Jackie-Jiang commented on a change in pull request #7959:
URL: https://github.com/apache/pinot/pull/7959#discussion_r792966519
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File path:
pinot-broker/src/main/java/org/apache/pinot/broker/requesthandler/BaseBrokerRequestHandler.java
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@@ -1487,6 +1498,46 @@ static void updateColumnNames(String rawTableName,
PinotQuery pinotQuery, boolea
}
}
+ private static void expandStarExpressionToActualColumns(PinotQuery
pinotQuery, Map<String, String> columnNameMap,
+ Expression selectStarExpr) {
+ List<Expression> originalSelections = pinotQuery.getSelectList();
+ // Avoid using stream apis in query path because we have found that it has
poorer performance compared to
+ // regular apis.
+ Set<String> originallySelectedColumnNames = new HashSet<>();
+ for (Expression originalSelection : originalSelections) {
+ if (originalSelection.isSetIdentifier()) {
+
originallySelectedColumnNames.add(originalSelection.getIdentifier().getName());
+ }
+ }
+ List<Expression> newSelections = new ArrayList<>();
+ for (Expression selection : originalSelections) {
+ if (selection.equals(selectStarExpr)) {
+ //expand '*' to actual columns, exclude default virtual columns
+ for (String tableCol : columnNameMap.values()) {
+ //we exclude default virtual columns and those columns that are
already a part of originalSelections (to
+ // dedup columns that are selected multiple times)
Review comment:
I feel there is no SQL standard for this. Returning duplicate columns
can add extra workload and traffic without providing much value to the user, so
I prefer deduping the columns.
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