-- Default set of tests for TOAST compression, independent on compression -- methods supported by the build. CREATE SCHEMA pglz; SET search_path TO pglz, public; \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 "pglz.cmdata" Column | Type | Collation | Nullable | Default | Storage | Compression | Stats target | Description --------+------+-----------+----------+---------+----------+-------------+--------------+------------- f1 | text | | | | extended | pglz | | Indexes: "idx" btree (f1) -- verify stored compression method in the data SELECT pg_column_compression(f1) FROM cmdata; pg_column_compression ----------------------- pglz (1 row) -- decompress data slice SELECT SUBSTR(f1, 200, 5) FROM cmdata; substr -------- 01234 (1 row) -- copy with table creation SELECT * INTO cmmove1 FROM cmdata; \d+ cmmove1 Table "pglz.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) -- try setting compression for incompressible data type CREATE TABLE cmdata2 (f1 int COMPRESSION pglz); ERROR: column data type integer does not support compression -- test externally stored compressed data CREATE OR REPLACE FUNCTION large_val() RETURNS TEXT LANGUAGE SQL AS 'select array_agg(fipshash(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) SELECT SUBSTR(f1, 200, 5) FROM cmdata2; substr -------- 79026 (1 row) DROP TABLE cmdata2; --test column type update varlena/non-varlena CREATE TABLE cmdata2 (f1 int); \d+ cmdata2 Table "pglz.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 "pglz.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 "pglz.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 "pglz.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 "pglz.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 inheritance CREATE TABLE cmdata3(f1 text); CREATE TABLE cminh() INHERITS (cmdata, cmdata3); NOTICE: merging multiple inherited definitions of column "f1" -- test default_toast_compression GUC -- suppress machine-dependent details \set VERBOSITY terse SET default_toast_compression = ''; ERROR: invalid value for parameter "default_toast_compression": "" SET default_toast_compression = 'I do not exist compression'; ERROR: invalid value for parameter "default_toast_compression": "I do not exist compression" SET default_toast_compression = 'pglz'; \set VERBOSITY default ALTER TABLE cmdata2 ALTER COLUMN f1 SET COMPRESSION default; \d+ cmdata2 Table "pglz.cmdata2" Column | Type | Collation | Nullable | Default | Storage | Compression | Stats target | Description --------+-------------------+-----------+----------+---------+---------+-------------+--------------+------------- f1 | character varying | | | | plain | | | DROP TABLE cmdata2; -- VACUUM FULL does not recompress SELECT pg_column_compression(f1) FROM cmdata; pg_column_compression ----------------------- pglz (1 row) VACUUM FULL cmdata; SELECT pg_column_compression(f1) FROM cmdata; pg_column_compression ----------------------- pglz (1 row) -- check data is ok SELECT length(f1) FROM cmdata; length -------- 10000 (1 row) SELECT length(f1) FROM cmmove1; length -------- 10000 (1 row) 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