postgresql/contrib/pageinspect/sql/btree.sql
Michael Paquier 79fed072ba 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 15:09:42 +09:00

49 lines
1.6 KiB
SQL

CREATE TABLE test1 (a int8, b int4range);
INSERT INTO test1 VALUES (72057594037927937, '[0,1)');
CREATE INDEX test1_a_idx ON test1 USING btree (a);
\x
SELECT * FROM bt_metap('test1_a_idx');
SELECT * FROM bt_page_stats('test1_a_idx', 0);
SELECT * FROM bt_page_stats('test1_a_idx', 1);
SELECT * FROM bt_page_stats('test1_a_idx', 2);
SELECT * FROM bt_page_items('test1_a_idx', 0);
SELECT * FROM bt_page_items('test1_a_idx', 1);
SELECT * FROM bt_page_items('test1_a_idx', 2);
SELECT * FROM bt_page_items(get_raw_page('test1_a_idx', 0));
SELECT * FROM bt_page_items(get_raw_page('test1_a_idx', 1));
SELECT * FROM bt_page_items(get_raw_page('test1_a_idx', 2));
-- Failure when using a non-btree index.
CREATE INDEX test1_a_hash ON test1 USING hash(a);
SELECT bt_metap('test1_a_hash');
SELECT bt_page_stats('test1_a_hash', 0);
SELECT bt_page_items('test1_a_hash', 0);
SELECT bt_page_items(get_raw_page('test1_a_hash', 0));
CREATE INDEX test1_b_gist ON test1 USING gist(b);
-- Special area of GiST is the same as btree, this complains about inconsistent
-- leaf data on the page.
SELECT bt_page_items(get_raw_page('test1_b_gist', 0));
-- Several failure modes.
-- Suppress the DETAIL message, to allow the tests to work across various
-- page sizes and architectures.
\set VERBOSITY terse
-- invalid page size
SELECT bt_page_items('aaa'::bytea);
-- invalid special area size
CREATE INDEX test1_a_brin ON test1 USING brin(a);
SELECT bt_page_items(get_raw_page('test1', 0));
SELECT bt_page_items(get_raw_page('test1_a_brin', 0));
\set VERBOSITY default
-- Tests with all-zero pages.
SHOW block_size \gset
SELECT bt_page_items(decode(repeat('00', :block_size), 'hex'));
DROP TABLE test1;