This bug was originally filed and fixed as Bug#12612184. The original
fix was buggy, and it was patched by Bug#12704861. Also that patch was
buggy (potentially breaking crash recovery), and both fixes were
reverted.
This fix was not ported to the built-in InnoDB of MySQL 5.1, because
the function signatures of many core functions are different from
InnoDB Plugin and later versions. The block allocation routines and
their callers would have to changed so that they handle block
descriptors instead of page frames.
When a record is updated so that its size grows, non-updated columns
can be selected for external (off-page) storage. The bug is that the
initially inserted updated record contains an all-zero BLOB pointer to
the field that was not updated. Only after the BLOB pages have been
allocated and written, the valid pointer can be written to the record.
Between the release of the page latch in mtr_commit(mtr) after
btr_cur_pessimistic_update() and the re-latching of the page in
btr_pcur_restore_position(), other threads can see the invalid BLOB
pointer consisting of 20 zero bytes. Moreover, if the system crashes
at this point, the situation could persist after crash recovery, and
the contents of the non-updated column would be permanently lost.
The problem is amplified by the ROW_FORMAT=DYNAMIC and
ROW_FORMAT=COMPRESSED that were introduced in
innodb_file_format=barracuda in InnoDB Plugin, but the bug does exist
in all InnoDB versions.
The fix is as follows. After a pessimistic B-tree operation that needs
to write out off-page columns, allocate the pages for these columns in
the mini-transaction that performed the B-tree operation (btr_mtr),
but write the pages in a separate mini-transaction (blob_mtr). Do
mtr_commit(blob_mtr) before mtr_commit(btr_mtr). A quirk: Do not reuse
pages that were previously freed in btr_mtr. Only write the off-page
columns to 'fresh' pages.
In this way, crash recovery will see redo log entries for blob_mtr
before any redo log entry for btr_mtr. It will apply the BLOB page
writes to pages that were marked free at that point. If crash recovery
fails to see all of the btr_mtr redo log, there will be some
unreachable BLOB data in free pages, but the B-tree will be in a
consistent state.
btr_page_alloc_low(): Renamed from btr_page_alloc(). Add the parameter
init_mtr. Return an allocated block, or NULL. If init_mtr!=mtr but
the page was already X-latched in mtr, do not initialize the page.
btr_page_alloc(): Wrapper for btr_page_alloc_for_ibuf() and
btr_page_alloc_low().
btr_page_free(): Add a debug assertion that the page was a B-tree page.
btr_lift_page_up(): Return the father block.
btr_compress(), btr_cur_compress_if_useful(): Add the parameter ibool
adjust, for adjusting the cursor position.
btr_cur_pessimistic_update(): Preserve the cursor position when
big_rec will be written and the new flag BTR_KEEP_POS_FLAG is defined.
Remove a duplicate rec_get_offsets() call. Keep the X-latch on
index->lock when big_rec is needed.
btr_store_big_rec_extern_fields(): Replace update_inplace with
an operation code, and local_mtr with btr_mtr. When not doing a
fresh insert and btr_mtr has freed pages, put aside any pages that
were previously X-latched in btr_mtr, and free the pages after
writing out all data. The data must be written to 'fresh' pages,
because btr_mtr will be committed and written to the redo log after
the BLOB writes have been written to the redo log.
btr_blob_op_is_update(): Check if an operation passed to
btr_store_big_rec_extern_fields() is an update or insert-by-update.
fseg_alloc_free_page_low(), fsp_alloc_free_page(),
fseg_alloc_free_extent(), fseg_alloc_free_page_general(): Add the
parameter init_mtr. Return an allocated block, or NULL. If
init_mtr!=mtr but the page was already X-latched in mtr, do not
initialize the page.
xdes_get_descriptor_with_space_hdr(): Assert that the file space
header is being X-latched.
fsp_alloc_from_free_frag(): Refactored from fsp_alloc_free_page().
fsp_page_create(): New function, for allocating, X-latching and
potentially initializing a page. If init_mtr!=mtr but the page was
already X-latched in mtr, do not initialize the page.
fsp_free_page(): Add ut_ad(0) to the error outcomes.
fsp_free_page(), fseg_free_page_low(): Increment mtr->n_freed_pages.
fsp_alloc_seg_inode_page(), fseg_create_general(): Assert that the
page was not previously X-latched in the mini-transaction. A file
segment or inode page should never be allocated in the middle of an
mini-transaction that frees pages, such as btr_cur_pessimistic_delete().
fseg_alloc_free_page_low(): If the hinted page was allocated, skip the
check if the tablespace should be extended. Return NULL instead of
FIL_NULL on failure. Remove the flag frag_page_allocated. Instead,
return directly, because the page would already have been initialized.
fseg_find_free_frag_page_slot() would return ULINT_UNDEFINED on error,
not FIL_NULL. Correct a bogus assertion.
fseg_alloc_free_page(): Redefine as a wrapper macro around
fseg_alloc_free_page_general().
buf_block_buf_fix_inc(): Move the definition from the buf0buf.ic to
buf0buf.h, so that it can be called from other modules.
mtr_t: Add n_freed_pages (number of pages that have been freed).
page_rec_get_nth_const(), page_rec_get_nth(): The inverse function of
page_rec_get_n_recs_before(), get the nth record of the record
list. This is faster than iterating the linked list. Refactored from
page_get_middle_rec().
trx_undo_rec_copy(): Add a debug assertion for the length.
trx_undo_add_page(): Return a block descriptor or NULL instead of a
page number or FIL_NULL.
trx_undo_report_row_operation(): Add debug assertions.
trx_sys_create_doublewrite_buf(): Assert that each page was not
previously X-latched.
page_cur_insert_rec_zip_reorg(): Make use of page_rec_get_nth().
row_ins_clust_index_entry_by_modify(): Pass BTR_KEEP_POS_FLAG, so that
the repositioning of the cursor can be avoided.
row_ins_index_entry_low(): Add DEBUG_SYNC points before and after
writing off-page columns. If inserting by updating a delete-marked
record, do not reposition the cursor or commit the mini-transaction
before writing the off-page columns.
row_build(): Tighten a debug assertion about null BLOB pointers.
row_upd_clust_rec(): Add DEBUG_SYNC points before and after writing
off-page columns. Do not reposition the cursor or commit the
mini-transaction before writing the off-page columns.
rb:939 approved by Jimmy Yang
OF WIDE RECORDS
row_ins_index_entry_low(), row_upd_clust_rec(): Make a redo log
checkpoint if a DEBUG flag is set. Add DEBUG_SYNC around
btr_store_big_rec_extern_fields().
rb:946 approved by Jimmy Yang
During FIC error handling the trx->error_state was not being set to DB_SUCCESS
after failure, before attempting the next DDL SQL operation. This reset to
DB_SUCCESS is somewhat of a requirement though not explicitly stated anywhere.
The fix is to reset it to DB_SUCCESS in row0merge.cc if row_merge_rename_indexes
or row_merge_drop_index functions fail, also reset to DB_SUCCESS at trx commit.
rb://935 Approved by Jimmy Yang.
GRACEFUL SHUTDOWN
During startup mysql picks up .frm files from the tmpdir directory and
tries to drop those tables in the storage engine.
The problem is that when tmpdir ends in / then ha_innobase::delete_table()
is passed a string like "/var/tmp//#sql123", then it wrongly normalizes it
to "/#sql123" and calls row_drop_table_for_mysql() which of course fails
to delete the table entry from the InnoDB dictionary cache.
ha_innobase::delete_table() returns an error but nevertheless mysql wipes
away the .frm file and the entry in the InnoDB dictionary cache remains
orphaned with no easy way to remove it.
The "no easy" way to remove it is to create a similar temporary table again,
copy its .frm file to tmpdir under "#sql123.frm" and restart mysqld with
tmpdir=/var/tmp (no trailing slash) - this way mysql will pick the .frm file
after restart and will try to issue drop table for "/var/tmp/#sql123"
(notice do double slash), ha_innobase::delete_table() will normalize it to
"tmp/#sql123" and row_drop_table_for_mysql() will successfully remove the
table entry from the dictionary cache.
The solution is to fix normalize_table_name_low() to normalize things like
"/var/tmp//table" correctly to "tmp/table".
This patch also adds a test function which invokes
normalize_table_name_low() with various inputs to make sure it works
correctly and a mtr test that calls this test function.
Reviewed by: Marko (http://bur03.no.oracle.com/rb/r/929/)
CORRUPTED WHEN RUN CONCURRENTLY WITH
ISSUE: Table corruption due to concurrent queries.
Different threads running check, repair query
along with insert. Locks not properly acquired
in repair query. Rows are inserted inbetween
repair query.
SOLUTION: Mutex lock is acquired before the
repair call. Concurrent queries wont
effect the call to repair.
CASES RESETS DATA POINTER TO SMAL
ISSUE: Myisamchk doing sort recover
on a table reduces data_file_length.
Maximum size of data file decreases,
lesser number of rows are stored.
SOLUTION: Size of data_file_length is
fixed to the original length.
CASES RESETS DATA POINTER TO SMAL
ISSUE: Myisamchk doing sort recover
on a table reduces data_file_length.
Maximum size of data file decreases,
lesser number of rows are stored.
SOLUTION: Size of data_file_length is
fixed to the original length.
rb://914
approved by: Marko Makela
Poll in fil_rename_tablespace() after setting ::stop_ios flag can
result in a hang because the other thread actually dispatching the IO
won't wake IO helper threads or flush the tablespace before starting
wait in fil_mutex_enter_and_prepare_for_io().
When mode==BUF_KEEP_OLD, buffered inserts are being merged to the page.
It is possible that a read request for a page was pending while the page
was freed in DROP INDEX or DROP TABLE. In these cases, it is OK (although
useless) to merge the buffered changes to the freed page.
ISSUES WITH COPYING PARTITIONED INNODB TABLES FROM LINUX TO WINDOWS
This problem was already fixed in mysql-trunk as part of bug #11755924. I am
backporting the fix to mysql-5.1.
If we meet DB_TOO_MANY_CONCURRENT_TRXS during the execution tab_create_graph from row_create_table_for_mysql(), .ibd file for the table should be created already but was not deleted for the error handling.
rb:875 approved by Jimmy Yang
InnoDB: Remove HAVE_purify, UNIV_INIT_MEM_TO_ZERO, UNIV_SET_MEM_TO_ZERO.
The compile-time setting HAVE_purify can mask potential bugs.
It is being set in PB2 Valgrind runs. We should simply get rid of it,
and replace it with UNIV_MEM_INVALID() to declare uninitialized memory
as such in Valgrind-instrumented binaries.
os_mem_alloc_large(), ut_malloc_low(): Remove the parameter set_to_zero.
ut_malloc(): Define as a macro that invokes ut_malloc_low().
buf_pool_init(): Never initialize the buffer pool frames. All pages
must be initialized before flushing them to disk.
mem_heap_alloc(): Never initialize the allocated memory block.
os_mem_alloc_nocache(), ut_test_malloc(): Unused function, remove.
rb:813 approved by Jimmy Yang
COMMUNICATION PACKETS, ERROR_CODE: 1160
If idle FEDERATED table is evicted from the table cache when
a connection to remote server is lost, query that initiated
eviction may fail.
If this query is executed by slave SQL thread it may fail as well.
An error of close was stored in diagnostics area, which was later
attributed to the statement that caused eviction.
With this patch FEDERATED clears an error of close.
CREATE TABLE bug13510739 (c INTEGER NOT NULL, PRIMARY KEY (c)) ENGINE=INNODB;
INSERT INTO bug13510739 VALUES (1), (2), (3), (4);
DELETE FROM bug13510739 WHERE c=2;
HANDLER bug13510739 OPEN;
HANDLER bug13510739 READ `primary` = (2);
HANDLER bug13510739 READ `primary` NEXT; <-- crash
The bug is that in the particular testcase row_search_for_mysql() picked up
a delete-marked record and quit, leaving the cursor non-positioned state and
on the subsequent 'get next' call the code crashed because of the
non-positioned cursor.
In row0sel.cc (line numbers from mysql-trunk):
4653 if (rec_get_deleted_flag(rec, comp)) {
...
4679 if (index == clust_index && unique_search) {
4680
4681 err = DB_RECORD_NOT_FOUND;
4682
4683 goto normal_return;
4684 }
it quit from here, not storing the cursor position.
In contrast, if the record=2 is not found at all (e.g. sleep(1) after DELETE
to let the purge wipe it away completely) then 'get = 2' does find record=3
and quits from here:
4366 if (0 != cmp_dtuple_rec(search_tuple, rec, offsets)) {
...
4394 btr_pcur_store_position(pcur, &mtr);
4395
4396 err = DB_RECORD_NOT_FOUND;
4397 #if 0
4398 ut_print_name(stderr, trx, FALSE, index->name);
4399 fputs(" record not found 3\n", stderr);
4400 #endif
4401
4402 goto normal_return;
Another fix could be to extend the condition on line 4366 to hold only if
seach_tuple matches rec AND if rec is not delete marked.
Notice that in the above test case if we wait about 1 second somewhere after
DELETE and before 'get = 2', then the testcase does not crash and returns 4
instead. Not sure if this is the correct behavior, but this bugfix removes
the crash and makes the code return what it also returns in the non-crashing
case (if rec=2 is not found during 'get = 2', e.g. we have sleep(1) there).
Approved by: Marko (http://bur03.no.oracle.com/rb/r/863/)
The counter handler_read_key (SSV::ha_read_key_count) is incremented
incorrectly.
The mysql server maintains a per thread system_status_var (SSV)
object. This object contains among other things the counter
SSV::ha_read_key_count. The purpose of this counter is to measure the
number of requests to read a row based on a key (or the number of
index lookups).
This counter was wrongly incremented in the
ha_innobase::innobase_get_index(). The fix removes
this increment statement (for both innodb and innodb_plugin).
The various callers of the innobase_get_index() was checked to
determine if anybody must increment this counter (if they first call
innobase_get_index() and then perform an index lookup). It was found
that no caller of innobase_get_index() needs to worry about the
SSV::ha_read_key_count counter.
WITH MYISAM_USE_MMAP ENABLED
MySQL server can crash due to segmentation fault when
started with myisam_use_mmap.
The reason behind this being, while making a request to
unmap (munmap) the previously mapped memory (mmap), the
size passed was 7 bytes larger than the size requested at
the time of mapping. This can eventually unmap the adjacent
memory mapped block, belonging to some other memory-map pool.
Hence the subsequent call to mmap can map a region which was
still a valid memory mapped area.
Fixed by removing the extra 7-byte margin which was erroneously
added to the size, used for unmappping.
storage/myisam/mi_close.c:
Bug#11756764 48726: MYSQLD KEEPS CRASHING WITH SIGSEGV
WITH MYISAM_USE_MMAP ENABLED
Added a condition to call _mi_unmap_file() in case
of compressed records. mi_munmap_file() is called
otherwise.
storage/myisam/mi_packrec.c:
Bug#11756764 48726: MYSQLD KEEPS CRASHING WITH SIGSEGV
WITH MYISAM_USE_MMAP ENABLED
mi_dynmap_file() function, after successfully executing
mmap, stores the total size in info->s->mapped_length
variable. Now, if mi_dynmap_file() is invoked with a size
with an extra 7-byte margin (MEMMAP_EXTRA_MARGIN),
the margin will eventually also get stored in mapped_length.
So, un-mapping function can simply use the value stored in
mapped_length in order to unmap the previously mapped
region.
AND HANG IN SHOW TABLE STATUS.
ISSUE: Table corruption due to concurrent queries.
Different threads running insert and check
query leads to table corruption. Not properly locked,
rows are inserted in between check query.
SOLUTION: In check query mutex lock is acquired
for a longer time to handle concurrent
insert and check query.
NOTE: Additionally we backported the fix for CHECKSUM
issue(bug#11758979).
rb://816
approved by: Marko Makela
The title is misleading. This bug was actually introduced by
bug 12635227 and was unearthed by a later optimization.
We need to free buf_page_t structs that we are allocating using
malloc() at shutdown.
a.k.a. Bug#7975 deadlock without any locking, simple select and update
Bug#7975 was reintroduced when the storage engine API was made
pluggable in MySQL 5.1. Instead of looking at thd->lex directly, we
rely on handler::extra(). But, we were looking at the wrong extra()
flag, and we were ignoring the TRX_DUP_REPLACE flag in places where we
should obey it.
innodb_replace.test: Add tests for hopefully all affected statement
types, so that bug should never ever resurface. This kind of tests
should have been added when fixing Bug#7975 in MySQL 5.0.3 in the
first place.
rb:806 approved by Sunny Bains
btr_pcur_restore_position_func(): When the cursor was positioned at
the tree infimum or supremum, initialize pos_state and latch_mode. The
assertion failed, because pos_state was BTR_PCUR_WAS_POSITIONED. In
the test failure of WL#5874, the purge thread attempted to restore the
cursor position on the infimum record (the clustered index was empty).
btr_pcur_detach(), btr_pcur_is_detached(): Unused functions, remove.
rb:804 approved by Inaam Rana
row_rename_table_for_mysql(): Return DB_ERROR instead of DB_SUCCESS
when fil_rename_tablespace() returns an error. This bug was introduced
in the InnoDB Plugin.
Approved by Sunny Bains over IM.
Bug#12612184 RACE CONDITION AFTER BTR_CUR_PESSIMISTIC_UPDATE()
The fix introduced potentially more severe crash recovery problems
than the bug causes. Revert the fix for now.
This was an attempt to address problems with the Bug#12612184 fix.
Even with this follow-up fix, crash recovery can be broken.
Let us fix the bug later.
In the ON UPDATE CASCADE clause of FOREIGN KEY constraints, the
calculated update vector was not fully initialized. This bug was
introduced in the InnoDB Plugin when implementing support for
ROW_FORMAT=DYNAMIC.
Additionally, the data type information was not initialized, but
apparently it has never been needed in this case. Nevertheless, it is
not good programming practice to pass uninitialized values around.
calc_row_difference(): Declare the update field uninitialized in
Valgrind. Copy the data type information as well, except when the
field is SQL NULL. In the built-in InnoDB, initialize
ufield->extern_storage = FALSE (an initialization bug that had gone
unnoticed this far). The InnoDB Plugin and later have this flag to
dfield_t and have always initialized it properly.
row_ins_cascade_calc_update_vec(): Reduce the scope of some
pointers. Initialize orig_len. (This caused the bug in InnoDB Plugin
and later.)
row_ins_foreign_check_on_constraint(): Simplify a condition. Declare
the update vector uninitialized.
rb:771 approved by Jimmy Yang
btr_record_not_null_field_in_rec(): Remove the parameter rec.
Use rec_offs_nth_sql_null() instead of rec_get_nth_field().
rb:788 approved by Jimmy Yang
USING MYISAM_USE_MMAP ON WINDOWS
When OPTIMIZE/REPAIR TABLE is switching to new data file,
old data file is removed while memory mapping is still
active.
With 5.1 implementation of nt_share_delete() it is not
permitted to remove mmaped file.
This fix disables memory mapping for mi_repair() operations.
mysql-test/r/myisam.result:
A test case for BUG#11757032.
mysql-test/t/myisam.test:
A test case for BUG#11757032.
storage/myisam/ha_myisam.cc:
mi_repair*() functions family use file I/O even if memory
mapping is available.
Since mixing mmap I/O and file I/O may cause various artifacts,
memory mapping must be disabled.
storage/myisam/mi_delete_all.c:
Clean-up: do not attempt to remap file after truncate, since
there is nothing to map.
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
