本篇内容主要讲解“PostgreSQL 聚合函数的实现教程”，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习“PostgreSQL 聚合函数的实现教程”吧!
AggState
聚合函数执行时状态结构体,内含AggStatePerAgg等结构体
/* ---------------------
* AggState information
*
* ss.ss_ScanTupleSlot refers to output of underlying plan.
* ss.ss_ScanTupleSlot指的是基础计划的输出.
* (ss = ScanState,ps = PlanState)
*
* Note: ss.ps.ps_ExprContext contains ecxt_aggvalues and
* ecxt_aggnulls arrays, which hold the computed agg values for the current
* input group during evaluation of an Agg node's output tuple(s). We
* create a second ExprContext, tmpcontext, in which to evaluate input
* expressions and run the aggregate transition functions.
* 注意:ss.ps.ps_ExprContext包含了ecxt_aggvalues和ecxt_aggnulls数组,
* 这两个数组保存了在计算agg节点的输出元组时当前输入组已计算的agg值.
* ---------------------
*/
/* these structs are private in nodeAgg.c: */
//在nodeAgg.c中私有的结构体
typedef struct AggStatePerAggData *AggStatePerAgg;
typedef struct AggStatePerTransData *AggStatePerTrans;
typedef struct AggStatePerGroupData *AggStatePerGroup;
typedef struct AggStatePerPhaseData *AggStatePerPhase;
typedef struct AggStatePerHashData *AggStatePerHash;
typedef struct AggState
{
//第一个字段是NodeTag(继承自ScanState)
ScanState ss; /* its first field is NodeTag */
//targetlist和quals中所有的Aggref
List *aggs; /* all Aggref nodes in targetlist & quals */
//链表的大小(可以为0)
int numaggs; /* length of list (could be zero!) */
//pertrans条目大小
int numtrans; /* number of pertrans items */
//Agg策略模式
AggStrategy aggstrategy; /* strategy mode */
//agg-splitting模式,参见nodes.h
AggSplit aggsplit; /* agg-splitting mode, see nodes.h */
//指向当前步骤数据的指针
AggStatePerPhase phase; /* pointer to current phase data */
//步骤数(包括0)
int numphases; /* number of phases (including phase 0) */
//当前步骤
int current_phase; /* current phase number */
//per-Aggref信息
AggStatePerAgg peragg; /* per-Aggref information */
//per-Trans状态信息
AggStatePerTrans pertrans; /* per-Trans state information */
//长生命周期数据的ExprContexts(hashtable)
ExprContext *hashcontext; /* econtexts for long-lived data (hashtable) */
////长生命周期数据的ExprContexts(每一个GS使用)
ExprContext **aggcontexts; /* econtexts for long-lived data (per GS) */
//输入表达式的ExprContext
ExprContext *tmpcontext; /* econtext for input expressions */
#define FIELDNO_AGGSTATE_CURAGGCONTEXT 14
//当前活跃的aggcontext
ExprContext *curaggcontext; /* currently active aggcontext */
//当前活跃的aggregate(如存在)
AggStatePerAgg curperagg; /* currently active aggregate, if any */
#define FIELDNO_AGGSTATE_CURPERTRANS 16
//当前活跃的trans state
AggStatePerTrans curpertrans; /* currently active trans state, if any */
//输入结束?
bool input_done; /* indicates end of input */
//Agg扫描结束?
bool agg_done; /* indicates completion of Agg scan */
//最后一个grouping set
int projected_set; /* The last projected grouping set */
#define FIELDNO_AGGSTATE_CURRENT_SET 20
//将要解析的当前grouping set
int current_set; /* The current grouping set being evaluated */
//当前投影操作的分组列
Bitmapset *grouped_cols; /* grouped cols in current projection */
//倒序的分组列链表
List *all_grouped_cols; /* list of all grouped cols in DESC order */
/* These fields are for grouping set phase data */
//-------- 下面的列用于grouping set步骤数据
//所有步骤中最大的sets大小
int maxsets; /* The max number of sets in any phase */
//所有步骤的数组
AggStatePerPhase phases; /* array of all phases */
//对于phases > 1,已排序的输入信息
Tuplesortstate *sort_in; /* sorted input to phases > 1 */
//对于下一个步骤,输入已拷贝
Tuplesortstate *sort_out; /* input is copied here for next phase */
//排序结果的slot
TupleTableSlot *sort_slot; /* slot for sort results */
/* these fields are used in AGG_PLAIN and AGG_SORTED modes: */
//------- 下面的列用于AGG_PLAIN和AGG_SORTED模式:
//per-group指针的grouping set编号数组
AggStatePerGroup *pergroups; /* grouping set indexed array of per-group
* pointers */
//当前组的第一个元组拷贝
HeapTuple grp_firstTuple; /* copy of first tuple of current group */
/* these fields are used in AGG_HASHED and AGG_MIXED modes: */
//--------- 下面的列用于AGG_HASHED和AGG_MIXED模式:
//是否已填充hash表?
bool table_filled; /* hash table filled yet? */
//hash桶数?
int num_hashes;
//相应的哈希表数据数组
AggStatePerHash perhash; /* array of per-hashtable data */
//per-group指针的grouping set编号数组
AggStatePerGroup *hash_pergroup; /* grouping set indexed array of
* per-group pointers */
/* support for evaluation of agg input expressions: */
//---------- agg输入表达式解析支持
#define FIELDNO_AGGSTATE_ALL_PERGROUPS 34
//首先是->pergroups,然后是hash_pergroup
AggStatePerGroup *all_pergroups; /* array of first ->pergroups, than
* ->hash_pergroup */
//投影实现机制
ProjectionInfo *combinedproj; /* projection machinery */
} AggState;
/* Primitive options supported by nodeAgg.c: */
//nodeag .c支持的基本选项
#define AGGSPLITOP_COMBINE 0x01 /* substitute combinefn for transfn */
#define AGGSPLITOP_SKIPFINAL 0x02 /* skip finalfn, return state as-is */
#define AGGSPLITOP_SERIALIZE 0x04 /* apply serializefn to output */
#define AGGSPLITOP_DESERIALIZE 0x08 /* apply deserializefn to input */
/* Supported operating modes (i.e., useful combinations of these options): */
//支持的操作模式
typedef enum AggSplit
{
/* Basic, non-split aggregation: */
//基本 : 非split聚合
AGGSPLIT_SIMPLE = 0,
/* Initial phase of partial aggregation, with serialization: */
//部分聚合的初始步骤,序列化
AGGSPLIT_INITIAL_SERIAL = AGGSPLITOP_SKIPFINAL | AGGSPLITOP_SERIALIZE,
/* Final phase of partial aggregation, with deserialization: */
//部分聚合的最终步骤,反序列化
AGGSPLIT_FINAL_DESERIAL = AGGSPLITOP_COMBINE | AGGSPLITOP_DESERIALIZE
} AggSplit;
/* Test whether an AggSplit value selects each primitive option: */
//测试AggSplit选择了哪些基本选项
#define DO_AGGSPLIT_COMBINE(as) (((as) & AGGSPLITOP_COMBINE) != 0)
#define DO_AGGSPLIT_SKIPFINAL(as) (((as) & AGGSPLITOP_SKIPFINAL) != 0)
#define DO_AGGSPLIT_SERIALIZE(as) (((as) & AGGSPLITOP_SERIALIZE) != 0)
#define DO_AGGSPLIT_DESERIALIZE(as) (((as) & AGGSPLITOP_DESERIALIZE) != 0)advance_aggregates函数最终会调用ExecInterpExpr函数(先前已介绍),通过一系列的步骤得到结果.
/*
* Advance each aggregate transition state for one input tuple. The input
* tuple has been stored in tmpcontext->ecxt_outertuple, so that it is
* accessible to ExecEvalExpr.
* 为每一个输入tuple推进每个聚合转换状态.
* 输入元组已存储在tmpcontext->ecxt_outertuple中,因此可访问ExecEvalExpr.
*
* We have two sets of transition states to handle: one for sorted aggregation
* and one for hashed; we do them both here, to avoid multiple evaluation of
* the inputs.
* 我们有两个转换状态集合需要处理:一个是已排序聚合,一个是已哈希聚合.
* 在这里同时进行处理,以避免输入的多种解析.
*
* When called, CurrentMemoryContext should be the per-query context.
* 一旦完成调用,CurrentMemoryContext应为per-query上下文.
*/
static void
advance_aggregates(AggState *aggstate)
{
bool dummynull;
ExecEvalExprSwitchContext(aggstate->phase->evaltrans,
aggstate->tmpcontext,
&dummynull);
}
/*
* ExecEvalExprSwitchContext
*
* Same as ExecEvalExpr, but get into the right allocation context explicitly.
* 与ExecEvalExpr一样,只是显式的进入内存上下文.
*/
#ifndef FRONTEND
static inline Datum
ExecEvalExprSwitchContext(ExprState *state,
ExprContext *econtext,
bool *isNull)
{
Datum retDatum;
MemoryContext oldContext;
oldContext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
retDatum = state->evalfunc(state, econtext, isNull);
MemoryContextSwitchTo(oldContext);
return retDatum;
}
#endif
/*
* Expression evaluation callback that performs extra checks before executing
* the expression. Declared extern so other methods of execution can use it
* too.
* 表达式解析回调函数,在执行表达式解析前执行额外的检查.
* 声明为extern以便其他方法可以使用.
*/
Datum
ExecInterpExprStillValid(ExprState *state, ExprContext *econtext, bool *isNull)
{
/*
* First time through, check whether attribute matches Var. Might not be
* ok anymore, due to schema changes.
* 第一次,需检查属性是否与Var匹配.
* 由于模式的变化,有可能会出问题.
*/
CheckExprStillValid(state, econtext);
/* skip the check during further executions */
//在后续的执行中,跳过检查.
state->evalfunc = (ExprStateEvalFunc) state->evalfunc_private;
/* and actually execute */
//执行解析函数,获取结果
return state->evalfunc(state, econtext, isNull);
}
//evalfunc_private --> ExecInterpExprExecInterpExpr
解析给定”econtext”在执行上下文中通过”state”标识的表达式.
//evalfunc_private --> ExecInterpExpr
/*
* Evaluate expression identified by "state" in the execution context
* given by "econtext". *isnull is set to the is-null flag for the result,
* and the Datum value is the function result.
* 解析给定"econtext"在执行上下文中通过"state"标识的表达式.
* *isnull用于设置结果是否为null,Datum是函数执行的结果.
*
* As a special case, return the dispatch table's address if state is NULL.
* This is used by ExecInitInterpreter to set up the dispatch_table global.
* (Only applies when EEO_USE_COMPUTED_GOTO is defined.)
* 作为一个特别的情况,如state为NULL,返回分发器表的地址.
* 这个情况用于ExecInitInterpreter配置dispatch_table.
* (只是在定义了EEO_USE_COMPUTED_GOTO时才应用)
*/
static Datum
ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
{
ExprEvalStep *op;
TupleTableSlot *resultslot;
TupleTableSlot *innerslot;
TupleTableSlot *outerslot;
TupleTableSlot *scanslot;
/*
* This array has to be in the same order as enum ExprEvalOp.
* 该数组在枚举类型ExprEvalOp中具有同样的顺序
*/
#if defined(EEO_USE_COMPUTED_GOTO)
static const void *const dispatch_table[] = {
&&CASE_EEOP_DONE,
&&CASE_EEOP_INNER_FETCHSOME,
&&CASE_EEOP_OUTER_FETCHSOME,
&&CASE_EEOP_SCAN_FETCHSOME,
&&CASE_EEOP_INNER_VAR,
&&CASE_EEOP_OUTER_VAR,
&&CASE_EEOP_SCAN_VAR,
&&CASE_EEOP_INNER_SYSVAR,
&&CASE_EEOP_OUTER_SYSVAR,
&&CASE_EEOP_SCAN_SYSVAR,
&&CASE_EEOP_WHOLEROW,
&&CASE_EEOP_ASSIGN_INNER_VAR,
&&CASE_EEOP_ASSIGN_OUTER_VAR,
&&CASE_EEOP_ASSIGN_SCAN_VAR,
&&CASE_EEOP_ASSIGN_TMP,
&&CASE_EEOP_ASSIGN_TMP_MAKE_RO,
&&CASE_EEOP_CONST,
&&CASE_EEOP_FUNCEXPR,
&&CASE_EEOP_FUNCEXPR_STRICT,
&&CASE_EEOP_FUNCEXPR_FUSAGE,
&&CASE_EEOP_FUNCEXPR_STRICT_FUSAGE,
&&CASE_EEOP_BOOL_AND_STEP_FIRST,
&&CASE_EEOP_BOOL_AND_STEP,
&&CASE_EEOP_BOOL_AND_STEP_LAST,
&&CASE_EEOP_BOOL_OR_STEP_FIRST,
&&CASE_EEOP_BOOL_OR_STEP,
&&CASE_EEOP_BOOL_OR_STEP_LAST,
&&CASE_EEOP_BOOL_NOT_STEP,
&&CASE_EEOP_QUAL,
&&CASE_EEOP_JUMP,
&&CASE_EEOP_JUMP_IF_NULL,
&&CASE_EEOP_JUMP_IF_NOT_NULL,
&&CASE_EEOP_JUMP_IF_NOT_TRUE,
&&CASE_EEOP_NULLTEST_ISNULL,
&&CASE_EEOP_NULLTEST_ISNOTNULL,
&&CASE_EEOP_NULLTEST_ROWISNULL,
&&CASE_EEOP_NULLTEST_ROWISNOTNULL,
&&CASE_EEOP_BOOLTEST_IS_TRUE,
&&CASE_EEOP_BOOLTEST_IS_NOT_TRUE,
&&CASE_EEOP_BOOLTEST_IS_FALSE,
&&CASE_EEOP_BOOLTEST_IS_NOT_FALSE,
&&CASE_EEOP_PARAM_EXEC,
&&CASE_EEOP_PARAM_EXTERN,
&&CASE_EEOP_PARAM_CALLBACK,
&&CASE_EEOP_CASE_TESTVAL,
&&CASE_EEOP_MAKE_READONLY,
&&CASE_EEOP_IOCOERCE,
&&CASE_EEOP_DISTINCT,
&&CASE_EEOP_NOT_DISTINCT,
&&CASE_EEOP_NULLIF,
&&CASE_EEOP_SQLVALUEFUNCTION,
&&CASE_EEOP_CURRENTOFEXPR,
&&CASE_EEOP_NEXTVALUEEXPR,
&&CASE_EEOP_ARRAYEXPR,
&&CASE_EEOP_ARRAYCOERCE,
&&CASE_EEOP_ROW,
&&CASE_EEOP_ROWCOMPARE_STEP,
&&CASE_EEOP_ROWCOMPARE_FINAL,
&&CASE_EEOP_MINMAX,
&&CASE_EEOP_FIELDSELECT,
&&CASE_EEOP_FIELDSTORE_DEFORM,
&&CASE_EEOP_FIELDSTORE_FORM,
&&CASE_EEOP_ARRAYREF_SUBSCRIPT,
&&CASE_EEOP_ARRAYREF_OLD,
&&CASE_EEOP_ARRAYREF_ASSIGN,
&&CASE_EEOP_ARRAYREF_FETCH,
&&CASE_EEOP_DOMAIN_TESTVAL,
&&CASE_EEOP_DOMAIN_NOTNULL,
&&CASE_EEOP_DOMAIN_CHECK,
&&CASE_EEOP_CONVERT_ROWTYPE,
&&CASE_EEOP_SCALARARRAYOP,
&&CASE_EEOP_XMLEXPR,
&&CASE_EEOP_AGGREF,
&&CASE_EEOP_GROUPING_FUNC,
&&CASE_EEOP_WINDOW_FUNC,
&&CASE_EEOP_SUBPLAN,
&&CASE_EEOP_ALTERNATIVE_SUBPLAN,
&&CASE_EEOP_AGG_STRICT_DESERIALIZE,
&&CASE_EEOP_AGG_DESERIALIZE,
&&CASE_EEOP_AGG_STRICT_INPUT_CHECK,
&&CASE_EEOP_AGG_INIT_TRANS,
&&CASE_EEOP_AGG_STRICT_TRANS_CHECK,
&&CASE_EEOP_AGG_PLAIN_TRANS_BYVAL,
&&CASE_EEOP_AGG_PLAIN_TRANS,
&&CASE_EEOP_AGG_ORDERED_TRANS_DATUM,
&&CASE_EEOP_AGG_ORDERED_TRANS_TUPLE,
&&CASE_EEOP_LAST
};
StaticAssertStmt(EEOP_LAST + 1 == lengthof(dispatch_table),
"dispatch_table out of whack with ExprEvalOp");
if (unlikely(state == NULL))
//如state == NULL,则调用PointerGetDatum
return PointerGetDatum(dispatch_table);
#else
Assert(state != NULL);
#endif /* EEO_USE_COMPUTED_GOTO */
/* setup state */
//配置状态变量
op = state->steps;
resultslot = state->resultslot;
innerslot = econtext->ecxt_innertuple;
outerslot = econtext->ecxt_outertuple;
scanslot = econtext->ecxt_scantuple;
#if defined(EEO_USE_COMPUTED_GOTO)
EEO_DISPATCH();//分发
#endif
EEO_SWITCH()
{
EEO_CASE(EEOP_DONE)
{
goto out;
}
EEO_CASE(EEOP_INNER_FETCHSOME)
{
/* XXX: worthwhile to check tts_nvalid inline first? */
slot_getsomeattrs(innerslot, op->d.fetch.last_var);
EEO_NEXT();
}
EEO_CASE(EEOP_OUTER_FETCHSOME)
{
slot_getsomeattrs(outerslot, op->d.fetch.last_var);
EEO_NEXT();
}
EEO_CASE(EEOP_SCAN_FETCHSOME)
{
slot_getsomeattrs(scanslot, op->d.fetch.last_var);
EEO_NEXT();
}
EEO_CASE(EEOP_INNER_VAR)
{
int attnum = op->d.var.attnum;
/*
* Since we already extracted all referenced columns from the
* tuple with a FETCHSOME step, we can just grab the value
* directly out of the slot's decomposed-data arrays. But let's
* have an Assert to check that that did happen.
*/
Assert(attnum >= 0 && attnum < innerslot->tts_nvalid);
*op->resvalue = innerslot->tts_values[attnum];
*op->resnull = innerslot->tts_isnull[attnum];
EEO_NEXT();
}
EEO_CASE(EEOP_OUTER_VAR)
{
int attnum = op->d.var.attnum;
/* See EEOP_INNER_VAR comments */
Assert(attnum >= 0 && attnum < outerslot->tts_nvalid);
*op->resvalue = outerslot->tts_values[attnum];
*op->resnull = outerslot->tts_isnull[attnum];
EEO_NEXT();
}
EEO_CASE(EEOP_SCAN_VAR)
{
int attnum = op->d.var.attnum;
/* See EEOP_INNER_VAR comments */
Assert(attnum >= 0 && attnum < scanslot->tts_nvalid);
*op->resvalue = scanslot->tts_values[attnum];
*op->resnull = scanslot->tts_isnull[attnum];
EEO_NEXT();
}
EEO_CASE(EEOP_INNER_SYSVAR)
{
int attnum = op->d.var.attnum;
Datum d;
/* these asserts must match defenses in slot_getattr */
Assert(innerslot->tts_tuple != NULL);
Assert(innerslot->tts_tuple != &(innerslot->tts_minhdr));
/* heap_getsysattr has sufficient defenses against bad attnums */
d = heap_getsysattr(innerslot->tts_tuple, attnum,
innerslot->tts_tupleDescriptor,
op->resnull);
*op->resvalue = d;
EEO_NEXT();
}
EEO_CASE(EEOP_OUTER_SYSVAR)
{
int attnum = op->d.var.attnum;
Datum d;
/* these asserts must match defenses in slot_getattr */
Assert(outerslot->tts_tuple != NULL);
Assert(outerslot->tts_tuple != &(outerslot->tts_minhdr));
/* heap_getsysattr has sufficient defenses against bad attnums */
d = heap_getsysattr(outerslot->tts_tuple, attnum,
outerslot->tts_tupleDescriptor,
op->resnull);
*op->resvalue = d;
EEO_NEXT();
}
EEO_CASE(EEOP_SCAN_SYSVAR)
{
int attnum = op->d.var.attnum;
Datum d;
/* these asserts must match defenses in slot_getattr */
Assert(scanslot->tts_tuple != NULL);
Assert(scanslot->tts_tuple != &(scanslot->tts_minhdr));
/* heap_getsysattr has sufficient defenses against bad attnums */
d = heap_getsysattr(scanslot->tts_tuple, attnum,
scanslot->tts_tupleDescriptor,
op->resnull);
*op->resvalue = d;
EEO_NEXT();
}
EEO_CASE(EEOP_WHOLEROW)
{
/* too complex for an inline implementation */
ExecEvalWholeRowVar(state, op, econtext);
EEO_NEXT();
}
EEO_CASE(EEOP_ASSIGN_INNER_VAR)
{
int resultnum = op->d.assign_var.resultnum;
int attnum = op->d.assign_var.attnum;
/*
* We do not need CheckVarSlotCompatibility here; that was taken
* care of at compilation time. But see EEOP_INNER_VAR comments.
*/
Assert(attnum >= 0 && attnum < innerslot->tts_nvalid);
resultslot->tts_values[resultnum] = innerslot->tts_values[attnum];
resultslot->tts_isnull[resultnum] = innerslot->tts_isnull[attnum];
EEO_NEXT();
}
EEO_CASE(EEOP_ASSIGN_OUTER_VAR)
{
int resultnum = op->d.assign_var.resultnum;
int attnum = op->d.assign_var.attnum;
/*
* We do not need CheckVarSlotCompatibility here; that was taken
* care of at compilation time. But see EEOP_INNER_VAR comments.
*/
Assert(attnum >= 0 && attnum < outerslot->tts_nvalid);
resultslot->tts_values[resultnum] = outerslot->tts_values[attnum];
resultslot->tts_isnull[resultnum] = outerslot->tts_isnull[attnum];
EEO_NEXT();
}
EEO_CASE(EEOP_ASSIGN_SCAN_VAR)
{
int resultnum = op->d.assign_var.resultnum;
int attnum = op->d.assign_var.attnum;
/*
* We do not need CheckVarSlotCompatibility here; that was taken
* care of at compilation time. But see EEOP_INNER_VAR comments.
*/
Assert(attnum >= 0 && attnum < scanslot->tts_nvalid);
resultslot->tts_values[resultnum] = scanslot->tts_values[attnum];
resultslot->tts_isnull[resultnum] = scanslot->tts_isnull[attnum];
EEO_NEXT();
}
EEO_CASE(EEOP_ASSIGN_TMP)
{
int resultnum = op->d.assign_tmp.resultnum;
resultslot->tts_values[resultnum] = state->resvalue;
resultslot->tts_isnull[resultnum] = state->resnull;
EEO_NEXT();
}
EEO_CASE(EEOP_ASSIGN_TMP_MAKE_RO)
{
int resultnum = op->d.assign_tmp.resultnum;
resultslot->tts_isnull[resultnum] = state->resnull;
if (!resultslot->tts_isnull[resultnum])
resultslot->tts_values[resultnum] =
MakeExpandedObjectReadOnlyInternal(state->resvalue);
else
resultslot->tts_values[resultnum] = state->resvalue;
EEO_NEXT();
}
EEO_CASE(EEOP_CONST)
{
*op->resnull = op->d.constval.isnull;
*op->resvalue = op->d.constval.value;
EEO_NEXT();
}
/*
* Function-call implementations. Arguments have previously been
* evaluated directly into fcinfo->args.
*
* As both STRICT checks and function-usage are noticeable performance
* wise, and function calls are a very hot-path (they also back
* operators!), it's worth having so many separate opcodes.
*
* Note: the reason for using a temporary variable "d", here and in
* other places, is that some compilers think "*op->resvalue = f();"
* requires them to evaluate op->resvalue into a register before
* calling f(), just in case f() is able to modify op->resvalue
* somehow. The extra line of code can save a useless register spill
* and reload across the function call.
*/
EEO_CASE(EEOP_FUNCEXPR)
{
FunctionCallInfo fcinfo = op->d.func.fcinfo_data;
Datum d;
fcinfo->isnull = false;
d = op->d.func.fn_addr(fcinfo);
*op->resvalue = d;
*op->resnull = fcinfo->isnull;
EEO_NEXT();
}
EEO_CASE(EEOP_FUNCEXPR_STRICT)
{
FunctionCallInfo fcinfo = op->d.func.fcinfo_data;
bool *argnull = fcinfo->argnull;
int argno;
Datum d;
/* strict function, so check for NULL args */
for (argno = 0; argno < op->d.func.nargs; argno++)
{
if (argnull[argno])
{
*op->resnull = true;
goto strictfail;
}
}
fcinfo->isnull = false;
d = op->d.func.fn_addr(fcinfo);
*op->resvalue = d;
*op->resnull = fcinfo->isnull;
strictfail:
EEO_NEXT();
}
EEO_CASE(EEOP_FUNCEXPR_FUSAGE)
{
/* not common enough to inline */
ExecEvalFuncExprFusage(state, op, econtext);
EEO_NEXT();
}
EEO_CASE(EEOP_FUNCEXPR_STRICT_FUSAGE)
{
/* not common enough to inline */
ExecEvalFuncExprStrictFusage(state, op, econtext);
EEO_NEXT();
}
/*
* If any of its clauses is FALSE, an AND's result is FALSE regardless
* of the states of the rest of the clauses, so we can stop evaluating
* and return FALSE immediately. If none are FALSE and one or more is
* NULL, we return NULL; otherwise we return TRUE. This makes sense
* when you interpret NULL as "don't know": perhaps one of the "don't
* knows" would have been FALSE if we'd known its value. Only when
* all the inputs are known to be TRUE can we state confidently that
* the AND's result is TRUE.
*/
EEO_CASE(EEOP_BOOL_AND_STEP_FIRST)
{
*op->d.boolexpr.anynull = false;
/*
* EEOP_BOOL_AND_STEP_FIRST resets anynull, otherwise it's the
* same as EEOP_BOOL_AND_STEP - so fall through to that.
*/
/* FALL THROUGH */
}
EEO_CASE(EEOP_BOOL_AND_STEP)
{
if (*op->resnull)
{
*op->d.boolexpr.anynull = true;
}
else if (!DatumGetBool(*op->resvalue))
{
/* result is already set to FALSE, need not change it */
/* bail out early */
EEO_JUMP(op->d.boolexpr.jumpdone);
}
EEO_NEXT();
}
EEO_CASE(EEOP_BOOL_AND_STEP_LAST)
{
if (*op->resnull)
{
/* result is already set to NULL, need not change it */
}
else if (!DatumGetBool(*op->resvalue))
{
/* result is already set to FALSE, need not change it */
/*
* No point jumping early to jumpdone - would be same target
* (as this is the last argument to the AND expression),
* except more expensive.
*/
}
else if (*op->d.boolexpr.anynull)
{
*op->resvalue = (Datum) 0;
*op->resnull = true;
}
else
{
/* result is already set to TRUE, need not change it */
}
EEO_NEXT();
}
/*
* If any of its clauses is TRUE, an OR's result is TRUE regardless of
* the states of the rest of the clauses, so we can stop evaluating
* and return TRUE immediately. If none are TRUE and one or more is
* NULL, we return NULL; otherwise we return FALSE. This makes sense
* when you interpret NULL as "don't know": perhaps one of the "don't
* knows" would have been TRUE if we'd known its value. Only when all
* the inputs are known to be FALSE can we state confidently that the
* OR's result is FALSE.
*/
EEO_CASE(EEOP_BOOL_OR_STEP_FIRST)
{
*op->d.boolexpr.anynull = false;
/*
* EEOP_BOOL_OR_STEP_FIRST resets anynull, otherwise it's the same
* as EEOP_BOOL_OR_STEP - so fall through to that.
*/
/* FALL THROUGH */
}
EEO_CASE(EEOP_BOOL_OR_STEP)
{
if (*op->resnull)
{
*op->d.boolexpr.anynull = true;
}
else if (DatumGetBool(*op->resvalue))
{
/* result is already set to TRUE, need not change it */
/* bail out early */
EEO_JUMP(op->d.boolexpr.jumpdone);
}
EEO_NEXT();
}
EEO_CASE(EEOP_BOOL_OR_STEP_LAST)
{
if (*op->resnull)
{
/* result is already set to NULL, need not change it */
}
else if (DatumGetBool(*op->resvalue))
{
/* result is already set to TRUE, need not change it */
/*
* No point jumping to jumpdone - would be same target (as
* this is the last argument to the AND expression), except
* more expensive.
*/
}
else if (*op->d.boolexpr.anynull)
{
*op->resvalue = (Datum) 0;
*op->resnull = true;
}
else
{
/* result is already set to FALSE, need not change it */
}
EEO_NEXT();
}
EEO_CASE(EEOP_BOOL_NOT_STEP)
{
/*
* Evaluation of 'not' is simple... if expr is false, then return
* 'true' and vice versa. It's safe to do this even on a
* nominally null value, so we ignore resnull; that means that
* NULL in produces NULL out, which is what we want.
*/
*op->resvalue = BoolGetDatum(!DatumGetBool(*op->resvalue));
EEO_NEXT();
}
EEO_CASE(EEOP_QUAL)
{
/* simplified version of BOOL_AND_STEP for use by ExecQual() */
/* If argument (also result) is false or null ... */
if (*op->resnull ||
!DatumGetBool(*op->resvalue))
{
/* ... bail out early, returning FALSE */
*op->resnull = false;
*op->resvalue = BoolGetDatum(false);
EEO_JUMP(op->d.qualexpr.jumpdone);
}
/*
* Otherwise, leave the TRUE value in place, in case this is the
* last qual. Then, TRUE is the correct answer.
*/
EEO_NEXT();
}
EEO_CASE(EEOP_JUMP)
{
/* Unconditionally jump to target step */
EEO_JUMP(op->d.jump.jumpdone);
}
EEO_CASE(EEOP_JUMP_IF_NULL)
{
/* Transfer control if current result is null */
if (*op->resnull)
EEO_JUMP(op->d.jump.jumpdone);
EEO_NEXT();
}
EEO_CASE(EEOP_JUMP_IF_NOT_NULL)
{
/* Transfer control if current result is non-null */
if (!*op->resnull)
EEO_JUMP(op->d.jump.jumpdone);
EEO_NEXT();
}
EEO_CASE(EEOP_JUMP_IF_NOT_TRUE)
{
/* Transfer control if current result is null or false */
if (*op->resnull || !DatumGetBool(*op->resvalue))
EEO_JUMP(op->d.jump.jumpdone);
EEO_NEXT();
}
EEO_CASE(EEOP_NULLTEST_ISNULL)
{
*op->resvalue = BoolGetDatum(*op->resnull);
*op->resnull = false;
EEO_NEXT();
}
EEO_CASE(EEOP_NULLTEST_ISNOTNULL)
{
*op->resvalue = BoolGetDatum(!*op->resnull);
*op->resnull = false;
EEO_NEXT();
}
EEO_CASE(EEOP_NULLTEST_ROWISNULL)
{
/* out of line implementation: too large */
ExecEvalRowNull(state, op, econtext);
EEO_NEXT();
}
EEO_CASE(EEOP_NULLTEST_ROWISNOTNULL)
{
/* out of line implementation: too large */
ExecEvalRowNotNull(state, op, econtext);
EEO_NEXT();
}
/* BooleanTest implementations for all booltesttypes */
EEO_CASE(EEOP_BOOLTEST_IS_TRUE)
{
if (*op->resnull)
{
*op->resvalue = BoolGetDatum(false);
*op->resnull = false;
}
/* else, input value is the correct output as well */
EEO_NEXT();
}
EEO_CASE(EEOP_BOOLTEST_IS_NOT_TRUE)
{
if (*op->resnull)
{
*op->resvalue = BoolGetDatum(true);
*op->resnull = false;
}
else
*op->resvalue = BoolGetDatum(!DatumGetBool(*op->resvalue));
EEO_NEXT();
}
EEO_CASE(EEOP_BOOLTEST_IS_FALSE)
{
if (*op->resnull)
{
*op->resvalue = BoolGetDatum(false);
*op->resnull = false;
}
else
*op->resvalue = BoolGetDatum(!DatumGetBool(*op->resvalue));
EEO_NEXT();
}
EEO_CASE(EEOP_BOOLTEST_IS_NOT_FALSE)
{
if (*op->resnull)
{
*op->resvalue = BoolGetDatum(true);
*op->resnull = false;
}
/* else, input value is the correct output as well */
EEO_NEXT();
}
EEO_CASE(EEOP_PARAM_EXEC)
{
/* out of line implementation: too large */
ExecEvalParamExec(state, op, econtext);
EEO_NEXT();
}
EEO_CASE(EEOP_PARAM_EXTERN)
{
/* out of line implementation: too large */
ExecEvalParamExtern(state, op, econtext);
EEO_NEXT();
}
EEO_CASE(EEOP_PARAM_CALLBACK)
{
/* allow an extension module to supply a PARAM_EXTERN value */
op->d.cparam.paramfunc(state, op, econtext);
EEO_NEXT();
}
EEO_CASE(EEOP_CASE_TESTVAL)
{
/*
* Normally upper parts of the expression tree have setup the
* values to be returned here, but some parts of the system
* currently misuse {caseValue,domainValue}_{datum,isNull} to set
* run-time data. So if no values have been set-up, use
* ExprContext's. This isn't pretty, but also not *that* ugly,
* and this is unlikely to be performance sensitive enough to
* worry about an extra branch.
*/
if (op->d.casetest.value)
{
*op->resvalue = *op->d.casetest.value;
*op->resnull = *op->d.casetest.isnull;
}
else
{
*op->resvalue = econtext->caseValue_datum;
*op->resnull = econtext->caseValue_isNull;
}
EEO_NEXT();
}
EEO_CASE(EEOP_DOMAIN_TESTVAL)
{
/*
* See EEOP_CASE_TESTVAL comment.
*/
if (op->d.casetest.value)
{
*op->resvalue = *op->d.casetest.value;
*op->resnull = *op->d.casetest.isnull;
}
else
{
*op->resvalue = econtext->domainValue_datum;
*op->resnull = econtext->domainValue_isNull;
}
EEO_NEXT();
}
EEO_CASE(EEOP_MAKE_READONLY)
{
/*
* Force a varlena value that might be read multiple times to R/O
*/
if (!*op->d.make_readonly.isnull)
*op->resvalue =
MakeExpandedObjectReadOnlyInternal(*op->d.make_readonly.value);
*op->resnull = *op->d.make_readonly.isnull;
EEO_NEXT();
}
EEO_CASE(EEOP_IOCOERCE)
{
/*
* Evaluate a CoerceViaIO node. This can be quite a hot path, so
* inline as much work as possible. The source value is in our
* result variable.
*/
char *str;
/* call output function (similar to OutputFunctionCall) */
if (*op->resnull)
{
/* output functions are not called on nulls */
str = NULL;
}
else
{
FunctionCallInfo fcinfo_out;
fcinfo_out = op->d.iocoerce.fcinfo_data_out;
fcinfo_out->arg[0] = *op->resvalue;
fcinfo_out->argnull[0] = false;
fcinfo_out->isnull = false;
str = DatumGetCString(FunctionCallInvoke(fcinfo_out));
/* OutputFunctionCall assumes result isn't null */
Assert(!fcinfo_out->isnull);
}
/* call input function (similar to InputFunctionCall) */
if (!op->d.iocoerce.finfo_in->fn_strict || str != NULL)
{
FunctionCallInfo fcinfo_in;
Datum d;
fcinfo_in = op->d.iocoerce.fcinfo_data_in;
fcinfo_in->arg[0] = PointerGetDatum(str);
fcinfo_in->argnull[0] = *op->resnull;
/* second and third arguments are already set up */
fcinfo_in->isnull = false;
d = FunctionCallInvoke(fcinfo_in);
*op->resvalue = d;
/* Should get null result if and only if str is NULL */
if (str == NULL)
{
Assert(*op->resnull);
Assert(fcinfo_in->isnull);
}
else
{
Assert(!*op->resnull);
Assert(!fcinfo_in->isnull);
}
}
EEO_NEXT();
}
EEO_CASE(EEOP_DISTINCT)
{
/*
* IS DISTINCT FROM must evaluate arguments (already done into
* fcinfo->arg/argnull) to determine whether they are NULL; if
* either is NULL then the result is determined. If neither is
* NULL, then proceed to evaluate the comparison function, which
* is just the type's standard equality operator. We need not
* care whether that function is strict. Because the handling of
* nulls is different, we can't just reuse EEOP_FUNCEXPR.
*/
FunctionCallInfo fcinfo = op->d.func.fcinfo_data;
/* check function arguments for NULLness */
if (fcinfo->argnull[0] && fcinfo->argnull[1])
{
/* Both NULL? Then is not distinct... */
*op->resvalue = BoolGetDatum(false);
*op->resnull = false;
}
else if (fcinfo->argnull[0] || fcinfo->argnull[1])
{
/* Only one is NULL? Then is distinct... */
*op->resvalue = BoolGetDatum(true);
*op->resnull = false;
}
else
{
/* Neither null, so apply the equality function */
Datum eqresult;
fcinfo->isnull = false;
eqresult = op->d.func.fn_addr(fcinfo);
/* Must invert result of "="; safe to do even if null */
*op->resvalue = BoolGetDatum(!DatumGetBool(eqresult));
*op->resnull = fcinfo->isnull;
}
EEO_NEXT();
}
/* see EEOP_DISTINCT for comments, this is just inverted */
EEO_CASE(EEOP_NOT_DISTINCT)
{
FunctionCallInfo fcinfo = op->d.func.fcinfo_data;
if (fcinfo->argnull[0] && fcinfo->argnull[1])
{
*op->resvalue = BoolGetDatum(true);
*op->resnull = false;
}
else if (fcinfo->argnull[0] || fcinfo->argnull[1])
{
*op->resvalue = BoolGetDatum(false);
*op->resnull = false;
}
else
{
Datum eqresult;
fcinfo->isnull = false;
eqresult = op->d.func.fn_addr(fcinfo);
*op->resvalue = eqresult;
*op->resnull = fcinfo->isnull;
}
EEO_NEXT();
}
EEO_CASE(EEOP_NULLIF)
{
/*
* The arguments are already evaluated into fcinfo->arg/argnull.
*/
FunctionCallInfo fcinfo = op->d.func.fcinfo_data;
/* if either argument is NULL they can't be equal */
if (!fcinfo->argnull[0] && !fcinfo->argnull[1])
{
Datum result;
fcinfo->isnull = false;
result = op->d.func.fn_addr(fcinfo);
/* if the arguments are equal return null */
if (!fcinfo->isnull && DatumGetBool(result))
{
*op->resvalue = (Datum) 0;
*op->resnull = true;
EEO_NEXT();
}
}
/* Arguments aren't equal, so return the first one */
*op->resvalue = fcinfo->arg[0];
*op->resnull = fcinfo->argnull[0];
EEO_NEXT();
}
EEO_CASE(EEOP_SQLVALUEFUNCTION)
{
/*
* Doesn't seem worthwhile to have an inline implementation
* efficiency-wise.
*/
ExecEvalSQLValueFunction(state, op);
EEO_NEXT();
}
EEO_CASE(EEOP_CURRENTOFEXPR)
{
/* error invocation uses space, and shouldn't ever occur */
ExecEvalCurrentOfExpr(state, op);
EEO_NEXT();
}
EEO_CASE(EEOP_NEXTVALUEEXPR)
{
/*
* Doesn't seem worthwhile to have an inline implementation
* efficiency-wise.
*/
ExecEvalNextValueExpr(state, op);
EEO_NEXT();
}
EEO_CASE(EEOP_ARRAYEXPR)
{
/* too complex for an inline implementation */
ExecEvalArrayExpr(state, op);
EEO_NEXT();
}
EEO_CASE(EEOP_ARRAYCOERCE)
{
/* too complex for an inline implementation */
ExecEvalArrayCoerce(state, op, econtext);
EEO_NEXT();
}
EEO_CASE(EEOP_ROW)
{
/* too complex for an inline implementation */
ExecEvalRow(state, op);
EEO_NEXT();
}
EEO_CASE(EEOP_ROWCOMPARE_STEP)
{
FunctionCallInfo fcinfo = op->d.rowcompare_step.fcinfo_data;
Datum d;
/* force NULL result if strict fn and NULL input */
if (op->d.rowcompare_step.finfo->fn_strict &&
(fcinfo->argnull[0] || fcinfo->argnull[1]))
{
*op->resnull = true;
EEO_JUMP(op->d.rowcompare_step.jumpnull);
}
/* Apply comparison function */
fcinfo->isnull = false;
d = op->d.rowcompare_step.fn_addr(fcinfo);
*op->resvalue = d;
/* force NULL result if NULL function result */
if (fcinfo->isnull)
{
*op->resnull = true;
EEO_JUMP(op->d.rowcompare_step.jumpnull);
}
*op->resnull = false;
/* If unequal, no need to compare remaining columns */
if (DatumGetInt32(*op->resvalue) != 0)
{
EEO_JUMP(op->d.rowcompare_step.jumpdone);
}
EEO_NEXT();
}
EEO_CASE(EEOP_ROWCOMPARE_FINAL)
{
int32 cmpresult = DatumGetInt32(*op->resvalue);
RowCompareType rctype = op->d.rowcompare_final.rctype;
*op->resnull = false;
switch (rctype)
{
/* EQ and NE cases aren't allowed here */
case ROWCOMPARE_LT:
*op->resvalue = BoolGetDatum(cmpresult < 0);
break;
case ROWCOMPARE_LE:
*op->resvalue = BoolGetDatum(cmpresult <= 0);
break;
case ROWCOMPARE_GE:
*op->resvalue = BoolGetDatum(cmpresult >= 0);
break;
case ROWCOMPARE_GT:
*op->resvalue = BoolGetDatum(cmpresult > 0);
break;
default:
Assert(false);
break;
}
EEO_NEXT();
}
EEO_CASE(EEOP_MINMAX)
{
/* too complex for an inline implementation */
ExecEvalMinMax(state, op);
EEO_NEXT();
}
EEO_CASE(EEOP_FIELDSELECT)
{
/* too complex for an inline implementation */
ExecEvalFieldSelect(state, op, econtext);
EEO_NEXT();
}
EEO_CASE(EEOP_FIELDSTORE_DEFORM)
{
/* too complex for an inline implementation */
ExecEvalFieldStoreDeForm(state, op, econtext);
EEO_NEXT();
}
EEO_CASE(EEOP_FIELDSTORE_FORM)
{
/* too complex for an inline implementation */
ExecEvalFieldStoreForm(state, op, econtext);
EEO_NEXT();
}
EEO_CASE(EEOP_ARRAYREF_SUBSCRIPT)
{
/* Process an array subscript */
/* too complex for an inline implementation */
if (ExecEvalArrayRefSubscript(state, op))
{
EEO_NEXT();
}
else
{
/* Subscript is null, short-circuit ArrayRef to NULL */
EEO_JUMP(op->d.arrayref_subscript.jumpdone);
}
}
EEO_CASE(EEOP_ARRAYREF_OLD)
{
/*
* Fetch the old value in an arrayref assignment, in case it's
* referenced (via a CaseTestExpr) inside the assignment
* expression.
*/
/* too complex for an inline implementation */
ExecEvalArrayRefOld(state, op);
EEO_NEXT();
}
/*
* Perform ArrayRef assignment
*/
EEO_CASE(EEOP_ARRAYREF_ASSIGN)
{
/* too complex for an inline implementation */
ExecEvalArrayRefAssign(state, op);
EEO_NEXT();
}
/*
* Fetch subset of an array.
*/
EEO_CASE(EEOP_ARRAYREF_FETCH)
{
/* too complex for an inline implementation */
ExecEvalArrayRefFetch(state, op);
EEO_NEXT();
}
EEO_CASE(EEOP_CONVERT_ROWTYPE)
{
/* too complex for an inline implementation */
ExecEvalConvertRowtype(state, op, econtext);
EEO_NEXT();
}
EEO_CASE(EEOP_SCALARARRAYOP)
{
/* too complex for an inline implementation */
ExecEvalScalarArrayOp(state, op);
EEO_NEXT();
}
EEO_CASE(EEOP_DOMAIN_NOTNULL)
{
/* too complex for an inline implementation */
ExecEvalConstraintNotNull(state, op);
EEO_NEXT();
}
EEO_CASE(EEOP_DOMAIN_CHECK)
{
/* too complex for an inline implementation */
ExecEvalConstraintCheck(state, op);
EEO_NEXT();
}
EEO_CASE(EEOP_XMLEXPR)
{
/* too complex for an inline implementation */
ExecEvalXmlExpr(state, op);
EEO_NEXT();
}
EEO_CASE(EEOP_AGGREF)
{
/*
* Returns a Datum whose value is the precomputed aggregate value
* found in the given expression context.
*/
AggrefExprState *aggref = op->d.aggref.astate;
Assert(econtext->ecxt_aggvalues != NULL);
*op->resvalue = econtext->ecxt_aggvalues[aggref->aggno];
*op->resnull = econtext->ecxt_aggnulls[aggref->aggno];
EEO_NEXT();
}
EEO_CASE(EEOP_GROUPING_FUNC)
{
/* too complex/uncommon for an inline implementation */
ExecEvalGroupingFunc(state, op);
EEO_NEXT();
}
EEO_CASE(EEOP_WINDOW_FUNC)
{
/*
* Like Aggref, just return a precomputed value from the econtext.
*/
WindowFuncExprState *wfunc = op->d.window_func.wfstate;
Assert(econtext->ecxt_aggvalues != NULL);
*op->resvalue = econtext->ecxt_aggvalues[wfunc->wfuncno];
*op->resnull = econtext->ecxt_aggnulls[wfunc->wfuncno];
EEO_NEXT();
}
EEO_CASE(EEOP_SUBPLAN)
{
/* too complex for an inline implementation */
ExecEvalSubPlan(state, op, econtext);
EEO_NEXT();
}
EEO_CASE(EEOP_ALTERNATIVE_SUBPLAN)
{
/* too complex for an inline implementation */
ExecEvalAlternativeSubPlan(state, op, econtext);
EEO_NEXT();
}
/* evaluate a strict aggregate deserialization function */
EEO_CASE(EEOP_AGG_STRICT_DESERIALIZE)
{
bool *argnull = op->d.agg_deserialize.fcinfo_data->argnull;
/* Don't call a strict deserialization function with NULL input */
if (argnull[0])
EEO_JUMP(op->d.agg_deserialize.jumpnull);
/* fallthrough */
}
/* evaluate aggregate deserialization function (non-strict portion) */
EEO_CASE(EEOP_AGG_DESERIALIZE)
{
FunctionCallInfo fcinfo = op->d.agg_deserialize.fcinfo_data;
AggState *aggstate = op->d.agg_deserialize.aggstate;
MemoryContext oldContext;
/*
* We run the deserialization functions in per-input-tuple memory
* context.
*/
oldContext = MemoryContextSwitchTo(aggstate->tmpcontext->ecxt_per_tuple_memory);
fcinfo->isnull = false;
*op->resvalue = FunctionCallInvoke(fcinfo);
*op->resnull = fcinfo->isnull;
MemoryContextSwitchTo(oldContext);
EEO_NEXT();
}
/*
* Check that a strict aggregate transition / combination function's
* input is not NULL.
*/
EEO_CASE(EEOP_AGG_STRICT_INPUT_CHECK)
{
int argno;
bool *nulls = op->d.agg_strict_input_check.nulls;
int nargs = op->d.agg_strict_input_check.nargs;
for (argno = 0; argno < nargs; argno++)
{
if (nulls[argno])
EEO_JUMP(op->d.agg_strict_input_check.jumpnull);
}
EEO_NEXT();
}
/*
* Initialize an aggregate's first value if necessary.
*/
EEO_CASE(EEOP_AGG_INIT_TRANS)
{
AggState *aggstate;
AggStatePerGroup pergroup;
aggstate = op->d.agg_init_trans.aggstate;
pergroup = &aggstate->all_pergroups
[op->d.agg_init_trans.setoff]
[op->d.agg_init_trans.transno];
/* If transValue has not yet been initialized, do so now. */
if (pergroup->noTransValue)
{
AggStatePerTrans pertrans = op->d.agg_init_trans.pertrans;
aggstate->curaggcontext = op->d.agg_init_trans.aggcontext;
aggstate->current_set = op->d.agg_init_trans.setno;
ExecAggInitGroup(aggstate, pertrans, pergroup);
/* copied trans value from input, done this round */
EEO_JUMP(op->d.agg_init_trans.jumpnull);
}
EEO_NEXT();
}
/* check that a strict aggregate's input isn't NULL */
EEO_CASE(EEOP_AGG_STRICT_TRANS_CHECK)
{
AggState *aggstate;
AggStatePerGroup pergroup;
aggstate = op->d.agg_strict_trans_check.aggstate;
pergroup = &aggstate->all_pergroups
[op->d.agg_strict_trans_check.setoff]
[op->d.agg_strict_trans_check.transno];
if (unlikely(pergroup->transValueIsNull))
EEO_JUMP(op->d.agg_strict_trans_check.jumpnull);
EEO_NEXT();
}
/*
* Evaluate aggregate transition / combine function that has a
* by-value transition type. That's a seperate case from the
* by-reference implementation because it's a bit simpler.
*/
EEO_CASE(EEOP_AGG_PLAIN_TRANS_BYVAL)
{
AggState *aggstate;
AggStatePerTrans pertrans;
AggStatePerGroup pergroup;
FunctionCallInfo fcinfo;
MemoryContext oldContext;
Datum newVal;
aggstate = op->d.agg_trans.aggstate;
pertrans = op->d.agg_trans.pertrans;
pergroup = &aggstate->all_pergroups
[op->d.agg_trans.setoff]
[op->d.agg_trans.transno];
Assert(pertrans->transtypeByVal);
fcinfo = &pertrans->transfn_fcinfo;
/* cf. select_current_set() */
aggstate->curaggcontext = op->d.agg_trans.aggcontext;
aggstate->current_set = op->d.agg_trans.setno;
/* set up aggstate->curpertrans for AggGetAggref() */
aggstate->curpertrans = pertrans;
/* invoke transition function in per-tuple context */
oldContext = MemoryContextSwitchTo(aggstate->tmpcontext->ecxt_per_tuple_memory);
fcinfo->arg[0] = pergroup->transValue;
fcinfo->argnull[0] = pergroup->transValueIsNull;
fcinfo->isnull = false; /* just in case transfn doesn't set it */
newVal = FunctionCallInvoke(fcinfo);
pergroup->transValue = newVal;
pergroup->transValueIsNull = fcinfo->isnull;
MemoryContextSwitchTo(oldContext);
EEO_NEXT();
}
/*
* Evaluate aggregate transition / combine function that has a
* by-reference transition type.
*
* Could optimize a bit further by splitting off by-reference
* fixed-length types, but currently that doesn't seem worth it.
*/
EEO_CASE(EEOP_AGG_PLAIN_TRANS)
{
AggState *aggstate;
AggStatePerTrans pertrans;
AggStatePerGroup pergroup;
FunctionCallInfo fcinfo;
MemoryContext oldContext;
Datum newVal;
aggstate = op->d.agg_trans.aggstate;
pertrans = op->d.agg_trans.pertrans;
pergroup = &aggstate->all_pergroups
[op->d.agg_trans.setoff]
[op->d.agg_trans.transno];
Assert(!pertrans->transtypeByVal);
fcinfo = &pertrans->transfn_fcinfo;
/* cf. select_current_set() */
aggstate->curaggcontext = op->d.agg_trans.aggcontext;
aggstate->current_set = op->d.agg_trans.setno;
/* set up aggstate->curpertrans for AggGetAggref() */
aggstate->curpertrans = pertrans;
/* invoke transition function in per-tuple context */
oldContext = MemoryContextSwitchTo(aggstate->tmpcontext->ecxt_per_tuple_memory);
fcinfo->arg[0] = pergroup->transValue;
fcinfo->argnull[0] = pergroup->transValueIsNull;
fcinfo->isnull = false; /* just in case transfn doesn't set it */
newVal = FunctionCallInvoke(fcinfo);
/*
* For pass-by-ref datatype, must copy the new value into
* aggcontext and free the prior transValue. But if transfn
* returned a pointer to its first input, we don't need to do
* anything. Also, if transfn returned a pointer to a R/W
* expanded object that is already a child of the aggcontext,
* assume we can adopt that value without copying it.
*/
if (DatumGetPointer(newVal) != DatumGetPointer(pergroup->transValue))
newVal = ExecAggTransReparent(aggstate, pertrans,
newVal, fcinfo->isnull,
pergroup->transValue,
pergroup->transValueIsNull);
pergroup->transValue = newVal;
pergroup->transValueIsNull = fcinfo->isnull;
MemoryContextSwitchTo(oldContext);
EEO_NEXT();
}
/* process single-column ordered aggregate datum */
EEO_CASE(EEOP_AGG_ORDERED_TRANS_DATUM)
{
/* too complex for an inline implementation */
ExecEvalAggOrderedTransDatum(state, op, econtext);
EEO_NEXT();
}
/* process multi-column ordered aggregate tuple */
EEO_CASE(EEOP_AGG_ORDERED_TRANS_TUPLE)
{
/* too complex for an inline implementation */
ExecEvalAggOrderedTransTuple(state, op, econtext);
EEO_NEXT();
}
EEO_CASE(EEOP_LAST)
{
/* unreachable */
Assert(false);
goto out;
}
}
out:
*isnull = state->resnull;
return state->resvalue;
}到此，相信大家对“PostgreSQL 聚合函数的实现教程”有了更深的了解，不妨来实际操作一番吧！这里是亿速云网站，更多相关内容可以进入相关频道进行查询，关注我们，继续学习！
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