greenplumn CDatumGenericGPDB 代码
文件路径：/src/backend/gporca/libnaucrates/include/naucrates/base/CDatumGenericGPDB.h
/---------------------------------------------------------------------------
/ Greenplum Database
/ Copyright (C) 2011 EMC Corp.
/
/ @filename:
/ CDatumGenericGPDB.h
/
/ @doc:
/ GPDB-specific generic datum representation
/---------------------------------------------------------------------------
#ifndef GPNAUCRATES_CDatumGenericGPDB_H
#define GPNAUCRATES_CDatumGenericGPDB_H
#include "gpos/base.h"
#include "naucrates/base/IDatumGeneric.h"
#include "naucrates/md/CMDTypeGenericGPDB.h"
#define GPDB_DATUM_HDRSZ 4
namespace gpnaucrates
{
/---------------------------------------------------------------------------
/ @class:
/ CDatumGenericGPDB
/
/ @doc:
/ GPDB-specific generic datum representation
/
/---------------------------------------------------------------------------
class CDatumGenericGPDB : public IDatumGeneric
{
private:
/ memory pool
CMemoryPool *m_mp;
/ size in bytes
ULONG m_size;
/ a pointer to datum value
BYTE *m_bytearray_value;
/ is null
BOOL m_is_null;
/ type information
IMDId *m_mdid;
INT m_type_modifier;
/ cached type information (can be set from const methods)
mutable const IMDType *m_cached_type;
/ long int value used for statistic computation
LINT m_stats_comp_val_int;
/ double value used for statistic computation
CDouble m_stats_comp_val_double;
public:
CDatumGenericGPDB(const CDatumGenericGPDB &) = delete;
/ ctor
CDatumGenericGPDB(CMemoryPool *mp, IMDId *mdid, INT type_modifier,
const void *src, ULONG size, BOOL is_null,
LINT stats_comp_val_int, CDouble stats_comp_val_double);
/ dtor
~CDatumGenericGPDB() override;
/ accessor of metadata type id
IMDId *MDId() const override;
INT TypeModifier() const override;
/ accessor of size
ULONG Size() const override;
/ accessor of is null
BOOL IsNull() const override;
/ return string representation
const CWStringConst *GetStrRepr(CMemoryPool *mp) const override;
/ hash function
ULONG HashValue() const override;
/ match function for datums
BOOL Matches(const IDatum *datum) const override;
/ copy datum
IDatum *MakeCopy(CMemoryPool *mp) const override;
/ print function
IOstream &OsPrint(IOstream &os) const override;
/ accessor to bytearray, creates a copy
virtual BYTE *MakeCopyOfValue(CMemoryPool *mp, ULONG *pulLength) const;
/ statistics related APIs
/ can datum be mapped to a double
BOOL IsDatumMappableToDouble() const override;
/ map to double for stats computation
CDouble
GetDoubleMapping() const override
{
GPOS_ASSERT(IsDatumMappableToDouble());
return m_stats_comp_val_double;
}
/ can datum be mapped to LINT
BOOL IsDatumMappableToLINT() const override;
/ map to LINT for statistics computation
LINT
GetLINTMapping() const override
{
GPOS_ASSERT(IsDatumMappableToLINT());
return m_stats_comp_val_int;
}
/ byte array representation of datum
const BYTE *GetByteArrayValue() const override;
/ stats equality
BOOL StatsAreEqual(const IDatum *datum) const override;
/ does the datum need to be padded before statistical derivation
BOOL NeedsPadding() const override;
/ return the padded datum
IDatum *MakePaddedDatum(CMemoryPool *mp, ULONG col_len) const override;
/ does datum support like predicate
BOOL
SupportsLikePredicate() const override
{
return true;
}
/ return the default scale factor of like predicate
CDouble GetLikePredicateScaleFactor() const override;
/ default selectivity of the trailing wildcards
virtual CDouble GetTrailingWildcardSelectivity(const BYTE *pba,
ULONG ulPos) const;
/ selectivities needed for LIKE predicate statistics evaluation
static const CDouble DefaultFixedCharSelectivity;
static const CDouble DefaultCharRangeSelectivity;
static const CDouble DefaultAnyCharSelectivity;
static const CDouble DefaultCdbRanchorSelectivity;
static const CDouble DefaultCdbRolloffSelectivity;
}; / class CDatumGenericGPDB
} / namespace gpnaucrates
#endif / !GPNAUCRATES_CDatumGenericGPDB_H
/ EOF