MDEV-16283 ALTER TABLE...DISCARD TABLESPACE still takes long on a large buffer pool

Also fixes MDEV-14727, MDEV-14491
InnoDB: Error: Waited for 5 secs for hash index ref_count (1) to drop to 0
by replacing the flawed wait logic in dict_index_remove_from_cache_low().

On DISCARD TABLESPACE, there is no need to drop the adaptive hash index.
We must drop it on IMPORT TABLESPACE, and eventually on DROP TABLE or
DROP INDEX. As long as the dict_index_t object remains in the cache
and the table remains inaccessible, the adaptive hash index entries
to orphaned pages would not do any harm. They would be dropped when
buffer pool pages are reused for something else.

btr_search_drop_page_hash_when_freed(), buf_LRU_drop_page_hash_batch():
Remove the parameter zip_size, and pass 0 to buf_page_get_gen().

buf_page_get_gen(): Ignore zip_size if mode==BUF_PEEK_IF_IN_POOL.

buf_LRU_drop_page_hash_for_tablespace(): Drop the adaptive hash index
even if the tablespace is inaccessible.

buf_LRU_drop_page_hash_for_tablespace(): New global function, to drop
the adaptive hash index.

buf_LRU_flush_or_remove_pages(), fil_delete_tablespace():
Remove the parameter drop_ahi.

dict_index_remove_from_cache_low(): Actively drop the adaptive hash index
if entries exist. This should prevent InnoDB hangs on DROP TABLE or
DROP INDEX.

row_import_for_mysql(): Drop any adaptive hash index entries for the table.

row_drop_table_for_mysql(): Drop any adaptive hash index for the table,
except if the table resides in the system tablespace. (DISCARD TABLESPACE
does not apply to the system tablespace, and we do no want to drop the
adaptive hash index for other tables than the one that is being dropped.)

row_truncate_table_for_mysql(): Drop any adaptive hash index entries for
the table, except if the table resides in the system tablespace.

1 files changed, 5 insertions, 10 deletions

diff --git a/storage/xtradb/btr/btr0sea.cc b/storage/xtradb/btr/btr0sea.cc
index 12c99246f16..713a584ee7e 100644
--- a/storage/xtradb/btr/btr0sea.cc
+++ b/storage/xtradb/btr/btr0sea.cc
@@ -2,6 +2,7 @@
 
 Copyright (c) 1996, 2016, Oracle and/or its affiliates. All Rights Reserved.
 Copyright (c) 2008, Google Inc.
+Copyright (c) 2018, MariaDB Corporation.
 
 Portions of this file contain modifications contributed and copyrighted by
 Google, Inc. Those modifications are gratefully acknowledged and are described
@@ -1299,17 +1300,11 @@ cleanup:
 	mem_free(folds);
 }
 
-/********************************************************************//**
-Drops a possible page hash index when a page is evicted from the buffer pool
-or freed in a file segment. */
+/** Drop possible adaptive hash index entries when a page is evicted
+from the buffer pool or freed in a file, or the index is being dropped. */
 UNIV_INTERN
 void
-btr_search_drop_page_hash_when_freed(
-/*=================================*/
-	ulint	space,		/*!< in: space id */
-	ulint	zip_size,	/*!< in: compressed page size in bytes
-				or 0 for uncompressed pages */
-	ulint	page_no)	/*!< in: page number */
+btr_search_drop_page_hash_when_freed(ulint space, ulint page_no)
 {
 	buf_block_t*	block;
 	mtr_t		mtr;
@@ -1322,7 +1317,7 @@ btr_search_drop_page_hash_when_freed(
 	are possibly holding, we cannot s-latch the page, but must
 	(recursively) x-latch it, even though we are only reading. */
 
-	block = buf_page_get_gen(space, zip_size, page_no, RW_X_LATCH, NULL,
+	block = buf_page_get_gen(space, 0, page_no, RW_X_LATCH, NULL,
 				 BUF_PEEK_IF_IN_POOL, __FILE__, __LINE__,
 				 &mtr);