hash index at shutdown
btr_search_disable(): Just drop the entire adaptive hash index,
without dropping every record separately.
buf_pool_clear_hash_index(): Renamed and simplified from
buf_pool_drop_hash_index(). Set block->index = NULL for every block in
the buffer pool. Do not release the btr_search_latch. The caller will
have to adjust other data structures.
Remove block->is_hashed. It is redundant, should be always equal to
block->index != NULL.
Remove btr_search_fully_disabled, btr_search_enabled_mutex, and
SYNC_SEARCH_SYS_CONF. We drop the AHI in one pass, without releasing
the btr_search_latch in between.
Replace void* with const rec_t* and add assertions on btr_search_latch
and btr_search_enabled to ha0ha.h, ha0ha.ic, ha0ha.c.
page_set_max_trx_id(): Ignore the adaptive hash index. I forgot to
push this in rb:750.
btr0sea.c: Always after acquiring btr_search_latch, check for
block->index==NULL or !btr_search_enabled. We can now set
block->index=NULL while only holding btr_search_latch in exclusive
mode. Always acquire btr_search_latch before reading block->index,
except in shortcuts when testing for block->index == NULL.
ha_clear(), ha_search(): Unused function, remove.
buf_page_peek_if_search_hashed(): Remove. This function may avoid
latching a page at the cost of doing a duplicate buf_pool->page_hash
lookup.
rb:775 approved by Inaam Rana
discarded in buf_page_create()
This bug turned out to be a false alarm, a bug in the UNIV_SYNC_DEBUG
diagnostic code. Because of this, the patch was not backported to the
built-in InnoDB in MySQL 5.1. Furthermore, there is no test case for
InnoDB Plugin in MySQL 5.1, because the delete buffering in MySQL 5.5
makes triggering the failure much easier.
When a freed page for which there exist orphaned buffered changes is
allocated and reused for something else, buf_page_create() will discard
the buffered changes by invoking ibuf_merge_or_delete_for_page().
This would violate the InnoDB latching order.
Tweak the latching order as follows. Move SYNC_IBUF_MUTEX below
SYNC_FSP_PAGE, where it logically belongs, and assign new latching
levels for the ibuf->index->lock and the insert buffer B-tree pages:
#define SYNC_IBUF_MUTEX 370 /* ibuf_mutex */
#define SYNC_IBUF_INDEX_TREE 360
#define SYNC_IBUF_TREE_NODE_NEW 359
#define SYNC_IBUF_TREE_NODE 358
btr_block_get(), btr_page_get(): In UNIV_SYNC_DEBUG, add the parameter
"index" for determining the appropriate latching order
(SYNC_IBUF_TREE_NODE or SYNC_TREE_NODE).
btr_page_alloc_for_ibuf(), btr_create(): Use SYNC_IBUF_TREE_NODE_NEW
instead of SYNC_TREE_NODE_NEW for insert buffer pages.
btr_cur_search_to_nth_level(), btr_pcur_restore_position_func(): Use
SYNC_IBUF_TREE_NODE instead of SYNC_TREE_NODE for insert buffer pages.
btr_search_guess_on_hash(): Assert that the index is not an insert buffer tree.
dict_index_add_to_cache(): Use SYNC_IBUF_INDEX_TREE for the insert
buffer tree (ibuf->index->lock).
ibuf0ibuf.c: Use SYNC_IBUF_TREE_NODE or SYNC_IBUF_TREE_NODE_NEW for
all B-tree pages.
ibuf_merge_or_delete_for_page(): Assert that the user page is
BUF_IO_READ fixed. Only in this way it is OK to latch it as
SYNC_IBUF_TREE_NODE instead of the proper SYNC_TREE_NODE (which would
violate the changed latching order).
sync_thread_add_level(): Remove the special tweak for
SYNC_IBUF_MUTEX. Add rules for the added latching levels.
rb:591 approved by Jimmy Yang
btr_cur_compress_if_useful(), btr_compress(): Add the parameter ibool
adjust. If adjust=TRUE, adjust the cursor position after compressing
the page.
btr_lift_page_up(): Return a pointer to the father page.
BTR_KEEP_POS_FLAG: A new flag for btr_cur_pessimistic_update().
btr_cur_pessimistic_update(): If *big_rec != NULL and flags &
BTR_KEEP_POS_FLAG, keep the cursor positioned on the updated record.
Also, do not release the index tree x-lock if *big_rec != NULL.
btr_cur_mtr_commit_and_start(): Commits and restarts a
mini-transaction so that it will retain an x-lock on index->lock and
the page of the cursor. This is invoked when
btr_cur_pessimistic_update() returns *big_rec != NULL.
In all callers of btr_cur_pessimistic_update() that do not pass
BTR_KEEP_POS_FLAG, assert that *big_rec == NULL.
btr_cur_compress(): Unused function [in the built-in MySQL 5.1], remove.
page_rec_get_nth(): Return the nth record on the page (an inverse
function of page_rec_get_n_recs_before()). Refactored from
page_get_middle_rec().
page_get_middle_rec(): Invoke page_rec_get_nth().
page_cur_insert_rec_zip_reorg(): Make use of the page directory
shortcuts in page_rec_get_nth() instead of scanning the whole list of
records.
row_ins_clust_index_entry_by_modify(): Pass BTR_KEEP_POS_FLAG to
btr_cur_pessimistic_update().
row_ins_index_entry_low(): If row_ins_clust_index_entry_by_modify()
returns a big_rec, invoke btr_cur_mtr_commit_and_start() in order to
commit and start the mini-transaction without releasing the x-locks on
index->lock and the cursor page, and write the big_rec. Releasing the
page latch in mtr_commit() caused a race condition.
row_upd_clust_rec(): Pass BTR_KEEP_POS_FLAG to
btr_cur_pessimistic_update(). If it returns a big_rec, invoke
btr_cur_mtr_commit_and_start() in order to commit and start the
mini-transaction without releasing the x-locks on index->lock and the
cursor page, and write the big_rec. Releasing the page latch in
mtr_commit() caused a race condition.
sync_thread_add_level(): Add the parameter ibool relock. When TRUE,
bypass the latching order rules.
rw_lock_add_debug_info(): For nested X-lock requests, pass relock=TRUE
to sync_thread_add_level().
rb:678 approved by Jimmy Yang
and clarifies the invariant in dict_table_get_on_id().
In Mar 2007 Marko observed a crash during recovery, the crash resulted from
an UNDO operation on a system table. His solution was to acquire an X lock on
the data dictionary, this in hindsight was an overkill. It is unclear what
caused the crash, current hypothesis is that it was a memory corruption.
The X lock results in performance issues by when undoing changes due to
rollback during normal operation on regular tables.
Why the change is safe:
======================
The InnoDB code has changed since the original X lock change was made. In the
new code we always lock the data dictionary in X mode during startup when
UNDOing operations on the system tables (this is a given). This ensures that
the crash Marko observed cannot happen as long as all transactions that update
the system tables follow the standard rules by setting the appropriate DICT_OP
flag when writing the log records when they make the changes.
If transactions violate the above mentioned rule then during recovery (at
startup) the rollback code (see trx0roll.c) will not acquire the X lock
and we will see the crash again. This will however be a different bug.
Detailed revision comments:
r6749 | vasil | 2010-02-20 18:45:41 +0200 (Sat, 20 Feb 2010) | 5 lines
Non-functional change: update copyright year to 2010 of the files
that have been modified after 2010-01-01 according to svn.
for f in $(svn log -v -r{2010-01-01}:HEAD |grep "^ M " |cut -b 16- |sort -u) ; do sed -i "" -E 's/(Copyright \(c\) [0-9]{4},) [0-9]{4}, (.*Innobase Oy.+All Rights Reserved)/\1 2010, \2/' $f ; done
Detailed revision comments:
r6449 | marko | 2010-01-13 22:38:53 +0200 (Wed, 13 Jan 2010) | 18 lines
branches/zip: lock_rec_validate_page(): Only validate the record
queues when the thread is not holding a space->latch.
When UNIV_DEBUG is defined while UNIV_SYNC_DEBUG is not,
latching order violations will still occur and deadlocks will be possible.
sync_thread_levels_nonempty_gen(): Renamed from
sync_thread_levels_empty_gen(). Return the violating latch or NULL
instead of FALSE or TRUE, except that there will be a ut_error before
the non-NULL return.
sync_thread_levels_empty_gen(): A macro that negates the return value of
sync_thread_levels_nonempty_gen().
sync_thread_levels_contains(): New function, based on
sync_thread_levels_nonempty_gen().
This should fix Issue #441.
