YiwenWu commented on code in PR #3664:
URL: https://github.com/apache/calcite/pull/3664#discussion_r1475566245
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core/src/main/java/org/apache/calcite/rel/rel2sql/RelToSqlConverter.java:
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@@ -437,11 +437,43 @@ public Result visit(Filter e) {
final Result x = visitInput(e, 0, Clause.WHERE);
parseCorrelTable(e, x);
final Builder builder = x.builder(e);
+ if (input instanceof Join) {
+ final Context context = x.qualifiedContext();
+ final ImmutableList.Builder<SqlNode> selectList =
ImmutableList.builder();
+ // Fieldnames are unique since they are created by
SqlValidatorUtil.deriveJoinRowType()
+ final List<String> uniqueFieldNames =
input.getRowType().getFieldNames();
+ boolean selectListRequired = false;
+ for (int i = 0; i < context.fieldCount; i++) {
+ final SqlNode field = context.field(i);
+ final String fieldName = uniqueFieldNames.get(i);
+ if (fieldWasRenamedByJoinDueToNameClash(field, fieldName)) {
+ selectListRequired = true;
+ }
+ selectList.add(
+ SqlStdOperatorTable.AS.createCall(POS, field,
+ new SqlIdentifier(fieldName, POS)));
+ }
+ if (selectListRequired) {
+ builder.setSelect(new SqlNodeList(selectList.build(), POS));
+ }
+ }
builder.setWhere(builder.context.toSql(null, e.getCondition()));
return builder.result();
}
}
+ private static boolean fieldWasRenamedByJoinDueToNameClash(SqlNode field,
String fieldName) {
+ if (!(field instanceof SqlIdentifier)) {
Review Comment:
context(AliasContext) field is only allowed to return SqlIdentifier.
and Is there any other simpler way to determine whether rename is needed?
can we identify the Duplicate name by only
Result.qualifiedContext().fieldList()
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