[ORCA] Support hash partitioning in ORCA

src/backend/gpopt/translate/CTranslatorRelcacheToDXL.cpp

@@ -2692,11 +2692,14 @@ CTranslatorRelcacheToDXL::RetrievePartKeysAndTypes(CMemoryPool *mp,
 				   GPOS_WSZ_LIT("partitioning by expression"));
 	}
 
-	if (PARTITION_STRATEGY_HASH == part_type)
-	{
-		GPOS_RAISE(gpdxl::ExmaMD, gpdxl::ExmiMDObjUnsupported,
-				   GPOS_WSZ_LIT("hash partitioning"));
-	}
+	// Hash-partitioned tables are supported for scanning only. ORCA cannot
+	// express a hash partition's membership rule (the satisfies_hash_partition
+	// call, i.e. hash(key) mod modulus = remainder) as a btree interval
+	// constraint, so it does no static partition pruning for hash partitions
+	// and simply scans every leaf partition. Range and list partitions keep
+	// full pruning support. Letting the strategy flow through here (instead of
+	// raising ExmiMDObjUnsupported) keeps such queries inside ORCA rather than
+	// falling back to the Postgres planner.
 
 	(*part_keys)->Append(GPOS_NEW(mp) ULONG(attno - 1));
 	(*part_types)->Append(GPOS_NEW(mp) CHAR(part_type));

src/backend/gporca/libgpopt/include/gpopt/operators/CExpressionPreprocessor.h

@@ -215,6 +215,24 @@ class CExpressionPreprocessor
 												 CColRefArray *pdrgpcrOutput,
 												 ColRefToUlongMap *col_mapping);
 
+	// translate a child partition's part-constraint DXL into a CExpression over
+	// the root table's colrefs (NULL if the child has no stored constraint)
+	static CExpression *PexprPartConstraintFromChild(
+		CMemoryPool *mp, const IMDRelation *partrel, CColRefArray *pdrgpcrOutput,
+		ColRefToUlongMap *root_col_mapping);
+
+	// find a "colref = const" equality among the given conjuncts and return its
+	// const subexpression (NULL if none)
+	static CExpression *PexprColumnEqualityConst(
+		CExpressionArray *pdrgpexprConjuncts, const CColRef *colref);
+
+	// static hash-partition pruning: true if the leaf provably cannot contain
+	// any row matching the query's equality predicates on the partition key
+	static BOOL FHashPartitionPruned(CMemoryPool *mp, const IMDRelation *partrel,
+									 CColRefArray *pdrgpcrOutput,
+									 ColRefToUlongMap *root_col_mapping,
+									 CExpressionArray *pdrgpexprConjuncts);
+
 	// swap logical select over logical project
 	static CExpression *PexprTransposeSelectAndProject(CMemoryPool *mp,
 													   CExpression *pexpr);

src/backend/gporca/libgpopt/src/eval/CConstExprEvaluatorDXL.cpp

@@ -24,6 +24,8 @@
 #include "gpopt/operators/CExpression.h"
 #include "gpopt/operators/CPredicateUtils.h"
 
+#include "naucrates/md/IMDFunction.h"
+
 using namespace gpdxl;
 using namespace gpmd;
 using namespace gpopt;
@@ -72,7 +74,15 @@ CConstExprEvaluatorDXL::PexprEval(CExpression *pexpr)
 {
 	GPOS_ASSERT(nullptr != pexpr);
 
-	if (!CPredicateUtils::FCompareConstToConstIgnoreCast(pexpr))
+	// We can evaluate (a) the (const cmp const) expressions used by the
+	// comparator, and (b) any column-free IMMUTABLE expression (e.g.
+	// satisfies_hash_partition() over constants, used for hash partition
+	// pruning). We must not fold expressions that reference columns, nor
+	// volatile/stable ones, since their value is not fixed at plan time.
+	if (!(CPredicateUtils::FCompareConstToConstIgnoreCast(pexpr) ||
+		  (0 == pexpr->DeriveUsedColumns()->Size() &&
+		   IMDFunction::EfsImmutable ==
+			   pexpr->DeriveScalarFunctionProperties()->Efs())))
 	{
 		GPOS_RAISE(gpopt::ExmaGPOPT, gpopt::ExmiEvalUnsupportedScalarExpr);
 	}