Jackie-Jiang commented on a change in pull request #8228:
URL: https://github.com/apache/pinot/pull/8228#discussion_r812421122
##########
File path:
pinot-core/src/main/java/org/apache/pinot/core/operator/query/SelectionOrderByOperator.java
##########
@@ -117,6 +118,31 @@ public String toExplainString() {
return stringBuilder.append(')').toString();
}
+ private boolean isAllOrderByColumnsSorted() {
+ // Order by col1, col2 limit k will take all the n matching rows
+ // and add it to a priority queue of size k.
+ // This is nlogk operation which can be quite expensive for a large n.
+ // This function, prunes out any order by clause that matches columns
sorting order.
+ // In the above example, if the docs are already sorted by both col1, col2
then there is no need for any
+ // sorting at all (only limit is needed).
+ //
+ // This function just tracks the columns that are already sorted. If all
them are sorted already, we can
+ // use that info to short circuit the looping.
+ int numOrderByExpressions = _orderByExpressions.size();
+ for (int i = 0; i < numOrderByExpressions; i++) {
+ OrderByExpressionContext expressionContext = _orderByExpressions.get(0);
+ if
(!expressionContext.getExpression().getType().equals(ExpressionContext.Type.IDENTIFIER)
Review comment:
(minor)
```suggestion
if (!expressionContext.getExpression().getType() ==
ExpressionContext.Type.IDENTIFIER
```
##########
File path:
pinot-core/src/main/java/org/apache/pinot/core/operator/query/SelectionOrderByOperator.java
##########
@@ -82,6 +82,7 @@
private final int _numRowsToKeep;
private final PriorityQueue<Object[]> _rows;
+ private int _numOrderByColsPreSorted = 0;
Review comment:
Remove this unused variable
##########
File path:
pinot-core/src/main/java/org/apache/pinot/core/operator/query/SelectionOrderByOperator.java
##########
@@ -117,6 +118,31 @@ public String toExplainString() {
return stringBuilder.append(')').toString();
}
+ private boolean isAllOrderByColumnsSorted() {
+ // Order by col1, col2 limit k will take all the n matching rows
Review comment:
Let's revise the comments to match the functionality and put it as
javadoc for this method
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