UNION/CROSS/JOIN operations should not allow 1 operand
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Key: PIG-118
URL: https://issues.apache.org/jira/browse/PIG-118
Project: Pig
Issue Type: Bug
Components: impl
Affects Versions: 0.0.0
Reporter: Pi Song
At the moment UNION/CROSS/JOIN allow 1 operand.
You can write:-
{noformat}
b = UNION a ;
c = CROSS b ;
d = JOIN c BY $0 ;
{noformat}
Possibly UNION with 1 operand might be needed for implementing Sigma-styled
union (Ui=1..n An) but for CROSS/JOIN I think nobody would do such operation.
By simply replacing "*" with "+" in the parser tree should fix this problem.
Should this be fixed?
{noformat}
LogicalOperator CrossClause() : {LogicalOperator op; ArrayList<OperatorKey>
inputs = new ArrayList<OperatorKey>();}
{
(
op = NestedExpr() { inputs.add(op.getOperatorKey()); }
("," op = NestedExpr() { inputs.add(op.getOperatorKey()); })*
)
{return rewriteCross(inputs);}
}
LogicalOperator JoinClause() : {CogroupInput gi; ArrayList<CogroupInput> gis =
new ArrayList<CogroupInput>();}
{
(gi = GroupItem() { gis.add(gi); }
("," gi = GroupItem() { gis.add(gi); })*)
{return rewriteJoin(gis);}
}
LogicalOperator UnionClause() : {LogicalOperator op; ArrayList<OperatorKey>
inputs = new ArrayList<OperatorKey>();}
{
(op = NestedExpr() { inputs.add(op.getOperatorKey()); }
("," op = NestedExpr() { inputs.add(op.getOperatorKey()); })*)
{return new LOUnion(opTable, scope, getNextId(), inputs);}
}
{noformat}
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