Implement UNIV_BLOB_DEBUG. An early version of this caught Bug #55284.

This option is known to be broken when tablespaces contain off-page
columns after crash recovery. It has only been tested when creating
the data files from the scratch.

btr_blob_dbg_t: A map from page_no:heap_no:field_no to first_blob_page_no.
This map is instantiated for every clustered index in index->blobs.
It is protected by index->blobs_mutex.

btr_blob_dbg_msg_issue(): Issue a diagnostic message.
Invoked when btr_blob_dbg_msg is set.

btr_blob_dbg_rbt_insert(): Insert a btr_blob_dbg_t into index->blobs.

btr_blob_dbg_rbt_delete(): Remove a btr_blob_dbg_t from index->blobs.

btr_blob_dbg_cmp(): Comparator for btr_blob_dbg_t.

btr_blob_dbg_add_blob(): Add a BLOB reference to the map.

btr_blob_dbg_add_rec(): Add all BLOB references from a record to the map.

btr_blob_dbg_print(): Display the map of BLOB references in an index.

btr_blob_dbg_remove_rec(): Remove all BLOB references of a record from
the map.

btr_blob_dbg_is_empty(): Check that no BLOB references exist to or
from a page. Disowned references from delete-marked records are
tolerated.

btr_blob_dbg_op(): Perform an operation on all BLOB references on a
B-tree page.

btr_blob_dbg_add(): Add all BLOB references from a B-tree page to the
map.

btr_blob_dbg_remove(): Remove all BLOB references from a B-tree page
from the map.

btr_blob_dbg_restore(): Restore the BLOB references after a failed
page reorganize.

btr_blob_dbg_set_deleted_flag(): Modify the 'deleted' flag in the BLOB
references of a record.

btr_blob_dbg_owner(): Own or disown a BLOB reference.

btr_page_create(), btr_page_free_low(): Assert that no BLOB references exist.

btr_create(): Create index->blobs for clustered indexes.

btr_page_reorganize_low(): Invoke btr_blob_dbg_remove() before copying
the records. Invoke btr_blob_dbg_restore() if the operation fails.

btr_page_empty(), btr_lift_page_up(), btr_compress(), btr_discard_page():
Invoke btr_blob_dbg_remove().

btr_cur_del_mark_set_clust_rec(): Invoke btr_blob_dbg_set_deleted_flag().

Other cases of modifying the delete mark are either in the secondary
index or during crash recovery, which we do not promise to support.

btr_cur_set_ownership_of_extern_field(): Invoke btr_blob_dbg_owner().

btr_store_big_rec_extern_fields(): Invoke btr_blob_dbg_add_blob().

btr_free_externally_stored_field(): Invoke btr_blob_dbg_assert_empty()
on the first BLOB page.

page_cur_insert_rec_low(), page_cur_insert_rec_zip(),
page_copy_rec_list_end_to_created_page(): Invoke btr_blob_dbg_add_rec().

page_cur_insert_rec_zip_reorg(), page_copy_rec_list_end(),
page_copy_rec_list_start(): After failure, invoke
btr_blob_dbg_remove() and btr_blob_dbg_add().

page_cur_delete_rec(): Invoke btr_blob_dbg_remove_rec().

page_delete_rec_list_end(): Invoke btr_blob_dbg_op(btr_blob_dbg_remove_rec).

page_zip_reorganize(): Invoke btr_blob_dbg_remove() before copying the records.

page_zip_copy_recs(): Invoke btr_blob_dbg_add().

row_upd_rec_in_place(): Invoke btr_blob_dbg_rbt_delete() and
btr_blob_dbg_rbt_insert().

innobase_start_or_create_for_mysql(): Warn when UNIV_BLOB_DEBUG is enabled.

rb://550 approved by Jimmy Yang

13 files changed, 910 insertions, 2 deletions

diff --git a/storage/innodb_plugin/btr/btr0btr.c b/storage/innodb_plugin/btr/btr0btr.c
index 3d8d6048603..46810c011c4 100644
--- a/storage/innodb_plugin/btr/btr0btr.c
+++ b/storage/innodb_plugin/btr/btr0btr.c
@@ -42,6 +42,560 @@ Created 6/2/1994 Heikki Tuuri
 #include "ibuf0ibuf.h"
 #include "trx0trx.h"
 
+#ifdef UNIV_BLOB_DEBUG
+# include "srv0srv.h"
+# include "ut0rbt.h"
+
+/** TRUE when messages about index->blobs modification are enabled. */
+static ibool btr_blob_dbg_msg;
+
+/** Issue a message about an operation on index->blobs.
+@param op	operation
+@param b	the entry being subjected to the operation
+@param ctx	the context of the operation */
+#define btr_blob_dbg_msg_issue(op, b, ctx)			\
+	fprintf(stderr, op " %u:%u:%u->%u %s(%u,%u,%u)\n",	\
+		(b)->ref_page_no, (b)->ref_heap_no,		\
+		(b)->ref_field_no, (b)->blob_page_no, ctx,	\
+		(b)->owner, (b)->always_owner, (b)->del)
+
+/** Insert to index->blobs a reference to an off-page column.
+@param index	the index tree
+@param b	the reference
+@param ctx	context (for logging) */
+UNIV_INTERN
+void
+btr_blob_dbg_rbt_insert(
+/*====================*/
+	dict_index_t*		index,	/*!< in/out: index tree */
+	const btr_blob_dbg_t*	b,	/*!< in: the reference */
+	const char*		ctx)	/*!< in: context (for logging) */
+{
+	if (btr_blob_dbg_msg) {
+		btr_blob_dbg_msg_issue("insert", b, ctx);
+	}
+	mutex_enter(&index->blobs_mutex);
+	rbt_insert(index->blobs, b, b);
+	mutex_exit(&index->blobs_mutex);
+}
+
+/** Remove from index->blobs a reference to an off-page column.
+@param index	the index tree
+@param b	the reference
+@param ctx	context (for logging) */
+UNIV_INTERN
+void
+btr_blob_dbg_rbt_delete(
+/*====================*/
+	dict_index_t*		index,	/*!< in/out: index tree */
+	const btr_blob_dbg_t*	b,	/*!< in: the reference */
+	const char*		ctx)	/*!< in: context (for logging) */
+{
+	if (btr_blob_dbg_msg) {
+		btr_blob_dbg_msg_issue("delete", b, ctx);
+	}
+	mutex_enter(&index->blobs_mutex);
+	ut_a(rbt_delete(index->blobs, b));
+	mutex_exit(&index->blobs_mutex);
+}
+
+/**************************************************************//**
+Comparator for items (btr_blob_dbg_t) in index->blobs.
+The key in index->blobs is (ref_page_no, ref_heap_no, ref_field_no).
+@return negative, 0 or positive if *a<*b, *a=*b, *a>*b */
+static
+int
+btr_blob_dbg_cmp(
+/*=============*/
+	const void*	a,	/*!< in: first btr_blob_dbg_t to compare */
+	const void*	b)	/*!< in: second btr_blob_dbg_t to compare */
+{
+	const btr_blob_dbg_t*	aa	= a;
+	const btr_blob_dbg_t*	bb	= b;
+
+	ut_ad(aa != NULL);
+	ut_ad(bb != NULL);
+
+	if (aa->ref_page_no != bb->ref_page_no) {
+		return(aa->ref_page_no < bb->ref_page_no ? -1 : 1);
+	}
+	if (aa->ref_heap_no != bb->ref_heap_no) {
+		return(aa->ref_heap_no < bb->ref_heap_no ? -1 : 1);
+	}
+	if (aa->ref_field_no != bb->ref_field_no) {
+		return(aa->ref_field_no < bb->ref_field_no ? -1 : 1);
+	}
+	return(0);
+}
+
+/**************************************************************//**
+Add a reference to an off-page column to the index->blobs map. */
+UNIV_INTERN
+void
+btr_blob_dbg_add_blob(
+/*==================*/
+	const rec_t*	rec,		/*!< in: clustered index record */
+	ulint		field_no,	/*!< in: off-page column number */
+	ulint		page_no,	/*!< in: start page of the column */
+	dict_index_t*	index,		/*!< in/out: index tree */
+	const char*	ctx)		/*!< in: context (for logging) */
+{
+	btr_blob_dbg_t	b;
+	const page_t*	page	= page_align(rec);
+
+	ut_a(index->blobs);
+
+	b.blob_page_no = page_no;
+	b.ref_page_no = page_get_page_no(page);
+	b.ref_heap_no = page_rec_get_heap_no(rec);
+	b.ref_field_no = field_no;
+	ut_a(b.ref_field_no >= index->n_uniq);
+	b.always_owner = b.owner = TRUE;
+	b.del = FALSE;
+	ut_a(!rec_get_deleted_flag(rec, page_is_comp(page)));
+	btr_blob_dbg_rbt_insert(index, &b, ctx);
+}
+
+/**************************************************************//**
+Add to index->blobs any references to off-page columns from a record.
+@return number of references added */
+UNIV_INTERN
+ulint
+btr_blob_dbg_add_rec(
+/*=================*/
+	const rec_t*	rec,	/*!< in: record */
+	dict_index_t*	index,	/*!< in/out: index */
+	const ulint*	offsets,/*!< in: offsets */
+	const char*	ctx)	/*!< in: context (for logging) */
+{
+	ulint		count	= 0;
+	ulint		i;
+	btr_blob_dbg_t	b;
+	ibool		del;
+
+	ut_ad(rec_offs_validate(rec, index, offsets));
+
+	if (!rec_offs_any_extern(offsets)) {
+		return(0);
+	}
+
+	b.ref_page_no = page_get_page_no(page_align(rec));
+	b.ref_heap_no = page_rec_get_heap_no(rec);
+	del = (rec_get_deleted_flag(rec, rec_offs_comp(offsets)) != 0);
+
+	for (i = 0; i < rec_offs_n_fields(offsets); i++) {
+		if (rec_offs_nth_extern(offsets, i)) {
+			ulint		len;
+			const byte*	field_ref = rec_get_nth_field(
+				rec, offsets, i, &len);
+
+			ut_a(len != UNIV_SQL_NULL);
+			ut_a(len >= BTR_EXTERN_FIELD_REF_SIZE);
+			field_ref += len - BTR_EXTERN_FIELD_REF_SIZE;
+
+			if (!memcmp(field_ref, field_ref_zero,
+				    BTR_EXTERN_FIELD_REF_SIZE)) {
+				/* the column has not been stored yet */
+				continue;
+			}
+
+			b.ref_field_no = i;
+			b.blob_page_no = mach_read_from_4(
+				field_ref + BTR_EXTERN_PAGE_NO);
+			ut_a(b.ref_field_no >= index->n_uniq);
+			b.always_owner = b.owner
+				= !(field_ref[BTR_EXTERN_LEN]
+				    & BTR_EXTERN_OWNER_FLAG);
+			b.del = del;
+
+			btr_blob_dbg_rbt_insert(index, &b, ctx);
+			count++;
+		}
+	}
+
+	return(count);
+}
+
+/**************************************************************//**
+Display the references to off-page columns.
+This function is to be called from a debugger,
+for example when a breakpoint on ut_dbg_assertion_failed is hit. */
+UNIV_INTERN
+void
+btr_blob_dbg_print(
+/*===============*/
+	const dict_index_t*	index)	/*!< in: index tree */
+{
+	const ib_rbt_node_t*	node;
+
+	if (!index->blobs) {
+		return;
+	}
+
+	/* We intentionally do not acquire index->blobs_mutex here.
+	This function is to be called from a debugger, and the caller
+	should make sure that the index->blobs_mutex is held. */
+
+	for (node = rbt_first(index->blobs);
+	     node != NULL; node = rbt_next(index->blobs, node)) {
+		const btr_blob_dbg_t*	b
+			= rbt_value(btr_blob_dbg_t, node);
+		fprintf(stderr, "%u:%u:%u->%u%s%s%s\n",
+			b->ref_page_no, b->ref_heap_no, b->ref_field_no,
+			b->blob_page_no,
+			b->owner ? "" : "(disowned)",
+			b->always_owner ? "" : "(has disowned)",
+			b->del ? "(deleted)" : "");
+	}
+}
+
+/**************************************************************//**
+Remove from index->blobs any references to off-page columns from a record.
+@return number of references removed */
+UNIV_INTERN
+ulint
+btr_blob_dbg_remove_rec(
+/*====================*/
+	const rec_t*	rec,	/*!< in: record */
+	dict_index_t*	index,	/*!< in/out: index */
+	const ulint*	offsets,/*!< in: offsets */
+	const char*	ctx)	/*!< in: context (for logging) */
+{
+	ulint		i;
+	ulint		count	= 0;
+	btr_blob_dbg_t	b;
+
+	ut_ad(rec_offs_validate(rec, index, offsets));
+
+	if (!rec_offs_any_extern(offsets)) {
+		return(0);
+	}
+
+	b.ref_page_no = page_get_page_no(page_align(rec));
+	b.ref_heap_no = page_rec_get_heap_no(rec);
+
+	for (i = 0; i < rec_offs_n_fields(offsets); i++) {
+		if (rec_offs_nth_extern(offsets, i)) {
+			ulint		len;
+			const byte*	field_ref = rec_get_nth_field(
+				rec, offsets, i, &len);
+
+			ut_a(len != UNIV_SQL_NULL);
+			ut_a(len >= BTR_EXTERN_FIELD_REF_SIZE);
+			field_ref += len - BTR_EXTERN_FIELD_REF_SIZE;
+
+			b.ref_field_no = i;
+			b.blob_page_no = mach_read_from_4(
+				field_ref + BTR_EXTERN_PAGE_NO);
+
+			switch (b.blob_page_no) {
+			case 0:
+				/* The column has not been stored yet.
+				The BLOB pointer must be all zero.
+				There cannot be a BLOB starting at
+				page 0, because page 0 is reserved for
+				the tablespace header. */
+				ut_a(!memcmp(field_ref, field_ref_zero,
+					     BTR_EXTERN_FIELD_REF_SIZE));
+				/* fall through */
+			case FIL_NULL:
+				/* the column has been freed already */
+				continue;
+			}
+
+			btr_blob_dbg_rbt_delete(index, &b, ctx);
+			count++;
+		}
+	}
+
+	return(count);
+}
+
+/**************************************************************//**
+Check that there are no references to off-page columns from or to
+the given page. Invoked when freeing or clearing a page.
+@return TRUE when no orphan references exist */
+UNIV_INTERN
+ibool
+btr_blob_dbg_is_empty(
+/*==================*/
+	dict_index_t*	index,		/*!< in: index */
+	ulint		page_no)	/*!< in: page number */
+{
+	const ib_rbt_node_t*	node;
+	ibool			success	= TRUE;
+
+	if (!index->blobs) {
+		return(success);
+	}
+
+	mutex_enter(&index->blobs_mutex);
+
+	for (node = rbt_first(index->blobs);
+	     node != NULL; node = rbt_next(index->blobs, node)) {
+		const btr_blob_dbg_t*	b
+			= rbt_value(btr_blob_dbg_t, node);
+
+		if (b->ref_page_no != page_no && b->blob_page_no != page_no) {
+			continue;
+		}
+
+		fprintf(stderr,
+			"InnoDB: orphan BLOB ref%s%s%s %u:%u:%u->%u\n",
+			b->owner ? "" : "(disowned)",
+			b->always_owner ? "" : "(has disowned)",
+			b->del ? "(deleted)" : "",
+			b->ref_page_no, b->ref_heap_no, b->ref_field_no,
+			b->blob_page_no);
+
+		if (b->blob_page_no != page_no || b->owner || !b->del) {
+			success = FALSE;
+		}
+	}
+
+	mutex_exit(&index->blobs_mutex);
+	return(success);
+}
+
+/**************************************************************//**
+Count and process all references to off-page columns on a page.
+@return number of references processed */
+UNIV_INTERN
+ulint
+btr_blob_dbg_op(
+/*============*/
+	const page_t*		page,	/*!< in: B-tree leaf page */
+	const rec_t*		rec,	/*!< in: record to start from
+					(NULL to process the whole page) */
+	dict_index_t*		index,	/*!< in/out: index */
+	const char*		ctx,	/*!< in: context (for logging) */
+	const btr_blob_dbg_op_f	op)	/*!< in: operation on records */
+{
+	ulint		count	= 0;
+	mem_heap_t*	heap	= NULL;
+	ulint		offsets_[REC_OFFS_NORMAL_SIZE];
+	ulint*		offsets	= offsets_;
+	rec_offs_init(offsets_);
+
+	ut_a(fil_page_get_type(page) == FIL_PAGE_INDEX);
+	ut_a(!rec || page_align(rec) == page);
+
+	if (!index->blobs || !page_is_leaf(page)
+	    || !dict_index_is_clust(index)) {
+		return(0);
+	}
+
+	if (rec == NULL) {
+		rec = page_get_infimum_rec(page);
+	}
+
+	do {
+		offsets = rec_get_offsets(rec, index, offsets,
+					  ULINT_UNDEFINED, &heap);
+		count += op(rec, index, offsets, ctx);
+		rec = page_rec_get_next_const(rec);
+	} while (!page_rec_is_supremum(rec));
+
+	if (UNIV_LIKELY_NULL(heap)) {
+		mem_heap_free(heap);
+	}
+
+	return(count);
+}
+
+/**************************************************************//**
+Count and add to index->blobs any references to off-page columns
+from records on a page.
+@return number of references added */
+UNIV_INTERN
+ulint
+btr_blob_dbg_add(
+/*=============*/
+	const page_t*	page,	/*!< in: rewritten page */
+	dict_index_t*	index,	/*!< in/out: index */
+	const char*	ctx)	/*!< in: context (for logging) */
+{
+	btr_blob_dbg_assert_empty(index, page_get_page_no(page));
+
+	return(btr_blob_dbg_op(page, NULL, index, ctx, btr_blob_dbg_add_rec));
+}
+
+/**************************************************************//**
+Count and remove from index->blobs any references to off-page columns
+from records on a page.
+Used when reorganizing a page, before copying the records.
+@return number of references removed */
+UNIV_INTERN
+ulint
+btr_blob_dbg_remove(
+/*================*/
+	const page_t*	page,	/*!< in: b-tree page */
+	dict_index_t*	index,	/*!< in/out: index */
+	const char*	ctx)	/*!< in: context (for logging) */
+{
+	ulint	count;
+
+	count = btr_blob_dbg_op(page, NULL, index, ctx,
+				btr_blob_dbg_remove_rec);
+
+	/* Check that no references exist. */
+	btr_blob_dbg_assert_empty(index, page_get_page_no(page));
+
+	return(count);
+}
+
+/**************************************************************//**
+Restore in index->blobs any references to off-page columns
+Used when page reorganize fails due to compressed page overflow. */
+UNIV_INTERN
+void
+btr_blob_dbg_restore(
+/*=================*/
+	const page_t*	npage,	/*!< in: page that failed to compress  */
+	const page_t*	page,	/*!< in: copy of original page */
+	dict_index_t*	index,	/*!< in/out: index */
+	const char*	ctx)	/*!< in: context (for logging) */
+{
+	ulint	removed;
+	ulint	added;
+
+	ut_a(page_get_page_no(npage) == page_get_page_no(page));
+	ut_a(page_get_space_id(npage) == page_get_space_id(page));
+
+	removed = btr_blob_dbg_remove(npage, index, ctx);
+	added = btr_blob_dbg_add(page, index, ctx);
+	ut_a(added == removed);
+}
+
+/**************************************************************//**
+Modify the 'deleted' flag of a record. */
+UNIV_INTERN
+void
+btr_blob_dbg_set_deleted_flag(
+/*==========================*/
+	const rec_t*		rec,	/*!< in: record */
+	dict_index_t*		index,	/*!< in/out: index */
+	const ulint*		offsets,/*!< in: rec_get_offs(rec, index) */
+	ibool			del)	/*!< in: TRUE=deleted, FALSE=exists */
+{
+	const ib_rbt_node_t*	node;
+	btr_blob_dbg_t		b;
+	btr_blob_dbg_t*		c;
+	ulint			i;
+
+	ut_ad(rec_offs_validate(rec, index, offsets));
+	ut_a(dict_index_is_clust(index));
+	ut_a(del == !!del);/* must be FALSE==0 or TRUE==1 */
+
+	if (!rec_offs_any_extern(offsets) || !index->blobs) {
+
+		return;
+	}
+
+	b.ref_page_no = page_get_page_no(page_align(rec));
+	b.ref_heap_no = page_rec_get_heap_no(rec);
+
+	for (i = 0; i < rec_offs_n_fields(offsets); i++) {
+		if (rec_offs_nth_extern(offsets, i)) {
+			ulint		len;
+			const byte*	field_ref = rec_get_nth_field(
+				rec, offsets, i, &len);
+
+			ut_a(len != UNIV_SQL_NULL);
+			ut_a(len >= BTR_EXTERN_FIELD_REF_SIZE);
+			field_ref += len - BTR_EXTERN_FIELD_REF_SIZE;
+
+			b.ref_field_no = i;
+			b.blob_page_no = mach_read_from_4(
+				field_ref + BTR_EXTERN_PAGE_NO);
+
+			switch (b.blob_page_no) {
+			case 0:
+				ut_a(memcmp(field_ref, field_ref_zero,
+					    BTR_EXTERN_FIELD_REF_SIZE));
+				/* page number 0 is for the
+				page allocation bitmap */
+			case FIL_NULL:
+				/* the column has been freed already */
+				ut_error;
+			}
+
+			mutex_enter(&index->blobs_mutex);
+			node = rbt_lookup(index->blobs, &b);
+			ut_a(node);
+
+			c = rbt_value(btr_blob_dbg_t, node);
+			/* The flag should be modified. */
+			c->del = del;
+			if (btr_blob_dbg_msg) {
+				b = *c;
+				mutex_exit(&index->blobs_mutex);
+				btr_blob_dbg_msg_issue("del_mk", &b, "");
+			} else {
+				mutex_exit(&index->blobs_mutex);
+			}
+		}
+	}
+}
+
+/**************************************************************//**
+Change the ownership of an off-page column. */
+UNIV_INTERN
+void
+btr_blob_dbg_owner(
+/*===============*/
+	const rec_t*		rec,	/*!< in: record */
+	dict_index_t*		index,	/*!< in/out: index */
+	const ulint*		offsets,/*!< in: rec_get_offs(rec, index) */
+	ulint			i,	/*!< in: ith field in rec */
+	ibool			own)	/*!< in: TRUE=owned, FALSE=disowned */
+{
+	const ib_rbt_node_t*	node;
+	btr_blob_dbg_t		b;
+	const byte*		field_ref;
+	ulint			len;
+
+	ut_ad(rec_offs_validate(rec, index, offsets));
+	ut_a(rec_offs_nth_extern(offsets, i));
+
+	field_ref = rec_get_nth_field(rec, offsets, i, &len);
+	ut_a(len != UNIV_SQL_NULL);
+	ut_a(len >= BTR_EXTERN_FIELD_REF_SIZE);
+	field_ref += len - BTR_EXTERN_FIELD_REF_SIZE;
+
+	b.ref_page_no = page_get_page_no(page_align(rec));
+	b.ref_heap_no = page_rec_get_heap_no(rec);
+	b.ref_field_no = i;
+	b.owner = !(field_ref[BTR_EXTERN_LEN] & BTR_EXTERN_OWNER_FLAG);
+	b.blob_page_no = mach_read_from_4(field_ref + BTR_EXTERN_PAGE_NO);
+
+	ut_a(b.owner == own);
+
+	mutex_enter(&index->blobs_mutex);
+	node = rbt_lookup(index->blobs, &b);
+	/* row_ins_clust_index_entry_by_modify() invokes
+	btr_cur_unmark_extern_fields() also for the newly inserted
+	references, which are all zero bytes until the columns are stored.
+	The node lookup must fail if and only if that is the case. */
+	ut_a(!memcmp(field_ref, field_ref_zero, BTR_EXTERN_FIELD_REF_SIZE)
+	     == !node);
+
+	if (node) {
+		btr_blob_dbg_t*	c = rbt_value(btr_blob_dbg_t, node);
+		/* Some code sets ownership from TRUE to TRUE.
+		We do not allow changing ownership from FALSE to FALSE. */
+		ut_a(own || c->owner);
+
+		c->owner = own;
+		if (!own) {
+			c->always_owner = FALSE;
+		}
+	}
+
+	mutex_exit(&index->blobs_mutex);
+}
+#endif /* UNIV_BLOB_DEBUG */
+
 /*
 Latching strategy of the InnoDB B-tree
 --------------------------------------
@@ -296,6 +850,7 @@ btr_page_create(
 	page_t*		page = buf_block_get_frame(block);
 
 	ut_ad(mtr_memo_contains(mtr, block, MTR_MEMO_PAGE_X_FIX));
+	btr_blob_dbg_assert_empty(index, buf_block_get_page_no(block));
 
 	if (UNIV_LIKELY_NULL(page_zip)) {
 		page_create_zip(block, index, level, mtr);
@@ -489,6 +1044,7 @@ btr_page_free_low(
 	modify clock */
 
 	buf_block_modify_clock_inc(block);
+	btr_blob_dbg_assert_empty(index, buf_block_get_page_no(block));
 
 	if (dict_index_is_ibuf(index)) {
 
@@ -773,6 +1329,13 @@ btr_create(
 		block = buf_page_get(space, zip_size, page_no,
 				     RW_X_LATCH, mtr);
 	} else {
+#ifdef UNIV_BLOB_DEBUG
+		if ((type & DICT_CLUSTERED) && !index->blobs) {
+			mutex_create(&index->blobs_mutex, SYNC_ANY_LATCH);
+			index->blobs = rbt_create(sizeof(btr_blob_dbg_t),
+						  btr_blob_dbg_cmp);
+		}
+#endif /* UNIV_BLOB_DEBUG */
 		block = fseg_create(space, 0,
 				    PAGE_HEADER + PAGE_BTR_SEG_TOP, mtr);
 	}
@@ -996,6 +1559,7 @@ btr_page_reorganize_low(
 
 	block->check_index_page_at_flush = TRUE;
 #endif /* !UNIV_HOTBACKUP */
+	btr_blob_dbg_remove(page, index, "btr_page_reorganize");
 
 	/* Recreate the page: note that global data on page (possible
 	segment headers, next page-field, etc.) is preserved intact */
@@ -1024,6 +1588,8 @@ btr_page_reorganize_low(
 	    (!page_zip_compress(page_zip, page, index, NULL))) {
 
 		/* Restore the old page and exit. */
+		btr_blob_dbg_restore(page, temp_page, index,
+				     "btr_page_reorganize_compress_fail");
 
 #if defined UNIV_DEBUG || defined UNIV_ZIP_DEBUG
 		/* Check that the bytes that we skip are identical. */
@@ -1157,6 +1723,7 @@ btr_page_empty(
 #endif /* UNIV_ZIP_DEBUG */
 
 	btr_search_drop_page_hash_index(block);
+	btr_blob_dbg_remove(page, index, "btr_page_empty");
 
 	/* Recreate the page: note that global data on page (possible
 	segment headers, next page-field, etc.) is preserved intact */
@@ -2497,6 +3064,7 @@ btr_lift_page_up(
 						       index);
 	}
 
+	btr_blob_dbg_remove(page, index, "btr_lift_page_up");
 	lock_update_copy_and_discard(father_block, block);
 
 	/* Go upward to root page, decrementing levels by one. */
@@ -2758,6 +3326,7 @@ err_exit:
 		lock_update_merge_right(merge_block, orig_succ, block);
 	}
 
+	btr_blob_dbg_remove(page, index, "btr_compress");
 	mem_heap_free(heap);
 
 	if (!dict_index_is_clust(index) && page_is_leaf(merge_page)) {
@@ -2988,6 +3557,8 @@ btr_discard_page(
 				    block);
 	}
 
+	btr_blob_dbg_remove(page, index, "btr_discard_page");
+
 	/* Free the file page */
 	btr_page_free(index, block, mtr);
 
diff --git a/storage/innodb_plugin/btr/btr0cur.c b/storage/innodb_plugin/btr/btr0cur.c
index 704cc606a5f..86d77c79e7b 100644
--- a/storage/innodb_plugin/btr/btr0cur.c
+++ b/storage/innodb_plugin/btr/btr0cur.c
@@ -2572,6 +2572,7 @@ btr_cur_del_mark_set_clust_rec(
 
 	page_zip = buf_block_get_page_zip(block);
 
+	btr_blob_dbg_set_deleted_flag(rec, index, offsets, val);
 	btr_rec_set_deleted_flag(rec, page_zip, val);
 
 	trx = thr_get_trx(thr);
@@ -3595,6 +3596,8 @@ btr_cur_set_ownership_of_extern_field(
 	} else {
 		mach_write_to_1(data + local_len + BTR_EXTERN_LEN, byte_val);
 	}
+
+	btr_blob_dbg_owner(rec, index, offsets, i, val);
 }
 
 /*******************************************************************//**
@@ -4094,6 +4097,11 @@ btr_store_big_rec_extern_fields_func(
 				}
 
 				if (prev_page_no == FIL_NULL) {
+					btr_blob_dbg_add_blob(
+						rec, big_rec_vec->fields[i]
+						.field_no, page_no, index,
+						"store");
+
 					mach_write_to_4(field_ref
 							+ BTR_EXTERN_SPACE_ID,
 							space_id);
@@ -4169,6 +4177,11 @@ next_zip_page:
 						 MLOG_4BYTES, &mtr);
 
 				if (prev_page_no == FIL_NULL) {
+					btr_blob_dbg_add_blob(
+						rec, big_rec_vec->fields[i]
+						.field_no, page_no, index,
+						"store");
+
 					mlog_write_ulint(field_ref
 							 + BTR_EXTERN_SPACE_ID,
 							 space_id,
@@ -4337,6 +4350,37 @@ btr_free_externally_stored_field(
 		rec_zip_size = 0;
 	}
 
+#ifdef UNIV_BLOB_DEBUG
+	if (!(field_ref[BTR_EXTERN_LEN] & BTR_EXTERN_OWNER_FLAG)
+	    && !((field_ref[BTR_EXTERN_LEN] & BTR_EXTERN_INHERITED_FLAG)
+		 && (rb_ctx == RB_NORMAL || rb_ctx == RB_RECOVERY))) {
+		/* This off-page column will be freed.
+		Check that no references remain. */
+
+		btr_blob_dbg_t	b;
+
+		b.blob_page_no = mach_read_from_4(
+			field_ref + BTR_EXTERN_PAGE_NO);
+
+		if (rec) {
+			/* Remove the reference from the record to the
+			BLOB. If the BLOB were not freed, the
+			reference would be removed when the record is
+			removed. Freeing the BLOB will overwrite the
+			BTR_EXTERN_PAGE_NO in the field_ref of the
+			record with FIL_NULL, which would make the
+			btr_blob_dbg information inconsistent with the
+			record. */
+			b.ref_page_no = page_get_page_no(page_align(rec));
+			b.ref_heap_no = page_rec_get_heap_no(rec);
+			b.ref_field_no = i;
+			btr_blob_dbg_rbt_delete(index, &b, "free");
+		}
+
+		btr_blob_dbg_assert_empty(index, b.blob_page_no);
+	}
+#endif /* UNIV_BLOB_DEBUG */
+
 	for (;;) {
 #ifdef UNIV_SYNC_DEBUG
 		buf_block_t*	rec_block;
diff --git a/storage/innodb_plugin/dict/dict0mem.c b/storage/innodb_plugin/dict/dict0mem.c
index 3287247029f..aef815dd2f6 100644
--- a/storage/innodb_plugin/dict/dict0mem.c
+++ b/storage/innodb_plugin/dict/dict0mem.c
@@ -36,6 +36,9 @@ Created 1/8/1996 Heikki Tuuri
 #ifndef UNIV_HOTBACKUP
 # include "lock0lock.h"
 #endif /* !UNIV_HOTBACKUP */
+#ifdef UNIV_BLOB_DEBUG
+# include "ut0rbt.h"
+#endif /* UNIV_BLOB_DEBUG */
 
 #define	DICT_HEAP_SIZE		100	/*!< initial memory heap size when
 					creating a table or index object */
@@ -316,6 +319,12 @@ dict_mem_index_free(
 {
 	ut_ad(index);
 	ut_ad(index->magic_n == DICT_INDEX_MAGIC_N);
+#ifdef UNIV_BLOB_DEBUG
+	if (index->blobs) {
+		mutex_free(&index->blobs_mutex);
+		rbt_free(index->blobs);
+	}
+#endif /* UNIV_BLOB_DEBUG */
 
 	mem_heap_free(index->heap);
 }
diff --git a/storage/innodb_plugin/include/btr0btr.h b/storage/innodb_plugin/include/btr0btr.h
index dde3a0bab69..5aa02694e0e 100644
--- a/storage/innodb_plugin/include/btr0btr.h
+++ b/storage/innodb_plugin/include/btr0btr.h
@@ -81,6 +81,91 @@ UNIQUE definition on secondary indexes when we decide if we can use
 the insert buffer to speed up inserts */
 #define BTR_IGNORE_SEC_UNIQUE	2048
 
+#ifdef UNIV_BLOB_DEBUG
+# include "ut0rbt.h"
+/** An index->blobs entry for keeping track of off-page column references */
+struct btr_blob_dbg_struct
+{
+	unsigned	blob_page_no:32;	/*!< first BLOB page number */
+	unsigned	ref_page_no:32;		/*!< referring page number */
+	unsigned	ref_heap_no:16;		/*!< referring heap number */
+	unsigned	ref_field_no:10;	/*!< referring field number */
+	unsigned	owner:1;		/*!< TRUE if BLOB owner */
+	unsigned	always_owner:1;		/*!< TRUE if always
+						has been the BLOB owner;
+						reset to TRUE on B-tree
+						page splits and merges */
+	unsigned	del:1;			/*!< TRUE if currently
+						delete-marked */
+};
+
+/**************************************************************//**
+Add a reference to an off-page column to the index->blobs map. */
+UNIV_INTERN
+void
+btr_blob_dbg_add_blob(
+/*==================*/
+	const rec_t*	rec,		/*!< in: clustered index record */
+	ulint		field_no,	/*!< in: number of off-page column */
+	ulint		page_no,	/*!< in: start page of the column */
+	dict_index_t*	index,		/*!< in/out: index tree */
+	const char*	ctx)		/*!< in: context (for logging) */
+	__attribute__((nonnull));
+/**************************************************************//**
+Display the references to off-page columns.
+This function is to be called from a debugger,
+for example when a breakpoint on ut_dbg_assertion_failed is hit. */
+UNIV_INTERN
+void
+btr_blob_dbg_print(
+/*===============*/
+	const dict_index_t*	index)	/*!< in: index tree */
+	__attribute__((nonnull));
+/**************************************************************//**
+Check that there are no references to off-page columns from or to
+the given page. Invoked when freeing or clearing a page.
+@return TRUE when no orphan references exist */
+UNIV_INTERN
+ibool
+btr_blob_dbg_is_empty(
+/*==================*/
+	dict_index_t*	index,		/*!< in: index */
+	ulint		page_no)	/*!< in: page number */
+	__attribute__((nonnull, warn_unused_result));
+
+/**************************************************************//**
+Modify the 'deleted' flag of a record. */
+UNIV_INTERN
+void
+btr_blob_dbg_set_deleted_flag(
+/*==========================*/
+	const rec_t*		rec,	/*!< in: record */
+	dict_index_t*		index,	/*!< in/out: index */
+	const ulint*		offsets,/*!< in: rec_get_offs(rec, index) */
+	ibool			del)	/*!< in: TRUE=deleted, FALSE=exists */
+	__attribute__((nonnull));
+/**************************************************************//**
+Change the ownership of an off-page column. */
+UNIV_INTERN
+void
+btr_blob_dbg_owner(
+/*===============*/
+	const rec_t*		rec,	/*!< in: record */
+	dict_index_t*		index,	/*!< in/out: index */
+	const ulint*		offsets,/*!< in: rec_get_offs(rec, index) */
+	ulint			i,	/*!< in: ith field in rec */
+	ibool			own)	/*!< in: TRUE=owned, FALSE=disowned */
+	__attribute__((nonnull));
+/** Assert that there are no BLOB references to or from the given page. */
+# define btr_blob_dbg_assert_empty(index, page_no)	\
+	ut_a(btr_blob_dbg_is_empty(index, page_no))
+#else /* UNIV_BLOB_DEBUG */
+# define btr_blob_dbg_add_blob(rec, field_no, page, index, ctx)	((void) 0)
+# define btr_blob_dbg_set_deleted_flag(rec, index, offsets, del)((void) 0)
+# define btr_blob_dbg_owner(rec, index, offsets, i, val)	((void) 0)
+# define btr_blob_dbg_assert_empty(index, page_no)		((void) 0)
+#endif /* UNIV_BLOB_DEBUG */
+
 /**************************************************************//**
 Gets the root node of a tree and x-latches it.
 @return	root page, x-latched */
diff --git a/storage/innodb_plugin/include/btr0types.h b/storage/innodb_plugin/include/btr0types.h
index ef4a6b04b34..07c06fb18d7 100644
--- a/storage/innodb_plugin/include/btr0types.h
+++ b/storage/innodb_plugin/include/btr0types.h
@@ -38,6 +38,131 @@ typedef struct btr_cur_struct		btr_cur_t;
 /** B-tree search information for the adaptive hash index */
 typedef struct btr_search_struct	btr_search_t;
 
+#ifdef UNIV_BLOB_DEBUG
+# include "buf0types.h"
+/** An index->blobs entry for keeping track of off-page column references */
+typedef struct btr_blob_dbg_struct btr_blob_dbg_t;
+
+/** Insert to index->blobs a reference to an off-page column.
+@param index	the index tree
+@param b	the reference
+@param ctx	context (for logging) */
+UNIV_INTERN
+void
+btr_blob_dbg_rbt_insert(
+/*====================*/
+	dict_index_t*		index,	/*!< in/out: index tree */
+	const btr_blob_dbg_t*	b,	/*!< in: the reference */
+	const char*		ctx)	/*!< in: context (for logging) */
+	__attribute__((nonnull));
+
+/** Remove from index->blobs a reference to an off-page column.
+@param index	the index tree
+@param b	the reference
+@param ctx	context (for logging) */
+UNIV_INTERN
+void
+btr_blob_dbg_rbt_delete(
+/*====================*/
+	dict_index_t*		index,	/*!< in/out: index tree */
+	const btr_blob_dbg_t*	b,	/*!< in: the reference */
+	const char*		ctx)	/*!< in: context (for logging) */
+	__attribute__((nonnull));
+
+/**************************************************************//**
+Add to index->blobs any references to off-page columns from a record.
+@return number of references added */
+UNIV_INTERN
+ulint
+btr_blob_dbg_add_rec(
+/*=================*/
+	const rec_t*	rec,	/*!< in: record */
+	dict_index_t*	index,	/*!< in/out: index */
+	const ulint*	offsets,/*!< in: offsets */
+	const char*	ctx)	/*!< in: context (for logging) */
+	__attribute__((nonnull));
+/**************************************************************//**
+Remove from index->blobs any references to off-page columns from a record.
+@return number of references removed */
+UNIV_INTERN
+ulint
+btr_blob_dbg_remove_rec(
+/*====================*/
+	const rec_t*	rec,	/*!< in: record */
+	dict_index_t*	index,	/*!< in/out: index */
+	const ulint*	offsets,/*!< in: offsets */
+	const char*	ctx)	/*!< in: context (for logging) */
+	__attribute__((nonnull));
+/**************************************************************//**
+Count and add to index->blobs any references to off-page columns
+from records on a page.
+@return number of references added */
+UNIV_INTERN
+ulint
+btr_blob_dbg_add(
+/*=============*/
+	const page_t*	page,	/*!< in: rewritten page */
+	dict_index_t*	index,	/*!< in/out: index */
+	const char*	ctx)	/*!< in: context (for logging) */
+	__attribute__((nonnull));
+/**************************************************************//**
+Count and remove from index->blobs any references to off-page columns
+from records on a page.
+Used when reorganizing a page, before copying the records.
+@return number of references removed */
+UNIV_INTERN
+ulint
+btr_blob_dbg_remove(
+/*================*/
+	const page_t*	page,	/*!< in: b-tree page */
+	dict_index_t*	index,	/*!< in/out: index */
+	const char*	ctx)	/*!< in: context (for logging) */
+	__attribute__((nonnull));
+/**************************************************************//**
+Restore in index->blobs any references to off-page columns
+Used when page reorganize fails due to compressed page overflow. */
+UNIV_INTERN
+void
+btr_blob_dbg_restore(
+/*=================*/
+	const page_t*	npage,	/*!< in: page that failed to compress */
+	const page_t*	page,	/*!< in: copy of original page */
+	dict_index_t*	index,	/*!< in/out: index */
+	const char*	ctx)	/*!< in: context (for logging) */
+	__attribute__((nonnull));
+
+/** Operation that processes the BLOB references of an index record
+@param[in]	rec	record on index page
+@param[in/out]	index	the index tree of the record
+@param[in]	offsets	rec_get_offsets(rec,index)
+@param[in]	ctx	context (for logging)
+@return			number of BLOB references processed */
+typedef ulint (*btr_blob_dbg_op_f)
+(const rec_t* rec,dict_index_t* index,const ulint* offsets,const char* ctx);
+
+/**************************************************************//**
+Count and process all references to off-page columns on a page.
+@return number of references processed */
+UNIV_INTERN
+ulint
+btr_blob_dbg_op(
+/*============*/
+	const page_t*		page,	/*!< in: B-tree leaf page */
+	const rec_t*		rec,	/*!< in: record to start from
+					(NULL to process the whole page) */
+	dict_index_t*		index,	/*!< in/out: index */
+	const char*		ctx,	/*!< in: context (for logging) */
+	const btr_blob_dbg_op_f	op)	/*!< in: operation on records */
+	__attribute__((nonnull(1,3,4,5)));
+#else /* UNIV_BLOB_DEBUG */
+# define btr_blob_dbg_add_rec(rec, index, offsets, ctx)		((void) 0)
+# define btr_blob_dbg_add(page, index, ctx)			((void) 0)
+# define btr_blob_dbg_remove_rec(rec, index, offsets, ctx)	((void) 0)
+# define btr_blob_dbg_remove(page, index, ctx)			((void) 0)
+# define btr_blob_dbg_restore(npage, page, index, ctx)		((void) 0)
+# define btr_blob_dbg_op(page, rec, index, ctx, op)		((void) 0)
+#endif /* UNIV_BLOB_DEBUG */
+
 /** The size of a reference to data stored on a different page.
 The reference is stored at the end of the prefix of the field
 in the index record. */
diff --git a/storage/innodb_plugin/include/dict0mem.h b/storage/innodb_plugin/include/dict0mem.h
index 09a068ccb93..bd32a239cfd 100644
--- a/storage/innodb_plugin/include/dict0mem.h
+++ b/storage/innodb_plugin/include/dict0mem.h
@@ -340,6 +340,13 @@ struct dict_index_struct{
 				index, or 0 if the index existed
 				when InnoDB was started up */
 #endif /* !UNIV_HOTBACKUP */
+#ifdef UNIV_BLOB_DEBUG
+	mutex_t		blobs_mutex;
+				/*!< mutex protecting blobs */
+	void*		blobs;	/*!< map of (page_no,heap_no,field_no)
+				to first_blob_page_no; protected by
+				blobs_mutex; @see btr_blob_dbg_t */
+#endif /* UNIV_BLOB_DEBUG */
 #ifdef UNIV_DEBUG
 	ulint		magic_n;/*!< magic number */
 /** Value of dict_index_struct::magic_n */
diff --git a/storage/innodb_plugin/include/page0zip.h b/storage/innodb_plugin/include/page0zip.h
index 574809e5227..00c1d0516e6 100644
--- a/storage/innodb_plugin/include/page0zip.h
+++ b/storage/innodb_plugin/include/page0zip.h
@@ -420,7 +420,7 @@ page_zip_copy_recs(
 	const page_t*		src,		/*!< in: page */
 	dict_index_t*		index,		/*!< in: index of the B-tree */
 	mtr_t*			mtr)		/*!< in: mini-transaction */
-	__attribute__((nonnull(1,2,3,4)));
+	__attribute__((nonnull));
 #endif /* !UNIV_HOTBACKUP */
 
 /**********************************************************************//**
diff --git a/storage/innodb_plugin/include/univ.i b/storage/innodb_plugin/include/univ.i
index 690bfd5d6a9..6dd38df3782 100644
--- a/storage/innodb_plugin/include/univ.i
+++ b/storage/innodb_plugin/include/univ.i
@@ -194,6 +194,8 @@ this will break redo log file compatibility, but it may be useful when
 debugging redo log application problems. */
 #define UNIV_MEM_DEBUG				/* detect memory leaks etc */
 #define UNIV_IBUF_DEBUG				/* debug the insert buffer */
+#define UNIV_BLOB_DEBUG				/* track BLOB ownership;
+assumes that no BLOBs survive server restart */
 #define UNIV_IBUF_COUNT_DEBUG			/* debug the insert buffer;
 this limits the database to IBUF_COUNT_N_SPACES and IBUF_COUNT_N_PAGES,
 and the insert buffer must be empty when the database is started */
diff --git a/storage/innodb_plugin/page/page0cur.c b/storage/innodb_plugin/page/page0cur.c
index f10f16a7dd9..936762b986a 100644
--- a/storage/innodb_plugin/page/page0cur.c
+++ b/storage/innodb_plugin/page/page0cur.c
@@ -1149,6 +1149,8 @@ use_heap:
 					      current_rec, index, mtr);
 	}
 
+	btr_blob_dbg_add_rec(insert_rec, index, offsets, "insert");
+
 	return(insert_rec);
 }
 
@@ -1195,10 +1197,12 @@ page_cur_insert_rec_zip_reorg(
 	}
 
 	/* Out of space: restore the page */
+	btr_blob_dbg_remove(page, index, "insert_zip_fail");
 	if (!page_zip_decompress(page_zip, page, FALSE)) {
 		ut_error; /* Memory corrupted? */
 	}
 	ut_ad(page_validate(page, index));
+	btr_blob_dbg_add(page, index, "insert_zip_fail");
 	return(NULL);
 }
 
@@ -1490,6 +1494,8 @@ use_heap:
 
 	page_zip_write_rec(page_zip, insert_rec, index, offsets, 1);
 
+	btr_blob_dbg_add_rec(insert_rec, index, offsets, "insert_zip_ok");
+
 	/* 9. Write log record of the insert */
 	if (UNIV_LIKELY(mtr != NULL)) {
 		page_cur_insert_rec_write_log(insert_rec, rec_size,
@@ -1697,6 +1703,9 @@ page_copy_rec_list_end_to_created_page(
 
 		heap_top += rec_size;
 
+		rec_offs_make_valid(insert_rec, index, offsets);
+		btr_blob_dbg_add_rec(insert_rec, index, offsets, "copy_end");
+
 		page_cur_insert_rec_write_log(insert_rec, rec_size, prev_rec,
 					      index, mtr);
 		prev_rec = insert_rec;
@@ -1944,6 +1953,7 @@ page_cur_delete_rec(
 	page_dir_slot_set_n_owned(cur_dir_slot, page_zip, cur_n_owned - 1);
 
 	/* 6. Free the memory occupied by the record */
+	btr_blob_dbg_remove_rec(current_rec, index, offsets, "delete");
 	page_mem_free(page, page_zip, current_rec, index, offsets);
 
 	/* 7. Now we have decremented the number of owned records of the slot.
diff --git a/storage/innodb_plugin/page/page0page.c b/storage/innodb_plugin/page/page0page.c
index 10008f9ac25..6cae03e8829 100644
--- a/storage/innodb_plugin/page/page0page.c
+++ b/storage/innodb_plugin/page/page0page.c
@@ -685,12 +685,16 @@ page_copy_rec_list_end(
 			if (UNIV_UNLIKELY
 			    (!page_zip_reorganize(new_block, index, mtr))) {
 
+				btr_blob_dbg_remove(new_page, index,
+						    "copy_end_reorg_fail");
 				if (UNIV_UNLIKELY
 				    (!page_zip_decompress(new_page_zip,
 							  new_page, FALSE))) {
 					ut_error;
 				}
 				ut_ad(page_validate(new_page, index));
+				btr_blob_dbg_add(new_page, index,
+						 "copy_end_reorg_fail");
 				return(NULL);
 			} else {
 				/* The page was reorganized:
@@ -803,12 +807,16 @@ page_copy_rec_list_start(
 			if (UNIV_UNLIKELY
 			    (!page_zip_reorganize(new_block, index, mtr))) {
 
+				btr_blob_dbg_remove(new_page, index,
+						    "copy_start_reorg_fail");
 				if (UNIV_UNLIKELY
 				    (!page_zip_decompress(new_page_zip,
 							  new_page, FALSE))) {
 					ut_error;
 				}
 				ut_ad(page_validate(new_page, index));
+				btr_blob_dbg_add(new_page, index,
+						 "copy_start_reorg_fail");
 				return(NULL);
 			} else {
 				/* The page was reorganized:
@@ -1080,6 +1088,9 @@ page_delete_rec_list_end(
 	/* Remove the record chain segment from the record chain */
 	page_rec_set_next(prev_rec, page_get_supremum_rec(page));
 
+	btr_blob_dbg_op(page, rec, index, "delete_end",
+			btr_blob_dbg_remove_rec);
+
 	/* Catenate the deleted chain segment to the page free list */
 
 	page_rec_set_next(last_rec, page_header_get_ptr(page, PAGE_FREE));
diff --git a/storage/innodb_plugin/page/page0zip.c b/storage/innodb_plugin/page/page0zip.c
index bb9b0995c72..a1dd4177ba8 100644
--- a/storage/innodb_plugin/page/page0zip.c
+++ b/storage/innodb_plugin/page/page0zip.c
@@ -4451,6 +4451,8 @@ page_zip_reorganize(
 	/* Copy the old page to temporary space */
 	buf_frame_copy(temp_page, page);
 
+	btr_blob_dbg_remove(page, index, "zip_reorg");
+
 	/* Recreate the page: note that global data on page (possible
 	segment headers, next page-field, etc.) is preserved intact */
 
@@ -4509,7 +4511,7 @@ page_zip_copy_recs(
 	mtr_t*			mtr)		/*!< in: mini-transaction */
 {
 	ut_ad(mtr_memo_contains_page(mtr, page, MTR_MEMO_PAGE_X_FIX));
-	ut_ad(mtr_memo_contains_page(mtr, (page_t*) src, MTR_MEMO_PAGE_X_FIX));
+	ut_ad(mtr_memo_contains_page(mtr, src, MTR_MEMO_PAGE_X_FIX));
 	ut_ad(!dict_index_is_ibuf(index));
 #ifdef UNIV_ZIP_DEBUG
 	/* The B-tree operations that call this function may set
@@ -4579,6 +4581,7 @@ page_zip_copy_recs(
 #ifdef UNIV_ZIP_DEBUG
 	ut_a(page_zip_validate(page_zip, page));
 #endif /* UNIV_ZIP_DEBUG */
+	btr_blob_dbg_add(page, index, "page_zip_copy_recs");
 
 	page_zip_compress_write_log(page_zip, page, index, mtr);
 }
diff --git a/storage/innodb_plugin/row/row0upd.c b/storage/innodb_plugin/row/row0upd.c
index 9ded3d68018..3a6de4b94a7 100644
--- a/storage/innodb_plugin/row/row0upd.c
+++ b/storage/innodb_plugin/row/row0upd.c
@@ -498,14 +498,49 @@ row_upd_rec_in_place(
 	n_fields = upd_get_n_fields(update);
 
 	for (i = 0; i < n_fields; i++) {
+#ifdef UNIV_BLOB_DEBUG
+		btr_blob_dbg_t	b;
+		const byte*	field_ref	= NULL;
+#endif /* UNIV_BLOB_DEBUG */
+
 		upd_field = upd_get_nth_field(update, i);
 		new_val = &(upd_field->new_val);
 		ut_ad(!dfield_is_ext(new_val) ==
 		      !rec_offs_nth_extern(offsets, upd_field->field_no));
+#ifdef UNIV_BLOB_DEBUG
+		if (dfield_is_ext(new_val)) {
+			ulint	len;
+			field_ref = rec_get_nth_field(rec, offsets, i, &len);
+			ut_a(len != UNIV_SQL_NULL);
+			ut_a(len >= BTR_EXTERN_FIELD_REF_SIZE);
+			field_ref += len - BTR_EXTERN_FIELD_REF_SIZE;
+
+			b.ref_page_no = page_get_page_no(page_align(rec));
+			b.ref_heap_no = page_rec_get_heap_no(rec);
+			b.ref_field_no = i;
+			b.blob_page_no = mach_read_from_4(
+				field_ref + BTR_EXTERN_PAGE_NO);
+			ut_a(b.ref_field_no >= index->n_uniq);
+			btr_blob_dbg_rbt_delete(index, &b, "upd_in_place");
+		}
+#endif /* UNIV_BLOB_DEBUG */
 
 		rec_set_nth_field(rec, offsets, upd_field->field_no,
 				  dfield_get_data(new_val),
 				  dfield_get_len(new_val));
+
+#ifdef UNIV_BLOB_DEBUG
+		if (dfield_is_ext(new_val)) {
+			b.blob_page_no = mach_read_from_4(
+				field_ref + BTR_EXTERN_PAGE_NO);
+			b.always_owner = b.owner = !(field_ref[BTR_EXTERN_LEN]
+						     & BTR_EXTERN_OWNER_FLAG);
+			b.del = rec_get_deleted_flag(
+				rec, rec_offs_comp(offsets));
+
+			btr_blob_dbg_rbt_insert(index, &b, "upd_in_place");
+		}
+#endif /* UNIV_BLOB_DEBUG */
 	}
 
 	if (UNIV_LIKELY_NULL(page_zip)) {
diff --git a/storage/innodb_plugin/srv/srv0start.c b/storage/innodb_plugin/srv/srv0start.c
index 73f8f319704..f8b5049ca65 100644
--- a/storage/innodb_plugin/srv/srv0start.c
+++ b/storage/innodb_plugin/srv/srv0start.c
@@ -1061,6 +1061,12 @@ innobase_start_or_create_for_mysql(void)
 		);
 #endif
 
+#ifdef UNIV_BLOB_DEBUG
+	fprintf(stderr,
+		"InnoDB: !!!!!!!! UNIV_BLOB_DEBUG switched on !!!!!!!!!\n"
+		"InnoDB: Server restart may fail with UNIV_BLOB_DEBUG\n");
+#endif /* UNIV_BLOB_DEBUG */
+
 #ifdef UNIV_SYNC_DEBUG
 	fprintf(stderr,
 		"InnoDB: !!!!!!!! UNIV_SYNC_DEBUG switched on !!!!!!!!!\n");