[jira] [Work logged] (HIVE-26524) Use Calcite to remove sections of a query plan known never produces rows

[ASF GitHub Bot (Jira)]

     [ 
https://issues.apache.org/jira/browse/HIVE-26524?focusedWorklogId=813662&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-813662
 ]

ASF GitHub Bot logged work on HIVE-26524:
-----------------------------------------

                Author: ASF GitHub Bot
            Created on: 30/Sep/22 10:57
            Start Date: 30/Sep/22 10:57
    Worklog Time Spent: 10m 
      Work Description: zabetak commented on code in PR #3588:
URL: https://github.com/apache/hive/pull/3588#discussion_r984472066


##########
ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/translator/ASTConverter.java:
##########
@@ -121,7 +127,87 @@ public static ASTNode convert(final RelNode relNode, 
List<FieldSchema> resultSch
     return c.convert();
   }
 
+  //    TOK_QUERY
+  //      TOK_INSERT
+  //         TOK_DESTINATION
+  //            TOK_DIR
+  //               TOK_TMP_FILE
+  //         TOK_SELECT
+  //            TOK_SELEXPR
+  //               TOK_FUNCTION
+  //                  TOK_<type>
+  //                  TOK_NULL
+  //               alias0
+  //            ...
+  //            TOK_SELEXPR
+  //               TOK_FUNCTION
+  //                  TOK_<type>
+  //                  TOK_NULL
+  //               aliasn
+  //         TOK_LIMIT
+  //            0
+  //            0
+  public static ASTNode emptyPlan(RelDataType dataType) {
+    if (dataType.getFieldCount() == 0) {
+      throw new IllegalArgumentException("Schema is empty.");
+    }
+
+    ASTBuilder select = ASTBuilder.construct(HiveParser.TOK_SELECT, 
"TOK_SELECT");
+    for (int i = 0; i < dataType.getFieldCount(); ++i) {
+      RelDataTypeField fieldType = dataType.getFieldList().get(i);
+      if (fieldType.getValue().getSqlTypeName() == SqlTypeName.NULL) {
+        select.add(ASTBuilder.selectExpr(
+                ASTBuilder.construct(HiveParser.TOK_NULL, "TOK_NULL").node(),
+                fieldType.getName()));
+      } else {
+        ASTNode typeNode = createCast(fieldType);
+        select.add(ASTBuilder.selectExpr(
+                ASTBuilder.construct(HiveParser.TOK_FUNCTION, "TOK_FUNCTION")
+                        .add(typeNode)
+                        .add(ASTBuilder.construct(HiveParser.TOK_NULL, 
"TOK_NULL").node()).node(),
+                fieldType.getName()));
+      }
+    }
+
+    ASTNode insert = ASTBuilder.
+            construct(HiveParser.TOK_INSERT, "TOK_INSERT").
+            add(ASTBuilder.destNode()).
+            add(select).
+            add(ASTBuilder.limit(0, 0)).
+            node();
+
+    return ASTBuilder.
+            construct(HiveParser.TOK_QUERY, "TOK_QUERY").
+            add(insert).
+            node();
+  }
+
+  private static ASTNode createCast(RelDataTypeField fieldType) {
+    HiveToken ht = TypeConverter.hiveToken(fieldType.getType());
+    ASTNode typeNode;
+    if (ht == null) {
+      typeNode = ASTBuilder.construct(
+              HiveParser.Identifier, 
fieldType.getType().getSqlTypeName().getName().toLowerCase()).node();
+    } else {
+      ASTBuilder typeNodeBuilder = ASTBuilder.construct(ht.type, ht.text);
+      if (ht.args != null) {
+        for (String castArg : ht.args) {
+          typeNodeBuilder.add(HiveParser.Identifier, castArg);
+        }
+      }
+      typeNode = typeNodeBuilder.node();
+    }
+    return typeNode;
+  }
+
   private ASTNode convert() throws CalciteSemanticException {
+    if (root instanceof HiveValues) {
+      HiveValues values = (HiveValues) root;
+      if (isEmpty(values)) {
+        select = values;
+        return emptyPlan(values.getRowType());
+      }

Review Comment:
   Exception or assertion both are fine with me; as you prefer as long as it 
fails fast :)





Issue Time Tracking
-------------------

    Worklog Id:     (was: 813662)
    Time Spent: 5h  (was: 4h 50m)

> Use Calcite to remove sections of a query plan known never produces rows
> ------------------------------------------------------------------------
>
>                 Key: HIVE-26524
>                 URL: https://issues.apache.org/jira/browse/HIVE-26524
>             Project: Hive
>          Issue Type: Improvement
>          Components: CBO
>            Reporter: Krisztian Kasa
>            Assignee: Krisztian Kasa
>            Priority: Major
>              Labels: pull-request-available
>          Time Spent: 5h
>  Remaining Estimate: 0h
>
> Calcite has a set of rules to remove sections of a query plan known never 
> produces any rows. In some cases the whole plan can be removed. Such plans 
> are represented with a single {{Values}} operators with no tuples. ex.:
> {code:java}
> select y + 1 from (select a1 y, b1 z from t1 where b1 > 10) q WHERE 1=0
> {code}
> {code:java}
> HiveValues(tuples=[[]])
> {code}
> Other cases when plan has outer join or set operators some branches can be 
> replaced with empty values moving forward in some cases the join/set operator 
> can be removed
> {code:java}
> select a2, b2 from t2 where 1=0
> union
> select a1, b1 from t1
> {code}
> {code:java}
> HiveAggregate(group=[{0, 1}])
>   HiveTableScan(table=[[default, t1]], table:alias=[t1])
> {code}



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