row0mysql.c:

  Allow always DROPping of a table which is only referenced by FOREIGN KEY constraints from the same table
Many files:
  Do not let REPLACE to perform internally an UPDATE if the table is referenced by a FOREIGN KEY: the manual says that REPLACE must resolve a duplicate key error semantically with DELETE(s) + INSERT, and not by an UPDATE; the internal update caused foreign key checks and cascaded operations to behave in a semantically wrong way

3 files changed, 34 insertions, 0 deletions

diff --git a/innobase/dict/dict0dict.c b/innobase/dict/dict0dict.c
index e0597c66dba..5b2a16ce9f3 100644
--- a/innobase/dict/dict0dict.c
+++ b/innobase/dict/dict0dict.c
@@ -1846,6 +1846,24 @@ dict_index_build_internal_non_clust(
 /*====================== FOREIGN KEY PROCESSING ========================*/
 
 /*************************************************************************
+Checks if a table is referenced by foreign keys. */
+
+ibool
+dict_table_referenced_by_foreign_key(
+/*=================================*/
+				/* out: TRUE if table is referenced by a
+				foreign key */
+	dict_table_t*	table)	/* in: InnoDB table */
+{
+	if (UT_LIST_GET_LEN(table->referenced_list) > 0) {
+		
+		return(TRUE);
+	}
+
+	return(FALSE);
+}
+
+/*************************************************************************
 Frees a foreign key struct. */
 static
 void
diff --git a/innobase/include/dict0dict.h b/innobase/include/dict0dict.h
index 6f56c54224b..7d55521f228 100644
--- a/innobase/include/dict0dict.h
+++ b/innobase/include/dict0dict.h
@@ -206,6 +206,15 @@ dict_foreign_add_to_cache(
 					/* out: DB_SUCCESS or error code */
 	dict_foreign_t*	foreign);	/* in, own: foreign key constraint */
 /*************************************************************************
+Checks if a table is referenced by foreign keys. */
+
+ibool
+dict_table_referenced_by_foreign_key(
+/*=================================*/
+				/* out: TRUE if table is referenced by a
+				foreign key */
+	dict_table_t*	table);	/* in: InnoDB table */
+/*************************************************************************
 Scans a table create SQL string and adds to the data dictionary
 the foreign key constraints declared in the string. This function
 should be called after the indexes for a table have been created.
diff --git a/innobase/row/row0mysql.c b/innobase/row/row0mysql.c
index ce88bcc5933..a95d0fc6b95 100644
--- a/innobase/row/row0mysql.c
+++ b/innobase/row/row0mysql.c
@@ -1997,8 +1997,15 @@ row_drop_table_for_mysql(
 		goto funct_exit;
 	}
 
+	/* Check if the table is referenced by foreign key constraints from
+	some other table (not the table itself) */
+
 	foreign = UT_LIST_GET_FIRST(table->referenced_list);
 	
+	while (foreign && foreign->foreign_table == table) {
+		foreign = UT_LIST_GET_NEXT(referenced_list, foreign);
+	}
+
 	if (foreign && trx->check_foreigns) {
 		char*	buf	= dict_foreign_err_buf;