(calcite) branch main updated: [CALCITE-6720] Refactor cross product logic in RelMdUniqueKeys#getPassedThroughCols using Linq4j#product

[mbudiu]

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The following commit(s) were added to refs/heads/main by this push:
     new c8a513b961 [CALCITE-6720] Refactor cross product logic in 
RelMdUniqueKeys#getPassedThroughCols using Linq4j#product
c8a513b961 is described below

commit c8a513b96185374345ea24e64deebfdbcd126268
Author: Stamatis Zampetakis <zabe...@gmail.com>
AuthorDate: Fri Dec 6 12:51:37 2024 +0100

    [CALCITE-6720] Refactor cross product logic in 
RelMdUniqueKeys#getPassedThroughCols using Linq4j#product
    
    The RelMdUniqueKeys#getPassedThroughCols method exists only for performing 
a cross product of the various mappings between input and output "pass through" 
columns.
    
    The entire method can be replaced by exploiting the built-in Linq4j#product 
API and few other utility methods.
    
    After the refactoring the code is easier to follow and potentially more 
efficient since the result is computed gradually and we don't have to retain 
the entire cross product result in memory.
---
 .../calcite/rel/metadata/RelMdUniqueKeys.java      | 29 +++-------------------
 1 file changed, 4 insertions(+), 25 deletions(-)

diff --git 
a/core/src/main/java/org/apache/calcite/rel/metadata/RelMdUniqueKeys.java 
b/core/src/main/java/org/apache/calcite/rel/metadata/RelMdUniqueKeys.java
index 8745d06064..ced86022cb 100644
--- a/core/src/main/java/org/apache/calcite/rel/metadata/RelMdUniqueKeys.java
+++ b/core/src/main/java/org/apache/calcite/rel/metadata/RelMdUniqueKeys.java
@@ -336,7 +336,9 @@ public class RelMdUniqueKeys
       final ImmutableSet.Builder<ImmutableBitSet> keysBuilder = 
ImmutableSet.builder();
       if (inputUniqueKeys != null) {
         for (ImmutableBitSet inputKey : inputUniqueKeys) {
-          keysBuilder.addAll(getPassedThroughCols(inputKey, rel));
+          Iterable<List<Integer>> product =
+              Linq4j.product(Util.transform(inputKey, i -> 
getPassedThroughCols(i, rel)));
+          keysBuilder.addAll(Util.transform(product, ImmutableBitSet::of));
         }
       }
 
@@ -371,30 +373,6 @@ public class RelMdUniqueKeys
     return minimalKeys;
   }
 
-  /**
-   * Given a set of columns in the input of an Aggregate rel, returns the set 
of mappings from the
-   * input columns to the output of the aggregations. A mapping for a 
particular column exists if
-   * it is part of a simple group by and/or it is "passed through" unmodified 
by a
-   * {@link RelMdColumnUniqueness#PASSTHROUGH_AGGREGATIONS pass-through 
aggregation function}.
-   */
-  private static Set<ImmutableBitSet> getPassedThroughCols(
-      ImmutableBitSet inputColumns, Aggregate rel) {
-    checkArgument(Aggregate.isSimple(rel));
-    Set<ImmutableBitSet> conbinations = new HashSet<>();
-    conbinations.add(ImmutableBitSet.of());
-    for (Integer inputColumn : inputColumns.asSet()) {
-      final ImmutableBitSet passedThroughCols = 
getPassedThroughCols(inputColumn, rel);
-      final Set<ImmutableBitSet> crossProduct = new HashSet<>();
-      for (ImmutableBitSet set : conbinations) {
-        for (Integer passedThroughCol : passedThroughCols) {
-          crossProduct.add(set.rebuild().set(passedThroughCol).build());
-        }
-      }
-      conbinations = crossProduct;
-    }
-    return conbinations;
-  }
-
   /**
    * Given a column in the input of an Aggregate rel, returns the mappings 
from the input column to
    * the output of the aggregations. A mapping for the column exists if it is 
part of a simple
@@ -403,6 +381,7 @@ public class RelMdUniqueKeys
    */
   private static ImmutableBitSet getPassedThroughCols(Integer inputColumn,
       Aggregate rel) {
+    checkArgument(Aggregate.isSimple(rel));
     final ImmutableBitSet.Builder builder = ImmutableBitSet.builder();
     if (rel.getGroupSet().get(inputColumn)) {
       builder.set(inputColumn);