Do not compare the 'default row' to user data

page_cur_search_with_match_bytes(): Skip the comparison of the
MIN_REC_FLAG record. Also, remove some dead code
(we asserted that the search tuple carries no MIN_REC_FLAG).

storage/innobase/page/page0cur.cc

@@ -730,6 +730,19 @@ page_cur_search_with_match_bytes(
 			    low_matched_fields, low_matched_bytes,
 			    up_matched_fields, up_matched_bytes);
 
+		if (UNIV_UNLIKELY(rec_get_info_bits(
+					  mid_rec,
+					  dict_table_is_comp(index->table))
+				  & REC_INFO_MIN_REC_FLAG)) {
+			ut_ad(mach_read_from_4(FIL_PAGE_PREV
+					       + page_align(mid_rec))
+			      == FIL_NULL);
+			ut_ad(!page_rec_is_leaf(mid_rec)
+			      || rec_is_default_row(mid_rec, index));
+			cmp = 1;
+			goto low_rec_match;
+		}
+
 		offsets = rec_get_offsets(
 			mid_rec, index, offsets_, is_leaf,
 			dtuple_get_n_fields_cmp(tuple), &heap);
@@ -763,23 +776,6 @@ page_cur_search_with_match_bytes(
 			   || mode == PAGE_CUR_LE_OR_EXTENDS
 #endif /* PAGE_CUR_LE_OR_EXTENDS */
 			   ) {
-			if (!cmp && !cur_matched_fields) {
-#ifdef UNIV_DEBUG
-				mtr_t	mtr;
-				mtr_start(&mtr);
-
-				/* We got a match, but cur_matched_fields is
-				0, it must have REC_INFO_MIN_REC_FLAG */
-				ulint   rec_info = rec_get_info_bits(mid_rec,
-                                                     rec_offs_comp(offsets));
-				ut_ad(rec_info & REC_INFO_MIN_REC_FLAG);
-				ut_ad(btr_page_get_prev(page, &mtr) == FIL_NULL);
-				mtr_commit(&mtr);
-#endif
-
-				cur_matched_fields = dtuple_get_n_fields_cmp(tuple);
-			}
-
 			goto low_rec_match;
 		} else {
 

storage/innobase/rem/rem0cmp.cc

@@ -806,11 +806,9 @@ cmp_dtuple_rec_with_match_bytes(
 	ut_ad(dtuple_check_typed(dtuple));
 	ut_ad(rec_offs_validate(rec, index, offsets));
 	ut_ad(!(REC_INFO_MIN_REC_FLAG
-		& dtuple_get_info_bits(dtuple))
-	      || (page_is_leaf(page_align(rec)) && index->is_instant()));
+		& dtuple_get_info_bits(dtuple)));
 	ut_ad(!(REC_INFO_MIN_REC_FLAG
-		& rec_get_info_bits(rec, rec_offs_comp(offsets)))
-	      || (page_is_leaf(page_align(rec)) && index->is_instant()));
+		& rec_get_info_bits(rec, rec_offs_comp(offsets))));
 
 	cur_field = *matched_fields;
 	cur_bytes = *matched_bytes;