This is a regression from the fix for bug no 38999. A storage engine capable
of reading only a subset of a table's columns updates corresponding bits in
the read buffer to signal that it has read NULL values for the corresponding
columns. It cannot, and should not, update any other bits. Bug no 38999
occurred because the implementation of UPDATE statements compare the NULL bits
using memcmp, inadvertently comparing bits that were never requested from the
storage engine. The regression was caused by the storage engine trying to
alleviate the situation by writing to all NULL bits, even those that it had no
knowledge of. This has devastating effects for the index merge algorithm,
which relies on all NULL bits, except those explicitly requested, being left
unchanged.
The fix reverts the fix for bug no 38999 in both InnoDB and InnoDB plugin and
changes the server's method of comparing records. For engines that always read
entire rows, we proceed as usual. For engines capable of reading only select
columns, the record buffers are now compared on a column by column basis. An
assertion was also added so that non comparable buffers are never read. Some
relevant copy-pasted code was also consolidated in a new function.
This is a simple optimization issue. All stats are related to only indexed
columns, index size or number of rows in the whole table. UPDATEs that touch
only non-indexed columns cannot affect stats and we can avoid calling the
function row_update_statistics_if_needed() which may result in unnecessary I/O.
Approved by: Marko (rb://466)
TYPE __sync_lock_test_and_set (TYPE *ptr, TYPE value, ...)
it is not documented what happens if the two arguments are of different
type like it was before: the first one was lock_word_t (byte) and the
second one was 1 or 0 (int).
Approved by: Marko (via IRC)
Use UNINIT_VAR workaround instead of LINT_INIT. The former can
also be used to silence false-positives in non-debug builds as
it actually does not cause new code to be generated.
Fix compiler warning:
trx/trx0undo.c: In function 'trx_undo_truncate_end':
trx/trx0undo.c:1069:14: error: variable 'rseg' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
trx/trx0undo.c: In function 'trx_undo_set_state_at_prepare':
trx/trx0undo.c:1871:16: error: variable 'page_hdr' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
trx/trx0trx.c: In function 'trx_prepare_off_kernel':
trx/trx0trx.c:1808:11: error: variable 'update_hdr_page' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
trx/trx0sys.c: In function 'trx_sys_create_doublewrite_buf':
trx/trx0sys.c:244:15: error: variable 'new_block' set but not used [-Werror=unused-but-set-variable]
Fix compiler warnings:
trx/trx0roll.c: In function 'trx_undo_arr_remove_info':
trx/trx0roll.c:744:9: error: variable 'n' set but not used [-Werror=unused-but-set-variable]
trx/trx0roll.c:743:9: error: variable 'n_used' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
trx/trx0purge.c: In function 'trx_purge_rec_release':
trx/trx0purge.c:1071:18: error: variable 'arr' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
trx/trx0purge.c: In function 'trx_purge_rseg_get_next_history_log':
trx/trx0purge.c:660:15: error: variable 'seg_hdr' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
trx/trx0purge.c: In function 'trx_purge_add_update_undo_to_history':
trx/trx0purge.c:307:15: error: variable 'seg_header' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
trx/trx0purge.c: In function 'trx_purge_add_update_undo_to_history':
trx/trx0purge.c:309:16: error: variable 'page_header' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
row/row0vers.c: In function 'row_vers_impl_x_locked_off_kernel':
row/row0vers.c:74:9: error: variable 'err' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
row/row0umod.c: In function 'row_undo_mod_clust_low':
row/row0umod.c:117:9: error: variable 'success' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
row/row0purge.c: In function 'row_purge_step':
row/row0purge.c:687:9: error: variable 'err' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
que/que0que.c: In function 'que_run_threads_low':
que/que0que.c:1287:9: error: variable 'cumul_resource' set but not used [-Werror=unused-but-set-variable]
Fix compiler warnings:
os/os0file.c: In function 'os_file_create':
os/os0file.c:1371:14: error: variable 'purpose_str' set but not used [-Werror=unused-but-set-variable]
os/os0file.c:1370:14: error: variable 'type_str' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
log/log0recv.c: In function 'recv_synchronize_groups':
log/log0recv.c:562:14: error: variable 'limit_lsn' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
log/log0recv.c: In function 'recv_recovery_from_checkpoint_start_func':
log/log0recv.c:2894:14: error: variable 'archived_lsn' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
handler/i_s.cc: In function 'int trx_i_s_common_fill_table(THD*, TABLE_LIST*, COND*)':
handler/i_s.cc:931:8: error: variable 'ret' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
handler/ha_innodb.cc: In function 'void innobase_drop_database(handlerton*, char*)':
handler/ha_innodb.cc:7010:6: error: variable 'error' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
handler/ha_innodb.cc: In function 'bool innodb_show_status(handlerton*, THD*, bool (*)(THD*, const char*, uint, const char*, uint, const char*, uint))':
handler/ha_innodb.cc:8851:7: error: variable 'result' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
eval/eval0eval.c: In function 'eval_notfound':
eval/eval0eval.c:388:14: error: variable 'arg2' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
dict/dict0dict.c: In function 'dict_index_print_low':
dict/dict0dict.c:4444:14: error: variable 'type_string' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
dict/dict0crea.c: In function 'dict_create_index_tree_step':
dict/dict0crea.c:630:16: error: variable 'table' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
buf/buf0flu.c: In function 'buf_flush_batch':
buf/buf0flu.c:1274:9: error: variable 'old_page_count' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
buf/buf0flu.c: In function 'buf_flush_delete_from_flush_rbt':
buf/buf0flu.c:131:8: error: variable 'ret' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
btr/btr0sea.c: In function 'btr_search_update_hash_on_delete':
btr/btr0sea.c:1498:9: error: variable 'found' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
btr/btr0pcur.c: In function 'btr_pcur_move_backward_from_page':
btr/btr0pcur.c:455:9: error: variable 'space' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
btr/btr0cur.c: In function 'btr_free_externally_stored_field':
btr/btr0cur.c:4281:16: error: variable 'rec_block' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
btr/btr0cur.c: In function 'btr_cur_optimistic_update':
btr/btr0cur.c:1839:10: error: variable 'orig_rec' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
btr/btr0btr.c: In function 'btr_compress':
btr/btr0btr.c:2564:9: error: variable 'level' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
btr/btr0btr.c: In function 'btr_page_split_and_insert':
btr/btr0btr.c:1898:11: error: variable 'insert_page' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
./include/ut0rnd.ic: In function 'ut_rnd_gen_ulint':
./include/ut0rnd.ic:88:8: error: variable 'n_bits' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
handler/ha_innodb.cc: In function 'bool innodb_show_status(handlerton*, THD*, bool (*)(THD*, const char*, uint, const char*, uint, const char*, uint))':
handler/ha_innodb.cc:7539:7: error: variable 'result' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
handler/ha_innodb.cc: In function 'void innobase_drop_database(handlerton*, char*)':
handler/ha_innodb.cc:5969:6: error: variable 'error' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
trx/trx0undo.c: In function 'trx_undo_set_state_at_prepare':
trx/trx0undo.c:1798:16: error: variable 'page_hdr' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
trx/trx0undo.c: In function 'trx_undo_truncate_end':
trx/trx0undo.c:1015:14: error: variable 'rseg' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
trx/trx0trx.c: In function 'trx_prepare_off_kernel':
trx/trx0trx.c:1830:11: error: variable 'update_hdr_page' set but not used [-Werror=unused-but-set-variable]
Fix compiler warning:
trx/trx0sys.c: In function 'trx_sys_create_doublewrite_buf':
trx/trx0sys.c:168:10: error: variable 'new_page' set but not used [-Werror=unused-but-set-variable]
Fix compiler warnings:
trx/trx0roll.c: In function 'trx_undo_arr_remove_info':
trx/trx0roll.c:717:9: error: variable 'n' set but not used [-Werror=unused-but-set-variable]
trx/trx0roll.c:716:9: error: variable 'n_used' set but not used [-Werror=unused-but-set-variable]
