Bug #18634201 - Upgrade from 5.6.10 to 5.6.16 crashes and leaves unausable DB

When user tries to upgrade from 5.6.10 to latest 5.6, the rename of aux
tables could make server crash, since we don't get rid of those obsolete
tables, which were removed away since 5.6.11.

The patch fixed 2 issues:
1) We shouldn't try to rename those obsolete tables.
2) We should try to drop those obsolete tables when upgrade, so that those
   obsolete tables would not be left in the data directory.

rb#5202, approved by Jimmy.

Author: bin.x.su@oracle.com

storage/innobase/fts/fts0fts.cc

@@ -44,6 +44,13 @@ static const ulint FTS_MAX_ID_LEN = 32;
 /** Column name from the FTS config table */
 #define FTS_MAX_CACHE_SIZE_IN_MB	"cache_size_in_mb"
 
+/** Verify if a aux table name is a obsolete table
+by looking up the key word in the obsolete table names */
+#define FTS_IS_OBSOLETE_AUX_TABLE(table_name)			\
+	(strstr((table_name), "DOC_ID") != NULL			\
+	 || strstr((table_name), "ADDED") != NULL		\
+	 || strstr((table_name), "STOPWORDS") != NULL)
+
 /** This is maximum FTS cache for each table and would be
 a configurable variable */
 ulong	fts_max_cache_size;
@@ -6038,6 +6045,12 @@ fts_is_aux_table_name(
 			}
 		}
 
+		/* Could be obsolete common tables. */
+		if (strncmp(ptr, "ADDED", len) == 0
+		    || strncmp(ptr, "STOPWORDS", len) == 0) {
+			return(true);
+		}
+
 		/* Try and read the index id. */
 		if (!fts_read_object_id(&table->index_id, ptr)) {
 			return(FALSE);
@@ -6631,6 +6644,56 @@ fts_check_and_drop_orphaned_tables(
 					::ut_free(path);
 				}
 			}
+		} else {
+			if (FTS_IS_OBSOLETE_AUX_TABLE(aux_table->name)) {
+
+				/* Current table could be one of the three
+				obsolete tables, in this case, we should
+				always try to drop it but not rename it.
+				This could happen when we try to upgrade
+				from older server to later one, which doesn't
+				contain these obsolete tables. */
+				drop = true;
+
+				dberr_t	err;
+				trx_t*	trx_drop =
+					trx_allocate_for_background();
+
+				trx_drop->op_info = "Drop obsolete aux tables";
+				trx_drop->dict_operation_lock_mode = RW_X_LATCH;
+
+				trx_start_for_ddl(trx_drop, TRX_DICT_OP_TABLE);
+
+				err = row_drop_table_for_mysql(
+					aux_table->name, trx_drop, false, true);
+
+				trx_drop->dict_operation_lock_mode = 0;
+
+				if (err != DB_SUCCESS) {
+					/* We don't need to worry about the
+					failure, since server would try to
+					drop it on next restart, even if
+					the table was broken. */
+
+					ib_logf(IB_LOG_LEVEL_WARN,
+						"Fail to drop obsolete aux"
+						" table '%s', which is"
+						" harmless. will try to drop"
+						" it on next restart.",
+						aux_table->name);
+
+					fts_sql_rollback(trx_drop);
+				} else {
+					ib_logf(IB_LOG_LEVEL_INFO,
+						"Dropped obsolete aux"
+						" table '%s'.",
+						aux_table->name);
+
+					fts_sql_commit(trx_drop);
+				}
+
+				trx_free_for_background(trx_drop);
+			}
 		}
 #ifdef _WIN32
 		if (!drop && rename) {