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

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 @@ btr_store_big_rec_extern_fields_func(
 						 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;

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);
 }

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 */

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. */

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 */

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 */
 
 /**********************************************************************//**

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 */

storage/innodb_plugin/page/page0cur.c

@@ -1149,6 +1149,8 @@ page_cur_insert_rec_low(
 					      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 @@ page_cur_insert_rec_zip(
 
 	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.

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));

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);
 }

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)) {

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");