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https://issues.apache.org/jira/browse/PHOENIX-4820?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16729237#comment-16729237
]
ASF GitHub Bot commented on PHOENIX-4820:
-----------------------------------------
Github user twdsilva commented on a diff in the pull request:
https://github.com/apache/phoenix/pull/417#discussion_r244065522
--- Diff:
phoenix-core/src/main/java/org/apache/phoenix/util/ExpressionUtil.java ---
@@ -68,4 +76,144 @@ public static boolean isPkPositionChanging(TableRef
tableRef, List<Expression> p
return false;
}
+ /**
+ * check the whereExpression to see if the columnExpression is
constant.
+ * eg. for "where a =3 and b > 9", a is constant,but b is not.
+ * @param columnExpression
+ * @param whereExpression
+ * @return
+ */
+ public static boolean isColumnExpressionConstant(ColumnExpression
columnExpression, Expression whereExpression) {
+ if(whereExpression == null) {
+ return false;
+ }
+ IsColumnConstantExpressionVisitor
isColumnConstantExpressionVisitor =
+ new IsColumnConstantExpressionVisitor(columnExpression);
+ whereExpression.accept(isColumnConstantExpressionVisitor);
+ return isColumnConstantExpressionVisitor.isConstant();
+ }
+
+ private static class IsColumnConstantExpressionVisitor extends
StatelessTraverseNoExpressionVisitor<Void> {
+ private final Expression columnExpression ;
+ private Expression firstRhsConstantExpression = null;
+ private int rhsConstantCount = 0;
+ private boolean isNullExpressionVisited = false;
+
+ public IsColumnConstantExpressionVisitor(Expression
columnExpression) {
+ this.columnExpression = columnExpression;
+ }
+ /**
+ * only conside and,for "where a = 3 or b = 9", neither a or b is
constant.
+ */
+ @Override
+ public Iterator<Expression> visitEnter(AndExpression
andExpression) {
+ if(rhsConstantCount > 1) {
+ return null;
+ }
+ return andExpression.getChildren().iterator();
+ }
+ /**
+ * <pre>
+ * We just conside {@link ComparisonExpression} because:
--- End diff --
nit: only consider
> Optimize OrderBy for ClientAggregatePlan
> ----------------------------------------
>
> Key: PHOENIX-4820
> URL: https://issues.apache.org/jira/browse/PHOENIX-4820
> Project: Phoenix
> Issue Type: Improvement
> Affects Versions: 4.14.0
> Reporter: chenglei
> Assignee: chenglei
> Priority: Major
> Fix For: 4.15.0
>
> Attachments: PHOENIX-4820-4.x-HBase-1.3.patch, PHOENIX-4820.diff
>
>
> Given a table
> {code}
> create table test (
> pk1 varchar not null ,
> pk2 varchar not null,
> pk3 varchar not null,
> v1 varchar,
> v2 varchar,
> CONSTRAINT TEST_PK PRIMARY KEY (
> pk1,
> pk2,
> pk3 ))
> {code}
> for following sql :
> {code}
> select a.ak3
> from (select substr(pk1,1,1) ak1,substr(pk2,1,1) ak2,substr(pk3,1,1)
> ak3,substr(v1,1,1) av1,substr(v2,1,1) av2 from test order by pk2,pk3 limit
> 10) a group by a.ak3,a.av1 order by a.ak3,a.av1
> {code}
> Intuitively, the above OrderBy statement {{order by a.ak3,a.av1}} should be
> compiled out because it match the group by statement, but in fact it is not.
> The problem is caused by the {{QueryCompiler.compileSingleQuery}} and
> {{QueryCompiler.compileSingleFlatQuery}},for
> {{QueryCompiler.compileSingleQuery}} method,because the inner query has order
> by, so in line 520, local variable {{isInRowKeyOrder}} is false:
> {code}
> 519 context.setCurrentTable(tableRef);
> 520 boolean isInRowKeyOrder = innerPlan.getGroupBy() ==
> GroupBy.EMPTY_GROUP_BY && innerPlan.getOrderBy() == OrderBy.EMPTY_ORDER_BY;
> {code}
> In {{QueryCompiler.compileSingleFlatQuery}},when {{OrderByCompiler.compile}}
> method is invoked, the last parameter {{isInRowKeyOrder}} is false:
> {code}
> 562 OrderBy orderBy = OrderByCompiler.compile(context, select,
> groupBy, limit, offset, projector,
> 563 groupBy == GroupBy.EMPTY_GROUP_BY ?
> innerPlanTupleProjector : null, isInRowKeyOrder);
> {code}
> So in following line 156 for {{OrderByCompiler.compile}},even though the
> {{tracker.isOrderPreserving}} is true, the OrderBy statement could not be
> compiled out.
> {code}
> 156 if (isInRowKeyOrder && tracker.isOrderPreserving()) {
> {code}
> In my opinion, with GroupBy, in following line 563 for
> {{QueryCompiler.compileSingleFlatQuery}} method, when we call
> {{OrderByCompiler.compile}} method, we no need to conside the
> {{isInRowKeyOrder}}, just like the previous parameter {{tupleProjector}}
> does.
> {code}
> 562 OrderBy orderBy = OrderByCompiler.compile(context, select,
> groupBy, limit, offset, projector,
> 563 groupBy == GroupBy.EMPTY_GROUP_BY ?
> innerPlanTupleProjector : null, isInRowKeyOrder);
> {code}
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