greenplumn CCostContext 代码
文件路径：/src/backend/gporca/libgpopt/include/gpopt/base/CCostContext.h
/---------------------------------------------------------------------------
/ Greenplum Database
/ Copyright (C) 2011 EMC Corp.
/
/ @filename:
/ CCostContext.h
/
/ @doc:
/ Cost context object stores the cost of a group expression under
/ a given optimization context
/---------------------------------------------------------------------------
#ifndef GPOPT_CCostContext_H
#define GPOPT_CCostContext_H
#include "gpos/base.h"
#include "gpos/common/CRefCount.h"
#include "gpopt/base/COptimizationContext.h"
#include "gpopt/cost/CCost.h"
#include "gpopt/cost/ICostModel.h"
/ infinite plan cost
#define GPOPT_INFINITE_COST CCost(1e+100)
/ invalid cost value
#define GPOPT_INVALID_COST CCost(-0.5)
namespace gpopt
{
using namespace gpos;
/ fwd declarations
class CDrvdPropPlan;
class CCostContext;
/ array of cost contexts
using CCostContextArray = CDynamicPtrArray<CCostContext, CleanupRelease>;
/ cost context pointer definition
using COSTCTXT_PTR = CCostContext *;
/ cost context pointer definition
using CONST_COSTCTXT_PTR = const CCostContext *;
/---------------------------------------------------------------------------
/ @class:
/ CCostContext
/
/ @doc:
/ Cost context
/
/---------------------------------------------------------------------------
class CCostContext : public CRefCount, public DbgPrintMixin<CCostContext>
{
public:
/ states of cost context
enum EState
{
estUncosted, / initial state
estCosting, / ongoing costing
estCosted, / done costing
estSentinel
};
private:
/ memory pool
CMemoryPool *m_mp;
/ cost of group expression under optimization context
CCost m_cost;
/ cost context state
EState m_estate;
/ back pointer to owner group expression
CGroupExpression *m_pgexpr;
/ group expression to be used stats derivation during costing
CGroupExpression *m_pgexprForStats;
/ array of optimization contexts of child groups
COptimizationContextArray *m_pdrgpoc;
/ derived properties of the carried plan
CDrvdPropPlan *m_pdpplan;
/ optimization request number
ULONG m_ulOptReq;
/ flag to indicate if cost context is pruned,
/ a cost context is pruned during branch-and-bound search if there exists
/ an equivalent context with better cost
BOOL m_fPruned;
/ stats of owner group expression
IStatistics *m_pstats;
/ derive stats of owner group expression
void DeriveStats();
/ return the number of rows per host
CDouble DRowsPerHost() const;
/ for two cost contexts with join plans of the same cost, break the tie based on join depth,
/ if tie-resolution succeeded, store a pointer to preferred cost context in output argument
static void BreakCostTiesForJoinPlans(const CCostContext *pccFst,
const CCostContext *pccSnd,
CONST_COSTCTXT_PTR *ppccPrefered,
BOOL *pfTiesResolved);
public:
CCostContext(const CCostContext &) = delete;
/ main optimization context
COptimizationContext *m_poc;
/ link for cost context hash table in CGroupExpression
SLink m_link;
/ ctor
CCostContext(CMemoryPool *mp, COptimizationContext *poc, ULONG ulOptReq,
CGroupExpression *pgexpr);
/ dtor
~CCostContext() override;
/ main optimization context accessor
COptimizationContext *
Poc() const
{
return m_poc;
}
/ accessor of optimization request number
ULONG
UlOptReq() const
{
return m_ulOptReq;
}
/ is context pruned based on cost comparison?
BOOL
FPruned() const
{
return m_fPruned;
}
/ set pruned flag
void
SetPruned()
{
GPOS_ASSERT(!m_fPruned);
m_fPruned = true;
}
/ accessor of child optimization contexts array
COptimizationContextArray *
Pdrgpoc() const
{
return m_pdrgpoc;
}
/ cost accessor
CCost
Cost() const
{
return m_cost;
}
/ state accessor
EState
Est() const
{
return m_estate;
}
/ owner group expression accessor
CGroupExpression *
Pgexpr() const
{
return m_pgexpr;
}
/ group expression for stats derivation
CGroupExpression *
PgexprForStats() const
{
return m_pgexprForStats;
}
/ return stats of owner group expression
IStatistics *
Pstats() const
{
return m_pstats;
}
/ check if we need to derive stats for this context
BOOL FNeedsNewStats() const;
/ check if new stats were derived for this context
BOOL FOwnsStats() const;
/ derived plan properties accessor
CDrvdPropPlan *
Pdpplan() const
{
return m_pdpplan;
}
/ set cost value
void
SetCost(CCost cost)
{
GPOS_ASSERT(cost > GPOPT_INVALID_COST);
m_cost = cost;
}
/ derive properties of the plan carried by cost context
void DerivePlanProps(CMemoryPool *mp);
/ set cost context state
void
SetState(EState estNewState)
{
GPOS_ASSERT(estNewState == (EState)(m_estate + 1));
m_estate = estNewState;
}
/ set child contexts
void
SetChildContexts(COptimizationContextArray *pdrgpoc)
{
GPOS_ASSERT(nullptr == m_pdrgpoc);
GPOS_ASSERT(nullptr != pdrgpoc);
m_pdrgpoc = pdrgpoc;
}
/ check validity by comparing derived and required properties
BOOL IsValid(CMemoryPool *mp);
/ comparison operator
BOOL operator==(const CCostContext &cc) const;
/ compute cost
CCost CostCompute(CMemoryPool *mp, CCostArray *pdrgpcostChildren);
/ is current context better than the given equivalent context based on cost?
BOOL FBetterThan(const CCostContext *pcc) const;
/ is this cost context of a two stage scalar DQA created by CXformSplitDQA
static BOOL IsTwoStageScalarDQACostCtxt(const CCostContext *pcc);
/ is this cost context of a three stage scalar DQA created by CXformSplitDQA
static BOOL IsThreeStageScalarDQACostCtxt(const CCostContext *pcc);
/ equality function
static BOOL
Equals(const CCostContext &ccLeft, const CCostContext &ccRight)
{
/ check if we are comparing against invalid context
if (nullptr == ccLeft.Poc() || nullptr == ccRight.Poc())
{
return nullptr == ccLeft.Poc() && nullptr == ccRight.Poc();
}
return ccLeft.UlOptReq() == ccRight.UlOptReq() &&
ccLeft.Pgexpr() == ccRight.Pgexpr() &&
ccLeft.Poc()->Matches(ccRight.Poc());
}
/ equality function
static BOOL
Equals(const CCostContext *pccLeft, const CCostContext *pccRight)
{
return Equals(*pccLeft, *pccRight);
}
/ hash function
static ULONG
HashValue(const CCostContext &cc)
{
return COptimizationContext::HashValue(*(cc.Poc()));
}
/ hash function
static ULONG
HashValue(const CCostContext *pcc)
{
return HashValue(*pcc);
}
/ debug print
IOstream &OsPrint(IOstream &os) const;
}; / class CCostContext
} / namespace gpopt
#endif / !GPOPT_CCostContext_H
/ EOF
相关信息
相关文章
greenplumn CColConstraintsArrayMapper 源码