greenplumn CPhysicalHashJoin 源码
greenplumn CPhysicalHashJoin 代码
文件路径：/src/backend/gporca/libgpopt/src/operators/CPhysicalHashJoin.cpp
//---------------------------------------------------------------------------
// Greenplum Database
// Copyright (C) 2012 EMC Corp.
//
// @filename:
// CPhysicalHashJoin.cpp
//
// @doc:
// Implementation of hash join operator
//---------------------------------------------------------------------------
#include "gpopt/operators/CPhysicalHashJoin.h"
#include "gpos/base.h"
#include "gpopt/base/CCastUtils.h"
#include "gpopt/base/CDistributionSpecHashed.h"
#include "gpopt/base/CDistributionSpecNonSingleton.h"
#include "gpopt/base/CDistributionSpecReplicated.h"
#include "gpopt/base/CDistributionSpecSingleton.h"
#include "gpopt/base/COptCtxt.h"
#include "gpopt/base/CUtils.h"
#include "gpopt/operators/CExpressionHandle.h"
#include "gpopt/operators/CPredicateUtils.h"
#include "gpopt/operators/CScalarConst.h"
#include "gpopt/operators/CScalarIdent.h"
using namespace gpopt;
// number of non-redistribute requests created by hash join
#define GPOPT_NON_HASH_DIST_REQUESTS 3
// maximum number of redistribute requests on single hash join keys
#define GPOPT_MAX_HASH_DIST_REQUESTS 6
//---------------------------------------------------------------------------
// @function:
// CPhysicalHashJoin::CPhysicalHashJoin
//
// @doc:
// Ctor
//
//---------------------------------------------------------------------------
CPhysicalHashJoin::CPhysicalHashJoin(CMemoryPool *mp,
CExpressionArray *pdrgpexprOuterKeys,
CExpressionArray *pdrgpexprInnerKeys,
IMdIdArray *hash_opfamilies,
CXform::EXformId origin_xform)
: CPhysicalJoin(mp, origin_xform),
m_pdrgpexprOuterKeys(pdrgpexprOuterKeys),
m_pdrgpexprInnerKeys(pdrgpexprInnerKeys),
m_hash_opfamilies(nullptr),
m_pdrgpdsRedistributeRequests(nullptr)
{
GPOS_ASSERT(nullptr != mp);
GPOS_ASSERT(nullptr != pdrgpexprOuterKeys);
GPOS_ASSERT(nullptr != pdrgpexprInnerKeys);
GPOS_ASSERT(pdrgpexprOuterKeys->Size() == pdrgpexprInnerKeys->Size());
if (GPOS_FTRACE(EopttraceConsiderOpfamiliesForDistribution))
{
GPOS_ASSERT(nullptr != hash_opfamilies);
m_hash_opfamilies = hash_opfamilies;
GPOS_ASSERT(pdrgpexprOuterKeys->Size() == m_hash_opfamilies->Size());
}
CreateOptRequests(mp);
}
//---------------------------------------------------------------------------
// @function:
// CPhysicalHashJoin::~CPhysicalHashJoin
//
// @doc:
// Dtor
//
//---------------------------------------------------------------------------
CPhysicalHashJoin::~CPhysicalHashJoin()
{
m_pdrgpexprOuterKeys->Release();
m_pdrgpexprInnerKeys->Release();
CRefCount::SafeRelease(m_hash_opfamilies);
CRefCount::SafeRelease(m_pdrgpdsRedistributeRequests);
}
//---------------------------------------------------------------------------
// @function:
// CPhysicalHashJoin::CreateHashRedistributeRequests
//
// @doc:
// Create the set of redistribute requests to send to first
// hash join child
//
//---------------------------------------------------------------------------
void
CPhysicalHashJoin::CreateHashRedistributeRequests(CMemoryPool *mp)
{
GPOS_ASSERT(nullptr == m_pdrgpdsRedistributeRequests);
GPOS_ASSERT(nullptr != m_pdrgpexprOuterKeys);
GPOS_ASSERT(nullptr != m_pdrgpexprInnerKeys);
CExpressionArray *pdrgpexpr = nullptr;
if (EceoRightToLeft == Eceo())
{
pdrgpexpr = m_pdrgpexprInnerKeys;
}
else
{
pdrgpexpr = m_pdrgpexprOuterKeys;
}
m_pdrgpdsRedistributeRequests = GPOS_NEW(mp) CDistributionSpecArray(mp);
const ULONG ulExprs =
std::min((ULONG) GPOPT_MAX_HASH_DIST_REQUESTS, pdrgpexpr->Size());
if (1 < ulExprs)
{
for (ULONG ul = 0; ul < ulExprs; ul++)
{
CExpressionArray *pdrgpexprCurrent =
GPOS_NEW(mp) CExpressionArray(mp);
CExpression *pexpr = (*pdrgpexpr)[ul];
pexpr->AddRef();
pdrgpexprCurrent->Append(pexpr);
IMdIdArray *opfamilies = nullptr;
if (GPOS_FTRACE(EopttraceConsiderOpfamiliesForDistribution))
{
GPOS_ASSERT(nullptr != m_hash_opfamilies);
opfamilies = GPOS_NEW(mp) IMdIdArray(mp);
IMDId *opfamily = (*m_hash_opfamilies)[ul];
opfamily->AddRef();
opfamilies->Append(opfamily);
}
// add a separate request for each hash join key
CDistributionSpecHashed *pdshashedCurrent =
GPOS_NEW(mp) CDistributionSpecHashed(
pdrgpexprCurrent, false /* fNullsCollocated */, opfamilies);
m_pdrgpdsRedistributeRequests->Append(pdshashedCurrent);
}
}
// add a request that contains all hash join keys
pdrgpexpr->AddRef();
if (GPOS_FTRACE(EopttraceConsiderOpfamiliesForDistribution))
{
GPOS_ASSERT(nullptr != m_hash_opfamilies);
m_hash_opfamilies->AddRef();
}
CDistributionSpecHashed *pdshashed = GPOS_NEW(mp) CDistributionSpecHashed(
pdrgpexpr, false /* fNullsCollocated */, m_hash_opfamilies);
m_pdrgpdsRedistributeRequests->Append(pdshashed);
}
//---------------------------------------------------------------------------
// @function:
// CPhysicalHashJoin::PosRequired
//
// @doc:
// Compute required sort order of the n-th child
//
//---------------------------------------------------------------------------
COrderSpec *
CPhysicalHashJoin::PosRequired(CMemoryPool *mp,
CExpressionHandle &, //exprhdl
COrderSpec *, // posInput,
ULONG
#ifdef GPOS_DEBUG
child_index
#endif // GPOS_DEBUG
,
CDrvdPropArray *, // pdrgpdpCtxt
ULONG // ulOptReq
) const
{
GPOS_ASSERT(
child_index < 2 &&
"Required sort order can be computed on the relational child only");
// hash join does not have order requirements to both children, and it
// does not preserve any sort order
return GPOS_NEW(mp) COrderSpec(mp);
}
//---------------------------------------------------------------------------
// @function:
// CPhysicalHashJoin::PrsRequired
//
// @doc:
// Compute required rewindability of the n-th child
//
//---------------------------------------------------------------------------
CRewindabilitySpec *
CPhysicalHashJoin::PrsRequired(CMemoryPool *mp, CExpressionHandle &exprhdl,
CRewindabilitySpec *prsRequired,
ULONG child_index,
CDrvdPropArray *, // pdrgpdpCtxt
ULONG // ulOptReq
) const
{
GPOS_ASSERT(
child_index < 2 &&
"Required rewindability can be computed on the relational child only");
if (1 == child_index)
{
// If the inner child contains outer references, and the required
// rewindability is not ErtNone, we must ensure that the inner subtree is
// at least rescannable, even though a Hash op on the inner side
// materialized the subtree results.
if (exprhdl.HasOuterRefs(1) &&
(prsRequired->Ert() == CRewindabilitySpec::ErtRescannable ||
prsRequired->Ert() == CRewindabilitySpec::ErtRewindable))
{
return GPOS_NEW(mp) CRewindabilitySpec(
CRewindabilitySpec::ErtRescannable, prsRequired->Emht());
}
// Otherwise, the inner Hash op will take care of materializing the
// subtree, so no rewindability type is required
else
{
return GPOS_NEW(mp) CRewindabilitySpec(CRewindabilitySpec::ErtNone,
prsRequired->Emht());
}
}
// pass through requirements to outer child
return PrsPassThru(mp, exprhdl, prsRequired, 0 /*child_index*/);
}
//---------------------------------------------------------------------------
// @function:
// CPhysicalHashJoin::PdsMatch
//
// @doc:
// Compute a distribution matching the distribution delivered by
// given child
//
//---------------------------------------------------------------------------
CDistributionSpec *
CPhysicalHashJoin::PdsMatch(CMemoryPool *mp, CDistributionSpec *pds,
ULONG ulSourceChildIndex) const
{
GPOS_ASSERT(nullptr != pds);
EChildExecOrder eceo = Eceo();
// check the type of distribution delivered by first (inner) child
switch (pds->Edt())
{
case CDistributionSpec::EdtUniversal:
// first child is universal, request second child to execute on a single host to avoid duplicates
return GPOS_NEW(mp) CDistributionSpecSingleton();
case CDistributionSpec::EdtSingleton:
case CDistributionSpec::EdtStrictSingleton:
// require second child to provide a matching singleton distribution
return PdssMatching(mp,
CDistributionSpecSingleton::PdssConvert(pds));
case CDistributionSpec::EdtHashed:
// require second child to provide a matching hashed distribution
return PdshashedMatching(mp,
CDistributionSpecHashed::PdsConvert(pds),
ulSourceChildIndex);
default:
GPOS_ASSERT(CDistributionSpec::EdtStrictReplicated == pds->Edt() ||
CDistributionSpec::EdtTaintedReplicated == pds->Edt());
if (EceoRightToLeft == eceo)
{
GPOS_ASSERT(1 == ulSourceChildIndex);
// inner child is replicated, for ROJ outer must be executed on a single (non-master) segment to avoid duplicates
if (this->Eopid() == EopPhysicalRightOuterHashJoin)
{
return GPOS_NEW(mp) CDistributionSpecSingleton(
CDistributionSpecSingleton::EstSegment);
}
// inner child is replicated, request outer child to have non-singleton distribution
return GPOS_NEW(mp) CDistributionSpecNonSingleton();
}
GPOS_ASSERT(0 == ulSourceChildIndex);
// outer child is replicated, replicate inner child too in order to preserve correctness of semi-join
return GPOS_NEW(mp) CDistributionSpecReplicated(
CDistributionSpec::EdtStrictReplicated);
}
}
//---------------------------------------------------------------------------
// @function:
// CPhysicalHashJoin::PdshashedMatching
//
// @doc:
// Compute a hashed distribution matching the given distribution
//
//---------------------------------------------------------------------------
CDistributionSpecHashed *
CPhysicalHashJoin::PdshashedMatching(
CMemoryPool *mp, CDistributionSpecHashed *pdshashed,
ULONG
ulSourceChild // index of child that delivered the given hashed distribution
) const
{
GPOS_ASSERT(2 > ulSourceChild);
CExpressionArray *pdrgpexprSource = m_pdrgpexprOuterKeys;
CExpressionArray *pdrgpexprTarget = m_pdrgpexprInnerKeys;
if (1 == ulSourceChild)
{
pdrgpexprSource = m_pdrgpexprInnerKeys;
pdrgpexprTarget = m_pdrgpexprOuterKeys;
}
const CExpressionArray *pdrgpexprDist = pdshashed->Pdrgpexpr();
const ULONG ulDlvrdSize = pdrgpexprDist->Size();
const ULONG ulSourceSize = pdrgpexprSource->Size();
// construct an array of target key expressions matching source key expressions
CExpressionArray *pdrgpexpr = GPOS_NEW(mp) CExpressionArray(mp);
CExpressionArrays *all_equiv_exprs = pdshashed->HashSpecEquivExprs();
IMdIdArray *opfamilies = nullptr;
if (GPOS_FTRACE(EopttraceConsiderOpfamiliesForDistribution))
{
opfamilies = GPOS_NEW(mp) IMdIdArray(mp);
}
for (ULONG ulDlvrdIdx = 0; ulDlvrdIdx < ulDlvrdSize; ulDlvrdIdx++)
{
CExpression *pexprDlvrd = (*pdrgpexprDist)[ulDlvrdIdx];
CExpressionArray *equiv_distribution_exprs = nullptr;
if (nullptr != all_equiv_exprs && all_equiv_exprs->Size() > 0)
{
equiv_distribution_exprs = (*all_equiv_exprs)[ulDlvrdIdx];
}
for (ULONG idx = 0; idx < ulSourceSize; idx++)
{
BOOL fSuccess = false;
CExpression *source_expr = (*pdrgpexprSource)[idx];
fSuccess = CUtils::Equals(pexprDlvrd, source_expr);
if (!fSuccess)
{
// if failed to find a equal match in the source distribution expr
// array, check the equivalent exprs to find a match
fSuccess =
CUtils::Contains(equiv_distribution_exprs, source_expr);
}
if (fSuccess)
{
// TODO: 02/21/2012 - ; source column may be mapped to multiple
// target columns (e.g. i=j and i=k);
// in this case, we need to generate multiple optimization requests to the target child
CExpression *pexprTarget = (*pdrgpexprTarget)[idx];
pexprTarget->AddRef();
pdrgpexpr->Append(pexprTarget);
if (nullptr != opfamilies)
{
GPOS_ASSERT(nullptr != m_hash_opfamilies);
IMDId *opfamily = (*m_hash_opfamilies)[idx];
opfamily->AddRef();
opfamilies->Append(opfamily);
}
break;
}
}
}
// check if we failed to compute required distribution
if (pdrgpexpr->Size() != ulDlvrdSize)
{
pdrgpexpr->Release();
if (nullptr != pdshashed->PdshashedEquiv())
{
CRefCount::SafeRelease(opfamilies);
// try again using the equivalent hashed distribution
return PdshashedMatching(mp, pdshashed->PdshashedEquiv(),
ulSourceChild);
}
}
if (pdrgpexpr->Size() != ulDlvrdSize)
{
// it should never happen, but instead of creating wrong spec, raise an exception
GPOS_RAISE(
CException::ExmaInvalid, CException::ExmiInvalid,
GPOS_WSZ_LIT("Unable to create matching hashed distribution."));
}
// nulls colocated for inner hash joins, but not colocated in outer hash joins
BOOL fNullsColocated = true;
if (COperator::EopPhysicalLeftOuterHashJoin == Eopid() ||
COperator::EopPhysicalRightOuterHashJoin == Eopid())
{
fNullsColocated = false;
}
return GPOS_NEW(mp)
CDistributionSpecHashed(pdrgpexpr, fNullsColocated, opfamilies);
}
//---------------------------------------------------------------------------
// @function:
// CPhysicalHashJoin::PdsRequiredSingleton
//
// @doc:
// Create (singleton, singleton) optimization request
//
//
//---------------------------------------------------------------------------
CDistributionSpec *
CPhysicalHashJoin::PdsRequiredSingleton(CMemoryPool *mp,
CExpressionHandle &, // exprhdl
CDistributionSpec *, // pdsInput
ULONG child_index,
CDrvdPropArray *pdrgpdpCtxt) const
{
if (FFirstChildToOptimize(child_index))
{
// require first child to be singleton
return GPOS_NEW(mp) CDistributionSpecSingleton();
}
// require a matching distribution from second child
GPOS_ASSERT(nullptr != pdrgpdpCtxt);
CDistributionSpec *pdsFirst =
CDrvdPropPlan::Pdpplan((*pdrgpdpCtxt)[0])->Pds();
GPOS_ASSERT(nullptr != pdsFirst);
if (CDistributionSpec::EdtUniversal == pdsFirst->Edt() ||
CDistributionSpec::EdtTaintedReplicated == pdsFirst->Edt())
{
// first child is universal, request second child to execute on a single host to avoid duplicates
return GPOS_NEW(mp) CDistributionSpecSingleton();
}
if (COptCtxt::PoctxtFromTLS()->OptimizeDMLQueryWithSingletonSegment() &&
CDistributionSpec::EdtStrictReplicated == pdsFirst->Edt())
{
// For a DML query that can be optimized by enforcing a non-master gather motion,
// we request singleton-segment distribution on the outer child. If the outer child
// is replicated, no enforcer gets added; in which case pdsFirst is EdtStrictReplicated.
// Hence handle this scenario here and require a singleton-segment on the
// inner child to produce a singleton execution alternavtive for the HJ.
return GPOS_NEW(mp)
CDistributionSpecSingleton(CDistributionSpecSingleton::EstSegment);
}
GPOS_ASSERT(CDistributionSpec::EdtSingleton == pdsFirst->Edt() ||
CDistributionSpec::EdtStrictSingleton == pdsFirst->Edt());
// require second child to have matching singleton distribution
return CPhysical::PdssMatching(
mp, CDistributionSpecSingleton::PdssConvert(pdsFirst));
}
//---------------------------------------------------------------------------
// @function:
// CPhysicalHashJoin::PdsRequiredReplicate
//
// @doc:
// Create (hashed/non-singleton, broadcast) optimization request
//
//
//---------------------------------------------------------------------------
CDistributionSpec *
CPhysicalHashJoin::PdsRequiredReplicate(
CMemoryPool *mp, CExpressionHandle &exprhdl, CDistributionSpec *pdsInput,
ULONG child_index, CDrvdPropArray *pdrgpdpCtxt, ULONG ulOptReq,
CReqdPropPlan *prppInput)
{
EChildExecOrder eceo = Eceo();
if (EceoLeftToRight == eceo)
{
// if optimization order is left to right, fall-back to implementation of parent Join operator
CEnfdDistribution *ped = CPhysicalJoin::Ped(
mp, exprhdl, prppInput, child_index, pdrgpdpCtxt, ulOptReq);
CDistributionSpec *pds = ped->PdsRequired();
pds->AddRef();
SafeRelease(ped);
return pds;
}
GPOS_ASSERT(EceoRightToLeft == eceo);
if (1 == child_index)
{
// require inner child to be replicated
return GPOS_NEW(mp)
CDistributionSpecReplicated(CDistributionSpec::EdtReplicated);
}
GPOS_ASSERT(0 == child_index);
// require a matching distribution from outer child
CDistributionSpec *pdsInner =
CDrvdPropPlan::Pdpplan((*pdrgpdpCtxt)[0])->Pds();
GPOS_ASSERT(nullptr != pdsInner);
if (CDistributionSpec::EdtUniversal == pdsInner->Edt())
{
// first child is universal, request second child to execute on a single host to avoid duplicates
return GPOS_NEW(mp) CDistributionSpecSingleton();
}
if (ulOptReq == m_pdrgpdsRedistributeRequests->Size() &&
CDistributionSpec::EdtHashed == pdsInput->Edt())
{
// attempt to propagate hashed request to child
CDistributionSpecHashed *pdshashed = PdshashedPassThru(
mp, exprhdl, CDistributionSpecHashed::PdsConvert(pdsInput),
child_index, pdrgpdpCtxt, ulOptReq);
if (nullptr != pdshashed)
{
return pdshashed;
}
}
// otherwise, require second child to deliver non-singleton distribution
GPOS_ASSERT(CDistributionSpec::EdtStrictReplicated == pdsInner->Edt() ||
CDistributionSpec::EdtTaintedReplicated == pdsInner->Edt());
return GPOS_NEW(mp) CDistributionSpecNonSingleton();
}
//---------------------------------------------------------------------------
// @function:
// CPhysicalHashJoin::PdshashedPassThru
//
// @doc:
// Create a child hashed distribution request based on input hashed
// distribution,
// return NULL if no such request can be created
//
//
//---------------------------------------------------------------------------
CDistributionSpecHashed *
CPhysicalHashJoin::PdshashedPassThru(CMemoryPool *mp,
CExpressionHandle &exprhdl,
CDistributionSpecHashed *pdshashedInput,
ULONG, // child_index
CDrvdPropArray *, // pdrgpdpCtxt
ULONG ulOptReq GPOS_UNUSED)
{
GPOS_ASSERT(nullptr != pdshashedInput);
if (!GPOS_FTRACE(EopttraceEnableRedistributeBroadcastHashJoin))
{
// this option is disabled
return nullptr;
}
// since incoming request is hashed, we attempt here to propagate this request to outer child
CColRefSet *pcrsOuterOutput =
exprhdl.DeriveOutputColumns(0 /*child_index*/);
CExpressionArray *pdrgpexprIncomingRequest = pdshashedInput->Pdrgpexpr();
CColRefSet *pcrsAllUsed =
CUtils::PcrsExtractColumns(mp, pdrgpexprIncomingRequest);
BOOL fSubset = pcrsOuterOutput->ContainsAll(pcrsAllUsed);
BOOL fDisjoint = pcrsOuterOutput->IsDisjoint(pcrsAllUsed);
pcrsAllUsed->Release();
if (fSubset)
{
// incoming request uses columns from outer child only, pass it through
// but create a copy
CDistributionSpecHashed *pdsHashedRequired = pdshashedInput->Copy(mp);
return pdsHashedRequired;
}
if (!fDisjoint)
{
// incoming request intersects with columns from outer child,
// we restrict the request to outer child columns only, then we pass it through
CExpressionArray *pdrgpexprChildRequest =
GPOS_NEW(mp) CExpressionArray(mp);
const ULONG size = pdrgpexprIncomingRequest->Size();
for (ULONG ul = 0; ul < size; ul++)
{
CExpression *pexpr = (*pdrgpexprIncomingRequest)[ul];
CColRefSet *pcrsUsed = pexpr->DeriveUsedColumns();
if (pcrsOuterOutput->ContainsAll(pcrsUsed))
{
// hashed expression uses columns from outer child only, add it to request
pexpr->AddRef();
pdrgpexprChildRequest->Append(pexpr);
}
}
GPOS_ASSERT(0 < pdrgpexprChildRequest->Size());
CDistributionSpecHashed *pdshashed =
GPOS_NEW(mp) CDistributionSpecHashed(
pdrgpexprChildRequest, pdshashedInput->FNullsColocated());
// since the other child of the join is replicated, we need to enforce hashed-distribution across segments here
pdshashed->MarkUnsatisfiableBySingleton();
return pdshashed;
}
return nullptr;
}
//---------------------------------------------------------------------------
// @function:
// CPhysicalHashJoin::PdsRequiredRedistribute
//
// @doc:
// Compute (redistribute, redistribute) optimization request
//
//
//---------------------------------------------------------------------------
CDistributionSpec *
CPhysicalHashJoin::PdsRequiredRedistribute(CMemoryPool *mp,
CExpressionHandle &exprhdl,
CDistributionSpec *, // pdsInput
ULONG child_index,
CDrvdPropArray *pdrgpdpCtxt,
ULONG ulOptReq) const
{
if (FFirstChildToOptimize(child_index))
{
// require first child to provide a hashed distribution,
return PdshashedRequired(mp, child_index, ulOptReq);
}
// find the distribution delivered by first child
CDistributionSpec *pdsFirst =
CDrvdPropPlan::Pdpplan((*pdrgpdpCtxt)[0])->Pds();
GPOS_ASSERT(nullptr != pdsFirst);
CDistributionSpec *pdsInputForMatch = nullptr;
if (pdsFirst->Edt() == CDistributionSpec::EdtHashed)
{
// we need to create a matching required spec based on the derived distribution spec from
// the first child. Since that does not contain the m_equiv_hash_exprs (as they are not populated
// for derived specs), so compute that here.
CDistributionSpecHashed *pdsHashedFirstChild =
CDistributionSpecHashed::PdsConvert(pdsFirst);
CDistributionSpecHashed *pdsHashed = pdsHashedFirstChild->Copy(mp);
pdsHashed->ComputeEquivHashExprs(mp, exprhdl);
pdsInputForMatch = pdsHashed;
}
else
{
pdsInputForMatch = pdsFirst;
}
// find the index of the first child
ULONG ulFirstChild = 0;
if (EceoRightToLeft == Eceo())
{
ulFirstChild = 1;
}
// return a matching distribution request for the second child
CDistributionSpec *pdsMatch = PdsMatch(mp, pdsInputForMatch, ulFirstChild);
if (pdsFirst->Edt() == CDistributionSpec::EdtHashed)
{
// if the input spec was created as a copy, release it
pdsInputForMatch->Release();
}
return pdsMatch;
}
//---------------------------------------------------------------------------
// @function:
// CPhysicalHashJoin::PdsRequired
//
// @doc:
// Compute required distribution of the n-th child;
// this function creates three optimization requests to join children:
// Req(1 to N) (redistribute, redistribute), where we request the first hash join child
// to be distributed on single hash join keys separately, as well as the set
// of all hash join keys,
// the second hash join child is always required to match the distribution returned
// by first child
// Req(N + 1) (hashed, broadcast)
// Req(N + 2) (non-singleton, broadcast)
// Req(N + 3) (singleton, singleton)
//
// we always check the distribution delivered by the first child (as
// given by child optimization order), and then match the delivered
// distribution on the second child
//
//
//---------------------------------------------------------------------------
CDistributionSpec *
CPhysicalHashJoin::PdsRequired(
CMemoryPool *mp GPOS_UNUSED, CExpressionHandle &exprhdl GPOS_UNUSED,
CDistributionSpec *pdsInput GPOS_UNUSED, ULONG child_index GPOS_UNUSED,
CDrvdPropArray *pdrgpdpCtxt GPOS_UNUSED,
ULONG ulOptReq
GPOS_UNUSED // identifies which optimization request should be created
) const
{
GPOS_RAISE(
CException::ExmaInvalid, CException::ExmiInvalid,
GPOS_WSZ_LIT("PdsRequired should not be called for CPhysicalHashJoin"));
return nullptr;
}
CEnfdDistribution *
CPhysicalHashJoin::Ped(CMemoryPool *mp, CExpressionHandle &exprhdl,
CReqdPropPlan *prppInput, ULONG child_index,
CDrvdPropArray *pdrgpdpCtxt, ULONG ulOptReq)
{
GPOS_ASSERT(2 > child_index);
GPOS_ASSERT(ulOptReq < UlDistrRequests());
CEnfdDistribution::EDistributionMatching dmatch =
Edm(prppInput, child_index, pdrgpdpCtxt, ulOptReq);
CDistributionSpec *const pdsInput = prppInput->Ped()->PdsRequired();
// if expression has to execute on a single host then we need a gather
if (exprhdl.NeedsSingletonExecution())
{
return GPOS_NEW(mp) CEnfdDistribution(
PdsRequireSingleton(mp, exprhdl, pdsInput, child_index), dmatch);
}
if (exprhdl.HasOuterRefs())
{
if (CDistributionSpec::EdtSingleton == pdsInput->Edt() ||
CDistributionSpec::EdtStrictReplicated == pdsInput->Edt())
{
return GPOS_NEW(mp) CEnfdDistribution(
PdsPassThru(mp, exprhdl, pdsInput, child_index), dmatch);
}
return GPOS_NEW(mp)
CEnfdDistribution(GPOS_NEW(mp) CDistributionSpecReplicated(
CDistributionSpec::EdtStrictReplicated),
dmatch);
}
const ULONG ulHashDistributeRequests =
m_pdrgpdsRedistributeRequests->Size();
if (ulOptReq < ulHashDistributeRequests)
{
// requests 1 .. N are (redistribute, redistribute)
CDistributionSpec *pds = PdsRequiredRedistribute(
mp, exprhdl, pdsInput, child_index, pdrgpdpCtxt, ulOptReq);
if (CDistributionSpec::EdtHashed == pds->Edt())
{
CDistributionSpecHashed *pdsHashed =
CDistributionSpecHashed::PdsConvert(pds);
pdsHashed->ComputeEquivHashExprs(mp, exprhdl);
}
return GPOS_NEW(mp) CEnfdDistribution(pds, dmatch);
}
if (ulOptReq == ulHashDistributeRequests ||
ulOptReq == ulHashDistributeRequests + 1)
{
// requests N+1, N+2 are (hashed/non-singleton, replicate)
CDistributionSpec *pds =
PdsRequiredReplicate(mp, exprhdl, pdsInput, child_index,
pdrgpdpCtxt, ulOptReq, prppInput);
if (CDistributionSpec::EdtHashed == pds->Edt())
{
CDistributionSpecHashed *pdsHashed =
CDistributionSpecHashed::PdsConvert(pds);
pdsHashed->ComputeEquivHashExprs(mp, exprhdl);
}
return GPOS_NEW(mp) CEnfdDistribution(pds, dmatch);
}
GPOS_ASSERT(ulOptReq == ulHashDistributeRequests + 2);
// requests N+3 is (singleton, singleton)
return GPOS_NEW(mp) CEnfdDistribution(
PdsRequiredSingleton(mp, exprhdl, pdsInput, child_index, pdrgpdpCtxt),
dmatch);
}
//---------------------------------------------------------------------------
// @function:
// CPhysicalHashJoin::PdshashedRequired
//
// @doc:
// Compute required hashed distribution of the n-th child
//
//---------------------------------------------------------------------------
CDistributionSpecHashed *
CPhysicalHashJoin::PdshashedRequired(CMemoryPool *, // mp
ULONG, // child_index
ULONG ulReqIndex) const
{
GPOS_ASSERT(ulReqIndex < m_pdrgpdsRedistributeRequests->Size());
CDistributionSpec *pds = (*m_pdrgpdsRedistributeRequests)[ulReqIndex];
pds->AddRef();
return CDistributionSpecHashed::PdsConvert(pds);
}
//---------------------------------------------------------------------------
// @function:
// CPhysicalHashJoin::EpetOrder
//
// @doc:
// Return the enforcing type for order property based on this operator;
//
//
//---------------------------------------------------------------------------
CEnfdProp::EPropEnforcingType
CPhysicalHashJoin::EpetOrder(CExpressionHandle &, // exprhdl
const CEnfdOrder *
#ifdef GPOS_DEBUG
peo
#endif // GPOS_DEBUG
) const
{
GPOS_ASSERT(nullptr != peo);
GPOS_ASSERT(!peo->PosRequired()->IsEmpty());
// hash join is not order-preserving;
// any order requirements have to be enforced on top
return CEnfdProp::EpetRequired;
}
//---------------------------------------------------------------------------
// @function:
// CPhysicalHashJoin::FNullableInnerHashKeys
//
// @doc:
// Check whether the hash keys from one child are nullable. pcrsNotNull must
// be all the "not null" columns coming from that child
//
//---------------------------------------------------------------------------
BOOL
CPhysicalHashJoin::FNullableHashKeys(CColRefSet *pcrsNotNull, BOOL fInner) const
{
ULONG ulHashKeys = 0;
if (fInner)
{
ulHashKeys = m_pdrgpexprInnerKeys->Size();
}
else
{
ulHashKeys = m_pdrgpexprOuterKeys->Size();
}
for (ULONG ul = 0; ul < ulHashKeys; ul++)
{
if (FNullableHashKey(ul, pcrsNotNull, fInner))
{
return true;
}
}
return false;
}
//---------------------------------------------------------------------------
// @function:
// CPhysicalHashJoin::FNullableHashKey
//
// @doc:
// Check whether a hash key is nullable
//
//---------------------------------------------------------------------------
BOOL
CPhysicalHashJoin::FNullableHashKey(ULONG ulKey, CColRefSet *pcrsNotNull,
BOOL fInner) const
{
COperator *pop = nullptr;
if (fInner)
{
pop = (*m_pdrgpexprInnerKeys)[ulKey]->Pop();
}
else
{
pop = (*m_pdrgpexprOuterKeys)[ulKey]->Pop();
}
EOperatorId op_id = pop->Eopid();
if (COperator::EopScalarIdent == op_id)
{
const CColRef *colref = CScalarIdent::PopConvert(pop)->Pcr();
return (!pcrsNotNull->FMember(colref));
}
if (COperator::EopScalarConst == op_id)
{
return CScalarConst::PopConvert(pop)->GetDatum()->IsNull();
}
// be conservative for all other scalar expressions where we cannot easily
// determine nullability
return true;
}
void
CPhysicalHashJoin::CreateOptRequests(CMemoryPool *mp)
{
CreateHashRedistributeRequests(mp);
// given an optimization context, HJN creates three optimization requests
// to enforce distribution of its children:
// Req(1 to N) (redistribute, redistribute), where we request the first hash join child
// to be distributed on single hash join keys separately, as well as the set
// of all hash join keys,
// the second hash join child is always required to match the distribution returned
// by first child
// Req(N + 1) (hashed, broadcast)
// Req(N + 2) (non-singleton, broadcast)
// Req(N + 3) (singleton, singleton)
ULONG ulDistrReqs =
GPOPT_NON_HASH_DIST_REQUESTS + m_pdrgpdsRedistributeRequests->Size();
SetDistrRequests(ulDistrReqs);
// With DP enabled, there are several (max 10 controlled by macro)
// alternatives generated for a join tree and during optimization of those
// alternatives expressions PS is inserted in almost all the groups possibly.
// However, if DP is turned off, i.e in query or greedy join order,
// PS must be inserted in the group with DTS else in some cases HJ plan
// cannot be created. So, to ensure pushing PS without DPE 2 partition
// propagation request are required if DP is disabled.
// Req 0 => Push PS with considering DPE possibility
// Req 1 => Push PS without considering DPE possibility
// Ex case: select * from non_part_tbl1 t1, part_tbl t2, non_part_tbl2 t3
// where t1.b = t2.b and t2.b = t3.b;
// Note: b is the partitioned column for part_tbl. If DP is turned off, HJ
// will not be created for the above query if we send only 1 request.
// Also, increasing the number of request increases the optimization time, so
// set 2 only when needed.
//
// There are also cases where greedy does generate a better plan
// without DPE. This adds some overhead (<10%)to optimization time in
// some cases, but can create better alternatives to DPE, so
// we also generate this additional request for expressions that originated
// from CXformExpandNAryJoinGreedy.
CPhysicalJoin *physical_join = dynamic_cast<CPhysicalJoin *>(this);
if ((GPOPT_FDISABLED_XFORM(CXform::ExfExpandNAryJoinDP) &&
GPOPT_FDISABLED_XFORM(CXform::ExfExpandNAryJoinDPv2)) ||
physical_join->OriginXform() == CXform::ExfExpandNAryJoinGreedy)
{
SetPartPropagateRequests(2);
}
else
{
SetPartPropagateRequests(1);
}
}
// EOF
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