[GitHub] [calcite] HanumathRao commented on a diff in pull request #2935: [CALCITE-5314] Prune empty parts of a query by exploiting stats/metadata

[GitBox <gi...@apache.org>]

HanumathRao commented on code in PR #2935:
URL: https://github.com/apache/calcite/pull/2935#discussion_r1002223406


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core/src/test/resources/org/apache/calcite/test/RelOptRulesTest.xml:
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@@ -3058,6 +3058,50 @@ LogicalSort(sort0=[$7], dir0=[ASC], fetch=[0])
     <Resource name="planAfter">
       <![CDATA[
 LogicalValues(tuples=[[]])
+]]>
+    </Resource>
+  </TestCase>
+  <TestCase name="testEmptyTable">
+    <Resource name="sql">
+      <![CDATA[select * from EMPTY_PRODUCTS
+]]>
+    </Resource>
+    <Resource name="planBefore">
+      <![CDATA[
+LogicalProject(PRODUCTID=[$0], NAME=[$1], SUPPLIERID=[$2])
+  LogicalTableScan(table=[[CATALOG, SALES, EMPTY_PRODUCTS]])
+]]>
+    </Resource>
+    <Resource name="planAfter">
+      <![CDATA[
+LogicalValues(tuples=[[]])
+]]>
+    </Resource>
+  </TestCase>
+  <TestCase name="testEmptyTableInComplexQuery">
+    <Resource name="sql">
+      <![CDATA[select * from products left join (select * from products as e
+ inner join EMPTY_PRODUCTS as d on e.PRODUCTID = d.PRODUCTID  where e.SUPPLIERID > 10) dt
+ on products.PRODUCTID = dt.PRODUCTID]]>
+    </Resource>
+    <Resource name="planBefore">
+      <![CDATA[
+LogicalProject(PRODUCTID=[$0], NAME=[$1], SUPPLIERID=[$2], PRODUCTID0=[$3], NAME0=[$4], SUPPLIERID0=[$5], PRODUCTID00=[$6], NAME00=[$7], SUPPLIERID00=[$8])
+  LogicalJoin(condition=[=($0, $3)], joinType=[left])
+    LogicalTableScan(table=[[CATALOG, SALES, PRODUCTS]])
+    LogicalProject(PRODUCTID=[$0], NAME=[$1], SUPPLIERID=[$2], PRODUCTID0=[$3], NAME0=[$4], SUPPLIERID0=[$5])
+      LogicalFilter(condition=[>($2, 10)])
+        LogicalJoin(condition=[=($0, $3)], joinType=[inner])
+          LogicalTableScan(table=[[CATALOG, SALES, PRODUCTS]])
+          LogicalTableScan(table=[[CATALOG, SALES, EMPTY_PRODUCTS]])
+]]>
+    </Resource>
+    <Resource name="planAfter">
+      <![CDATA[
+LogicalProject(PRODUCTID=[$0], NAME=[$1], SUPPLIERID=[$2], PRODUCTID0=[$3], NAME0=[$4], SUPPLIERID0=[$5], PRODUCTID00=[$6], NAME00=[$7], SUPPLIERID00=[$8])
+  LogicalJoin(condition=[=($0, $3)], joinType=[left])

Review Comment:
   I have tried to use most of the PruneEmptyRules and it didn't prune the Left join. This is because of the way the rules are applied one after the other. There is a dependency of the rules in this particular example PROJECT (EMPTY) needs to be applied before LEFT JOIN(TABLE, EMPTY). PROJECT(EMPTY) depends on the INNER JOIN (TABLE, EMPTY) to be applied. Please let me know if you have any particular rule in mind, then I can try it out. thanks



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