Support 'DROP INDEX table.index' and 'DROP INDEX ix ON schema.table' (b…

…abelfish-for-postgresql#2216)

To support the syntax DROP INDEX table.index, the statement is rewritten in ANTLR as DROP INDEX index ON table, which is picked up by the backend parser.

To support the syntax DROP INDEX schema.table.index and DROP INDEX index ON schema.table, the statement is rewritten in ANTLR as DROP INDEX index ON table SCHEMA schema, which is picked up by the backend parser. Adding the SCHEMA clause for this case was necessary to avoid Bison reduce conflicts which resulted from seemingly more straightforward syntax options. 

In the backend parser, the trick is then to create an object reference in the DropStmt structure for the schema-qualified index with the schema name from the SCHEMA clause that was added, since PG's DROP INDEX only references the index, instead of its table like in T-SQL.

Also, proper error messages are now raised when attempting DROP INDEX with a 3-part of 4-part name.

Signed-off-by: Rob Verschoor [email protected]
Issues Resolved

BABEL-1483 Support DROP INDEX table.index syntax
BABEL-1652 Support DROP INDEX ix ON schema.table syntax

contrib/babelfishpg_tsql/src/backend_parser/gram-tsql-decl.y

@@ -16,6 +16,7 @@
 
 %type <node> tsql_CreateFunctionStmt tsql_VariableSetStmt tsql_CreateTrigStmt tsql_TransactionStmt tsql_UpdateStmt tsql_DeleteStmt tsql_IndexStmt
 %type <node> tsql_DropIndexStmt tsql_InsertStmt
+%type <str> tsql_DropIndexStmtSchema
 %type <node> tsql_CreateLoginStmt tsql_AlterLoginStmt tsql_DropLoginStmt
 %type <node> tsql_CreateUserStmt tsql_DropRoleStmt tsql_AlterUserStmt
 %type <node> tsql_CreateRoleStmt

contrib/babelfishpg_tsql/src/backend_parser/gram-tsql-rule.y

@@ -1183,8 +1183,13 @@ DropStmt:
 				}
 			;
 
+tsql_DropIndexStmtSchema:
+            SCHEMA name     { $$ = $2;  }
+            | /* EMPTY */   { $$ = NULL; }
+            ;
+
 tsql_DropIndexStmt:
-			DROP object_type_any_name name ON name_list
+			DROP object_type_any_name name ON name_list tsql_DropIndexStmtSchema
 				{
 					DropStmt *n = makeNode(DropStmt);
 					if(sql_dialect != SQL_DIALECT_TSQL)
@@ -1203,12 +1208,21 @@ tsql_DropIndexStmt:
 					}
 					n->removeType = $2;
 					n->missing_ok = false;
-					n->objects = list_make1(list_make1(makeString(construct_unique_index_name($3, makeRangeVarFromAnyName($5, @5, yyscanner)->relname))));
+					if ($6 != NULL)
+					{
+						/* SCHEMA clause present, use it to qualify the index name */
+						n->objects = list_make1(list_make2(makeString($6), makeString(construct_unique_index_name($3, makeRangeVarFromAnyName($5, @5, yyscanner)->relname))));  
+					}
+					else 
+					{
+						/* SCHEMA clause not present */
+						n->objects = list_make1(list_make1(makeString(construct_unique_index_name($3, makeRangeVarFromAnyName($5, @5, yyscanner)->relname))));   
+					}
 					n->behavior = DROP_CASCADE;
 					n->concurrent = false;
 					$$ = (Node *)n;
 				}
-			| DROP object_type_any_name IF_P EXISTS name ON name_list
+			| DROP object_type_any_name IF_P EXISTS name ON name_list tsql_DropIndexStmtSchema
 				{
 					DropStmt *n = makeNode(DropStmt);
 					if(sql_dialect != SQL_DIALECT_TSQL)
@@ -1227,7 +1241,16 @@ tsql_DropIndexStmt:
 					}
 					n->removeType = $2;
 					n->missing_ok = true;
-					n->objects = list_make1(list_make1(makeString(construct_unique_index_name($5, makeRangeVarFromAnyName($7, @5, yyscanner)->relname))));
+					if ($8 != NULL)
+					{
+						/* SCHEMA clause present, use it to qualify the index name */
+						n->objects = list_make1(list_make2(makeString($8), makeString(construct_unique_index_name($5, makeRangeVarFromAnyName($7, @5, yyscanner)->relname))));  
+					}
+					else 
+					{
+						/* SCHEMA clause not present */
+						n->objects = list_make1(list_make1(makeString(construct_unique_index_name($5, makeRangeVarFromAnyName($7, @5, yyscanner)->relname))));   
+					}
 					n->behavior = DROP_CASCADE;
 					n->concurrent = false;
 					$$ = (Node *)n;

contrib/babelfishpg_tsql/src/tsqlIface.cpp

@@ -2408,6 +2408,39 @@ class tsqlBuilder : public tsqlCommonMutator
 		}
 	}
 
+	void exitDrop_relational_or_xml_or_spatial_index(TSqlParser::Drop_relational_or_xml_or_spatial_indexContext *ctx) override
+	{
+		/* 
+		 * Rewrite 'DROP INDEX index_name ON schema.table' as 'DROP INDEX index_name ON table SCHEMA schema'
+		 * Note that using a 3-part or 4-part table name is not currently supported and has already been intercepted at this point.
+		 */
+		Assert(ctx->full_object_name());
+		if (ctx->full_object_name()->schema)
+		{
+			std::string str = getFullText(ctx->full_object_name());				
+			size_t startPosition = ctx->full_object_name()->start->getStartIndex();
+			std::string tbName = getFullText(ctx->full_object_name()->object_name);	
+			std::string schemaName = " SCHEMA " +getFullText(ctx->full_object_name()->schema);	
+			rewritten_query_fragment.emplace(std::make_pair(startPosition, std::make_pair(str, tbName+schemaName)));		
+		}
+	}
+
+	void exitDrop_backward_compatible_index(TSqlParser::Drop_backward_compatible_indexContext *ctx) override
+	{
+		/*
+		 * Rewrite 'DROP INDEX [schema.]table.index_name' as 'DROP INDEX index_name ON table [ SCHEMA schema ]'
+		 */
+		std::string str = getFullText(ctx);
+		size_t startPosition = ctx->start->getStartIndex();
+		std::string ixName = getFullText(ctx->index_name);
+		std::string tbName = getFullText(ctx->table_or_view_name);
+		std::string schemaName = "";
+		if (ctx->owner_name) {
+			schemaName = " SCHEMA " +getFullText(ctx->owner_name);
+		}
+		rewritten_query_fragment.emplace(std::make_pair(startPosition, std::make_pair(str, ixName+" ON "+tbName+schemaName)));
+	}
+
 	//////////////////////////////////////////////////////////////////////////////
 	// Special handling of ITVF
 	//////////////////////////////////////////////////////////////////////////////

contrib/babelfishpg_tsql/src/tsqlUnsupportedFeatureHandler.cpp

@@ -1068,6 +1068,25 @@ antlrcpp::Any TsqlUnsupportedFeatureHandlerImpl::visitDdl_statement(TSqlParser::
 	{
 		handle(INSTR_UNSUPPORTED_TSQL_UNKNOWN_DDL, "ALTER FULLTEXT INDEX",  getLineAndPos(ctx));
 	}
+	if (ctx->drop_index())
+	{
+		auto drop_index = ctx->drop_index();
+		if (drop_index->drop_relational_or_xml_or_spatial_index().size() > 0)
+		{
+			/* Raise proper error messages for the non-supported cases */
+			if (drop_index->drop_relational_or_xml_or_spatial_index(0)->full_object_name()->server)
+			{
+				/* DROP INDEX index_name ON srv.db.owner.table */
+				handle(INSTR_TSQL_DROP_INDEX, "DROP INDEX on remote table",  getLineAndPos(ctx));
+			}
+			else if (drop_index->drop_relational_or_xml_or_spatial_index(0)->full_object_name()->database)
+			{
+				/* DROP INDEX index_name ON db.owner.table */
+				handle(INSTR_TSQL_DROP_INDEX, "DROP INDEX cross-database",  getLineAndPos(ctx));
+			}
+		}
+	}
+
 	/*
 	 * We have more than 100 DDLs but support a few of them.
 	 * manage the whitelist here.

test/JDBC/expected/drop_index-vu-cleanup.out

@@ -0,0 +1,17 @@
+use master
+go
+drop table guest.t1_drop_index
+go
+drop table dbo.t1_drop_index
+go
+drop procedure dbo.p1_drop_index
+go
+drop procedure dbo.p2_drop_index
+go
+
+use tempdb
+go
+drop table guest.t1_drop_index
+go
+drop table dbo.t1_drop_index
+go

test/JDBC/expected/drop_index-vu-prepare.out

@@ -0,0 +1,25 @@
+use master
+go
+
+create procedure p1_drop_index @p int=0
+as
+if @p = 0
+	drop index guest.t1_drop_index.ix1
+else
+	drop index if exists guest.t1_drop_index.ix1	
+	select db_name(), object_name(id), object_schema_name(id), name from sysindexes where name like 'ix1%' order by 1,2,3,4	
+go
+
+
+create procedure p2_drop_index @p int=0
+as
+if @p = 0
+	drop index ix1 on guest.t1_drop_index
+else
+	drop index if exists ix1 on guest.t1_drop_index	
+	select db_name(), object_name(id), object_schema_name(id), name from sysindexes where name like 'ix1%' order by 1,2,3,4	
+go
+
+use tempdb
+go
+