postgresql/contrib/pageinspect/sql/gin.sql
Michael Paquier cd4868a570 pageinspect: Fix handling of all-zero pages
Getting from get_raw_page() an all-zero page is considered as a valid
case by the buffer manager and it can happen for example when finding a
corrupted page with zero_damaged_pages enabled (using zero_damaged_pages
to look at corrupted pages happens), or after a crash when a relation
file is extended before any WAL for its new data is generated (before a
vacuum or autovacuum job comes in to do some cleanup).

However, all the functions of pageinspect, as of the index AMs (except
hash that has its own idea of new pages), heap, the FSM or the page
header have never worked with all-zero pages, causing various crashes
when going through the page internals.

This commit changes all the pageinspect functions to be compliant with
all-zero pages, where the choice is made to return NULL or no rows for
SRFs when finding a new page.  get_raw_page() still works the same way,
returning a batch of zeros in the bytea of the page retrieved.  A hard
error could be used but NULL, while more invasive, is useful when
scanning relation files in full to get a batch of results for a single
relation in one query.  Tests are added for all the code paths
impacted.

Reported-by: Daria Lepikhova
Author: Michael Paquier
Discussion: https://postgr.es/m/561e187b-3549-c8d5-03f5-525c14e65bd0@postgrespro.ru
Backpatch-through: 10
2022-04-14 15:08:03 +09:00

42 lines
1.5 KiB
SQL

CREATE TABLE test1 (x int, y int[]);
INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
\x
SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 0));
SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 1));
SELECT * FROM gin_page_opaque_info(get_raw_page('test1_y_idx', 1));
SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
SELECT COUNT(*) > 0
FROM gin_leafpage_items(get_raw_page('test1_y_idx',
(pg_relation_size('test1_y_idx') /
current_setting('block_size')::bigint)::int - 1));
-- Failure with various modes.
-- Suppress the DETAIL message, to allow the tests to work across various
-- page sizes and architectures.
\set VERBOSITY terse
-- invalid page size
SELECT gin_leafpage_items('aaa'::bytea);
SELECT gin_metapage_info('bbb'::bytea);
SELECT gin_page_opaque_info('ccc'::bytea);
-- invalid special area size
SELECT * FROM gin_metapage_info(get_raw_page('test1', 0));
SELECT * FROM gin_page_opaque_info(get_raw_page('test1', 0));
SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
\set VERBOSITY default
-- Tests with all-zero pages.
SHOW block_size \gset
SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
SELECT gin_page_opaque_info(decode(repeat('00', :block_size), 'hex'));
DROP TABLE test1;