diff --git a/mysql-test/suite/innodb/r/alter_partitioned_debug.result b/mysql-test/suite/innodb/r/alter_partitioned_debug.result
new file mode 100644
index 00000000000..d2ec602c6d7
--- /dev/null
+++ b/mysql-test/suite/innodb/r/alter_partitioned_debug.result
@@ -0,0 +1,27 @@
+CREATE TABLE t1 (a INT, b VARCHAR(10)) ENGINE=InnoDB
+PARTITION BY RANGE(a)
+(PARTITION pa VALUES LESS THAN (3),
+PARTITION pb VALUES LESS THAN (5));
+INSERT INTO t1 VALUES(2,'two'),(2,'two'),(4,'four');
+connect ddl,localhost,root,,test;
+SET DEBUG_SYNC = 'inplace_after_index_build SIGNAL go WAIT_FOR done';
+ALTER TABLE t1 ADD UNIQUE KEY (a,b(3));
+connection default;
+SET DEBUG_SYNC = 'now WAIT_FOR go';
+BEGIN;
+SELECT * FROM t1 FOR UPDATE;
+a	b
+2	two
+2	two
+4	four
+SET DEBUG_SYNC = 'now SIGNAL done';
+connection ddl;
+ERROR 23000: Duplicate entry '2-two' for key 'a'
+connection default;
+DELETE FROM t1;
+disconnect ddl;
+SET DEBUG_SYNC = 'RESET';
+CHECK TABLE t1;
+Table	Op	Msg_type	Msg_text
+test.t1	check	status	OK
+DROP TABLE t1;
diff --git a/mysql-test/suite/innodb/t/alter_partitioned_debug.test b/mysql-test/suite/innodb/t/alter_partitioned_debug.test
new file mode 100644
index 00000000000..34565e12036
--- /dev/null
+++ b/mysql-test/suite/innodb/t/alter_partitioned_debug.test
@@ -0,0 +1,34 @@
+--source include/have_innodb.inc
+--source include/have_partition.inc
+--source include/have_debug.inc
+--source include/have_debug_sync.inc
+
+CREATE TABLE t1 (a INT, b VARCHAR(10)) ENGINE=InnoDB
+PARTITION BY RANGE(a)
+(PARTITION pa VALUES LESS THAN (3),
+PARTITION pb VALUES LESS THAN (5));
+
+INSERT INTO t1 VALUES(2,'two'),(2,'two'),(4,'four');
+
+connect ddl,localhost,root,,test;
+SET DEBUG_SYNC = 'inplace_after_index_build SIGNAL go WAIT_FOR done';
+send ALTER TABLE t1 ADD UNIQUE KEY (a,b(3));
+
+connection default;
+SET DEBUG_SYNC = 'now WAIT_FOR go';
+BEGIN;
+SELECT * FROM t1 FOR UPDATE;
+SET DEBUG_SYNC = 'now SIGNAL done';
+
+connection ddl;
+--error ER_DUP_ENTRY
+reap;
+
+connection default;
+DELETE FROM t1;
+disconnect ddl;
+
+SET DEBUG_SYNC = 'RESET';
+
+CHECK TABLE t1;
+DROP TABLE t1;
diff --git a/storage/innobase/dict/dict0defrag_bg.cc b/storage/innobase/dict/dict0defrag_bg.cc
index 7b9a0373c48..949bbbc0d74 100644
--- a/storage/innobase/dict/dict0defrag_bg.cc
+++ b/storage/innobase/dict/dict0defrag_bg.cc
@@ -1,6 +1,6 @@
 /*****************************************************************************
 
-Copyright (c) 2016, MariaDB Corporation. All Rights Reserved.
+Copyright (c) 2016, 2018, MariaDB Corporation.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -232,7 +232,7 @@ dict_stats_process_entry_from_defrag_pool()
 		? dict_table_find_index_on_id(table, index_id)
 		: NULL;
 
-	if (!index || dict_index_is_corrupted(index)) {
+	if (!index || index->is_corrupted()) {
 		if (table) {
 			dict_table_close(table, TRUE, FALSE);
 		}
diff --git a/storage/innobase/dict/dict0load.cc b/storage/innobase/dict/dict0load.cc
index 1bebab914c8..f39c4900995 100644
--- a/storage/innobase/dict/dict0load.cc
+++ b/storage/innobase/dict/dict0load.cc
@@ -2521,10 +2521,10 @@ dict_load_indexes(
 		}
 
 		ut_ad(index);
+		ut_ad(!dict_index_is_online_ddl(index));
 
 		/* Check whether the index is corrupted */
-		if (dict_index_is_corrupted(index)) {
-
+		if (index->is_corrupted()) {
 			ib::error() << "Index " << index->name
 				<< " of table " << table->name
 				<< " is corrupted";
@@ -3044,10 +3044,7 @@ err_exit:
 			table = NULL;
 			goto func_exit;
 		} else {
-			dict_index_t*	clust_index;
-			clust_index = dict_table_get_first_index(table);
-
-			if (dict_index_is_corrupted(clust_index)) {
+			if (table->indexes.start->is_corrupted()) {
 				table->corrupted = true;
 			}
 		}
@@ -3095,14 +3092,11 @@ err_exit:
 
 		if (!srv_force_recovery
 		    || !index
-		    || !dict_index_is_clust(index)) {
-
+		    || !index->is_primary()) {
 			dict_table_remove_from_cache(table);
 			table = NULL;
-
-		} else if (dict_index_is_corrupted(index)
+		} else if (index->is_corrupted()
 			   && table->is_readable()) {
-
 			/* It is possible we force to load a corrupted
 			clustered index if srv_load_corrupted is set.
 			Mark the table as corrupted in this case */
diff --git a/storage/innobase/dict/dict0stats.cc b/storage/innobase/dict/dict0stats.cc
index 67991814540..98a846bcaba 100644
--- a/storage/innobase/dict/dict0stats.cc
+++ b/storage/innobase/dict/dict0stats.cc
@@ -158,9 +158,8 @@ dict_stats_should_ignore_index(
 /*===========================*/
 	const dict_index_t*	index)	/*!< in: index */
 {
-	return((index->type & DICT_FTS)
-	       || dict_index_is_corrupted(index)
-	       || dict_index_is_spatial(index)
+	return((index->type & (DICT_FTS | DICT_SPATIAL))
+	       || index->is_corrupted()
 	       || index->to_be_dropped
 	       || !index->is_committed());
 }
@@ -2228,7 +2227,7 @@ dict_stats_update_persistent(
 	index = dict_table_get_first_index(table);
 
 	if (index == NULL
-	    || dict_index_is_corrupted(index)
+	    || index->is_corrupted()
 	    || (index->type | DICT_UNIQUE) != (DICT_CLUSTERED | DICT_UNIQUE)) {
 
 		/* Table definition is corrupt */
diff --git a/storage/innobase/fts/fts0fts.cc b/storage/innobase/fts/fts0fts.cc
index c42cba4c12e..b5c4a44514d 100644
--- a/storage/innobase/fts/fts0fts.cc
+++ b/storage/innobase/fts/fts0fts.cc
@@ -6549,7 +6549,7 @@ fts_check_corrupt_index(
 		if (index->id == aux_table->index_id) {
 			ut_ad(index->type & DICT_FTS);
 			dict_table_close(table, true, false);
-			return(dict_index_is_corrupted(index));
+			return index->is_corrupted();
 		}
 	}
 
diff --git a/storage/innobase/handler/ha_innodb.cc b/storage/innobase/handler/ha_innodb.cc
index fd8e2de4819..bf2294f0774 100644
--- a/storage/innobase/handler/ha_innodb.cc
+++ b/storage/innobase/handler/ha_innodb.cc
@@ -9406,13 +9406,13 @@ ha_innobase::index_read(
 
 	dict_index_t*	index = m_prebuilt->index;
 
-	if (index == NULL || dict_index_is_corrupted(index)) {
+	if (index == NULL || index->is_corrupted()) {
 		m_prebuilt->index_usable = FALSE;
 		DBUG_RETURN(HA_ERR_CRASHED);
 	}
 
 	if (!m_prebuilt->index_usable) {
-		DBUG_RETURN(dict_index_is_corrupted(index)
+		DBUG_RETURN(index->is_corrupted()
 			    ? HA_ERR_INDEX_CORRUPT
 			    : HA_ERR_TABLE_DEF_CHANGED);
 	}
@@ -9671,14 +9671,14 @@ ha_innobase::change_active_index(
 		m_prebuilt->trx, m_prebuilt->index);
 
 	if (!m_prebuilt->index_usable) {
-		if (dict_index_is_corrupted(m_prebuilt->index)) {
+		if (m_prebuilt->index->is_corrupted()) {
 			char	table_name[MAX_FULL_NAME_LEN + 1];
 
 			innobase_format_name(
 				table_name, sizeof table_name,
 				m_prebuilt->index->table->name.m_name);
 
-			if (dict_index_is_clust(m_prebuilt->index)) {
+			if (m_prebuilt->index->is_primary()) {
 				ut_ad(m_prebuilt->index->table->corrupted);
 				push_warning_printf(
 					m_user_thd, Sql_condition::WARN_LEVEL_WARN,
@@ -13662,7 +13662,7 @@ ha_innobase::records_in_range(
 		n_rows = HA_POS_ERROR;
 		goto func_exit;
 	}
-	if (dict_index_is_corrupted(index)) {
+	if (index->is_corrupted()) {
 		n_rows = HA_ERR_INDEX_CORRUPT;
 		goto func_exit;
 	}
@@ -14522,7 +14522,7 @@ ha_innobase::defragment_table(
 	for (index = dict_table_get_first_index(table); index;
 	     index = dict_table_get_next_index(index)) {
 
-		if (dict_index_is_corrupted(index)) {
+		if (index->is_corrupted()) {
 			continue;
 		}
 
@@ -14721,7 +14721,7 @@ ha_innobase::check(
 		clustered index, we will do so here */
 		index = dict_table_get_first_index(m_prebuilt->table);
 
-		if (!dict_index_is_corrupted(index)) {
+		if (!index->is_corrupted()) {
 			dict_set_corrupted(
 				index, m_prebuilt->trx, "CHECK TABLE");
 		}
@@ -14759,7 +14759,7 @@ ha_innobase::check(
 		}
 
 		if (!(check_opt->flags & T_QUICK)
-		    && !dict_index_is_corrupted(index)) {
+		    && !index->is_corrupted()) {
 			/* Enlarge the fatal lock wait timeout during
 			CHECK TABLE. */
 			my_atomic_addlong(
@@ -14811,7 +14811,7 @@ ha_innobase::check(
 
 		DBUG_EXECUTE_IF(
 			"dict_set_index_corrupted",
-			if (!dict_index_is_clust(index)) {
+			if (!index->is_primary()) {
 				m_prebuilt->index_usable = FALSE;
 				// row_mysql_lock_data_dictionary(m_prebuilt->trx);
 				dict_set_corrupted(index, m_prebuilt->trx, "dict_set_index_corrupted");
@@ -14819,7 +14819,7 @@ ha_innobase::check(
 			});
 
 		if (UNIV_UNLIKELY(!m_prebuilt->index_usable)) {
-			if (dict_index_is_corrupted(m_prebuilt->index)) {
+			if (index->is_corrupted()) {
 				push_warning_printf(
 					m_user_thd,
 					Sql_condition::WARN_LEVEL_WARN,
@@ -14859,7 +14859,7 @@ ha_innobase::check(
 
 		DBUG_EXECUTE_IF(
 			"dict_set_index_corrupted",
-			if (!dict_index_is_clust(index)) {
+			if (!index->is_primary()) {
 				ret = DB_CORRUPTION;
 			});
 
diff --git a/storage/innobase/handler/handler0alter.cc b/storage/innobase/handler/handler0alter.cc
index d064ebccfe2..a8f05f039fa 100644
--- a/storage/innobase/handler/handler0alter.cc
+++ b/storage/innobase/handler/handler0alter.cc
@@ -4784,8 +4784,7 @@ new_clustered_failed:
 			     = dict_table_get_first_index(user_table);
 		     index != NULL;
 		     index = dict_table_get_next_index(index)) {
-			if (!index->to_be_dropped
-			    && dict_index_is_corrupted(index)) {
+			if (!index->to_be_dropped && index->is_corrupted()) {
 				my_error(ER_CHECK_NO_SUCH_TABLE, MYF(0));
 				goto error_handled;
 			}
@@ -4795,8 +4794,7 @@ new_clustered_failed:
 			     = dict_table_get_first_index(user_table);
 		     index != NULL;
 		     index = dict_table_get_next_index(index)) {
-			if (!index->to_be_dropped
-			    && dict_index_is_corrupted(index)) {
+			if (!index->to_be_dropped && index->is_corrupted()) {
 				my_error(ER_CHECK_NO_SUCH_TABLE, MYF(0));
 				goto error_handled;
 			}
@@ -5597,8 +5595,7 @@ ha_innobase::prepare_inplace_alter_table(
 
 	if (indexed_table->corrupted
 	    || dict_table_get_first_index(indexed_table) == NULL
-	    || dict_index_is_corrupted(
-		    dict_table_get_first_index(indexed_table))) {
+	    || dict_table_get_first_index(indexed_table)->is_corrupted()) {
 		/* The clustered index is corrupted. */
 		my_error(ER_CHECK_NO_SUCH_TABLE, MYF(0));
 		DBUG_RETURN(true);
@@ -5885,7 +5882,7 @@ found_fk:
 					" with name %s", key->name);
 			} else {
 				ut_ad(!index->to_be_dropped);
-				if (!dict_index_is_clust(index)) {
+				if (!index->is_primary()) {
 					drop_index[n_drop_index++] = index;
 				} else {
 					drop_primary = index;
@@ -5986,7 +5983,7 @@ check_if_can_drop_indexes:
 		for (dict_index_t* index = dict_table_get_first_index(indexed_table);
 		     index != NULL; index = dict_table_get_next_index(index)) {
 
-			if (!index->to_be_dropped && dict_index_is_corrupted(index)) {
+			if (!index->to_be_dropped && index->is_corrupted()) {
 				my_error(ER_INDEX_CORRUPT, MYF(0), index->name());
 				goto err_exit;
 			}
@@ -7717,7 +7714,7 @@ commit_try_rebuild(
 		DBUG_ASSERT(dict_index_get_online_status(index)
 			    == ONLINE_INDEX_COMPLETE);
 		DBUG_ASSERT(index->is_committed());
-		if (dict_index_is_corrupted(index)) {
+		if (index->is_corrupted()) {
 			my_error(ER_INDEX_CORRUPT, MYF(0), index->name());
 			DBUG_RETURN(true);
 		}
@@ -7966,7 +7963,7 @@ commit_try_norebuild(
 		DBUG_ASSERT(dict_index_get_online_status(index)
 			    == ONLINE_INDEX_COMPLETE);
 		DBUG_ASSERT(!index->is_committed());
-		if (dict_index_is_corrupted(index)) {
+		if (index->is_corrupted()) {
 			/* Report a duplicate key
 			error for the index that was
 			flagged corrupted, most likely
diff --git a/storage/innobase/include/dict0dict.h b/storage/innobase/include/dict0dict.h
index 82f3cf403ba..0592b64b669 100644
--- a/storage/innobase/include/dict0dict.h
+++ b/storage/innobase/include/dict0dict.h
@@ -702,7 +702,7 @@ dict_table_get_next_index(
 
 /* Skip corrupted index */
 #define dict_table_skip_corrupt_index(index)			\
-	while (index && dict_index_is_corrupted(index)) {	\
+	while (index && index->is_corrupted()) {		\
 		index = dict_table_get_next_index(index);	\
 	}
 
@@ -1835,16 +1835,6 @@ dict_table_is_corrupted(
 	const dict_table_t*	table)	/*!< in: table */
 	MY_ATTRIBUTE((nonnull, warn_unused_result));
 
-/**********************************************************************//**
-Check whether the index is corrupted.
-@return nonzero for corrupted index, zero for valid indexes */
-UNIV_INLINE
-ulint
-dict_index_is_corrupted(
-/*====================*/
-	const dict_index_t*	index)	/*!< in: index */
-	MY_ATTRIBUTE((nonnull, warn_unused_result));
-
 /**********************************************************************//**
 Flags an index and table corrupted both in the data dictionary cache
 and in the system table SYS_INDEXES. */
diff --git a/storage/innobase/include/dict0dict.ic b/storage/innobase/include/dict0dict.ic
index f93c803294d..e20da7c708a 100644
--- a/storage/innobase/include/dict0dict.ic
+++ b/storage/innobase/include/dict0dict.ic
@@ -1486,21 +1486,6 @@ dict_table_is_corrupted(
 	return(table->corrupted);
 }
 
-/********************************************************************//**
-Check whether the index is corrupted.
-@return nonzero for corrupted index, zero for valid indexes */
-UNIV_INLINE
-ulint
-dict_index_is_corrupted(
-/*====================*/
-	const dict_index_t*	index)	/*!< in: index */
-{
-	ut_ad(index->magic_n == DICT_INDEX_MAGIC_N);
-
-	return((index->type & DICT_CORRUPT)
-	        || (index->table && index->table->corrupted));
-}
-
 /********************************************************************//**
 Check if the tablespace for the table has been discarded.
 @return true if the tablespace has been discarded. */
diff --git a/storage/innobase/include/dict0mem.h b/storage/innobase/include/dict0mem.h
index 3c8366ae28e..18e600c25d3 100644
--- a/storage/innobase/include/dict0mem.h
+++ b/storage/innobase/include/dict0mem.h
@@ -980,6 +980,9 @@ struct dict_index_t{
 	{
 		return DICT_CLUSTERED == (type & (DICT_CLUSTERED | DICT_IBUF));
 	}
+
+	/** @return whether the index is corrupted */
+	inline bool is_corrupted() const;
 };
 
 /** The status of online index creation */
@@ -1724,6 +1727,13 @@ inline bool dict_index_t::is_readable() const
 	return(UNIV_LIKELY(!table->file_unreadable));
 }
 
+inline bool dict_index_t::is_corrupted() const
+{
+	return UNIV_UNLIKELY(online_status >= ONLINE_INDEX_ABORTED
+			     || (type & DICT_CORRUPT)
+			     || (table && table->corrupted));
+}
+
 /*******************************************************************//**
 Initialise the table lock list. */
 void
diff --git a/storage/innobase/row/row0ins.cc b/storage/innobase/row/row0ins.cc
index 76809222f2c..1aa97bc34c5 100644
--- a/storage/innobase/row/row0ins.cc
+++ b/storage/innobase/row/row0ins.cc
@@ -3686,8 +3686,7 @@ row_ins(
 			node->index = NULL; node->entry = NULL; break;);
 
 		/* Skip corrupted secondary index and its entry */
-		while (node->index && dict_index_is_corrupted(node->index)) {
-
+		while (node->index && node->index->is_corrupted()) {
 			node->index = dict_table_get_next_index(node->index);
 			node->entry = UT_LIST_GET_NEXT(tuple_list, node->entry);
 		}
diff --git a/storage/innobase/row/row0log.cc b/storage/innobase/row/row0log.cc
index 90f219dce6a..3dbc1a4b93e 100644
--- a/storage/innobase/row/row0log.cc
+++ b/storage/innobase/row/row0log.cc
@@ -293,7 +293,7 @@ row_log_online_op(
 	ut_ad(rw_lock_own(dict_index_get_lock(index), RW_LOCK_S)
 	      || rw_lock_own(dict_index_get_lock(index), RW_LOCK_X));
 
-	if (dict_index_is_corrupted(index)) {
+	if (index->is_corrupted()) {
 		return;
 	}
 
@@ -613,8 +613,8 @@ row_log_table_delete(
 			&index->lock,
 			RW_LOCK_FLAG_S | RW_LOCK_FLAG_X | RW_LOCK_FLAG_SX));
 
-	if (dict_index_is_corrupted(index)
-	    || !dict_index_is_online_ddl(index)
+	if (index->online_status != ONLINE_INDEX_CREATION
+	    || (index->type & DICT_CORRUPT) || index->table->corrupted
 	    || index->online_log->error != DB_SUCCESS) {
 		return;
 	}
@@ -922,8 +922,8 @@ row_log_table_low(
 	ut_ad(!old_pk || !insert);
 	ut_ad(!old_pk || old_pk->n_v_fields == 0);
 
-	if (dict_index_is_corrupted(index)
-	    || !dict_index_is_online_ddl(index)
+	if (index->online_status != ONLINE_INDEX_CREATION
+	    || (index->type & DICT_CORRUPT) || index->table->corrupted
 	    || index->online_log->error != DB_SUCCESS) {
 		return;
 	}
@@ -2672,7 +2672,7 @@ next_block:
 		goto interrupted;
 	}
 
-	if (dict_index_is_corrupted(index)) {
+	if (index->is_corrupted()) {
 		error = DB_INDEX_CORRUPT;
 		goto func_exit;
 	}
@@ -3167,7 +3167,7 @@ row_log_apply_op_low(
 	ut_ad(rw_lock_own(dict_index_get_lock(index), RW_LOCK_X)
 	      == has_index_lock);
 
-	ut_ad(!dict_index_is_corrupted(index));
+	ut_ad(!index->is_corrupted());
 	ut_ad(trx_id != 0 || op == ROW_OP_DELETE);
 
 	DBUG_LOG("ib_create_index",
@@ -3411,7 +3411,7 @@ row_log_apply_op(
 	ut_ad(rw_lock_own(dict_index_get_lock(index), RW_LOCK_X)
 	      == has_index_lock);
 
-	if (dict_index_is_corrupted(index)) {
+	if (index->is_corrupted()) {
 		*error = DB_INDEX_CORRUPT;
 		return(NULL);
 	}
@@ -3548,7 +3548,7 @@ next_block:
 		goto func_exit;
 	}
 
-	if (dict_index_is_corrupted(index)) {
+	if (index->is_corrupted()) {
 		error = DB_INDEX_CORRUPT;
 		goto func_exit;
 	}
diff --git a/storage/innobase/row/row0merge.cc b/storage/innobase/row/row0merge.cc
index cbd5aa2f316..0f55ce00336 100644
--- a/storage/innobase/row/row0merge.cc
+++ b/storage/innobase/row/row0merge.cc
@@ -4443,13 +4443,13 @@ row_merge_is_index_usable(
 	const trx_t*		trx,	/*!< in: transaction */
 	const dict_index_t*	index)	/*!< in: index to check */
 {
-	if (!dict_index_is_clust(index)
+	if (!index->is_primary()
 	    && dict_index_is_online_ddl(index)) {
 		/* Indexes that are being created are not useable. */
 		return(false);
 	}
 
-	return(!dict_index_is_corrupted(index)
+	return(!index->is_corrupted()
 	       && (dict_table_is_temporary(index->table)
 		   || index->trx_id == 0
 		   || !MVCC::is_view_active(trx->read_view)
diff --git a/storage/innobase/row/row0purge.cc b/storage/innobase/row/row0purge.cc
index 697d59598f2..448e2984b41 100644
--- a/storage/innobase/row/row0purge.cc
+++ b/storage/innobase/row/row0purge.cc
@@ -888,8 +888,7 @@ try_again:
 
 	clust_index = dict_table_get_first_index(node->table);
 
-	if (clust_index == NULL
-	    || dict_index_is_corrupted(clust_index)) {
+	if (!clust_index || clust_index->is_corrupted()) {
 		/* The table was corrupt in the data dictionary.
 		dict_set_corrupted() works on an index, and
 		we do not have an index to call it with. */
diff --git a/storage/innobase/row/row0sel.cc b/storage/innobase/row/row0sel.cc
index 9f14be17c11..b5e1bab352d 100644
--- a/storage/innobase/row/row0sel.cc
+++ b/storage/innobase/row/row0sel.cc
@@ -4253,18 +4253,14 @@ row_search_mvcc(
 	ut_ad(!sync_check_iterate(sync_check()));
 
 	if (dict_table_is_discarded(prebuilt->table)) {
-
 		DBUG_RETURN(DB_TABLESPACE_DELETED);
-
 	} else if (!prebuilt->table->is_readable()) {
 		DBUG_RETURN(fil_space_get(prebuilt->table->space)
 			    ? DB_DECRYPTION_FAILED
 			    : DB_TABLESPACE_NOT_FOUND);
 	} else if (!prebuilt->index_usable) {
 		DBUG_RETURN(DB_MISSING_HISTORY);
-
-	} else if (dict_index_is_corrupted(prebuilt->index)) {
-
+	} else if (prebuilt->index->is_corrupted()) {
 		DBUG_RETURN(DB_CORRUPTION);
 	}