SQL: Remove "useFallback" feature.

docs/content/configuration/index.md

@@ -1424,7 +1424,6 @@ The Druid SQL server is configured through the following properties on the Broke
 |`druid.sql.planner.selectThreshold`|Page size threshold for [Select queries](../querying/select-query.html). Select queries for larger resultsets will be issued back-to-back using pagination.|1000|
 |`druid.sql.planner.useApproximateCountDistinct`|Whether to use an approximate cardinalty algorithm for `COUNT(DISTINCT foo)`.|true|
 |`druid.sql.planner.useApproximateTopN`|Whether to use approximate [TopN queries](../querying/topnquery.html) when a SQL query could be expressed as such. If false, exact [GroupBy queries](../querying/groupbyquery.html) will be used instead.|true|
-|`druid.sql.planner.useFallback`|Whether to evaluate operations on the Broker when they cannot be expressed as Druid queries. This option is not recommended for production since it can generate unscalable query plans. If false, SQL queries that cannot be translated to Druid queries will fail.|false|
 |`druid.sql.planner.requireTimeCondition`|Whether to require SQL to have filter conditions on __time column so that all generated native queries will have user specified intervals. If true, all queries wihout filter condition on __time column will fail|false|
 |`druid.sql.planner.sqlTimeZone`|Sets the default time zone for the server, which will affect how time functions and timestamp literals behave. Should be a time zone name like "America/Los_Angeles" or offset like "-08:00".|UTC|
 |`druid.sql.planner.serializeComplexValues`|Whether to serialize "complex" output values, false will return the class name instead of the serialized value.|true|

docs/content/querying/sql.md

@@ -524,7 +524,6 @@ Connection context can be specified as JDBC connection properties or as a "conte
 |`sqlTimeZone`|Sets the time zone for this connection, which will affect how time functions and timestamp literals behave. Should be a time zone name like "America/Los_Angeles" or offset like "-08:00".|druid.sql.planner.sqlTimeZone on the Broker (default: UTC)|
 |`useApproximateCountDistinct`|Whether to use an approximate cardinalty algorithm for `COUNT(DISTINCT foo)`.|druid.sql.planner.useApproximateCountDistinct on the Broker (default: true)|
 |`useApproximateTopN`|Whether to use approximate [TopN queries](topnquery.html) when a SQL query could be expressed as such. If false, exact [GroupBy queries](groupbyquery.html) will be used instead.|druid.sql.planner.useApproximateTopN on the Broker (default: true)|
-|`useFallback`|Whether to evaluate operations on the Broker when they cannot be expressed as Druid queries. This option is not recommended for production since it can generate unscalable query plans. If false, SQL queries that cannot be translated to Druid queries will fail.|druid.sql.planner.useFallback on the Broker (default: false)|
 
 ### Retrieving metadata
 
@@ -725,7 +724,6 @@ The Druid SQL server is configured through the following properties on the Broke
 |`druid.sql.planner.metadataRefreshPeriod`|Throttle for metadata refreshes.|PT1M|
 |`druid.sql.planner.useApproximateCountDistinct`|Whether to use an approximate cardinalty algorithm for `COUNT(DISTINCT foo)`.|true|
 |`druid.sql.planner.useApproximateTopN`|Whether to use approximate [TopN queries](../querying/topnquery.html) when a SQL query could be expressed as such. If false, exact [GroupBy queries](../querying/groupbyquery.html) will be used instead.|true|
-|`druid.sql.planner.useFallback`|Whether to evaluate operations on the Broker when they cannot be expressed as Druid queries. This option is not recommended for production since it can generate unscalable query plans. If false, SQL queries that cannot be translated to Druid queries will fail.|false|
 |`druid.sql.planner.requireTimeCondition`|Whether to require SQL to have filter conditions on __time column so that all generated native queries will have user specified intervals. If true, all queries wihout filter condition on __time column will fail|false|
 |`druid.sql.planner.sqlTimeZone`|Sets the default time zone for the server, which will affect how time functions and timestamp literals behave. Should be a time zone name like "America/Los_Angeles" or offset like "-08:00".|UTC|
 |`druid.sql.planner.metadataSegmentCacheEnable`|Whether to keep a cache of published segments in broker. If true, broker polls coordinator in background to get segments from metadata store and maintains a local cache. If false, coordinator's REST api will be invoked when broker needs published segments info.|false|

sql/src/main/java/org/apache/druid/sql/calcite/planner/DruidPlanner.java

@@ -32,11 +32,9 @@
 import org.apache.calcite.linq4j.Enumerable;
 import org.apache.calcite.linq4j.Enumerator;
 import org.apache.calcite.plan.RelOptPlanner;
-import org.apache.calcite.plan.RelOptTable;
 import org.apache.calcite.plan.RelOptUtil;
 import org.apache.calcite.rel.RelNode;
 import org.apache.calcite.rel.RelRoot;
-import org.apache.calcite.rel.RelVisitor;
 import org.apache.calcite.rel.type.RelDataTypeFactory;
 import org.apache.calcite.rex.RexBuilder;
 import org.apache.calcite.rex.RexNode;
@@ -57,7 +55,6 @@
 
 import java.io.Closeable;
 import java.util.ArrayList;
-import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Set;
@@ -92,7 +89,7 @@ public PlannerResult plan(final String sql)
       return planWithDruidConvention(explain, root);
     }
     catch (RelOptPlanner.CannotPlanException e) {
-      // Try again with BINDABLE convention. Used for querying Values, metadata tables, and fallback.
+      // Try again with BINDABLE convention. Used for querying Values and metadata tables.
       try {
         return planWithBindableConvention(explain, root);
       }
@@ -193,29 +190,8 @@ private PlannerResult planWithBindableConvention(
       );
     }
 
-    final Set<String> datasourceNames = new HashSet<>();
-    bindableRel.childrenAccept(
-        new RelVisitor()
-        {
-          @Override
-          public void visit(RelNode node, int ordinal, RelNode parent)
-          {
-            if (node instanceof DruidRel) {
-              datasourceNames.addAll(((DruidRel) node).getDataSourceNames());
-            }
-            if (node instanceof Bindables.BindableTableScan) {
-              Bindables.BindableTableScan bts = (Bindables.BindableTableScan) node;
-              RelOptTable table = bts.getTable();
-              String tableName = table.getQualifiedName().get(0);
-              datasourceNames.add(tableName);
-            }
-            node.childrenAccept(this);
-          }
-        }
-    );
-
     if (explain != null) {
-      return planExplanation(bindableRel, explain, datasourceNames);
+      return planExplanation(bindableRel, explain, ImmutableSet.of());
     } else {
       final BindableRel theRel = bindableRel;
       final DataContext dataContext = plannerContext.createDataContext((JavaTypeFactory) planner.getTypeFactory());
@@ -252,7 +228,7 @@ public void cleanup(EnumeratorIterator iterFromMake)
             }
         ), () -> enumerator.close());
       };
-      return new PlannerResult(resultsSupplier, root.validatedRowType, datasourceNames);
+      return new PlannerResult(resultsSupplier, root.validatedRowType, ImmutableSet.of());
     }
   }
 

sql/src/main/java/org/apache/druid/sql/calcite/planner/PlannerConfig.java

@@ -31,7 +31,6 @@ public class PlannerConfig
 {
   public static final String CTX_KEY_USE_APPROXIMATE_COUNT_DISTINCT = "useApproximateCountDistinct";
   public static final String CTX_KEY_USE_APPROXIMATE_TOPN = "useApproximateTopN";
-  public static final String CTX_KEY_USE_FALLBACK = "useFallback";
 
   @JsonProperty
   private Period metadataRefreshPeriod = new Period("PT1M");
@@ -51,9 +50,6 @@ public class PlannerConfig
   @JsonProperty
   private boolean useApproximateTopN = true;
 
-  @JsonProperty
-  private boolean useFallback = false;
-
   @JsonProperty
   private boolean requireTimeCondition = false;
 
@@ -111,11 +107,6 @@ public boolean isUseApproximateTopN()
     return useApproximateTopN;
   }
 
-  public boolean isUseFallback()
-  {
-    return useFallback;
-  }
-
   public boolean isRequireTimeCondition()
   {
     return requireTimeCondition;
@@ -157,11 +148,6 @@ public PlannerConfig withOverrides(final Map<String, Object> context)
         CTX_KEY_USE_APPROXIMATE_TOPN,
         isUseApproximateTopN()
     );
-    newConfig.useFallback = getContextBoolean(
-        context,
-        CTX_KEY_USE_FALLBACK,
-        isUseFallback()
-    );
     newConfig.requireTimeCondition = isRequireTimeCondition();
     newConfig.sqlTimeZone = getSqlTimeZone();
     newConfig.awaitInitializationOnStart = isAwaitInitializationOnStart();
@@ -204,7 +190,6 @@ public boolean equals(final Object o)
            maxQueryCount == that.maxQueryCount &&
            useApproximateCountDistinct == that.useApproximateCountDistinct &&
            useApproximateTopN == that.useApproximateTopN &&
-           useFallback == that.useFallback &&
            requireTimeCondition == that.requireTimeCondition &&
            awaitInitializationOnStart == that.awaitInitializationOnStart &&
            metadataSegmentCacheEnable == that.metadataSegmentCacheEnable &&
@@ -225,7 +210,6 @@ public int hashCode()
         maxQueryCount,
         useApproximateCountDistinct,
         useApproximateTopN,
-        useFallback,
         requireTimeCondition,
         awaitInitializationOnStart,
         sqlTimeZone,
@@ -245,7 +229,6 @@ public String toString()
            ", maxQueryCount=" + maxQueryCount +
            ", useApproximateCountDistinct=" + useApproximateCountDistinct +
            ", useApproximateTopN=" + useApproximateTopN +
-           ", useFallback=" + useFallback +
            ", requireTimeCondition=" + requireTimeCondition +
            ", awaitInitializationOnStart=" + awaitInitializationOnStart +
            ", metadataSegmentCacheEnable=" + metadataSegmentCacheEnable +

sql/src/main/java/org/apache/druid/sql/calcite/planner/Rules.java

@@ -72,7 +72,6 @@
 import org.apache.calcite.tools.RelBuilder;
 import org.apache.druid.sql.calcite.rel.QueryMaker;
 import org.apache.druid.sql.calcite.rule.CaseFilteredAggregatorRule;
-import org.apache.druid.sql.calcite.rule.DruidRelToBindableRule;
 import org.apache.druid.sql.calcite.rule.DruidRelToDruidRule;
 import org.apache.druid.sql.calcite.rule.DruidRules;
 import org.apache.druid.sql.calcite.rule.DruidSemiJoinRule;
@@ -187,7 +186,7 @@ public static List<Program> programs(final PlannerContext plannerContext, final
         );
     return ImmutableList.of(
         Programs.sequence(hepProgram, Programs.ofRules(druidConventionRuleSet(plannerContext, queryMaker))),
-        Programs.sequence(hepProgram, Programs.ofRules(bindableConventionRuleSet(plannerContext, queryMaker)))
+        Programs.sequence(hepProgram, Programs.ofRules(bindableConventionRuleSet(plannerContext)))
     );
   }
 
@@ -196,28 +195,29 @@ private static List<RelOptRule> druidConventionRuleSet(
       final QueryMaker queryMaker
   )
   {
-    return ImmutableList.<RelOptRule>builder()
-        .addAll(baseRuleSet(plannerContext, queryMaker))
+    final ImmutableList.Builder<RelOptRule> retVal = ImmutableList.<RelOptRule>builder()
+        .addAll(baseRuleSet(plannerContext))
         .add(DruidRelToDruidRule.instance())
-        .build();
+        .add(new DruidTableScanRule(queryMaker))
+        .addAll(DruidRules.rules());
+
+    if (plannerContext.getPlannerConfig().getMaxSemiJoinRowsInMemory() > 0) {
+      retVal.add(DruidSemiJoinRule.instance());
+    }
+
+    return retVal.build();
   }
 
-  private static List<RelOptRule> bindableConventionRuleSet(
-      final PlannerContext plannerContext,
-      final QueryMaker queryMaker
-  )
+  private static List<RelOptRule> bindableConventionRuleSet(final PlannerContext plannerContext)
   {
     return ImmutableList.<RelOptRule>builder()
-        .addAll(baseRuleSet(plannerContext, queryMaker))
+        .addAll(baseRuleSet(plannerContext))
         .addAll(Bindables.RULES)
         .add(AggregateReduceFunctionsRule.INSTANCE)
         .build();
   }
 
-  private static List<RelOptRule> baseRuleSet(
-      final PlannerContext plannerContext,
-      final QueryMaker queryMaker
-  )
+  private static List<RelOptRule> baseRuleSet(final PlannerContext plannerContext)
   {
     final PlannerConfig plannerConfig = plannerContext.getPlannerConfig();
     final ImmutableList.Builder<RelOptRule> rules = ImmutableList.builder();
@@ -236,22 +236,10 @@ private static List<RelOptRule> baseRuleSet(
       rules.add(AggregateExpandDistinctAggregatesRule.JOIN);
     }
 
-    if (plannerConfig.isUseFallback()) {
-      rules.add(DruidRelToBindableRule.instance());
-    }
-
     rules.add(SortCollapseRule.instance());
     rules.add(CaseFilteredAggregatorRule.instance());
     rules.add(ProjectAggregatePruneUnusedCallRule.instance());
 
-    // Druid-specific rules.
-    rules.add(new DruidTableScanRule(queryMaker));
-    rules.addAll(DruidRules.rules());
-
-    if (plannerConfig.getMaxSemiJoinRowsInMemory() > 0) {
-      rules.add(DruidSemiJoinRule.instance());
-    }
-
     return rules.build();
   }
 

sql/src/main/java/org/apache/druid/sql/calcite/rel/DruidOuterQueryRel.java

@@ -22,7 +22,6 @@
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
-import org.apache.calcite.interpreter.BindableConvention;
 import org.apache.calcite.plan.RelOptCluster;
 import org.apache.calcite.plan.RelOptCost;
 import org.apache.calcite.plan.RelOptPlanner;
@@ -154,18 +153,6 @@ public DruidQuery toDruidQueryForExplaining()
     );
   }
 
-  @Override
-  public DruidOuterQueryRel asBindable()
-  {
-    return new DruidOuterQueryRel(
-        getCluster(),
-        getTraitSet().plus(BindableConvention.INSTANCE),
-        sourceRel,
-        partialQuery,
-        getQueryMaker()
-    );
-  }
-
   @Override
   public DruidOuterQueryRel asDruidConvention()
   {

sql/src/main/java/org/apache/druid/sql/calcite/rel/DruidQueryRel.java

@@ -21,7 +21,6 @@
 
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.google.common.base.Preconditions;
-import org.apache.calcite.interpreter.BindableConvention;
 import org.apache.calcite.plan.Convention;
 import org.apache.calcite.plan.RelOptCluster;
 import org.apache.calcite.plan.RelOptCost;
@@ -110,19 +109,6 @@ public DruidQuery toDruidQueryForExplaining()
     return toDruidQuery(false);
   }
 
-  @Override
-  public DruidQueryRel asBindable()
-  {
-    return new DruidQueryRel(
-        getCluster(),
-        getTraitSet().plus(BindableConvention.INSTANCE),
-        table,
-        druidTable,
-        getQueryMaker(),
-        partialQuery
-    );
-  }
-
   @Override
   public DruidQueryRel asDruidConvention()
   {

sql/src/main/java/org/apache/druid/sql/calcite/rel/DruidRel.java

@@ -19,12 +19,6 @@
 
 package org.apache.druid.sql.calcite.rel;
 
-import org.apache.calcite.DataContext;
-import org.apache.calcite.interpreter.BindableRel;
-import org.apache.calcite.interpreter.Node;
-import org.apache.calcite.interpreter.Row;
-import org.apache.calcite.interpreter.Sink;
-import org.apache.calcite.linq4j.Enumerable;
 import org.apache.calcite.plan.RelOptCluster;
 import org.apache.calcite.plan.RelTraitSet;
 import org.apache.calcite.rel.AbstractRelNode;
@@ -34,7 +28,7 @@
 import javax.annotation.Nullable;
 import java.util.List;
 
-public abstract class DruidRel<T extends DruidRel> extends AbstractRelNode implements BindableRel
+public abstract class DruidRel<T extends DruidRel> extends AbstractRelNode
 {
   private final QueryMaker queryMaker;
 
@@ -103,8 +97,6 @@ public boolean isValidDruidQuery()
    */
   public abstract DruidQuery toDruidQueryForExplaining();
 
-  public abstract T asBindable();
-
   public QueryMaker getQueryMaker()
   {
     return queryMaker;
@@ -121,34 +113,4 @@ public PlannerContext getPlannerContext()
    * Get a list of names of datasources read by this DruidRel
    */
   public abstract List<String> getDataSourceNames();
-
-  @Override
-  public Class<Object[]> getElementType()
-  {
-    return Object[].class;
-  }
-
-  @Override
-  public Node implement(InterpreterImplementor implementor)
-  {
-    final Sink sink = implementor.compiler.sink(this);
-    return () -> runQuery().accumulate(
-        sink,
-        (Sink theSink, Object[] in) -> {
-          try {
-            theSink.send(Row.of(in));
-          }
-          catch (InterruptedException e) {
-            throw new RuntimeException(e);
-          }
-          return theSink;
-        }
-    );
-  }
-
-  @Override
-  public Enumerable<Object[]> bind(final DataContext dataContext)
-  {
-    throw new UnsupportedOperationException();
-  }
 }

sql/src/main/java/org/apache/druid/sql/calcite/rel/DruidSemiJoin.java

@@ -22,7 +22,6 @@
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
-import org.apache.calcite.interpreter.BindableConvention;
 import org.apache.calcite.plan.RelOptCluster;
 import org.apache.calcite.plan.RelOptCost;
 import org.apache.calcite.plan.RelOptPlanner;
@@ -156,21 +155,6 @@ public DruidQuery toDruidQueryForExplaining()
     return left.toDruidQueryForExplaining();
   }
 
-  @Override
-  public DruidSemiJoin asBindable()
-  {
-    return new DruidSemiJoin(
-        getCluster(),
-        getTraitSet().replace(BindableConvention.INSTANCE),
-        left,
-        RelOptRule.convert(right, BindableConvention.INSTANCE),
-        leftExpressions,
-        rightKeys,
-        maxSemiJoinRowsInMemory,
-        getQueryMaker()
-    );
-  }
-
   @Override
   public DruidSemiJoin asDruidConvention()
   {