\set HIDE_TOAST_COMPRESSION false -- ensure we get stable results regardless of installation's default SET default_toast_compression = 'pglz'; -- test creating table with compression method CREATE TABLE cmdata(f1 text COMPRESSION pglz); CREATE INDEX idx ON cmdata(f1); INSERT INTO cmdata VALUES(repeat('1234567890', 1000)); \d+ cmdata Table "public.cmdata" Column | Type | Collation | Nullable | Default | Storage | Compression | Stats target | Description --------+------+-----------+----------+---------+----------+-------------+--------------+------------- f1 | text | | | | extended | pglz | | Indexes: "idx" btree (f1) CREATE TABLE cmdata1(f1 TEXT COMPRESSION lz4); INSERT INTO cmdata1 VALUES(repeat('1234567890', 1004)); \d+ cmdata1 Table "public.cmdata1" Column | Type | Collation | Nullable | Default | Storage | Compression | Stats target | Description --------+------+-----------+----------+---------+----------+-------------+--------------+------------- f1 | text | | | | extended | lz4 | | -- verify stored compression method in the data SELECT pg_column_compression(f1) FROM cmdata; pg_column_compression ----------------------- pglz (1 row) SELECT pg_column_compression(f1) FROM cmdata1; pg_column_compression ----------------------- lz4 (1 row) -- decompress data slice SELECT SUBSTR(f1, 200, 5) FROM cmdata; substr -------- 01234 (1 row) SELECT SUBSTR(f1, 2000, 50) FROM cmdata1; substr ---------------------------------------------------- 01234567890123456789012345678901234567890123456789 (1 row) -- copy with table creation SELECT * INTO cmmove1 FROM cmdata; \d+ cmmove1 Table "public.cmmove1" Column | Type | Collation | Nullable | Default | Storage | Compression | Stats target | Description --------+------+-----------+----------+---------+----------+-------------+--------------+------------- f1 | text | | | | extended | | | SELECT pg_column_compression(f1) FROM cmmove1; pg_column_compression ----------------------- pglz (1 row) -- copy to existing table CREATE TABLE cmmove3(f1 text COMPRESSION pglz); INSERT INTO cmmove3 SELECT * FROM cmdata; INSERT INTO cmmove3 SELECT * FROM cmdata1; SELECT pg_column_compression(f1) FROM cmmove3; pg_column_compression ----------------------- pglz lz4 (2 rows) -- test LIKE INCLUDING COMPRESSION CREATE TABLE cmdata2 (LIKE cmdata1 INCLUDING COMPRESSION); \d+ cmdata2 Table "public.cmdata2" Column | Type | Collation | Nullable | Default | Storage | Compression | Stats target | Description --------+------+-----------+----------+---------+----------+-------------+--------------+------------- f1 | text | | | | extended | lz4 | | DROP TABLE cmdata2; -- try setting compression for incompressible data type CREATE TABLE cmdata2 (f1 int COMPRESSION pglz); ERROR: column data type integer does not support compression -- update using datum from different table CREATE TABLE cmmove2(f1 text COMPRESSION pglz); INSERT INTO cmmove2 VALUES (repeat('1234567890', 1004)); SELECT pg_column_compression(f1) FROM cmmove2; pg_column_compression ----------------------- pglz (1 row) UPDATE cmmove2 SET f1 = cmdata1.f1 FROM cmdata1; SELECT pg_column_compression(f1) FROM cmmove2; pg_column_compression ----------------------- lz4 (1 row) -- test externally stored compressed data CREATE OR REPLACE FUNCTION large_val() RETURNS TEXT LANGUAGE SQL AS 'select array_agg(md5(g::text))::text from generate_series(1, 256) g'; CREATE TABLE cmdata2 (f1 text COMPRESSION pglz); INSERT INTO cmdata2 SELECT large_val() || repeat('a', 4000); SELECT pg_column_compression(f1) FROM cmdata2; pg_column_compression ----------------------- pglz (1 row) INSERT INTO cmdata1 SELECT large_val() || repeat('a', 4000); SELECT pg_column_compression(f1) FROM cmdata1; pg_column_compression ----------------------- lz4 lz4 (2 rows) SELECT SUBSTR(f1, 200, 5) FROM cmdata1; substr -------- 01234 8f14e (2 rows) SELECT SUBSTR(f1, 200, 5) FROM cmdata2; substr -------- 8f14e (1 row) DROP TABLE cmdata2; --test column type update varlena/non-varlena CREATE TABLE cmdata2 (f1 int); \d+ cmdata2 Table "public.cmdata2" Column | Type | Collation | Nullable | Default | Storage | Compression | Stats target | Description --------+---------+-----------+----------+---------+---------+-------------+--------------+------------- f1 | integer | | | | plain | | | ALTER TABLE cmdata2 ALTER COLUMN f1 TYPE varchar; \d+ cmdata2 Table "public.cmdata2" Column | Type | Collation | Nullable | Default | Storage | Compression | Stats target | Description --------+-------------------+-----------+----------+---------+----------+-------------+--------------+------------- f1 | character varying | | | | extended | | | ALTER TABLE cmdata2 ALTER COLUMN f1 TYPE int USING f1::integer; \d+ cmdata2 Table "public.cmdata2" Column | Type | Collation | Nullable | Default | Storage | Compression | Stats target | Description --------+---------+-----------+----------+---------+---------+-------------+--------------+------------- f1 | integer | | | | plain | | | --changing column storage should not impact the compression method --but the data should not be compressed ALTER TABLE cmdata2 ALTER COLUMN f1 TYPE varchar; ALTER TABLE cmdata2 ALTER COLUMN f1 SET COMPRESSION pglz; \d+ cmdata2 Table "public.cmdata2" Column | Type | Collation | Nullable | Default | Storage | Compression | Stats target | Description --------+-------------------+-----------+----------+---------+----------+-------------+--------------+------------- f1 | character varying | | | | extended | pglz | | ALTER TABLE cmdata2 ALTER COLUMN f1 SET STORAGE plain; \d+ cmdata2 Table "public.cmdata2" Column | Type | Collation | Nullable | Default | Storage | Compression | Stats target | Description --------+-------------------+-----------+----------+---------+---------+-------------+--------------+------------- f1 | character varying | | | | plain | pglz | | INSERT INTO cmdata2 VALUES (repeat('123456789', 800)); SELECT pg_column_compression(f1) FROM cmdata2; pg_column_compression ----------------------- (1 row) -- test compression with materialized view CREATE MATERIALIZED VIEW compressmv(x) AS SELECT * FROM cmdata1; \d+ compressmv Materialized view "public.compressmv" Column | Type | Collation | Nullable | Default | Storage | Compression | Stats target | Description --------+------+-----------+----------+---------+----------+-------------+--------------+------------- x | text | | | | extended | | | View definition: SELECT cmdata1.f1 AS x FROM cmdata1; SELECT pg_column_compression(f1) FROM cmdata1; pg_column_compression ----------------------- lz4 lz4 (2 rows) SELECT pg_column_compression(x) FROM compressmv; pg_column_compression ----------------------- lz4 lz4 (2 rows) -- test compression with partition CREATE TABLE cmpart(f1 text COMPRESSION lz4) PARTITION BY HASH(f1); CREATE TABLE cmpart1 PARTITION OF cmpart FOR VALUES WITH (MODULUS 2, REMAINDER 0); CREATE TABLE cmpart2(f1 text COMPRESSION pglz); ALTER TABLE cmpart ATTACH PARTITION cmpart2 FOR VALUES WITH (MODULUS 2, REMAINDER 1); INSERT INTO cmpart VALUES (repeat('123456789', 1004)); INSERT INTO cmpart VALUES (repeat('123456789', 4004)); SELECT pg_column_compression(f1) FROM cmpart1; pg_column_compression ----------------------- lz4 (1 row) SELECT pg_column_compression(f1) FROM cmpart2; pg_column_compression ----------------------- pglz (1 row) -- test compression with inheritance, error CREATE TABLE cminh() INHERITS(cmdata, cmdata1); NOTICE: merging multiple inherited definitions of column "f1" ERROR: column "f1" has a compression method conflict DETAIL: pglz versus lz4 CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata); NOTICE: merging column "f1" with inherited definition ERROR: column "f1" has a compression method conflict DETAIL: pglz versus lz4 -- test default_toast_compression GUC SET default_toast_compression = ''; ERROR: invalid value for parameter "default_toast_compression": "" HINT: Available values: pglz, lz4. SET default_toast_compression = 'I do not exist compression'; ERROR: invalid value for parameter "default_toast_compression": "I do not exist compression" HINT: Available values: pglz, lz4. SET default_toast_compression = 'lz4'; SET default_toast_compression = 'pglz'; -- test alter compression method ALTER TABLE cmdata ALTER COLUMN f1 SET COMPRESSION lz4; INSERT INTO cmdata VALUES (repeat('123456789', 4004)); \d+ cmdata Table "public.cmdata" Column | Type | Collation | Nullable | Default | Storage | Compression | Stats target | Description --------+------+-----------+----------+---------+----------+-------------+--------------+------------- f1 | text | | | | extended | lz4 | | Indexes: "idx" btree (f1) SELECT pg_column_compression(f1) FROM cmdata; pg_column_compression ----------------------- pglz lz4 (2 rows) ALTER TABLE cmdata2 ALTER COLUMN f1 SET COMPRESSION default; \d+ cmdata2 Table "public.cmdata2" Column | Type | Collation | Nullable | Default | Storage | Compression | Stats target | Description --------+-------------------+-----------+----------+---------+---------+-------------+--------------+------------- f1 | character varying | | | | plain | | | -- test alter compression method for materialized views ALTER MATERIALIZED VIEW compressmv ALTER COLUMN x SET COMPRESSION lz4; \d+ compressmv Materialized view "public.compressmv" Column | Type | Collation | Nullable | Default | Storage | Compression | Stats target | Description --------+------+-----------+----------+---------+----------+-------------+--------------+------------- x | text | | | | extended | lz4 | | View definition: SELECT cmdata1.f1 AS x FROM cmdata1; -- test alter compression method for partitioned tables ALTER TABLE cmpart1 ALTER COLUMN f1 SET COMPRESSION pglz; ALTER TABLE cmpart2 ALTER COLUMN f1 SET COMPRESSION lz4; -- new data should be compressed with the current compression method INSERT INTO cmpart VALUES (repeat('123456789', 1004)); INSERT INTO cmpart VALUES (repeat('123456789', 4004)); SELECT pg_column_compression(f1) FROM cmpart1; pg_column_compression ----------------------- lz4 pglz (2 rows) SELECT pg_column_compression(f1) FROM cmpart2; pg_column_compression ----------------------- pglz lz4 (2 rows) -- VACUUM FULL does not recompress SELECT pg_column_compression(f1) FROM cmdata; pg_column_compression ----------------------- pglz lz4 (2 rows) VACUUM FULL cmdata; SELECT pg_column_compression(f1) FROM cmdata; pg_column_compression ----------------------- pglz lz4 (2 rows) -- test expression index DROP TABLE cmdata2; CREATE TABLE cmdata2 (f1 TEXT COMPRESSION pglz, f2 TEXT COMPRESSION lz4); CREATE UNIQUE INDEX idx1 ON cmdata2 ((f1 || f2)); INSERT INTO cmdata2 VALUES((SELECT array_agg(md5(g::TEXT))::TEXT FROM generate_series(1, 50) g), VERSION()); -- check data is ok SELECT length(f1) FROM cmdata; length -------- 10000 36036 (2 rows) SELECT length(f1) FROM cmdata1; length -------- 10040 12449 (2 rows) SELECT length(f1) FROM cmmove1; length -------- 10000 (1 row) SELECT length(f1) FROM cmmove2; length -------- 10040 (1 row) SELECT length(f1) FROM cmmove3; length -------- 10000 10040 (2 rows) CREATE TABLE badcompresstbl (a text COMPRESSION I_Do_Not_Exist_Compression); -- fails ERROR: invalid compression method "i_do_not_exist_compression" CREATE TABLE badcompresstbl (a text); ALTER TABLE badcompresstbl ALTER a SET COMPRESSION I_Do_Not_Exist_Compression; -- fails ERROR: invalid compression method "i_do_not_exist_compression" DROP TABLE badcompresstbl; \set HIDE_TOAST_COMPRESSION true