greenplumn CDistributionSpec 代码
文件路径：/src/backend/gporca/libgpopt/include/gpopt/base/CDistributionSpec.h
/---------------------------------------------------------------------------
/ Greenplum Database
/ Copyright (C) 2011 EMC Corp.
/
/ @filename:
/ CDistributionSpec.h
/
/ @doc:
/ Description of distribution;
/ Can be used as required or derived property;
/---------------------------------------------------------------------------
#ifndef GPOPT_IDistributionSpec_H
#define GPOPT_IDistributionSpec_H
#include "gpos/base.h"
#include "gpos/utils.h"
#include "gpopt/base/CPropSpec.h"
namespace gpopt
{
using namespace gpos;
/---------------------------------------------------------------------------
/ @class:
/ CDistributionSpec
/
/ @doc:
/ Base class for representing distribution specification.
/
/---------------------------------------------------------------------------
class CDistributionSpec : public CPropSpec
{
public:
enum EDistributionType
{
EdtHashed, / data is hashed across all segments
EdtHashedNoOp, / same as hashed, used to force multiple slices for parallel union all. The motions always mirror the underlying distributions.
EdtStrictHashed, / same as hashed, used to force multiple slices for parallel union all. The motions mirror the distribution of the output columns.
EdtStrictReplicated, / data is strictly replicated across all segments
EdtReplicated, / data is strict or tainted replicated (required only)
EdtTaintedReplicated, / data once-replicated, after being processed by an input-order-sensitive operator or volatile function (derived only)
EdtAny, / data can be anywhere on the segments (required only)
EdtSingleton, / data is on a single segment or the master
EdtStrictSingleton, / data is on a single segment or the master (derived only, only compatible with other singleton distributions)
EdtRandom, / data is randomly distributed across all segments
EdtStrictRandom, / same as random, used to force multiple slices for parallel union all.
EdtRouted, / data is routed to a segment explicitly specified in the tuple,
EdtUniversal, / data is available everywhere (derived only)
EdtNonSingleton, / data can have any distribution except singleton (required only)
EdtSentinel
};
/ description of distribution spec in terms of partitioning data across segments
enum EDistributionPartitioningType
{
EdptPartitioned, / data partitioned on multiple segments, e.g., hashed/random distribution
EdptNonPartitioned, / data on a single segment, or replicated to all segments
EdptUnknown, / unknown behavior
EdptSentinel
};
private:
public:
CDistributionSpec(const CDistributionSpec &) = delete;
/ ctor
CDistributionSpec() = default;
/ dtor
~CDistributionSpec() override = default;
/ distribution type accessor
virtual EDistributionType Edt() const = 0;
/ does this distribution satisfy the given one
virtual BOOL FSatisfies(const CDistributionSpec *pds) const = 0;
/ default hash function for distribution spec
ULONG
HashValue() const override
{
ULONG ulEdt = (ULONG) Edt();
return gpos::HashValue<ULONG>(&ulEdt);
}
/ extract columns used by the distribution spec
CColRefSet *
PcrsUsed(CMemoryPool *mp) const override
{
/ by default, return an empty set
return GPOS_NEW(mp) CColRefSet(mp);
}
/ property type
EPropSpecType
Epst() const override
{
return EpstDistribution;
}
/ return true if distribution spec can be required
virtual BOOL
FRequirable() const
{
return true;
}
/ return true if distribution spec can be derived
virtual BOOL
FDerivable() const
{
return true;
}
/ default match function for distribution specs
virtual BOOL
Matches(const CDistributionSpec *pds) const
{
return Edt() == pds->Edt();
}
/ default implementation for all the classes inheriting from
/ CDistributionSpec, if any class requires special Equals
/ handling, they should override it.
virtual BOOL
Equals(const CDistributionSpec *pds) const
{
return Matches(pds);
}
/ return a copy of the distribution spec with remapped columns
virtual CDistributionSpec *
PdsCopyWithRemappedColumns(CMemoryPool *, /mp,
UlongToColRefMap *, /colref_mapping,
BOOL /must_exist
)
{
this->AddRef();
return this;
}
/ strip off any equivalent columns embedded in the distribution spec
/ (default implementation doesn't strip anything)
virtual CDistributionSpec *
StripEquivColumns(CMemoryPool *)
{
AddRef();
return this;
}
/ print
IOstream &OsPrint(IOstream &os) const override = 0;
/ return distribution partitioning type
virtual EDistributionPartitioningType Edpt() const = 0;
/ check if the distribution spec is either a singleton or a strict singleton distribution
BOOL
FSingletonOrStrictSingleton() const
{
return CDistributionSpec::EdtSingleton == Edt() ||
CDistributionSpec::EdtStrictSingleton == Edt();
}
}; / class CDistributionSpec
/ arrays of distribution spec
using CDistributionSpecArray =
CDynamicPtrArray<CDistributionSpec, CleanupRelease>;
} / namespace gpopt
#endif / !GPOPT_IDistributionSpec_H
/ EOF
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