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cd4868a570
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
54 lines
2.4 KiB
PL/PgSQL
54 lines
2.4 KiB
PL/PgSQL
-- The gist_page_opaque_info() function prints the page's LSN. Normally,
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-- that's constant 1 (GistBuildLSN) on every page of a freshly built GiST
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-- index. But with wal_level=minimal, the whole relation is dumped to WAL at
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-- the end of the transaction if it's smaller than wal_skip_threshold, which
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-- updates the LSNs. Wrap the tests on gist_page_opaque_info() in the
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-- same transaction with the CREATE INDEX so that we see the LSNs before
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-- they are possibly overwritten at end of transaction.
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BEGIN;
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-- Create a test table and GiST index.
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CREATE TABLE test_gist AS SELECT point(i,i) p, i::text t FROM
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generate_series(1,1000) i;
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CREATE INDEX test_gist_idx ON test_gist USING gist (p);
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-- Page 0 is the root, the rest are leaf pages
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SELECT * FROM gist_page_opaque_info(get_raw_page('test_gist_idx', 0));
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SELECT * FROM gist_page_opaque_info(get_raw_page('test_gist_idx', 1));
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SELECT * FROM gist_page_opaque_info(get_raw_page('test_gist_idx', 2));
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COMMIT;
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SELECT * FROM gist_page_items(get_raw_page('test_gist_idx', 0), 'test_gist_idx');
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SELECT * FROM gist_page_items(get_raw_page('test_gist_idx', 1), 'test_gist_idx') LIMIT 5;
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-- gist_page_items_bytea prints the raw key data as a bytea. The output of that is
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-- platform-dependent (endianness), so omit the actual key data from the output.
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SELECT itemoffset, ctid, itemlen FROM gist_page_items_bytea(get_raw_page('test_gist_idx', 0));
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-- Failure with non-GiST index.
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CREATE INDEX test_gist_btree on test_gist(t);
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SELECT gist_page_items(get_raw_page('test_gist_btree', 0), 'test_gist_btree');
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-- Failure with various modes.
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-- Suppress the DETAIL message, to allow the tests to work across various
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-- page sizes and architectures.
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\set VERBOSITY terse
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-- invalid page size
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SELECT gist_page_items_bytea('aaa'::bytea);
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SELECT gist_page_items('aaa'::bytea, 'test_gist_idx'::regclass);
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SELECT gist_page_opaque_info('aaa'::bytea);
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-- invalid special area size
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SELECT * FROM gist_page_opaque_info(get_raw_page('test_gist', 0));
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SELECT gist_page_items_bytea(get_raw_page('test_gist', 0));
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SELECT gist_page_items_bytea(get_raw_page('test_gist_btree', 0));
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\set VERBOSITY default
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-- Tests with all-zero pages.
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SHOW block_size \gset
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SELECT gist_page_items_bytea(decode(repeat('00', :block_size), 'hex'));
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SELECT gist_page_items(decode(repeat('00', :block_size), 'hex'), 'test_gist_idx'::regclass);
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SELECT gist_page_opaque_info(decode(repeat('00', :block_size), 'hex'));
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DROP TABLE test_gist;
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