siddharthteotia commented on a change in pull request #4535: Implement DISTINCT
clause
URL: https://github.com/apache/incubator-pinot/pull/4535#discussion_r327248213
##########
File path:
pinot-common/src/main/java/org/apache/pinot/pql/parsers/pql2/ast/FunctionCallAstNode.java
##########
@@ -75,22 +80,53 @@ public String getExpression() {
return _expression;
}
- public AggregationInfo buildAggregationInfo() {
+ AggregationInfo buildAggregationInfo() {
String expression;
// COUNT aggregation function always works on '*'
- if (_name.equalsIgnoreCase("count")) {
+ if (_name.equalsIgnoreCase(AggregationFunctionType.COUNT.getName())) {
expression = "*";
} else {
List<? extends AstNode> children = getChildren();
- if (children == null || children.size() != 1) {
- throw new Pql2CompilationException("Aggregation function expects exact
1 argument");
+ if (children == null || children.size() < 1) {
+ throw new Pql2CompilationException("Aggregation function expects
non-null argument");
+ }
+ if (!_name.equalsIgnoreCase(AggregationFunctionType.DISTINCT.getName()))
{
+ if (children.size() != 1) {
+ throw new Pql2CompilationException("Aggregation function expects
exactly 1 argument as column name");
+ } else {
+ expression =
TransformExpressionTree.getStandardExpression(children.get(0));
+ }
+ } else {
+ // DISTINCT
+ if (!Pql2Compiler.ENABLE_DISTINCT) {
+ throw new Pql2CompilationException("Support for DISTINCT is
currently disabled");
+ }
+ if (children.size() == 1) {
+ // single column DISTINCT query
+ // e.g SELECT DISTINCT(col) FROM foo
+ expression =
TransformExpressionTree.getStandardExpression(children.get(0));
+ } else {
+ // multi-column DISTINCT query
+ // e.g SELECT DISTINCT(col1, col2) FROM foo
+ // we will pass down the column expression to execution code
+ // as col1:col2
+ StringBuilder distinctColumnExpr = new StringBuilder();
+ int numChildren = children.size();
+ for (int i = 0; i < numChildren; ++i) {
+ expression =
TransformExpressionTree.getStandardExpression(children.get(i));
Review comment:
Done
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