greenplumn CStrictHashedDistributions 源码
greenplumn CStrictHashedDistributions 代码
文件路径：/src/backend/gporca/libgpopt/src/operators/CStrictHashedDistributions.cpp
// Greenplum Database
// Copyright (C) 2016 VMware, Inc. or its affiliates.
#include "gpopt/operators/CStrictHashedDistributions.h"
#include "gpopt/base/CDistributionSpecStrictRandom.h"
#include "gpopt/base/CUtils.h"
using namespace gpopt;
CStrictHashedDistributions::CStrictHashedDistributions(
CMemoryPool *mp, CColRefArray *pdrgpcrOutput,
CColRef2dArray *pdrgpdrgpcrInput)
: CDistributionSpecArray(mp)
{
const ULONG num_cols = pdrgpcrOutput->Size();
const ULONG arity = pdrgpdrgpcrInput->Size();
for (ULONG ulChild = 0; ulChild < arity; ulChild++)
{
CColRefArray *colref_array = (*pdrgpdrgpcrInput)[ulChild];
CExpressionArray *pdrgpexpr = GPOS_NEW(mp) CExpressionArray(mp);
for (ULONG ulCol = 0; ulCol < num_cols; ulCol++)
{
CColRef *colref = (*colref_array)[ulCol];
if (colref->RetrieveType()->IsRedistributable())
{
CExpression *pexpr = CUtils::PexprScalarIdent(mp, colref);
pdrgpexpr->Append(pexpr);
}
}
CDistributionSpec *pdshashed;
ULONG ulColumnsToRedistribute = pdrgpexpr->Size();
if (0 < ulColumnsToRedistribute)
{
// create a hashed distribution on input columns of the current child
BOOL fNullsColocated = true;
pdshashed = GPOS_NEW(mp)
CDistributionSpecStrictHashed(pdrgpexpr, fNullsColocated);
}
else
{
// None of the input columns are redistributable, but we want to
// parallelize the relations we are concatenating, so we generate
// a random redistribution.
// When given a plan containing a "hash" redistribution on _no_ columns,
// Some databases actually execute it as if it's a random redistribution.
// We should not generate such a plan, for clarity and our own sanity
pdshashed = GPOS_NEW(mp) CDistributionSpecStrictRandom();
pdrgpexpr->Release();
}
Append(pdshashed);
}
}
相关信息
相关文章
greenplumn CExpressionFactorizer 源码
greenplumn CExpressionHandle 源码
greenplumn CExpressionPreprocessor 源码
greenplumn CExpressionUtils 源码
0
赞
热门推荐
-
2、 - 优质文章
-
3、 gate.io
-
7、 golang
-
9、 openharmony
-
10、 Vue中input框自动聚焦