net.sf.saffron.rel.jdbc
Class AddProjectToQueryRule
java.lang.Object
|
+--net.sf.saffron.opt.VolcanoRule
|
+--net.sf.saffron.rel.jdbc.AddProjectToQueryRule
- class AddProjectToQueryRule
- extends VolcanoRule
A AddProjectToQueryRule
grafts a ProjectRel
onto a
JdbcQuery
. This rule does not apply if the query already has a
select list (other than the default, null, which means '*'). todo:
Write a rule to fuse two ProjectRel
s together.
- Since:
- Aug 7, 2002
- Version:
- $Id: //open/saffron/src/net/sf/saffron/rel/jdbc/AddProjectToQueryRule.java#3 $
- Author:
- jhyde
AddProjectToQueryRule
AddProjectToQueryRule()
onMatch
public void onMatch(VolcanoRuleCall call)
- Description copied from class:
VolcanoRule
- This method is called every time the rule matches. At the time that
this method is called,
call.rels
holds
the set of relational expressions which match the operands to the
rule; call.rels[0]
is the root expression.
Typically a rule would check that the nodes are valid matches, creates
a new expression, then calls back VolcanoRuleCall.transformTo(net.sf.saffron.rel.SaffronRel)
to register the expression.
- Specified by:
onMatch
in class VolcanoRule