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MDEV-21512 InnoDB may hang due to SPATIAL INDEX

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MySQL 5.7.29 includes the following fix:
Bug #30287668 INNODB: A LONG SEMAPHORE WAIT
mysql/mysql-server@5cdbb22b51

There is no test case. It seems that the problem could occur when
a spatial index is large and peculiar enough so that multiple R-tree
leaf pages will have the exactly same maximum bounding rectangle (MBR).

The commit message suggests that the hang can occur when R-tree
non-leaf pages are being merged, which should only be possible
during transaction rollback or the purge of transaction history,
when the R-tree index is at least 2 levels high and very many records
are being deleted. The message says that a comparison result that two
spatial index node pointer records are equal will cause an infinite loop
in rtr_page_copy_rec_list_end_no_locks(). Hence, we must include the
child page number in the comparison to be consistent with
mysql/mysql-server@2e11fe0e15.

We fix this bug in a simpler way, involving fewer code changes.

cmp_rec_rec(): Renamed from cmp_rec_rec_with_match().
Assert that rec2 always resides in an index page.
Treat non-leaf spatial index pages specially.
This commit is contained in:
Marko Mäkelä 2020-01-17 13:13:03 +02:00
commit 457ce97ef2
6 changed files with 87 additions and 138 deletions
Download patch file Download diff file Expand all files Collapse all files

17
storage/innobase/gis/gis0rtree.cc
View file

@ -1,7 +1,7 @@
/*****************************************************************************
Copyright (c) 2016, Oracle and/or its affiliates. All Rights Reserved.
Copyright (c) 2019, MariaDB Corporation.
Copyright (c) 2019, 2020, MariaDB Corporation.
This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
@ -1449,10 +1449,9 @@ rtr_page_copy_rec_list_end_no_locks(
offsets2 = rec_get_offsets(cur_rec, index, offsets2,
is_leaf,
ULINT_UNDEFINED, &heap);
cmp = cmp_rec_rec_with_match(cur1_rec, cur_rec,
offsets1, offsets2,
index, FALSE,
&cur_matched_fields);
cmp = cmp_rec_rec(cur1_rec, cur_rec,
offsets1, offsets2, index, false,
&cur_matched_fields);
if (cmp < 0) {
page_cur_move_to_prev(&page_cur);
break;
@ -1564,15 +1563,13 @@ rtr_page_copy_rec_list_start_no_locks(
while (!page_rec_is_supremum(cur_rec)) {
ulint cur_matched_fields = 0;
int cmp;
offsets2 = rec_get_offsets(cur_rec, index, offsets2,
is_leaf,
ULINT_UNDEFINED, &heap);
cmp = cmp_rec_rec_with_match(cur1_rec, cur_rec,
offsets1, offsets2,
index, FALSE,
&cur_matched_fields);
int cmp = cmp_rec_rec(cur1_rec, cur_rec,
offsets1, offsets2, index, false,
&cur_matched_fields);
if (cmp < 0) {
page_cur_move_to_prev(&page_cur);
cur_rec = page_cur_get_rec(&page_cur);