siddharthteotia commented on a change in pull request #4535: Implement DISTINCT
clause
URL: https://github.com/apache/incubator-pinot/pull/4535#discussion_r315338961
##########
File path:
pinot-common/src/main/java/org/apache/pinot/pql/parsers/pql2/ast/OutputColumnListAstNode.java
##########
@@ -41,8 +42,54 @@ public void addChild(AstNode childNode) {
}
}
+ private void validate() {
+ boolean identifierPresent = false;
+ boolean distinctPresent = false;
+ boolean aggregateFunctionPresent = false;
+ if (hasChildren()) {
+ for (AstNode child : getChildren()) {
+ if (child instanceof OutputColumnAstNode) {
+ if (child.hasChildren()) {
+ for (AstNode selectChild : child.getChildren()) {
+ if (selectChild instanceof IdentifierAstNode) {
+ if (distinctPresent) {
+ throw new Pql2CompilationException("Syntax error: SELECT
list columns should be part of DISTINCT clause");
+ } else if (aggregateFunctionPresent) {
+ throw new Pql2CompilationException("Syntax error:
Aggregation functions cannot be used with select list columns");
+ } else {
+ identifierPresent = true;
+ }
+ } else if (selectChild instanceof FunctionCallAstNode) {
+ if (((FunctionCallAstNode)
selectChild).getName().equalsIgnoreCase("distinct")) {
+ if (identifierPresent) {
+ throw new Pql2CompilationException("Syntax error: SELECT
list columns should be part of DISTINCT clause");
+ } else if (aggregateFunctionPresent) {
+ throw new Pql2CompilationException("Syntax error:
Aggregation functions cannot be used with DISTINCT clause");
+ } else if (distinctPresent) {
+ throw new Pql2CompilationException("Syntax error: DISTINCT
clause can be used only once in a query");
+ } else {
+ distinctPresent = true;
+ }
+ } else {
+ if (distinctPresent) {
+ throw new Pql2CompilationException("Syntax error:
Aggregation functions cannot be used with DISTINCT clause");
+ } else if (identifierPresent) {
+ throw new Pql2CompilationException("Syntax error:
Aggregation functions cannot be used with select list columns");
+ } else {
+ aggregateFunctionPresent = true;
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+
@Override
public void updateBrokerRequest(BrokerRequest brokerRequest) {
+ validate();
Review comment:
I may have used a not so good function name... by validation I still meant
to do further parsing and syntax analysis to catch bad queries at parse time
itself -- something that was mentioned in the design doc as well to catch
queries like following at parse time itself.
SELECT DISTINCT(col1), col2 FROM foo
SELECT col1, SUM(col2) FROM foo
Pql2CompilerTest.java has more tests for such situations...
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