy, while new tables will default to the updated hash partitioning. For safety, this change also blocks changing types on hash-partitioned columns, since it seems hard to guarantee the same hash result between different types.
67 lines
2.6 KiB
SQL
67 lines
2.6 KiB
SQL
--
|
|
-- This test will create chunks in two dimenisions, time (x) and
|
|
-- space (y), where the time dimension is aligned. The figure below
|
|
-- shows the expected result. The chunk number in the figure
|
|
-- indicates the creation order.
|
|
--
|
|
-- +
|
|
-- +
|
|
-- + +-----+ +-----+
|
|
-- + | 2 | | 3 |
|
|
-- + | +---+-+ |
|
|
-- + +-----+ 5 |6+-----+
|
|
-- + | 1 +---+-+-----+ +---------+
|
|
-- + | | |4| 7 | | 8 |
|
|
-- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
|
|
-- 0 5 10 15 20
|
|
--
|
|
-- Partitioning:
|
|
--
|
|
-- Chunk # | time | space
|
|
-- 1 | 3 | 2
|
|
-- 4 | 1 | 3
|
|
-- 5 | 5 | 3
|
|
--
|
|
|
|
CREATE TABLE chunk_test(time integer, temp float8, tag integer, color integer);
|
|
|
|
SELECT create_hypertable('chunk_test', 'time', 'tag', 2, chunk_time_interval => 3);
|
|
|
|
INSERT INTO chunk_test VALUES (4, 24.3, 1, 1);
|
|
|
|
SELECT * FROM _timescaledb_catalog.dimension_slice;
|
|
|
|
INSERT INTO chunk_test VALUES (4, 24.3, 2, 1);
|
|
INSERT INTO chunk_test VALUES (10, 24.3, 2, 1);
|
|
|
|
SELECT c.table_name AS chunk_name, d.id AS dimension_id, ds.id AS slice_id, range_start, range_end FROM _timescaledb_catalog.chunk c
|
|
LEFT JOIN _timescaledb_catalog.chunk_constraint cc ON (c.id = cc.chunk_id)
|
|
LEFT JOIN _timescaledb_catalog.dimension_slice ds ON (ds.id = cc.dimension_slice_id)
|
|
LEFT JOIN _timescaledb_catalog.dimension d ON (d.id = ds.dimension_id)
|
|
LEFT JOIN _timescaledb_catalog.hypertable h ON (d.hypertable_id = h.id)
|
|
WHERE h.schema_name = 'public' AND h.table_name = 'chunk_test'
|
|
ORDER BY c.id, d.id;
|
|
|
|
\c single :ROLE_SUPERUSER
|
|
UPDATE _timescaledb_catalog.dimension SET num_slices = 3 WHERE id = 2;
|
|
\c single :ROLE_DEFAULT_PERM_USER
|
|
SELECT set_chunk_time_interval('chunk_test', 1::bigint);
|
|
|
|
INSERT INTO chunk_test VALUES (8, 24.3, 11233, 1);
|
|
|
|
SELECT set_chunk_time_interval('chunk_test', 5::bigint);
|
|
|
|
SELECT * FROM _timescaledb_catalog.dimension;
|
|
INSERT INTO chunk_test VALUES (7, 24.3, 79669, 1);
|
|
INSERT INTO chunk_test VALUES (8, 24.3, 79669, 1);
|
|
INSERT INTO chunk_test VALUES (10, 24.3, 11233, 1);
|
|
INSERT INTO chunk_test VALUES (16, 24.3, 11233, 1);
|
|
|
|
SELECT c.table_name AS chunk_name, d.id AS dimension_id, ds.id AS slice_id, range_start, range_end FROM _timescaledb_catalog.chunk c
|
|
LEFT JOIN _timescaledb_catalog.chunk_constraint cc ON (c.id = cc.chunk_id)
|
|
LEFT JOIN _timescaledb_catalog.dimension_slice ds ON (ds.id = cc.dimension_slice_id)
|
|
LEFT JOIN _timescaledb_catalog.dimension d ON (d.id = ds.dimension_id)
|
|
LEFT JOIN _timescaledb_catalog.hypertable h ON (d.hypertable_id = h.id)
|
|
WHERE h.schema_name = 'public' AND h.table_name = 'chunk_test'
|
|
ORDER BY c.id, d.id;
|