From 55ecc709cf1b133a36f68347730cbdcc408d3193 Mon Sep 17 00:00:00 2001
From: Jesus Camacho Rodriguez <jcamacho@apache.org>
Date: Thu, 29 Sep 2016 15:20:20 +0100
Subject: [PATCH] [CALCITE-1402] Druid Filter translation incorrect if input
 reference is in RHS of comparison

---
 .../calcite/adapter/druid/DruidQuery.java     | 49 +++++++++++++------
 .../apache/calcite/test/DruidAdapterIT.java   | 13 +++++
 2 files changed, 48 insertions(+), 14 deletions(-)

diff --git a/druid/src/main/java/org/apache/calcite/adapter/druid/DruidQuery.java b/druid/src/main/java/org/apache/calcite/adapter/druid/DruidQuery.java
index fb48557f6a26..b5d6e30a7c2d 100644
--- a/druid/src/main/java/org/apache/calcite/adapter/druid/DruidQuery.java
+++ b/druid/src/main/java/org/apache/calcite/adapter/druid/DruidQuery.java
@@ -50,6 +50,7 @@
 import org.apache.calcite.rex.RexInputRef;
 import org.apache.calcite.rex.RexLiteral;
 import org.apache.calcite.rex.RexNode;
+import org.apache.calcite.rex.RexUtil;
 import org.apache.calcite.runtime.Hook;
 import org.apache.calcite.schema.ScannableTable;
 import org.apache.calcite.sql.type.SqlTypeName;
@@ -834,35 +835,55 @@ String translate(RexNode e, boolean set) {
       }
     }
 
-    private JsonFilter translateFilter(RexNode e) {
+    @SuppressWarnings("incomplete-switch") private JsonFilter translateFilter(RexNode e) {
       final RexCall call;
       switch (e.getKind()) {
       case EQUALS:
-        return new JsonSelector("selector", tr(e, 0), tr(e, 1));
       case NOT_EQUALS:
-        return new JsonCompositeFilter("not",
-            ImmutableList.of(new JsonSelector("selector", tr(e, 0), tr(e, 1))));
       case GREATER_THAN:
-        return new JsonBound("bound", tr(e, 0), tr(e, 1), true, null, false,
-            false);
       case GREATER_THAN_OR_EQUAL:
-        return new JsonBound("bound", tr(e, 0), tr(e, 1), false, null, false,
-            false);
       case LESS_THAN:
-        return new JsonBound("bound", tr(e, 0), null, false, tr(e, 1), true,
-            false);
       case LESS_THAN_OR_EQUAL:
-        return new JsonBound("bound", tr(e, 0), null, false, tr(e, 1), false,
-            false);
+        call = (RexCall) e;
+        int posRef;
+        int posConstant;
+        if (RexUtil.isConstant(call.getOperands().get(1))) {
+          posRef = 0;
+          posConstant = 1;
+        } else if (RexUtil.isConstant(call.getOperands().get(0))) {
+          posRef = 1;
+          posConstant = 0;
+        } else {
+          throw new AssertionError("it is not a valid comparison: " + e);
+        }
+        switch (e.getKind()) {
+        case EQUALS:
+          return new JsonSelector("selector", tr(e, posRef), tr(e, posConstant));
+        case NOT_EQUALS:
+          return new JsonCompositeFilter("not",
+              ImmutableList.of(new JsonSelector("selector", tr(e, posRef), tr(e, posConstant))));
+        case GREATER_THAN:
+          return new JsonBound("bound", tr(e, posRef), tr(e, posConstant), true, null, false,
+              false);
+        case GREATER_THAN_OR_EQUAL:
+          return new JsonBound("bound", tr(e, posRef), tr(e, posConstant), false, null, false,
+              false);
+        case LESS_THAN:
+          return new JsonBound("bound", tr(e, posRef), null, false, tr(e, posConstant), true,
+              false);
+        case LESS_THAN_OR_EQUAL:
+          return new JsonBound("bound", tr(e, posRef), null, false, tr(e, posConstant), false,
+              false);
+        }
+        break;
       case AND:
       case OR:
       case NOT:
         call = (RexCall) e;
         return new JsonCompositeFilter(e.getKind().toString().toLowerCase(),
             translateFilters(call.getOperands()));
-      default:
-        throw new AssertionError("cannot translate filter: " + e);
       }
+      throw new AssertionError("cannot translate filter: " + e);
     }
 
     private String tr(RexNode call, int index) {
diff --git a/druid/src/test/java/org/apache/calcite/test/DruidAdapterIT.java b/druid/src/test/java/org/apache/calcite/test/DruidAdapterIT.java
index 617321165f89..f88d8fb33ecf 100644
--- a/druid/src/test/java/org/apache/calcite/test/DruidAdapterIT.java
+++ b/druid/src/test/java/org/apache/calcite/test/DruidAdapterIT.java
@@ -928,6 +928,19 @@ public Void apply(ResultSet resultSet) {
         .returnsUnordered("C=6588");
   }
 
+  @Test public void testFilterSwapped() {
+    String sql = "select \"state_province\"\n"
+        + "from \"foodmart\"\n"
+        + "where 'High Top Dried Mushrooms' = \"product_name\"";
+    final String explain = "EnumerableInterpreter\n"
+        + "  DruidQuery(table=[[foodmart, foodmart]], intervals=[[1900-01-09T00:00:00.000Z/2992-01-10T00:00:00.000Z]], filter=[=('High Top Dried Mushrooms', CAST($3):VARCHAR(24) CHARACTER SET \"ISO-8859-1\" COLLATE \"ISO-8859-1$en_US$primary\")], projects=[[$30]])";
+    final String druidQuery = "'filter':{'type':'selector','dimension':'product_name',"
+        + "'value':'High Top Dried Mushrooms'}";
+    sql(sql)
+        .explainContains(explain)
+        .queryContains(druidChecker(druidQuery));
+  }
+
   /** Tests a query that exposed several bugs in the interpreter. */
   @Test public void testWhereGroupBy() {
     String sql = "select \"wikiticker\".\"countryName\" as \"c0\",\n"