open-dsi
/
postgres
mirror of https://github.com/postgres/postgres
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Add regression test for short varlenas saved in TOAST relations

Browse Source 
toast_save_datum() has for a very long time some code able to handle
short varlenas (values up to 126 bytes reduced to a 1-byte header),
converting such varlenas to an external on-disk TOAST pointer with the
value saved uncompressed in the secondary TOAST relation.

There was zero coverage for this code path.  This commit adds a test
able to exercise it, relying on two external attributes, one with a low
toast_tuple_target, so as it is possible to trigger the threshold for
the insertion of short varlenas into the TOAST relation.

Author: Nikhil Kumar Veldanda <veldanda.nikhilkumar17@gmail.com>
Co-authored-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/aJAl7-NvIk0kZByz@paquier.xyz
pull/239/head
Michael Paquier 1 month ago
parent 0b6aea0384
commit 225ebfe30a
2 changed files with 54 additions and 0 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Show Stats Download Patch File Download Diff File
  1. 34
      src/test/regress/expected/strings.out
  2. 20
      src/test/regress/sql/strings.sql

34
src/test/regress/expected/strings.out
Unescape View File

@ -2090,6 +2090,40 @@ SELECT c FROM toasttest;
x
(1 row)
DROP TABLE toasttest;
-- test with short varlenas (up to 126 data bytes reduced to a 1-byte header)
-- being toasted.
CREATE TABLE toasttest (f1 text, f2 text);
ALTER TABLE toasttest SET (toast_tuple_target = 128);
ALTER TABLE toasttest ALTER COLUMN f1 SET STORAGE EXTERNAL;
ALTER TABLE toasttest ALTER COLUMN f2 SET STORAGE EXTERNAL;
-- Here, the first value is a varlena large enough to make it toasted and
-- stored uncompressed. The second value is a short varlena, toasted
-- and stored uncompressed.
INSERT INTO toasttest values(repeat('1234', 1000), repeat('5678', 30));
SELECT reltoastrelid::regclass AS reltoastname FROM pg_class
WHERE oid = 'toasttest'::regclass \gset
-- There should be two values inserted in the toast relation.
SELECT count(*) FROM :reltoastname WHERE chunk_seq = 0;
count
-------
2
(1 row)
SELECT substr(f1, 5, 10) AS f1_data, substr(f2, 5, 10) AS f2_data
FROM toasttest;
f1_data | f2_data
------------+------------
1234123412 | 5678567856
(1 row)
SELECT pg_column_compression(f1) AS f1_comp, pg_column_compression(f2) AS f2_comp
FROM toasttest;
f1_comp | f2_comp
---------+---------
|
(1 row)
DROP TABLE toasttest;
--
-- test length

20
src/test/regress/sql/strings.sql
Unescape View File

@ -650,6 +650,26 @@ SELECT length(c), c::text FROM toasttest;
SELECT c FROM toasttest;
DROP TABLE toasttest;
-- test with short varlenas (up to 126 data bytes reduced to a 1-byte header)
-- being toasted.
CREATE TABLE toasttest (f1 text, f2 text);
ALTER TABLE toasttest SET (toast_tuple_target = 128);
ALTER TABLE toasttest ALTER COLUMN f1 SET STORAGE EXTERNAL;
ALTER TABLE toasttest ALTER COLUMN f2 SET STORAGE EXTERNAL;
-- Here, the first value is a varlena large enough to make it toasted and
-- stored uncompressed. The second value is a short varlena, toasted
-- and stored uncompressed.
INSERT INTO toasttest values(repeat('1234', 1000), repeat('5678', 30));
SELECT reltoastrelid::regclass AS reltoastname FROM pg_class
WHERE oid = 'toasttest'::regclass \gset
-- There should be two values inserted in the toast relation.
SELECT count(*) FROM :reltoastname WHERE chunk_seq = 0;
SELECT substr(f1, 5, 10) AS f1_data, substr(f2, 5, 10) AS f2_data
FROM toasttest;
SELECT pg_column_compression(f1) AS f1_comp, pg_column_compression(f2) AS f2_comp
FROM toasttest;
DROP TABLE toasttest;
--
-- test length
--

Write Preview
Loading…
Cancel
Save