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amcheck: Fix parent key check in gin_index_check()

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The checks introduced by commit 14ffaece0f did not get the parent key
checks quite right, missing some data corruption cases. In particular:

* The "rightlink" check was not working as intended, because rightlink
  is a BlockNumber, and InvalidBlockNumber is 0xFFFFFFFF, so

    !GinPageGetOpaque(page)->rightlink

  almost always evaluates to false (except for rightlink=0). So in most
  cases parenttup was left NULL, preventing any checks against parent.

* Use GinGetDownlink() to retrieve child blkno to avoid triggering
  Assert, same as the core GIN code.

Issues reported by Arseniy Mukhin, along with a proposed patch. Review
by Andrey M. Borodin, cleanup and improvements by me.

Author: Arseniy Mukhin <arseniy.mukhin.dev@gmail.com>
Reviewed-by: Andrey M. Borodin <x4mmm@yandex-team.ru>
Discussion: https://postgr.es/m/CAE7r3MJ611B9TE=YqBBncewp7-k64VWs+sjk7XF6fJUX77uFBA@mail.gmail.com
This commit is contained in:
Tomas Vondra
2025-06-17 15:46:26 +02:00
parent 0b54b39233
commit cdd1a431f2
2 changed files with 82 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

78
contrib/amcheck/t/006_verify_gin.pl
View File

@ -34,6 +34,8 @@ $node->safe_psql(
invalid_entry_order_leaf_page_test();
invalid_entry_order_inner_page_test();
invalid_entry_columns_order_test();
inconsistent_with_parent_key__parent_key_corrupted_test();
inconsistent_with_parent_key__child_key_corrupted_test();
sub invalid_entry_order_leaf_page_test
{
@ -159,6 +161,82 @@ sub invalid_entry_columns_order_test
like($stderr, qr/$expected/);
}
sub inconsistent_with_parent_key__parent_key_corrupted_test
{
my $relname = "test";
my $indexname = "test_gin_idx";
# fill the table until we have a split
$node->safe_psql(
'postgres', qq(
DROP TABLE IF EXISTS $relname;
CREATE TABLE $relname (a text[]);
INSERT INTO $relname (a) VALUES (('{' || 'llllllllll' || random_string($filler_size) ||'}')::text[]);
INSERT INTO $relname (a) VALUES (('{' || 'mmmmmmmmmm' || random_string($filler_size) ||'}')::text[]);
INSERT INTO $relname (a) VALUES (('{' || 'nnnnnnnnnn' || random_string($filler_size) ||'}')::text[]);
INSERT INTO $relname (a) VALUES (('{' || 'xxxxxxxxxx' || random_string($filler_size) ||'}')::text[]);
INSERT INTO $relname (a) VALUES (('{' || 'yyyyyyyyyy' || random_string($filler_size) ||'}')::text[]);
CREATE INDEX $indexname ON $relname USING gin (a);
));
my $relpath = relation_filepath($indexname);
$node->stop;
my $blkno = 1; # root
# we have nnnnnnnnnn... as parent key in the root, so replace it with something smaller then child's keys
string_replace_block(
$relpath,
'nnnnnnnnnn',
'aaaaaaaaaa',
$blkno
);
$node->start;
my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
my $expected = "index \"$indexname\" has inconsistent records on page 3 offset 3";
like($stderr, qr/$expected/);
}
sub inconsistent_with_parent_key__child_key_corrupted_test
{
my $relname = "test";
my $indexname = "test_gin_idx";
# fill the table until we have a split
$node->safe_psql(
'postgres', qq(
DROP TABLE IF EXISTS $relname;
CREATE TABLE $relname (a text[]);
INSERT INTO $relname (a) VALUES (('{' || 'llllllllll' || random_string($filler_size) ||'}')::text[]);
INSERT INTO $relname (a) VALUES (('{' || 'mmmmmmmmmm' || random_string($filler_size) ||'}')::text[]);
INSERT INTO $relname (a) VALUES (('{' || 'nnnnnnnnnn' || random_string($filler_size) ||'}')::text[]);
INSERT INTO $relname (a) VALUES (('{' || 'xxxxxxxxxx' || random_string($filler_size) ||'}')::text[]);
INSERT INTO $relname (a) VALUES (('{' || 'yyyyyyyyyy' || random_string($filler_size) ||'}')::text[]);
CREATE INDEX $indexname ON $relname USING gin (a);
));
my $relpath = relation_filepath($indexname);
$node->stop;
my $blkno = 3; # leaf
# we have nnnnnnnnnn... as parent key in the root, so replace child key with something bigger
string_replace_block(
$relpath,
'nnnnnnnnnn',
'pppppppppp',
$blkno
);
$node->start;
my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
my $expected = "index \"$indexname\" has inconsistent records on page 3 offset 3";
like($stderr, qr/$expected/);
}
# Returns the filesystem path for the named relation.
sub relation_filepath
{

8
contrib/amcheck/verify_gin.c
View File

@ -608,10 +608,10 @@ gin_check_parent_keys_consistency(Relation rel,
ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
ptr->depth = stack->depth + 1;
/* last tuple in layer has no high key */
if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
ptr->parenttup = CopyIndexTuple(idxtuple);
else
if (i == maxoff && rightlink == InvalidBlockNumber)
ptr->parenttup = NULL;
else
ptr->parenttup = CopyIndexTuple(idxtuple);
ptr->parentblk = stack->blkno;
ptr->blkno = GinGetDownlink(idxtuple);
ptr->next = stack->next;
@ -748,7 +748,7 @@ gin_refind_parent(Relation rel, BlockNumber parentblkno,
ItemId p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
IndexTuple itup = (IndexTuple) PageGetItem(parentpage, p_iid);
if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
if (GinGetDownlink(itup) == childblkno)
{
/* Found it! Make copy and return it */
result = CopyIndexTuple(itup);