[CALCITE-5251] Support SQL hint for Snapshot

core/src/main/java/org/apache/calcite/rel/core/Snapshot.java

@@ -21,12 +21,16 @@
 import org.apache.calcite.rel.RelNode;
 import org.apache.calcite.rel.RelWriter;
 import org.apache.calcite.rel.SingleRel;
+import org.apache.calcite.rel.hint.Hintable;
+import org.apache.calcite.rel.hint.RelHint;
 import org.apache.calcite.rel.type.RelDataType;
 import org.apache.calcite.rex.RexNode;
 import org.apache.calcite.rex.RexShuttle;
 import org.apache.calcite.sql.type.SqlTypeName;
 import org.apache.calcite.util.Litmus;
 
+import com.google.common.collect.ImmutableList;
+
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 import java.util.List;
@@ -43,30 +47,49 @@
  * returns the contents whose versions that overlap with the given specific
  * period (i.e. those that started before given period and ended after it).
  */
-public abstract class Snapshot extends SingleRel {
+public abstract class Snapshot extends SingleRel implements Hintable {
  //~ Instance fields --------------------------------------------------------
 
  private final RexNode period;
 
+ protected final ImmutableList<RelHint> hints;
+
  //~ Constructors -----------------------------------------------------------
 
  /**
  * Creates a Snapshot.
  *
  * @param cluster Cluster that this relational expression belongs to
  * @param traitSet The traits of this relational expression
+ * @param hints Hints for this node
  * @param input Input relational expression
  * @param period Timestamp expression which as the table was at the given
  * time in the past
  */
  @SuppressWarnings("method.invocation.invalid")
- protected Snapshot(RelOptCluster cluster, RelTraitSet traitSet, RelNode input,
- RexNode period) {
+ protected Snapshot(RelOptCluster cluster, RelTraitSet traitSet, List<RelHint> hints,
+ RelNode input, RexNode period) {
  super(cluster, traitSet, input);
  this.period = Objects.requireNonNull(period, "period");
+ this.hints = ImmutableList.copyOf(hints);
  assert isValid(Litmus.THROW, null);
  }
 
+ /**
+ * Creates a Snapshot.
+ *
+ * @param cluster Cluster that this relational expression belongs to
+ * @param traitSet The traits of this relational expression
+ * @param input Input relational expression
+ * @param period Timestamp expression which as the table was at the given
+ * time in the past
+ */
+ @SuppressWarnings("method.invocation.invalid")
+ protected Snapshot(
+ RelOptCluster cluster, RelTraitSet traitSet, RelNode input, RexNode period) {
+ this(cluster, traitSet, ImmutableList.of(), input, period);
+ }
+
  //~ Methods ----------------------------------------------------------------
 
  @Override public final RelNode copy(RelTraitSet traitSet, List<RelNode> inputs) {
@@ -100,4 +123,8 @@ public RexNode getPeriod() {
  }
  return litmus.succeed();
  }
+
+ @Override public ImmutableList<RelHint> getHints() {
+ return hints;
+ }
 }

core/src/main/java/org/apache/calcite/rel/hint/HintPredicates.java

@@ -80,6 +80,11 @@ public abstract class HintPredicates {
  public static final HintPredicate WINDOW =
  new NodeTypeHintPredicate(NodeTypeHintPredicate.NodeType.WINDOW);
 
+ /** A hint predicate that indicates a hint can only be used to
+ * {@link org.apache.calcite.rel.core.Snapshot} nodes. */
+ public static final HintPredicate SNAPSHOT =
+ new NodeTypeHintPredicate(NodeTypeHintPredicate.NodeType.SNAPSHOT);
+
  /**
  * Returns a composed hint predicate that represents a short-circuiting logical
  * AND of an array of hint predicates {@code hintPredicates}. When evaluating the composed

core/src/main/java/org/apache/calcite/rel/hint/NodeTypeHintPredicate.java

@@ -24,6 +24,7 @@
 import org.apache.calcite.rel.core.Join;
 import org.apache.calcite.rel.core.Project;
 import org.apache.calcite.rel.core.SetOp;
+import org.apache.calcite.rel.core.Snapshot;
 import org.apache.calcite.rel.core.Sort;
 import org.apache.calcite.rel.core.TableScan;
 import org.apache.calcite.rel.core.Values;
@@ -99,7 +100,12 @@ enum NodeType {
  /**
  * The hint would be propagated to the Window nodes.
  */
- WINDOW(Window.class);
+ WINDOW(Window.class),
+
+ /**
+ * The hint would be propagated to the Snapshot nodes.
+ */
+ SNAPSHOT(Snapshot.class);
 
  /** Relational expression clazz that the hint can apply to. */
  @SuppressWarnings("ImmutableEnumChecker")

core/src/main/java/org/apache/calcite/rel/logical/LogicalSnapshot.java

@@ -23,18 +23,39 @@
 import org.apache.calcite.rel.RelDistributionTraitDef;
 import org.apache.calcite.rel.RelNode;
 import org.apache.calcite.rel.core.Snapshot;
+import org.apache.calcite.rel.hint.RelHint;
 import org.apache.calcite.rel.metadata.RelMdCollation;
 import org.apache.calcite.rel.metadata.RelMdDistribution;
 import org.apache.calcite.rel.metadata.RelMetadataQuery;
 import org.apache.calcite.rex.RexNode;
 
+import com.google.common.collect.ImmutableList;
+
+import java.util.List;
+
 /**
  * Sub-class of {@link org.apache.calcite.rel.core.Snapshot}
  * not targeted at any particular engine or calling convention.
  */
 public class LogicalSnapshot extends Snapshot {
 
  //~ Constructors -----------------------------------------------------------
+ /**
+ * Creates a LogicalSnapshot.
+ *
+ * <p>Use {@link #create} unless you know what you're doing.
+ *
+ * @param cluster Cluster that this relational expression belongs to
+ * @param traitSet The traits of this relational expression
+ * @param hints Hints for this node
+ * @param input Input relational expression
+ * @param period Timestamp expression which as the table was at the given
+ * time in the past
+ */
+ public LogicalSnapshot(RelOptCluster cluster, RelTraitSet traitSet, List<RelHint> hints,
+ RelNode input, RexNode period) {
+ super(cluster, traitSet, hints, input, period);
+ }
 
  /**
  * Creates a LogicalSnapshot.
@@ -49,12 +70,12 @@ public class LogicalSnapshot extends Snapshot {
  */
  public LogicalSnapshot(RelOptCluster cluster, RelTraitSet traitSet,
  RelNode input, RexNode period) {
- super(cluster, traitSet, input, period);
+ super(cluster, traitSet, ImmutableList.of(), input, period);
  }
 
  @Override public Snapshot copy(RelTraitSet traitSet, RelNode input,
  RexNode period) {
- return new LogicalSnapshot(getCluster(), traitSet, input, period);
+ return new LogicalSnapshot(getCluster(), traitSet, hints, input, period);
  }
 
  /** Creates a LogicalSnapshot. */
@@ -69,4 +90,8 @@ public static LogicalSnapshot create(RelNode input, RexNode period) {
  () -> RelMdDistribution.snapshot(mq, input));
  return new LogicalSnapshot(cluster, traitSet, input, period);
  }
+
+ @Override public RelNode withHints(final List<RelHint> hintList) {
+ return new LogicalSnapshot(getCluster(), traitSet, hintList, input, getPeriod());
+ }
 }

core/src/test/java/org/apache/calcite/test/SqlHintsConverterTest.java

@@ -242,6 +242,13 @@ public final Fixture sql(String sql) {
  sql(sql).ok();
  }
 
+ @Test void testSnapshotHints() {
+ final String sql = "select /*+ fast_snapshot(products_temporal) */ stream * from\n"
+ + " orders join products_temporal for system_time as of timestamp '2022-08-11 15:00:00'\n"
+ + " on orders.productid = products_temporal.productid";
+ sql(sql).ok();
+ }
+
  @Test void testHintsInSubQueryWithDecorrelation() {
  final String sql = "select /*+ resource(parallelism='3'), AGG_STRATEGY(TWO_PHASE) */\n"
  + "sum(e1.empno) from emp e1, dept d1\n"
@@ -889,6 +896,11 @@ private static class HintCollector extends RelShuttleImpl {
  if (window.getHints().size() > 0) {
  this.hintsCollect.add("Window:" + window.getHints());
  }
+ } else if (other instanceof Snapshot) {
+ Snapshot snapshot = (Snapshot) other;
+ if (snapshot.getHints().size() > 0) {
+ this.hintsCollect.add("Snapshot:" + snapshot.getHints());
+ }
  }
  return super.visit(other);
  }
@@ -978,6 +990,7 @@ static HintStrategyTable createHintStrategies(HintStrategyTable.Builder builder)
  .hintStrategy("async_merge", HintPredicates.SORT)
  .hintStrategy("mini_batch",
  HintPredicates.and(HintPredicates.WINDOW, HintPredicates.PROJECT))
+ .hintStrategy("fast_snapshot", HintPredicates.SNAPSHOT)
  .hintStrategy("use_merge_join",
  HintStrategy.builder(
  HintPredicates.and(HintPredicates.JOIN, joinWithFixedTableName()))

core/src/test/resources/org/apache/calcite/test/SqlHintsConverterTest.xml

@@ -200,9 +200,8 @@ EnumerableProject(ENAME=[$3], JOB=[$4], SAL=[$7], NAME=[$1])
  </TestCase>
  <TestCase name="testHintsPropagationInVolcanoPlannerRules2">
  <Resource name="sql">
- <![CDATA[select /*+ my_hint */ ename, job
-from emp where not exists (select 1 from dept where emp.deptno = dept.deptno)
-]]>
+ <![CDATA[select /*+ no_hash_join */ ename, job
+from emp where not exists (select 1 from dept where emp.deptno = dept.deptno)]]>
  </Resource>
  <Resource name="planBefore">
  <![CDATA[
@@ -232,9 +231,8 @@ EnumerableProject(ENAME=[$0], JOB=[$1])
  </TestCase>
  <TestCase name="testHintsPropagationInVolcanoPlannerRules3">
  <Resource name="sql">
- <![CDATA[select /*+ my_hint */ ename, job
-from emp where not exists (select 1 from dept where emp.deptno = dept.deptno) order by ename
-]]>
+ <![CDATA[select /*+ no_hash_join */ ename, job
+from emp where not exists (select 1 from dept where emp.deptno = dept.deptno) order by ename]]>
  </Resource>
  <Resource name="planBefore">
  <![CDATA[
@@ -358,6 +356,19 @@ on emp.deptno = dept.deptno]]>
 Project:[[PROPERTIES inheritPath:[] options:{K1=v1, K2=v2}]]
 TableScan:[[INDEX inheritPath:[] options:[IDX1, IDX2]], [PROPERTIES inheritPath:[0, 0] options:{K1=v1, K2=v2}]]
 TableScan:[[PROPERTIES inheritPath:[] options:{K1=v1, K2=v2}], [PROPERTIES inheritPath:[0, 1] options:{K1=v1, K2=v2}]]
+]]>
+ </Resource>
+ </TestCase>
+ <TestCase name="testSnapshotHints">
+ <Resource name="sql">
+ <![CDATA[select /*+ fast_snapshot(products_temporal) */ stream * from
+ orders join products_temporal for system_time as of timestamp '2022-08-11 15:00:00'
+ on orders.productid = products_temporal.productid]]>
+ </Resource>
+ <Resource name="hints">
+ <![CDATA[
+Project:[[FAST_SNAPSHOT inheritPath:[] options:[PRODUCTS_TEMPORAL]]]
+Snapshot:[[FAST_SNAPSHOT inheritPath:[0, 1] options:[PRODUCTS_TEMPORAL]]]
 ]]>
  </Resource>
  </TestCase>