Merge mysql-5.1-innodb -> mysql-5.1

32 files changed, 400 insertions, 153 deletions

diff --git a/storage/innodb_plugin/ChangeLog b/storage/innodb_plugin/ChangeLog
index 8eb63fe8c78..18ab48f32a5 100644
--- a/storage/innodb_plugin/ChangeLog
+++ b/storage/innodb_plugin/ChangeLog
@@ -1,3 +1,54 @@
+2011-01-27	The InnoDB Team
+
+	* btr/btr0cur.c:
+	Bug#59465 btr_estimate_number_of_different_key_vals use
+	incorrect offset for external_size
+
+2011-01-27	The InnoDB Team
+
+	* include/trx0trx.h, trx/trx0trx.c:
+	Bug#59440 Race condition in XA ROLLBACK and XA COMMIT
+	after server restart
+
+2011-01-25	The InnoDB Team
+
+	* row/row0upd.c:
+	Bug#59585 Fix 58912 introduces compiler warning
+	due to potentially uninitialized variable
+
+2011-01-25	The InnoDB Team
+
+	* mtr/mtr0log.c:
+	Bug#59486 Incorrect usage of UNIV_UNLIKELY() in mlog_parse_string()
+
+2011-01-25	The InnoDB Team
+
+	* row/row0vers.c:
+	Fix Bug#59464 Race condition in row_vers_build_for_semi_consistent_read
+
+2011-01-25	The InnoDB Team
+
+	* btr/btr0btr.c, btr/btr0cur.c, btr/btr0sea.c,
+	buf/buf0buddy.c, buf/buf0buf.c, buf/buf0lru.c,
+	include/buf0buf.h, include/buf0buf.ic, include/buf0lru.h,
+	mem/mem0mem.c, page/page0zip.c:
+	Fix Bug#59707 Unused compression-related parameters
+	in buffer pool functions
+
+2011-01-18	The InnoDB Team
+
+	* include/sync0rw.h, sync/sync0arr.c, sync/sync0rw.c:
+	Fix Bug#59579 rw_lock_debug_print outputs to stderr, not to
+	SHOW ENGINE INNODB STATUS
+
+2011-01-14	The InnoDB Team
+	* btr/btr0cur.c, dict/dict0dict.c, handler/ha_innodb.cc,
+	include/btr0cur.h, include/dict0mem.h, include/rem0cmp.h,
+	include/rem0cmp.ic, include/srv0srv.h, rem/rem0cmp.c,
+	srv/srv0srv.c, innodb_bug30423.test:
+	Fix Bug#30423 InnoDBs treatment of NULL in index stats causes
+	bad "rows examined" estimates
+
 2011-01-06	The InnoDB Team
 	* handler/i_s.cc, include/trx0i_s.h, trx/trx0i_s.c:
 	Fix Bug#55397 cannot select from innodb_trx when trx_query contains
diff --git a/storage/innodb_plugin/btr/btr0btr.c b/storage/innodb_plugin/btr/btr0btr.c
index 32e2caecdb8..3d8d6048603 100644
--- a/storage/innodb_plugin/btr/btr0btr.c
+++ b/storage/innodb_plugin/btr/btr0btr.c
@@ -979,7 +979,7 @@ btr_page_reorganize_low(
 	log_mode = mtr_set_log_mode(mtr, MTR_LOG_NONE);
 
 #ifndef UNIV_HOTBACKUP
-	temp_block = buf_block_alloc(0);
+	temp_block = buf_block_alloc();
 #else /* !UNIV_HOTBACKUP */
 	ut_ad(block == back_block1);
 	temp_block = back_block2;
diff --git a/storage/innodb_plugin/btr/btr0cur.c b/storage/innodb_plugin/btr/btr0cur.c
index c57255a25ae..874db3066b5 100644
--- a/storage/innodb_plugin/btr/btr0cur.c
+++ b/storage/innodb_plugin/btr/btr0cur.c
@@ -100,6 +100,18 @@ can be released by page reorganize, then it is reorganized */
 /*--------------------------------------*/
 #define BTR_BLOB_HDR_SIZE		8	/*!< Size of a BLOB
 						part header, in bytes */
+
+/** Estimated table level stats from sampled value.
+@param value		sampled stats
+@param index		index being sampled
+@param sample		number of sampled rows
+@param ext_size		external stored data size
+@param not_empty	table not empty
+@return estimated table wide stats from sampled value */
+#define BTR_TABLE_STATS_FROM_SAMPLE(value, index, sample, ext_size, not_empty)\
+	(((value) * (ib_int64_t) index->stat_n_leaf_pages		\
+	  + (sample) - 1 + (ext_size) + (not_empty)) / ((sample) + (ext_size)))
+
 /* @} */
 #endif /* !UNIV_HOTBACKUP */
 
@@ -3201,9 +3213,54 @@ btr_estimate_n_rows_in_range(
 }
 
 /*******************************************************************//**
+Record the number of non_null key values in a given index for
+each n-column prefix of the index where n < dict_index_get_n_unique(index).
+The estimates are eventually stored in the array:
+index->stat_n_non_null_key_vals. */
+static
+void
+btr_record_not_null_field_in_rec(
+/*=============================*/
+	rec_t*		rec,		/*!< in: physical record */
+	ulint		n_unique,	/*!< in: dict_index_get_n_unique(index),
+					number of columns uniquely determine
+					an index entry */
+	const ulint*	offsets,	/*!< in: rec_get_offsets(rec, index),
+					its size could be for all fields or
+					that of "n_unique" */
+	ib_int64_t*	n_not_null)	/*!< in/out: array to record number of
+					not null rows for n-column prefix */
+{
+	ulint	i;
+
+	ut_ad(rec_offs_n_fields(offsets) >= n_unique);
+
+	if (n_not_null == NULL) {
+		return;
+	}
+
+	for (i = 0; i < n_unique; i++) {
+		ulint	rec_len;
+		byte*	field;
+
+		field = rec_get_nth_field(rec, offsets, i, &rec_len);
+
+		if (rec_len != UNIV_SQL_NULL) {
+			n_not_null[i]++;
+		} else {
+			/* Break if we hit the first NULL value */
+			break;
+		}
+	}
+}
+
+/*******************************************************************//**
 Estimates the number of different key values in a given index, for
 each n-column prefix of the index where n <= dict_index_get_n_unique(index).
-The estimates are stored in the array index->stat_n_diff_key_vals. */
+The estimates are stored in the array index->stat_n_diff_key_vals.
+If innodb_stats_method is "nulls_ignored", we also record the number of
+non-null values for each prefix and store the estimates in
+array index->stat_n_non_null_key_vals. */
 UNIV_INTERN
 void
 btr_estimate_number_of_different_key_vals(
@@ -3217,6 +3274,8 @@ btr_estimate_number_of_different_key_vals(
 	ulint		matched_fields;
 	ulint		matched_bytes;
 	ib_int64_t*	n_diff;
+	ib_int64_t*	n_not_null;
+	ibool		stats_null_not_equal;
 	ullint		n_sample_pages; /* number of pages to sample */
 	ulint		not_empty_flag	= 0;
 	ulint		total_external_size = 0;
@@ -3225,16 +3284,43 @@ btr_estimate_number_of_different_key_vals(
 	ullint		add_on;
 	mtr_t		mtr;
 	mem_heap_t*	heap		= NULL;
-	ulint		offsets_rec_[REC_OFFS_NORMAL_SIZE];
-	ulint		offsets_next_rec_[REC_OFFS_NORMAL_SIZE];
-	ulint*		offsets_rec	= offsets_rec_;
-	ulint*		offsets_next_rec= offsets_next_rec_;
-	rec_offs_init(offsets_rec_);
-	rec_offs_init(offsets_next_rec_);
+	ulint*		offsets_rec	= NULL;
+	ulint*		offsets_next_rec = NULL;
 
 	n_cols = dict_index_get_n_unique(index);
 
-	n_diff = mem_zalloc((n_cols + 1) * sizeof(ib_int64_t));
+	heap = mem_heap_create((sizeof *n_diff + sizeof *n_not_null)
+			       * (n_cols + 1)
+			       + dict_index_get_n_fields(index)
+			       * (sizeof *offsets_rec
+				  + sizeof *offsets_next_rec));
+
+	n_diff = mem_heap_zalloc(heap, (n_cols + 1) * sizeof(ib_int64_t));
+
+	n_not_null = NULL;
+
+	/* Check srv_innodb_stats_method setting, and decide whether we
+	need to record non-null value and also decide if NULL is
+	considered equal (by setting stats_null_not_equal value) */
+	switch (srv_innodb_stats_method) {
+	case SRV_STATS_NULLS_IGNORED:
+		n_not_null = mem_heap_zalloc(heap, (n_cols + 1)
+					     * sizeof *n_not_null);
+		/* fall through */
+
+	case SRV_STATS_NULLS_UNEQUAL:
+		/* for both SRV_STATS_NULLS_IGNORED and SRV_STATS_NULLS_UNEQUAL
+		case, we will treat NULLs as unequal value */
+		stats_null_not_equal = TRUE;
+		break;
+
+	case SRV_STATS_NULLS_EQUAL:
+		stats_null_not_equal = FALSE;
+		break;
+
+	default:
+		ut_error;
+        }
 
 	/* It makes no sense to test more pages than are contained
 	in the index, thus we lower the number if it is too high */
@@ -3251,7 +3337,6 @@ btr_estimate_number_of_different_key_vals(
 	/* We sample some pages in the index to get an estimate */
 
 	for (i = 0; i < n_sample_pages; i++) {
-		rec_t*	supremum;
 		mtr_start(&mtr);
 
 		btr_cur_open_at_rnd_pos(index, BTR_SEARCH_LEAF, &cursor, &mtr);
@@ -3264,18 +3349,25 @@ btr_estimate_number_of_different_key_vals(
 
 		page = btr_cur_get_page(&cursor);
 
-		supremum = page_get_supremum_rec(page);
 		rec = page_rec_get_next(page_get_infimum_rec(page));
 
-		if (rec != supremum) {
+		if (!page_rec_is_supremum(rec)) {
 			not_empty_flag = 1;
 			offsets_rec = rec_get_offsets(rec, index, offsets_rec,
 						      ULINT_UNDEFINED, &heap);
+
+			if (n_not_null) {
+				btr_record_not_null_field_in_rec(
+					rec, n_cols, offsets_rec, n_not_null);
+			}
 		}
 
-		while (rec != supremum) {
+		while (!page_rec_is_supremum(rec)) {
 			rec_t*	next_rec = page_rec_get_next(rec);
-			if (next_rec == supremum) {
+			if (page_rec_is_supremum(next_rec)) {
+				total_external_size +=
+					btr_rec_get_externally_stored_len(
+						rec, offsets_rec);
 				break;
 			}
 
@@ -3283,11 +3375,13 @@ btr_estimate_number_of_different_key_vals(
 			matched_bytes = 0;
 			offsets_next_rec = rec_get_offsets(next_rec, index,
 							   offsets_next_rec,
-							   n_cols, &heap);
+							   ULINT_UNDEFINED,
+							   &heap);
 
 			cmp_rec_rec_with_match(rec, next_rec,
 					       offsets_rec, offsets_next_rec,
-					       index, &matched_fields,
+					       index, stats_null_not_equal,
+					       &matched_fields,
 					       &matched_bytes);
 
 			for (j = matched_fields + 1; j <= n_cols; j++) {
@@ -3297,6 +3391,12 @@ btr_estimate_number_of_different_key_vals(
 				n_diff[j]++;
 			}
 
+			if (n_not_null) {
+				btr_record_not_null_field_in_rec(
+					next_rec, n_cols, offsets_next_rec,
+					n_not_null);
+			}
+
 			total_external_size
 				+= btr_rec_get_externally_stored_len(
 					rec, offsets_rec);
@@ -3331,10 +3431,6 @@ btr_estimate_number_of_different_key_vals(
 			}
 		}
 
-		offsets_rec = rec_get_offsets(rec, index, offsets_rec,
-					      ULINT_UNDEFINED, &heap);
-		total_external_size += btr_rec_get_externally_stored_len(
-			rec, offsets_rec);
 		mtr_commit(&mtr);
 	}
 
@@ -3348,13 +3444,9 @@ btr_estimate_number_of_different_key_vals(
 
 	for (j = 0; j <= n_cols; j++) {
 		index->stat_n_diff_key_vals[j]
-			= ((n_diff[j]
-			    * (ib_int64_t)index->stat_n_leaf_pages
-			    + n_sample_pages - 1
-			    + total_external_size
-			    + not_empty_flag)
-			   / (n_sample_pages
-			      + total_external_size));
+			= BTR_TABLE_STATS_FROM_SAMPLE(
+				n_diff[j], index, n_sample_pages,
+				total_external_size, not_empty_flag); 
 
 		/* If the tree is small, smaller than
 		10 * n_sample_pages + total_external_size, then
@@ -3373,12 +3465,20 @@ btr_estimate_number_of_different_key_vals(
 		}
 
 		index->stat_n_diff_key_vals[j] += add_on;
-	}
 
-	mem_free(n_diff);
-	if (UNIV_LIKELY_NULL(heap)) {
-		mem_heap_free(heap);
+		/* Update the stat_n_non_null_key_vals[] with our
+		sampled result. stat_n_non_null_key_vals[] is created
+		and initialized to zero in dict_index_add_to_cache(),
+		along with stat_n_diff_key_vals[] array */
+		if (n_not_null != NULL && (j < n_cols)) {
+			index->stat_n_non_null_key_vals[j] =
+				 BTR_TABLE_STATS_FROM_SAMPLE(
+					n_not_null[j], index, n_sample_pages,
+					total_external_size, not_empty_flag);
+		}
 	}
+
+	mem_heap_free(heap);
 }
 
 /*================== EXTERNAL STORAGE OF BIG FIELDS ===================*/
@@ -3667,13 +3767,12 @@ btr_blob_free(
 	    && buf_block_get_space(block) == space
 	    && buf_block_get_page_no(block) == page_no) {
 
-		if (buf_LRU_free_block(&block->page, all, NULL)
-		    != BUF_LRU_FREED
+		if (buf_LRU_free_block(&block->page, all) != BUF_LRU_FREED
 		    && all && block->page.zip.data) {
 			/* Attempt to deallocate the uncompressed page
 			if the whole block cannot be deallocted. */
 
-			buf_LRU_free_block(&block->page, FALSE, NULL);
+			buf_LRU_free_block(&block->page, FALSE);
 		}
 	}
 
diff --git a/storage/innodb_plugin/btr/btr0sea.c b/storage/innodb_plugin/btr/btr0sea.c
index 035fdbb61d2..9835efcf712 100644
--- a/storage/innodb_plugin/btr/btr0sea.c
+++ b/storage/innodb_plugin/btr/btr0sea.c
@@ -141,7 +141,7 @@ btr_search_check_free_space_in_heap(void)
 	be enough free space in the hash table. */
 
 	if (heap->free_block == NULL) {
-		buf_block_t*	block = buf_block_alloc(0);
+		buf_block_t*	block = buf_block_alloc();
 
 		rw_lock_x_lock(&btr_search_latch);
 
diff --git a/storage/innodb_plugin/buf/buf0buddy.c b/storage/innodb_plugin/buf/buf0buddy.c
index ee5a569c3ff..63c99571510 100644
--- a/storage/innodb_plugin/buf/buf0buddy.c
+++ b/storage/innodb_plugin/buf/buf0buddy.c
@@ -327,7 +327,7 @@ buf_buddy_alloc_low(
 
 	/* Try replacing an uncompressed page in the buffer pool. */
 	buf_pool_mutex_exit();
-	block = buf_LRU_get_free_block(0);
+	block = buf_LRU_get_free_block();
 	*lru = TRUE;
 	buf_pool_mutex_enter();
 
diff --git a/storage/innodb_plugin/buf/buf0buf.c b/storage/innodb_plugin/buf/buf0buf.c
index dac416f9472..6e76e4c65be 100644
--- a/storage/innodb_plugin/buf/buf0buf.c
+++ b/storage/innodb_plugin/buf/buf0buf.c
@@ -1283,7 +1283,7 @@ shrink_again:
 
 				buf_LRU_make_block_old(&block->page);
 				dirty++;
-			} else if (buf_LRU_free_block(&block->page, TRUE, NULL)
+			} else if (buf_LRU_free_block(&block->page, TRUE)
 				   != BUF_LRU_FREED) {
 				nonfree++;
 			}
@@ -1729,8 +1729,7 @@ err_exit:
 		mutex_enter(block_mutex);
 
 		/* Discard the uncompressed page frame if possible. */
-		if (buf_LRU_free_block(bpage, FALSE, NULL)
-		    == BUF_LRU_FREED) {
+		if (buf_LRU_free_block(bpage, FALSE) == BUF_LRU_FREED) {
 
 			mutex_exit(block_mutex);
 			goto lookup;
@@ -2165,7 +2164,7 @@ wait_until_unfixed:
 		buf_pool_mutex_exit();
 		mutex_exit(&buf_pool_zip_mutex);
 
-		block = buf_LRU_get_free_block(0);
+		block = buf_LRU_get_free_block();
 		ut_a(block);
 
 		buf_pool_mutex_enter();
@@ -2291,8 +2290,7 @@ wait_until_unfixed:
 		/* Try to evict the block from the buffer pool, to use the
 		insert buffer as much as possible. */
 
-		if (buf_LRU_free_block(&block->page, TRUE, NULL)
-		    == BUF_LRU_FREED) {
+		if (buf_LRU_free_block(&block->page, TRUE) == BUF_LRU_FREED) {
 			buf_pool_mutex_exit();
 			mutex_exit(&block->mutex);
 			fprintf(stderr,
@@ -2829,7 +2827,7 @@ buf_page_init_for_read(
 	    && UNIV_LIKELY(!recv_recovery_is_on())) {
 		block = NULL;
 	} else {
-		block = buf_LRU_get_free_block(0);
+		block = buf_LRU_get_free_block();
 		ut_ad(block);
 	}
 
@@ -3001,7 +2999,7 @@ buf_page_create(
 	ut_ad(mtr->state == MTR_ACTIVE);
 	ut_ad(space || !zip_size);
 
-	free_block = buf_LRU_get_free_block(0);
+	free_block = buf_LRU_get_free_block();
 
 	buf_pool_mutex_enter();
 
diff --git a/storage/innodb_plugin/buf/buf0lru.c b/storage/innodb_plugin/buf/buf0lru.c
index e4cf218bf2e..39feb06ff23 100644
--- a/storage/innodb_plugin/buf/buf0lru.c
+++ b/storage/innodb_plugin/buf/buf0lru.c
@@ -575,7 +575,7 @@ buf_LRU_free_from_unzip_LRU_list(
 		ut_ad(block->page.in_LRU_list);
 
 		mutex_enter(&block->mutex);
-		freed = buf_LRU_free_block(&block->page, FALSE, NULL);
+		freed = buf_LRU_free_block(&block->page, FALSE);
 		mutex_exit(&block->mutex);
 
 		switch (freed) {
@@ -636,7 +636,7 @@ buf_LRU_free_from_common_LRU_list(
 
 		mutex_enter(block_mutex);
 		accessed = buf_page_is_accessed(bpage);
-		freed = buf_LRU_free_block(bpage, TRUE, NULL);
+		freed = buf_LRU_free_block(bpage, TRUE);
 		mutex_exit(block_mutex);
 
 		switch (freed) {
@@ -798,10 +798,8 @@ LRU list to the free list.
 @return	the free control block, in state BUF_BLOCK_READY_FOR_USE */
 UNIV_INTERN
 buf_block_t*
-buf_LRU_get_free_block(
-/*===================*/
-	ulint	zip_size)	/*!< in: compressed page size in bytes,
-				or 0 if uncompressed tablespace */
+buf_LRU_get_free_block(void)
+/*========================*/
 {
 	buf_block_t*	block		= NULL;
 	ibool		freed;
@@ -877,26 +875,10 @@ loop:
 
 	/* If there is a block in the free list, take it */
 	block = buf_LRU_get_free_only();
-	if (block) {
-
-#ifdef UNIV_DEBUG
-		block->page.zip.m_start =
-#endif /* UNIV_DEBUG */
-			block->page.zip.m_end =
-			block->page.zip.m_nonempty =
-			block->page.zip.n_blobs = 0;
-
-		if (UNIV_UNLIKELY(zip_size)) {
-			ibool	lru;
-			page_zip_set_size(&block->page.zip, zip_size);
-			block->page.zip.data = buf_buddy_alloc(zip_size, &lru);
-			UNIV_MEM_DESC(block->page.zip.data, zip_size, block);
-		} else {
-			page_zip_set_size(&block->page.zip, 0);
-			block->page.zip.data = NULL;
-		}
+	buf_pool_mutex_exit();
 
-		buf_pool_mutex_exit();
+	if (block) {
+		memset(&block->page.zip, 0, sizeof block->page.zip);
 
 		if (started_monitor) {
 			srv_print_innodb_monitor = mon_value_was;
@@ -908,8 +890,6 @@ loop:
 	/* If no block was in the free list, search from the end of the LRU
 	list and try to free a block there */
 
-	buf_pool_mutex_exit();
-
 	freed = buf_LRU_search_and_free_block(n_iterations);
 
 	if (freed > 0) {
@@ -1378,12 +1358,8 @@ enum buf_lru_free_block_status
 buf_LRU_free_block(
 /*===============*/
 	buf_page_t*	bpage,	/*!< in: block to be freed */
-	ibool		zip,	/*!< in: TRUE if should remove also the
+	ibool		zip)	/*!< in: TRUE if should remove also the
 				compressed page of an uncompressed page */
-	ibool*		buf_pool_mutex_released)
-				/*!< in: pointer to a variable that will
-				be assigned TRUE if buf_pool_mutex
-				was temporarily released, or NULL */
 {
 	buf_page_t*	b = NULL;
 	mutex_t*	block_mutex = buf_page_get_mutex(bpage);
@@ -1554,10 +1530,6 @@ alloc:
 			b->io_fix = BUF_IO_READ;
 		}
 
-		if (buf_pool_mutex_released) {
-			*buf_pool_mutex_released = TRUE;
-		}
-
 		buf_pool_mutex_exit();
 		mutex_exit(block_mutex);
 
diff --git a/storage/innodb_plugin/dict/dict0dict.c b/storage/innodb_plugin/dict/dict0dict.c
index 67765555658..ff56e9cb76a 100644
--- a/storage/innodb_plugin/dict/dict0dict.c
+++ b/storage/innodb_plugin/dict/dict0dict.c
@@ -1669,6 +1669,12 @@ undo_size_ok:
 			new_index->heap,
 			(1 + dict_index_get_n_unique(new_index))
 			* sizeof(ib_int64_t));
+
+		new_index->stat_n_non_null_key_vals = mem_heap_zalloc(
+			new_index->heap,
+			(1 + dict_index_get_n_unique(new_index))
+			* sizeof(*new_index->stat_n_non_null_key_vals));
+
 		/* Give some sensible values to stat_n_... in case we do
 		not calculate statistics quickly enough */
 
@@ -4291,6 +4297,10 @@ dict_update_statistics(
 			for (i = dict_index_get_n_unique(index); i; ) {
 				index->stat_n_diff_key_vals[i--] = 1;
 			}
+
+			memset(index->stat_n_non_null_key_vals, 0,
+			       (1 + dict_index_get_n_unique(index))
+                               * sizeof(*index->stat_n_non_null_key_vals));
 		}
 
 		index = dict_table_get_next_index(index);
diff --git a/storage/innodb_plugin/handler/ha_innodb.cc b/storage/innodb_plugin/handler/ha_innodb.cc
index 86168e2bc9b..2d60c7397b0 100644
--- a/storage/innodb_plugin/handler/ha_innodb.cc
+++ b/storage/innodb_plugin/handler/ha_innodb.cc
@@ -174,6 +174,25 @@ static char*	internal_innobase_data_file_path	= NULL;
 
 static char*	innodb_version_str = (char*) INNODB_VERSION_STR;
 
+/** Possible values for system variable "innodb_stats_method". The values
+are defined the same as its corresponding MyISAM system variable
+"myisam_stats_method"(see "myisam_stats_method_names"), for better usability */
+static const char* innodb_stats_method_names[] = {
+	"nulls_equal",
+	"nulls_unequal",
+	"nulls_ignored",
+	NullS
+};
+
+/** Used to define an enumerate type of the system variable innodb_stats_method.
+This is the same as "myisam_stats_method_typelib" */
+static TYPELIB innodb_stats_method_typelib = {
+	array_elements(innodb_stats_method_names) - 1,
+	"innodb_stats_method_typelib",
+	innodb_stats_method_names,
+	NULL
+};
+
 /* The following counter is used to convey information to InnoDB
 about server activity: in selects it is not sensible to call
 srv_active_wake_master_thread after each fetch or search, we only do
@@ -7507,6 +7526,65 @@ innobase_get_mysql_key_number_for_index(
 
         return(0);
 }
+
+/*********************************************************************//**
+Calculate Record Per Key value. Need to exclude the NULL value if
+innodb_stats_method is set to "nulls_ignored"
+@return estimated record per key value */
+static
+ha_rows
+innodb_rec_per_key(
+/*===============*/
+	dict_index_t*	index,		/*!< in: dict_index_t structure */
+	ulint		i,		/*!< in: the column we are
+					calculating rec per key */
+	ha_rows		records)	/*!< in: estimated total records */
+{
+	ha_rows		rec_per_key;
+
+	ut_ad(i < dict_index_get_n_unique(index));
+
+	/* Note the stat_n_diff_key_vals[] stores the diff value with
+	n-prefix indexing, so it is always stat_n_diff_key_vals[i + 1] */
+	if (index->stat_n_diff_key_vals[i + 1] == 0) {
+
+		rec_per_key = records;
+	} else if (srv_innodb_stats_method == SRV_STATS_NULLS_IGNORED) {
+		ib_int64_t	num_null;
+
+		/* Number of rows with NULL value in this
+		field */
+		num_null = records - index->stat_n_non_null_key_vals[i];
+
+		/* In theory, index->stat_n_non_null_key_vals[i]
+		should always be less than the number of records.
+		Since this is statistics value, the value could
+		have slight discrepancy. But we will make sure
+		the number of null values is not a negative number. */
+		num_null = (num_null < 0) ? 0 : num_null;
+
+		/* If the number of NULL values is the same as or
+		large than that of the distinct values, we could
+		consider that the table consists mostly of NULL value. 
+		Set rec_per_key to 1. */
+		if (index->stat_n_diff_key_vals[i + 1] <= num_null) {
+			rec_per_key = 1;
+		} else {
+			/* Need to exclude rows with NULL values from
+			rec_per_key calculation */
+			rec_per_key = (ha_rows)(
+				(records - num_null)
+				/ (index->stat_n_diff_key_vals[i + 1]
+				   - num_null));
+		}
+	} else {
+		rec_per_key = (ha_rows)
+			 (records / index->stat_n_diff_key_vals[i + 1]);
+	}
+
+	return(rec_per_key);
+}
+
 /*********************************************************************//**
 Returns statistics information of the table to the MySQL interpreter,
 in various fields of the handle object. */
@@ -7737,13 +7815,8 @@ ha_innobase::info_low(
 					break;
 				}
 
-				if (index->stat_n_diff_key_vals[j + 1] == 0) {
-
-					rec_per_key = stats.records;
-				} else {
-					rec_per_key = (ha_rows)(stats.records /
-					 index->stat_n_diff_key_vals[j + 1]);
-				}
+				rec_per_key = innodb_rec_per_key(
+					index, j, stats.records);
 
 				/* Since MySQL seems to favor table scans
 				too much over index searches, we pretend
@@ -10934,6 +11007,13 @@ static MYSQL_SYSVAR_STR(change_buffering, innobase_change_buffering,
   innodb_change_buffering_validate,
   innodb_change_buffering_update, "inserts"); 
 
+static MYSQL_SYSVAR_ENUM(stats_method, srv_innodb_stats_method,
+   PLUGIN_VAR_RQCMDARG,
+  "Specifies how InnoDB index statistics collection code should "
+  "treat NULLs. Possible values are NULLS_EQUAL (default), "
+  "NULLS_UNEQUAL and NULLS_IGNORED",
+   NULL, NULL, SRV_STATS_NULLS_EQUAL, &innodb_stats_method_typelib);
+
 #if defined UNIV_DEBUG || defined UNIV_IBUF_DEBUG
 static MYSQL_SYSVAR_UINT(change_buffering_debug, ibuf_debug,
   PLUGIN_VAR_RQCMDARG,
@@ -10988,6 +11068,7 @@ static struct st_mysql_sys_var* innobase_system_variables[]= {
   MYSQL_SYSVAR(stats_on_metadata),
   MYSQL_SYSVAR(stats_sample_pages),
   MYSQL_SYSVAR(adaptive_hash_index),
+  MYSQL_SYSVAR(stats_method),
   MYSQL_SYSVAR(replication_delay),
   MYSQL_SYSVAR(status_file),
   MYSQL_SYSVAR(strict_mode),
diff --git a/storage/innodb_plugin/include/btr0cur.h b/storage/innodb_plugin/include/btr0cur.h
index b477ad0320a..cb8cb399715 100644
--- a/storage/innodb_plugin/include/btr0cur.h
+++ b/storage/innodb_plugin/include/btr0cur.h
@@ -478,7 +478,10 @@ btr_estimate_n_rows_in_range(
 /*******************************************************************//**
 Estimates the number of different key values in a given index, for
 each n-column prefix of the index where n <= dict_index_get_n_unique(index).
-The estimates are stored in the array index->stat_n_diff_key_vals. */
+The estimates are stored in the array index->stat_n_diff_key_vals.
+If innodb_stats_method is nulls_ignored, we also record the number of
+non-null values for each prefix and stored the estimates in
+array index->stat_n_non_null_key_vals. */
 UNIV_INTERN
 void
 btr_estimate_number_of_different_key_vals(
diff --git a/storage/innodb_plugin/include/buf0buf.h b/storage/innodb_plugin/include/buf0buf.h
index cd4ee5906f0..d903b443920 100644
--- a/storage/innodb_plugin/include/buf0buf.h
+++ b/storage/innodb_plugin/include/buf0buf.h
@@ -165,10 +165,8 @@ Allocates a buffer block.
 @return	own: the allocated block, in state BUF_BLOCK_MEMORY */
 UNIV_INLINE
 buf_block_t*
-buf_block_alloc(
-/*============*/
-	ulint	zip_size);	/*!< in: compressed page size in bytes,
-				or 0 if uncompressed tablespace */
+buf_block_alloc(void);
+/*=================*/
 /********************************************************************//**
 Frees a buffer block which does not contain a file page. */
 UNIV_INLINE
diff --git a/storage/innodb_plugin/include/buf0buf.ic b/storage/innodb_plugin/include/buf0buf.ic
index 23db684806c..0025bef5aac 100644
--- a/storage/innodb_plugin/include/buf0buf.ic
+++ b/storage/innodb_plugin/include/buf0buf.ic
@@ -719,14 +719,12 @@ Allocates a buffer block.
 @return	own: the allocated block, in state BUF_BLOCK_MEMORY */
 UNIV_INLINE
 buf_block_t*
-buf_block_alloc(
-/*============*/
-	ulint	zip_size)	/*!< in: compressed page size in bytes,
-				or 0 if uncompressed tablespace */
+buf_block_alloc(void)
+/*=================*/
 {
 	buf_block_t*	block;
 
-	block = buf_LRU_get_free_block(zip_size);
+	block = buf_LRU_get_free_block();
 
 	buf_block_set_state(block, BUF_BLOCK_MEMORY);
 
diff --git a/storage/innodb_plugin/include/buf0lru.h b/storage/innodb_plugin/include/buf0lru.h
index 5a9cfd059f3..d543bce53cd 100644
--- a/storage/innodb_plugin/include/buf0lru.h
+++ b/storage/innodb_plugin/include/buf0lru.h
@@ -110,12 +110,9 @@ enum buf_lru_free_block_status
 buf_LRU_free_block(
 /*===============*/
 	buf_page_t*	bpage,	/*!< in: block to be freed */
-	ibool		zip,	/*!< in: TRUE if should remove also the
+	ibool		zip)	/*!< in: TRUE if should remove also the
 				compressed page of an uncompressed page */
-	ibool*		buf_pool_mutex_released);
-				/*!< in: pointer to a variable that will
-				be assigned TRUE if buf_pool_mutex
-				was temporarily released, or NULL */
+	__attribute__((nonnull));
 /******************************************************************//**
 Try to free a replaceable block.
 @return	TRUE if found and freed */
@@ -146,10 +143,9 @@ LRU list to the free list.
 @return	the free control block, in state BUF_BLOCK_READY_FOR_USE */
 UNIV_INTERN
 buf_block_t*
-buf_LRU_get_free_block(
-/*===================*/
-	ulint	zip_size);	/*!< in: compressed page size in bytes,
-				or 0 if uncompressed tablespace */
+buf_LRU_get_free_block(void)
+/*========================*/
+	__attribute__((warn_unused_result));
 
 /******************************************************************//**
 Puts a block back to the free list. */
diff --git a/storage/innodb_plugin/include/dict0mem.h b/storage/innodb_plugin/include/dict0mem.h
index 19782c2e76a..09a068ccb93 100644
--- a/storage/innodb_plugin/include/dict0mem.h
+++ b/storage/innodb_plugin/include/dict0mem.h
@@ -321,6 +321,12 @@ struct dict_index_struct{
 				dict_get_n_unique(index); we
 				periodically calculate new
 				estimates */
+	ib_int64_t*	stat_n_non_null_key_vals;
+				/* approximate number of non-null key values
+				for this index, for each column where
+				n < dict_get_n_unique(index); This
+				is used when innodb_stats_method is
+				"nulls_ignored". */
 	ulint		stat_index_size;
 				/*!< approximate index size in
 				database pages */
diff --git a/storage/innodb_plugin/include/dict0types.h b/storage/innodb_plugin/include/dict0types.h
index 7ad69193cc9..f14b59a19d4 100644
--- a/storage/innodb_plugin/include/dict0types.h
+++ b/storage/innodb_plugin/include/dict0types.h
@@ -33,11 +33,6 @@ typedef struct dict_index_struct	dict_index_t;
 typedef struct dict_table_struct	dict_table_t;
 typedef struct dict_foreign_struct	dict_foreign_t;
 
-/* A cluster object is a table object with the type field set to
-DICT_CLUSTERED */
-
-typedef dict_table_t			dict_cluster_t;
-
 typedef struct ind_node_struct		ind_node_t;
 typedef struct tab_node_struct		tab_node_t;
 
diff --git a/storage/innodb_plugin/include/rem0cmp.h b/storage/innodb_plugin/include/rem0cmp.h
index 2f751a38864..a908521c9f7 100644
--- a/storage/innodb_plugin/include/rem0cmp.h
+++ b/storage/innodb_plugin/include/rem0cmp.h
@@ -165,6 +165,10 @@ cmp_rec_rec_with_match(
 	const ulint*	offsets1,/*!< in: rec_get_offsets(rec1, index) */
 	const ulint*	offsets2,/*!< in: rec_get_offsets(rec2, index) */
 	dict_index_t*	index,	/*!< in: data dictionary index */
+	ibool		nulls_unequal,
+				/* in: TRUE if this is for index statistics
+				cardinality estimation, and innodb_stats_method
+				is "nulls_unequal" or "nulls_ignored" */
 	ulint*		matched_fields, /*!< in/out: number of already completely
 				matched fields; when the function returns,
 				contains the value the for current
diff --git a/storage/innodb_plugin/include/rem0cmp.ic b/storage/innodb_plugin/include/rem0cmp.ic
index 39ef5f4fba3..63415fe7837 100644
--- a/storage/innodb_plugin/include/rem0cmp.ic
+++ b/storage/innodb_plugin/include/rem0cmp.ic
@@ -87,5 +87,5 @@ cmp_rec_rec(
 	ulint	match_b		= 0;
 
 	return(cmp_rec_rec_with_match(rec1, rec2, offsets1, offsets2, index,
-				      &match_f, &match_b));
+				      FALSE, &match_f, &match_b));
 }
diff --git a/storage/innodb_plugin/include/srv0srv.h b/storage/innodb_plugin/include/srv0srv.h
index 7aa2ce74720..91ae895040c 100644
--- a/storage/innodb_plugin/include/srv0srv.h
+++ b/storage/innodb_plugin/include/srv0srv.h
@@ -154,6 +154,11 @@ capacity. PCT_IO(5) -> returns the number of IO operations that
 is 5% of the max where max is srv_io_capacity.  */
 #define PCT_IO(p) ((ulong) (srv_io_capacity * ((double) p / 100.0)))
 
+/* The "innodb_stats_method" setting, decides how InnoDB is going
+to treat NULL value when collecting statistics. It is not defined
+as enum type because the configure option takes unsigned integer type. */
+extern ulong	srv_innodb_stats_method;
+
 #ifdef UNIV_LOG_ARCHIVE
 extern ibool	srv_log_archive_on;
 extern ibool	srv_archive_recovery;
@@ -363,6 +368,19 @@ enum {
 					in connection with recovery */
 };
 
+/* Alternatives for srv_innodb_stats_method, which could be changed by
+setting innodb_stats_method */
+enum srv_stats_method_name_enum {
+	SRV_STATS_NULLS_EQUAL,		/* All NULL values are treated as
+					equal. This is the default setting
+					for innodb_stats_method */
+	SRV_STATS_NULLS_UNEQUAL,	/* All NULL values are treated as
+					NOT equal. */
+	SRV_STATS_NULLS_IGNORED		/* NULL values are ignored */
+};
+
+typedef enum srv_stats_method_name_enum		srv_stats_method_name_t;
+
 #ifndef UNIV_HOTBACKUP
 /** Types of threads existing in the system. */
 enum srv_thread_type {
diff --git a/storage/innodb_plugin/include/sync0rw.h b/storage/innodb_plugin/include/sync0rw.h
index 175f3deb77c..47f7dbfe0eb 100644
--- a/storage/innodb_plugin/include/sync0rw.h
+++ b/storage/innodb_plugin/include/sync0rw.h
@@ -1,6 +1,6 @@
 /*****************************************************************************
 
-Copyright (c) 1995, 2010, Innobase Oy. All Rights Reserved.
+Copyright (c) 1995, 2011, Oracle and/or its affiliates. All Rights Reserved.
 Copyright (c) 2008, Google Inc.
 
 Portions of this file contain modifications contributed and copyrighted by
@@ -490,6 +490,7 @@ UNIV_INTERN
 void
 rw_lock_debug_print(
 /*================*/
+	FILE*			f,	/*!< in: output stream */
 	rw_lock_debug_t*	info);	/*!< in: debug struct */
 #endif /* UNIV_SYNC_DEBUG */
 
diff --git a/storage/innodb_plugin/include/trx0rseg.h b/storage/innodb_plugin/include/trx0rseg.h
index a25d84f1e84..e3674089735 100644
--- a/storage/innodb_plugin/include/trx0rseg.h
+++ b/storage/innodb_plugin/include/trx0rseg.h
@@ -135,9 +135,7 @@ struct trx_rseg_struct{
 	ulint		id;	/*!< rollback segment id == the index of
 				its slot in the trx system file copy */
 	mutex_t		mutex;	/*!< mutex protecting the fields in this
-				struct except id; NOTE that the latching
-				order must always be kernel mutex ->
-				rseg mutex */
+				struct except id, which is constant */
 	ulint		space;	/*!< space where the rollback segment is
 				header is placed */
 	ulint		zip_size;/* compressed page size of space
diff --git a/storage/innodb_plugin/include/trx0trx.h b/storage/innodb_plugin/include/trx0trx.h
index abd175d365b..833bae4a4ff 100644
--- a/storage/innodb_plugin/include/trx0trx.h
+++ b/storage/innodb_plugin/include/trx0trx.h
@@ -214,12 +214,12 @@ trx_recover_for_mysql(
 /*******************************************************************//**
 This function is used to find one X/Open XA distributed transaction
 which is in the prepared state
-@return	trx or NULL */
+@return	trx or NULL; on match, the trx->xid will be invalidated */
 UNIV_INTERN
 trx_t *
 trx_get_trx_by_xid(
 /*===============*/
-	XID*	xid);	/*!< in: X/Open XA transaction identification */
+	const XID*	xid);	/*!< in: X/Open XA transaction identifier */
 /**********************************************************************//**
 If required, flushes the log to disk if we called trx_commit_for_mysql()
 with trx->flush_log_later == TRUE.
diff --git a/storage/innodb_plugin/include/univ.i b/storage/innodb_plugin/include/univ.i
index bbff8ddf1e3..4425950748b 100644
--- a/storage/innodb_plugin/include/univ.i
+++ b/storage/innodb_plugin/include/univ.i
@@ -412,7 +412,7 @@ it is read or written. */
 /* Use sun_prefetch when compile with Sun Studio */
 # define UNIV_EXPECT(expr,value) (expr)
 # define UNIV_LIKELY_NULL(expr) (expr)
-# define UNIV_PREFETCH_R(addr) sun_prefetch_read_many(addr)
+# define UNIV_PREFETCH_R(addr) sun_prefetch_read_many((void*) addr)
 # define UNIV_PREFETCH_RW(addr) sun_prefetch_write_many(addr)
 #else
 /* Dummy versions of the macros */
diff --git a/storage/innodb_plugin/mem/mem0mem.c b/storage/innodb_plugin/mem/mem0mem.c
index 1dd4db30841..86100b04fd6 100644
--- a/storage/innodb_plugin/mem/mem0mem.c
+++ b/storage/innodb_plugin/mem/mem0mem.c
@@ -347,7 +347,7 @@ mem_heap_create_block(
 				return(NULL);
 			}
 		} else {
-			buf_block = buf_block_alloc(0);
+			buf_block = buf_block_alloc();
 		}
 
 		block = (mem_block_t*) buf_block->frame;
diff --git a/storage/innodb_plugin/mtr/mtr0log.c b/storage/innodb_plugin/mtr/mtr0log.c
index 3f3dab36b76..3349036b5b3 100644
--- a/storage/innodb_plugin/mtr/mtr0log.c
+++ b/storage/innodb_plugin/mtr/mtr0log.c
@@ -408,7 +408,7 @@ mlog_parse_string(
 	ptr += 2;
 
 	if (UNIV_UNLIKELY(offset >= UNIV_PAGE_SIZE)
-			|| UNIV_UNLIKELY(len + offset) > UNIV_PAGE_SIZE) {
+	    || UNIV_UNLIKELY(len + offset > UNIV_PAGE_SIZE)) {
 		recv_sys->found_corrupt_log = TRUE;
 
 		return(NULL);
diff --git a/storage/innodb_plugin/page/page0zip.c b/storage/innodb_plugin/page/page0zip.c
index d3b1edefc6b..bb9b0995c72 100644
--- a/storage/innodb_plugin/page/page0zip.c
+++ b/storage/innodb_plugin/page/page0zip.c
@@ -4439,7 +4439,7 @@ page_zip_reorganize(
 	log_mode = mtr_set_log_mode(mtr, MTR_LOG_NONE);
 
 #ifndef UNIV_HOTBACKUP
-	temp_block = buf_block_alloc(0);
+	temp_block = buf_block_alloc();
 	btr_search_drop_page_hash_index(block);
 	block->check_index_page_at_flush = TRUE;
 #else /* !UNIV_HOTBACKUP */
diff --git a/storage/innodb_plugin/rem/rem0cmp.c b/storage/innodb_plugin/rem/rem0cmp.c
index 35b67992558..04d2c15437b 100644
--- a/storage/innodb_plugin/rem/rem0cmp.c
+++ b/storage/innodb_plugin/rem/rem0cmp.c
@@ -862,6 +862,10 @@ cmp_rec_rec_with_match(
 	const ulint*	offsets1,/*!< in: rec_get_offsets(rec1, index) */
 	const ulint*	offsets2,/*!< in: rec_get_offsets(rec2, index) */
 	dict_index_t*	index,	/*!< in: data dictionary index */
+	ibool		nulls_unequal,
+				/* in: TRUE if this is for index statistics
+				cardinality estimation, and innodb_stats_method
+				is "nulls_unequal" or "nulls_ignored" */
 	ulint*		matched_fields, /*!< in/out: number of already completely
 				matched fields; when the function returns,
 				contains the value the for current
@@ -961,9 +965,13 @@ cmp_rec_rec_with_match(
 			    || rec2_f_len == UNIV_SQL_NULL) {
 
 				if (rec1_f_len == rec2_f_len) {
-
-					goto next_field;
-
+					/* This is limited to stats collection,
+					cannot use it for regular search */
+					if (nulls_unequal) {
+						ret = -1;
+					} else {
+						goto next_field;
+					}
 				} else if (rec2_f_len == UNIV_SQL_NULL) {
 
 					/* We define the SQL null to be the
diff --git a/storage/innodb_plugin/row/row0upd.c b/storage/innodb_plugin/row/row0upd.c
index 4aa1474a25b..691d263e6ed 100644
--- a/storage/innodb_plugin/row/row0upd.c
+++ b/storage/innodb_plugin/row/row0upd.c
@@ -1252,6 +1252,10 @@ row_upd_changes_ord_field_binary(
 		    || dfield_is_null(dfield)) {
 			/* do nothing special */
 		} else if (UNIV_LIKELY_NULL(ext)) {
+			/* Silence a compiler warning without
+			silencing a Valgrind error. */
+			dfield_len = 0;
+			UNIV_MEM_INVALID(&dfield_len, sizeof dfield_len);
 			/* See if the column is stored externally. */
 			buf = row_ext_lookup(ext, col_no, &dfield_len);
 
diff --git a/storage/innodb_plugin/row/row0vers.c b/storage/innodb_plugin/row/row0vers.c
index b6d35363f08..d4fde0b939b 100644
--- a/storage/innodb_plugin/row/row0vers.c
+++ b/storage/innodb_plugin/row/row0vers.c
@@ -669,11 +669,15 @@ row_vers_build_for_semi_consistent_read(
 
 		mutex_enter(&kernel_mutex);
 		version_trx = trx_get_on_id(version_trx_id);
+		if (version_trx
+		    && (version_trx->conc_state == TRX_COMMITTED_IN_MEMORY
+			|| version_trx->conc_state == TRX_NOT_STARTED)) {
+
+			version_trx = NULL;
+		}
 		mutex_exit(&kernel_mutex);
 
-		if (!version_trx
-		    || version_trx->conc_state == TRX_NOT_STARTED
-		    || version_trx->conc_state == TRX_COMMITTED_IN_MEMORY) {
+		if (!version_trx) {
 
 			/* We found a version that belongs to a
 			committed transaction: return it. */
diff --git a/storage/innodb_plugin/srv/srv0srv.c b/storage/innodb_plugin/srv/srv0srv.c
index f7e7e351bdc..3cf17f33c40 100644
--- a/storage/innodb_plugin/srv/srv0srv.c
+++ b/storage/innodb_plugin/srv/srv0srv.c
@@ -243,6 +243,11 @@ UNIV_INTERN ulong	srv_max_buf_pool_modified_pct	= 75;
 /* variable counts amount of data read in total (in bytes) */
 UNIV_INTERN ulint srv_data_read = 0;
 
+/* Internal setting for "innodb_stats_method". Decides how InnoDB treats
+NULL value when collecting statistics. By default, it is set to
+SRV_STATS_NULLS_EQUAL(0), ie. all NULL value are treated equal */
+ulong srv_innodb_stats_method = SRV_STATS_NULLS_EQUAL;
+
 /* here we count the amount of data written in total (in bytes) */
 UNIV_INTERN ulint srv_data_written = 0;
 
diff --git a/storage/innodb_plugin/sync/sync0arr.c b/storage/innodb_plugin/sync/sync0arr.c
index 3c825e2202b..ad29b90d344 100644
--- a/storage/innodb_plugin/sync/sync0arr.c
+++ b/storage/innodb_plugin/sync/sync0arr.c
@@ -1,6 +1,6 @@
 /*****************************************************************************
 
-Copyright (c) 1995, 2009, Innobase Oy. All Rights Reserved.
+Copyright (c) 1995, 2011, Oracle and/or its affiliates. All Rights Reserved.
 Copyright (c) 2008, Google Inc.
 
 Portions of this file contain modifications contributed and copyrighted by
@@ -715,7 +715,7 @@ print:
 					fprintf(stderr, "rw-lock %p ",
 						(void*) lock);
 					sync_array_cell_print(stderr, cell);
-					rw_lock_debug_print(debug);
+					rw_lock_debug_print(stderr, debug);
 					return(TRUE);
 				}
 			}
diff --git a/storage/innodb_plugin/sync/sync0rw.c b/storage/innodb_plugin/sync/sync0rw.c
index 572c3690a7f..00e0324becd 100644
--- a/storage/innodb_plugin/sync/sync0rw.c
+++ b/storage/innodb_plugin/sync/sync0rw.c
@@ -1,6 +1,6 @@
 /*****************************************************************************
 
-Copyright (c) 1995, 2009, Innobase Oy. All Rights Reserved.
+Copyright (c) 1995, 2011, Oracle and/or its affiliates. All Rights Reserved.
 Copyright (c) 2008, Google Inc.
 
 Portions of this file contain modifications contributed and copyrighted by
@@ -925,7 +925,7 @@ rw_lock_list_print_info(
 
 			info = UT_LIST_GET_FIRST(lock->debug_list);
 			while (info != NULL) {
-				rw_lock_debug_print(info);
+				rw_lock_debug_print(file, info);
 				info = UT_LIST_GET_NEXT(list, info);
 			}
 		}
@@ -973,7 +973,7 @@ rw_lock_print(
 
 		info = UT_LIST_GET_FIRST(lock->debug_list);
 		while (info != NULL) {
-			rw_lock_debug_print(info);
+			rw_lock_debug_print(stderr, info);
 			info = UT_LIST_GET_NEXT(list, info);
 		}
 	}
@@ -985,28 +985,29 @@ UNIV_INTERN
 void
 rw_lock_debug_print(
 /*================*/
+	FILE*			f,	/*!< in: output stream */
 	rw_lock_debug_t*	info)	/*!< in: debug struct */
 {
 	ulint	rwt;
 
 	rwt	  = info->lock_type;
 
-	fprintf(stderr, "Locked: thread %lu file %s line %lu  ",
+	fprintf(f, "Locked: thread %lu file %s line %lu  ",
 		(ulong) os_thread_pf(info->thread_id), info->file_name,
 		(ulong) info->line);
 	if (rwt == RW_LOCK_SHARED) {
-		fputs("S-LOCK", stderr);
+		fputs("S-LOCK", f);
 	} else if (rwt == RW_LOCK_EX) {
-		fputs("X-LOCK", stderr);
+		fputs("X-LOCK", f);
 	} else if (rwt == RW_LOCK_WAIT_EX) {
-		fputs("WAIT X-LOCK", stderr);
+		fputs("WAIT X-LOCK", f);
 	} else {
 		ut_error;
 	}
 	if (info->pass != 0) {
-		fprintf(stderr, " pass value %lu", (ulong) info->pass);
+		fprintf(f, " pass value %lu", (ulong) info->pass);
 	}
-	putc('\n', stderr);
+	putc('\n', f);
 }
 
 /***************************************************************//**
diff --git a/storage/innodb_plugin/trx/trx0trx.c b/storage/innodb_plugin/trx/trx0trx.c
index ee744fd58b1..f0bbf220815 100644
--- a/storage/innodb_plugin/trx/trx0trx.c
+++ b/storage/innodb_plugin/trx/trx0trx.c
@@ -2010,18 +2010,18 @@ trx_recover_for_mysql(
 /*******************************************************************//**
 This function is used to find one X/Open XA distributed transaction
 which is in the prepared state
-@return	trx or NULL */
+@return	trx or NULL; on match, the trx->xid will be invalidated */
 UNIV_INTERN
 trx_t*
 trx_get_trx_by_xid(
 /*===============*/
-	XID*	xid)	/*!< in: X/Open XA transaction identification */
+	const XID*	xid)	/*!< in: X/Open XA transaction identifier */
 {
 	trx_t*	trx;
 
 	if (xid == NULL) {
 
-		return (NULL);
+		return(NULL);
 	}
 
 	mutex_enter(&kernel_mutex);
@@ -2034,10 +2034,16 @@ trx_get_trx_by_xid(
 		of gtrid_lenght+bqual_length bytes should be
 		the same */
 
-		if (xid->gtrid_length == trx->xid.gtrid_length
+		if (trx->conc_state == TRX_PREPARED
+		    && xid->gtrid_length == trx->xid.gtrid_length
 		    && xid->bqual_length == trx->xid.bqual_length
 		    && memcmp(xid->data, trx->xid.data,
 			      xid->gtrid_length + xid->bqual_length) == 0) {
+
+			/* Invalidate the XID, so that subsequent calls
+			will not find it. */
+			memset(&trx->xid, 0, sizeof(trx->xid));
+			trx->xid.formatID = -1;
 			break;
 		}
 
@@ -2046,14 +2052,5 @@ trx_get_trx_by_xid(
 
 	mutex_exit(&kernel_mutex);
 
-	if (trx) {
-		if (trx->conc_state != TRX_PREPARED) {
-
-			return(NULL);
-		}
-
-		return(trx);
-	} else {
-		return(NULL);
-	}
+	return(trx);
 }