mspruc commented on issue #545:
URL: https://github.com/apache/wayang/issues/545#issuecomment-3949887108
@makarandhinge Multi condition refers to joins where we have additional
columns projected typically in `JOIN x.1 = y.1 AND x.2 = y.2`. How we approach
the SQL generation remains an open issue.
For some of the `Visitor`s I use `CallTreeFactory` to generate a Wayang side
representation of Calcites call trees. Maybe you can use some sort of pattern
like that to dynamically generate SQL?
Just be aware that the `JdbcExecutor` calls `createSqlClause()` on the given
operator, and the SQL statement needs to satisfy the pattern:
``` @Override
public String createSqlClause(Connection connection, FunctionCompiler
compiler) {
final Tuple<String, String> left =
this.keyDescriptor0.getSqlImplementation();
final Tuple<String, String> right =
this.keyDescriptor1.getSqlImplementation();
// LHS of join condition:
final String leftTableName = left.field0.strip();
final String leftKey = left.field1.strip();
// RHS of join condition
final String rightTableName = right.field0.strip();
final String rightKey = right.field1.strip();
// TODO: this aliasing should be handled more smoothly mb it could
be a field?
if (leftTableName.contains(" AS ")) {
final String unaliasedName = leftTableName.split(" AS
")[1].strip();
return "JOIN " + leftTableName + " ON " + unaliasedName + "." +
leftKey + "=" + rightTableName + "."
+ rightKey;
} else if (rightTableName.contains(" AS ")) {
final String unaliasedName = rightTableName.split(" AS
")[1].strip();
return "JOIN " + rightTableName + " ON " + leftTableName + "." +
leftKey + "=" + unaliasedName + "."
+ rightKey;
}
return "JOIN " + leftTableName + " ON " + leftTableName + "." +
leftKey + "=" + rightTableName + "." + rightKey;
}
```
This is not ideal either so if you have some sort of structural
changes/ideas for the `createSqlClause()` `.withSqlImplementation()` and
`JdbcExecutor` architecture I'm open for discussion.
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