Hello to all, a left join which have only right table columns in join condition seems to produce invalid bat. Assume we have the tables below: CREATE TABLE tableA(x integer, y integer); INSERT INTO tableA values(1,10); INSERT INTO tableA values(2,20); CREATE TABLE tableB(x integer, y integer); INSERT INTO tableB values(1,-10); INSERT INTO tableB values(2,-20); and pose the query: SELECT A.x, A.y, B.x, B.y FROM tableA A LEFT JOIN tableB B ON ( B.y < -10 ) ; the expected results are: +------+----- +------+------+ | x | y | x | y | +===+===+===+===+ | 1 | 10 | 2 | -20 | | 2 | 20 | 2 | -20 | +------+------+------+------+ but mclient prints this message: TypeException:user.s1_1[36]:'algebra.kdifference' undefined in: _55:any := algebra.kdifference(_54:bat[:oid,:int], _44:bat[:void,:oid]) TypeException:user.s1_1[37]:'algebra.markT' undefined in: _56:any := algebra.markT(_55:any, _21:oid) TypeException:user.s1_1[38]:'bat.reverse' undefined in: _57:any := bat.reverse(_56:any) TypeException:user.s1_1[39]:'algebra.join' undefined in: _58:any := algebra.join(_57:any, _20:bat[:oid,:int]) TypeException:user.s1_1[41]:'algebra.leftjoin' undefined in: _60:any := algebra.leftjoin(_59:bat[:oid,:void], _54:bat[:oid,:int]) TypeException:user.s1_1[43]:'bat.append' undefined in: _64:any := bat.append(_61:bat[:oid,:int], _60:any, _65:bit) TypeException:user.s1_1[44]:'bat.append' undefined in: _66:any := bat.append(_64:any, _58:any, _65:bit) TypeException:user.s1_1[55]:'algebra.join' undefined in: _80:any := algebra.join(_57:any, _79:bat[:oid,:int]) TypeException:user.s1_1[61]:'algebra.leftjoin' undefined in: _90:any := algebra.leftjoin(_59:bat[:oid,:void], _89:bat[:oid,:int]) TypeException:user.s1_1[63]:'bat.append' undefined in: _92:any := bat.append(_91:bat[:oid,:int], _90:any, _65:bit) TypeException:user.s1_1[64]:'bat.append' undefined in: _93:any := bat.append(_92:any, _80:any, _65:bit) TypeException:user.s1_1[70]:'algebra.project' undefined in: _102:any := algebra.project(_57:any, _100:int) TypeException:user.s1_1[83]:'bat.append' undefined in: _119:any := bat.append(_117:bat[:oid,:int], _102:any, _118:bit) TypeException:user.s1_1[89]:'algebra.project' undefined in: _126:any := algebra.project(_57:any, _125:int) TypeException:user.s1_1[96]:'bat.append' undefined in: _133:any := bat.append(_132:bat[:oid,:int], _126:any, _118:bit) SQLException:SQLengine:Program contains errors For ease I attach sql scripts for creating tables and posing the query Best regards, George Garbis