yjhjstz commented on code in PR #1398: URL: https://github.com/apache/cloudberry/pull/1398#discussion_r3231164678
########## src/backend/gporca/libgpopt/src/xforms/CXformGet2ParallelTableScan.cpp: ########## @@ -0,0 +1,265 @@ +/*------------------------------------------------------------------------- + * + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, + * software distributed under the License is distributed on an + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + * KIND, either express or implied. See the License for the + * specific language governing permissions and limitations + * under the License. + * + * CXformGet2ParallelTableScan.cpp + * + * IDENTIFICATION + * src/backend/gporca/libgpopt/src/xforms/CXformGet2ParallelTableScan.cpp + * + *------------------------------------------------------------------------- + */ + +#include "gpopt/xforms/CXformGet2ParallelTableScan.h" + +#include "gpos/base.h" + +#include "gpopt/base/COptCtxt.h" +#include "gpopt/hints/CHintUtils.h" +#include "gpopt/metadata/CTableDescriptor.h" +#include "gpopt/operators/CExpressionHandle.h" +#include "gpopt/operators/CLogicalGet.h" +#include "gpopt/operators/CPhysicalParallelTableScan.h" +#include "gpopt/optimizer/COptimizerConfig.h" +#include "naucrates/md/IMDRelation.h" +#include "gpopt/search/CGroupProxy.h" +#include "gpopt/search/CMemo.h" + + +// Use gpdbwrappers for parallel checks +extern int max_parallel_workers_per_gather; + +// Forward declarations for gpdbwrappers functions +namespace gpdb { + bool IsParallelModeOK(void); +} + +using namespace gpopt; + +//--------------------------------------------------------------------------- +// @function: +// CXformGet2ParallelTableScan::FHasParallelIncompatibleOps +// +// @doc: +// Check if memo contains logical operators that are incompatible +// with parallel execution (CTE, Dynamic scans, Foreign scans, etc.) +// +//--------------------------------------------------------------------------- +BOOL +CXformGet2ParallelTableScan::FHasParallelIncompatibleOps(CExpressionHandle &exprhdl) +{ + CGroupExpression *pgexprHandle = exprhdl.Pgexpr(); + if (nullptr == pgexprHandle) + { + return false; + } + + CGroup *pgroup = pgexprHandle->Pgroup(); + if (nullptr == pgroup) + { + return false; + } + + CMemo *pmemo = pgroup->Pmemo(); + if (nullptr == pmemo) + { + return false; + } + + // Iterate through all groups in memo to check for parallel-incompatible operations + const ULONG_PTR ulGroups = pmemo->UlpGroups(); + for (ULONG_PTR ul = 0; ul < ulGroups; ul++) + { + CGroup *pgroupCurrent = pmemo->Pgroup(ul); + if (nullptr == pgroupCurrent) + { + continue; + } + + // Check all group expressions in this group using CGroupProxy + CGroupProxy gp(pgroupCurrent); + CGroupExpression *pgexpr = gp.PgexprFirst(); + while (nullptr != pgexpr) + { + COperator::EOperatorId eopid = pgexpr->Pop()->Eopid(); + + // Check for CTE-related operators (incompatible with parallel execution) + if (COperator::EopLogicalCTEProducer == eopid || + COperator::EopLogicalCTEConsumer == eopid || + COperator::EopLogicalSequence == eopid || + COperator::EopLogicalSequenceProject == eopid) + { + return true; + } + + if (COperator::EopLogicalUnion == eopid || + COperator::EopLogicalUnionAll == eopid || + COperator::EopLogicalIntersect == eopid || + COperator::EopLogicalIntersectAll == eopid || + COperator::EopLogicalDifference == eopid || + COperator::EopLogicalDifferenceAll == eopid) + { + // Set operations are not supported in parallel plans + return true; + } + + pgexpr = gp.PgexprNext(pgexpr); + } + } + + return false; +} + +//--------------------------------------------------------------------------- +// @function: +// CXformGet2ParallelTableScan::CXformGet2ParallelTableScan +// +// @doc: +// Ctor +// +//--------------------------------------------------------------------------- +CXformGet2ParallelTableScan::CXformGet2ParallelTableScan(CMemoryPool *mp) + : CXformImplementation( + // pattern + GPOS_NEW(mp) CExpression(mp, GPOS_NEW(mp) CLogicalGet(mp))) +{ +} + +//--------------------------------------------------------------------------- +// @function: +// CXformGet2ParallelTableScan::Exfp +// +// @doc: +// Compute promise of xform based on GUC enable_parallel +// Uses unified parallel degree from max_parallel_workers_per_gather +// +//--------------------------------------------------------------------------- +CXform::EXformPromise +CXformGet2ParallelTableScan::Exfp(CExpressionHandle &exprhdl) const +{ + // Check if parallel plans are enabled in context and parallel processing is safe + if (!gpdb::IsParallelModeOK()) + { + return CXform::ExfpNone; + } + + // Check for parallel-incompatible operations that would conflict with parallel scans + if (FHasParallelIncompatibleOps(exprhdl)) + { + return CXform::ExfpNone; + } + + CLogicalGet *popGet = CLogicalGet::PopConvert(exprhdl.Pop()); + CTableDescriptor *ptabdesc = popGet->Ptabdesc(); + + // Don't use parallel scan for replicated tables + if (ptabdesc->GetRelDistribution() == IMDRelation::EreldistrReplicated || + ptabdesc->GetRelDistribution() == IMDRelation::EreldistrMasterOnly || + COptCtxt::PoctxtFromTLS()->HasReplicatedTables()) + { + //FIXME: Should we consider replicated tables. + return CXform::ExfpNone; + } + + // For AO/AOCO tables, check segfilecount early to avoid useless transformation + CMDAccessor *md_accessor = COptCtxt::PoctxtFromTLS()->Pmda(); + const IMDRelation *pmdrel = md_accessor->RetrieveRel(ptabdesc->MDId()); + IMDRelation::Erelstoragetype storage_type = pmdrel->RetrieveRelStorageType(); + + // Check if this is an AO/AOCO table + if (storage_type == IMDRelation::ErelstorageAppendOnlyRows || + storage_type == IMDRelation::ErelstorageAppendOnlyCols) + { + INT seg_file_count = pmdrel->SegFileCount(); + // Only reject if segfilecount is explicitly known to be 0 or 1 + // -1 means unknown (e.g., from DXL deserialization), so allow parallel in that case + if (seg_file_count >= 0 && seg_file_count <= 1) + { + // If segfilecount is 0 or 1, parallel execution is pointless + // Reject parallel scan early in promise phase + GPOS_TRACE_FORMAT("CXformGet2ParallelTableScan rejected for table %ls: AO/AOCO table has segfilecount=%d (needs >1 for parallel scan)", + ptabdesc->Name().Pstr()->GetBuffer(), seg_file_count); + return CXform::ExfpNone; + } + } + + // High promise for parallel scan when enabled + // All tables will use the same parallel degree from max_parallel_workers_per_gather + return CXform::ExfpHigh; +} + +//--------------------------------------------------------------------------- +// @function: +// CXformGet2ParallelTableScan::Transform +// +// @doc: +// Actual transformation +// +//--------------------------------------------------------------------------- +void +CXformGet2ParallelTableScan::Transform(CXformContext *pxfctxt, CXformResult *pxfres, + CExpression *pexpr) const +{ + GPOS_ASSERT(nullptr != pxfctxt); + GPOS_ASSERT(FPromising(pxfctxt->Pmp(), this, pexpr)); + GPOS_ASSERT(FCheckPattern(pexpr)); + + CLogicalGet *popGet = CLogicalGet::PopConvert(pexpr->Pop()); + + CMemoryPool *mp = pxfctxt->Pmp(); + + // create/extract components for alternative + CName *pname = GPOS_NEW(mp) CName(mp, popGet->Name()); + + CTableDescriptor *ptabdesc = popGet->Ptabdesc(); + ptabdesc->AddRef(); + + CColRefArray *pdrgpcrOutput = popGet->PdrgpcrOutput(); + GPOS_ASSERT(nullptr != pdrgpcrOutput); + pdrgpcrOutput->AddRef(); + + // Determine parallel workers degree + // Priority: table-level parallel_workers setting > GUC max_parallel_workers_per_gather > default + ULONG ulParallelWorkers = 2; // default Review Comment: add a macros. -- This is an automated message from the Apache Git Service. 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