PostgreSQL 源码解读（181）- 查询#97(聚合函数#2-ExecInitAgg)
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本节简单介绍了PostgreSQL执行聚合函数时的初始化工作,主要实现函数是ExecInitAgg.
一、数据结构
AggState
聚合函数执行时状态结构体,内含AggStatePerAgg等结构体
//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;
//targetlist和quals中所有的Aggref
List *aggs;
//链表的大小(可以为0)
int numaggs;
//pertrans条目大小
int numtrans;
//Agg策略模式
AggStrategy aggstrategy;
//agg-splitting模式,参见nodes.h
AggSplit aggsplit;
//指向当前步骤数据的指针
AggStatePerPhase phase;
//步骤数(包括0)
int numphases;
//当前步骤
int current_phase;
//per-Aggref信息
AggStatePerAgg peragg;
//per-Trans状态信息
AggStatePerTrans pertrans;
//长生命周期数据的ExprContexts(hashtable)
ExprContext *hashcontext;
////长生命周期数据的ExprContexts(每一个GS使用)
ExprContext **aggcontexts;
//输入表达式的ExprContext
ExprContext *tmpcontext;
#define FIELDNO_AGGSTATE_CURAGGCONTEXT 14
//当前活跃的aggcontext
ExprContext *curaggcontext;
//当前活跃的aggregate(如存在)
AggStatePerAgg curperagg;
#define FIELDNO_AGGSTATE_CURPERTRANS 16
//当前活跃的trans state
AggStatePerTrans curpertrans;
//输入结束?
bool input_done;
//Agg扫描结束?
bool agg_done;
//最后一个grouping set
int projected_set;
#define FIELDNO_AGGSTATE_CURRENT_SET 20
//将要解析的当前grouping set
int current_set;
//当前投影操作的分组列
Bitmapset *grouped_cols;
//倒序的分组列链表
List *all_grouped_cols;
//-------- 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;
//所有步骤的数组
AggStatePerPhase phases;
//对于phases > 1,已排序的输入信息
Tuplesortstate *sort_in;
//对于下一个步骤,输入已拷贝
Tuplesortstate *sort_out;
//排序结果的slot
TupleTableSlot *sort_slot;
//------- 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;
//当前组的第一个元组拷贝
HeapTuple grp_firstTuple;
//--------- 下面的列用于AGG_HASHED和AGG_MIXED模式:
//是否已填充hash表?
bool table_filled;
//hash桶数?
int num_hashes;
//相应的哈希表数据数组
AggStatePerHash perhash;
//per-group指针的grouping set编号数组
AggStatePerGroup *hash_pergroup;
//---------- 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;
//投影实现机制
ProjectionInfo *combinedproj;
} AggState;
//nodeag .c支持的基本选项
#define AGGSPLITOP_COMBINE 0x01
#define AGGSPLITOP_SKIPFINAL 0x02
#define AGGSPLITOP_SERIALIZE 0x04
#define AGGSPLITOP_DESERIALIZE 0x08
//支持的操作模式
typedef enum AggSplit
{
//基本 : 非split聚合
AGGSPLIT_SIMPLE = 0,
//部分聚合的初始步骤,序列化
AGGSPLIT_INITIAL_SERIAL = AGGSPLITOP_SKIPFINAL | AGGSPLITOP_SERIALIZE,
//部分聚合的最终步骤,反序列化
AGGSPLIT_FINAL_DESERIAL = AGGSPLITOP_COMBINE | AGGSPLITOP_DESERIALIZE
} AggSplit;
//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)
二、源码解读
ExecInitAgg为优化器生成的agg节点创建运行期信息并初始化outer子树(左树).
其主要实现逻辑如下:
1.初始化AggState结构体
2.计算分为几个阶段(Hash vs Group)
3.如存在grouping set,则初始化相关信息
4.分配内存上下文
5.初始化outer plan子节点
6.初始化结果类型,slot和投影
7.初始化子表达式
8.为AggStatePerPhaseData等结构体分配内存
9.循环遍历各个阶段
9.1计算分组列,存储在phasedata->grouped_cols数组和all_grouped_cols中
9.2初始化AggState->phases数组(数组元素对应的结构体为AggStatePerPhase)
9.3初始化AggState->perhash数组(对应的结构体为AggStatePerHash)
10.转换all_grouped_cols为倒序链表
11.在输出expr上下文中设置aggregate-result存储,同时分配私有per-agg工作存储
12.如使用Hash算法,则调用find_hash_columns和build_hash_table方法初始化相关数据
13.调用initialize_phase/select_current_set初始化阶段数据
14.检索聚合函数信息,初始化per-agg和per-trans数据不可变字段
15.构建一次就完成所有转换工作的表达式.
AggState *
ExecInitAgg(Agg *node, EState *estate, int eflags)
{
AggState *aggstate;//AggState结构体指针
AggStatePerAgg peraggs;//AggStatePerAggData结构体指针
AggStatePerTrans pertransstates;//聚合状态值信息
AggStatePerGroup *pergroups;//per-aggregate-per-group工作状态
Plan *outerPlan;//outer计划(左树)
ExprContext *econtext;//内存上下文
TupleDesc scanDesc;//扫描描述器
int numaggs,//agg个数
transno,//转换器
aggno;
int phase;//阶段
int phaseidx;//阶段编号
ListCell *l;//临时变量
Bitmapset *all_grouped_cols = NULL;//分组列集合
int numGroupingSets = 1;//Grouping Sets数
int numPhases;//阶段数
int numHashes;//
int i = 0;
int j = 0;
bool use_hashing = (node->aggstrategy == AGG_HASHED ||
node->aggstrategy == AGG_MIXED);//是否使用Hash聚合算法
//检查验证
Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
aggstate = makeNode(AggState);
aggstate->ss.ps.plan = (Plan *) node;
aggstate->ss.ps.state = estate;
aggstate->ss.ps.ExecProcNode = ExecAgg;
aggstate->aggs = NIL;
aggstate->numaggs = 0;
aggstate->numtrans = 0;
aggstate->aggstrategy = node->aggstrategy;
aggstate->aggsplit = node->aggsplit;
aggstate->maxsets = 0;
aggstate->projected_set = -1;
aggstate->current_set = 0;
aggstate->peragg = NULL;
aggstate->pertrans = NULL;
aggstate->curperagg = NULL;
aggstate->curpertrans = NULL;
aggstate->input_done = false;
aggstate->agg_done = false;
aggstate->pergroups = NULL;
aggstate->grp_firstTuple = NULL;
aggstate->sort_in = NULL;
aggstate->sort_out = NULL;
numPhases = (use_hashing ? 1 : 2);
numHashes = (use_hashing ? 1 : 0);
if (node->groupingSets)
{
//存在grouping sets
numGroupingSets = list_length(node->groupingSets);
foreach(l, node->chain)
{
Agg *agg = lfirst(l);
numGroupingSets = Max(numGroupingSets,
list_length(agg->groupingSets));
if (agg->aggstrategy != AGG_HASHED)
++numPhases;
else
++numHashes;
}
}
//赋值
aggstate->maxsets = numGroupingSets;
aggstate->numphases = numPhases;
aggstate->aggcontexts = (ExprContext **)
palloc0(sizeof(ExprContext *) * numGroupingSets);
//分配内存上下文
ExecAssignExprContext(estate, &aggstate->ss.ps);
aggstate->tmpcontext = aggstate->ss.ps.ps_ExprContext;
for (i = 0; i < numGroupingSets; ++i)
{
ExecAssignExprContext(estate, &aggstate->ss.ps);
aggstate->aggcontexts[i] = aggstate->ss.ps.ps_ExprContext;
}
if (use_hashing)
{
ExecAssignExprContext(estate, &aggstate->ss.ps);
aggstate->hashcontext = aggstate->ss.ps.ps_ExprContext;
}
ExecAssignExprContext(estate, &aggstate->ss.ps);
if (node->aggstrategy == AGG_HASHED)
eflags &= ~EXEC_FLAG_REWIND;
//获取outerPlan
outerPlan = outerPlan(node);
//初始化outerPlan
outerPlanState(aggstate) = ExecInitNode(outerPlan, estate, eflags);
ExecCreateScanSlotFromOuterPlan(estate, &aggstate->ss);
scanDesc = aggstate->ss.ss_ScanTupleSlot->tts_tupleDescriptor;
if (node->chain)
aggstate->sort_slot = ExecInitExtraTupleSlot(estate, scanDesc);
ExecInitResultTupleSlotTL(estate, &aggstate->ss.ps);
ExecAssignProjectionInfo(&aggstate->ss.ps, NULL);
aggstate->ss.ps.qual =
ExecInitQual(node->plan.qual, (PlanState *) aggstate);
numaggs = aggstate->numaggs;
Assert(numaggs == list_length(aggstate->aggs));
//分配内存
aggstate->phases = palloc0(numPhases * sizeof(AggStatePerPhaseData));
aggstate->num_hashes = numHashes;
if (numHashes)
{
aggstate->perhash = palloc0(sizeof(AggStatePerHashData) * numHashes);
aggstate->phases[0].numsets = 0;
aggstate->phases[0].gset_lengths = palloc(numHashes * sizeof(int));
aggstate->phases[0].grouped_cols = palloc(numHashes * sizeof(Bitmapset *));
}
phase = 0;
for (phaseidx = 0; phaseidx <= list_length(node->chain); ++phaseidx)
{
//------------ 遍历各个阶段
Agg *aggnode;
Sort *sortnode;
if (phaseidx > 0)
{
//不是第一个阶段,从node链表中取得节点
aggnode = list_nth_node(Agg, node->chain, phaseidx - 1);
//排序节点
sortnode = castNode(Sort, aggnode->plan.lefttree);
}
else
{
//第一阶段,直接赋值
aggnode = node;
sortnode = NULL;
}
Assert(phase <= 1 || sortnode);
if (aggnode->aggstrategy == AGG_HASHED
|| aggnode->aggstrategy == AGG_MIXED)
{
//---------- 使用Hash聚合
//阶段数据
AggStatePerPhase phasedata = &aggstate->phases[0];
AggStatePerHash perhash;
Bitmapset *cols = NULL;
Assert(phase == 0);
i = phasedata->numsets++;
perhash = &aggstate->perhash[i];
//使用Hash聚合,阶段0通常指向"实际的"Agg
phasedata->aggnode = node;
phasedata->aggstrategy = node->aggstrategy;
//但表示该Hash的实际的Agg节点保存在这里
perhash->aggnode = aggnode;
phasedata->gset_lengths[i] = perhash->numCols = aggnode->numCols;
//分组列放在集合中
for (j = 0; j < aggnode->numCols; ++j)
cols = bms_add_member(cols, aggnode->grpColIdx[j]);
//存储在阶段数据中
phasedata->grouped_cols[i] = cols;
//添加到大集合中
all_grouped_cols = bms_add_members(all_grouped_cols, cols);
continue;
}
else
{
//使用Group聚合
AggStatePerPhase phasedata = &aggstate->phases[++phase];
int num_sets;
phasedata->numsets = num_sets = list_length(aggnode->groupingSets);
if (num_sets)
{
phasedata->gset_lengths = palloc(num_sets * sizeof(int));
phasedata->grouped_cols = palloc(num_sets * sizeof(Bitmapset *));
i = 0;
foreach(l, aggnode->groupingSets)
{
int current_length = list_length(lfirst(l));
Bitmapset *cols = NULL;
for (j = 0; j < current_length; ++j)
cols = bms_add_member(cols, aggnode->grpColIdx[j]);
phasedata->grouped_cols[i] = cols;
phasedata->gset_lengths[i] = current_length;
++i;
}
all_grouped_cols = bms_add_members(all_grouped_cols,
phasedata->grouped_cols[0]);
}
else
{
Assert(phaseidx == 0);
phasedata->gset_lengths = NULL;
phasedata->grouped_cols = NULL;
}
if (aggnode->aggstrategy == AGG_SORTED)
{
int i = 0;
Assert(aggnode->numCols > 0);
phasedata->eqfunctions =
(ExprState **) palloc0(aggnode->numCols * sizeof(ExprState *));
//对于每一个grouping set进行处理
for (i = 0; i < phasedata->numsets; i++)
{
int length = phasedata->gset_lengths[i];
if (phasedata->eqfunctions[length - 1] != NULL)
continue;
phasedata->eqfunctions[length - 1] =
execTuplesMatchPrepare(scanDesc,
length,
aggnode->grpColIdx,
aggnode->grpOperators,
(PlanState *) aggstate);
}
//处理所有需要分组的列,除非已完成计算
if (phasedata->eqfunctions[aggnode->numCols - 1] == NULL)
{
phasedata->eqfunctions[aggnode->numCols - 1] =
execTuplesMatchPrepare(scanDesc,
aggnode->numCols,
aggnode->grpColIdx,
aggnode->grpOperators,
(PlanState *) aggstate);
}
}
phasedata->aggnode = aggnode;
phasedata->aggstrategy = aggnode->aggstrategy;
phasedata->sortnode = sortnode;
}
}
i = -1;
while ((i = bms_next_member(all_grouped_cols, i)) >= 0)
aggstate->all_grouped_cols = lcons_int(i, aggstate->all_grouped_cols);
econtext = aggstate->ss.ps.ps_ExprContext;
//分配工作空间
econtext->ecxt_aggvalues = (Datum *) palloc0(sizeof(Datum) * numaggs);
econtext->ecxt_aggnulls = (bool *) palloc0(sizeof(bool) * numaggs);
peraggs = (AggStatePerAgg) palloc0(sizeof(AggStatePerAggData) * numaggs);
pertransstates = (AggStatePerTrans) palloc0(sizeof(AggStatePerTransData) * numaggs);
aggstate->peragg = peraggs;
aggstate->pertrans = pertransstates;
aggstate->all_pergroups =
(AggStatePerGroup *) palloc0(sizeof(AggStatePerGroup)
* (numGroupingSets + numHashes));
pergroups = aggstate->all_pergroups;
if (node->aggstrategy != AGG_HASHED)
{
//---------- 使用Group聚合
for (i = 0; i < numGroupingSets; i++)
{
pergroups[i] = (AggStatePerGroup) palloc0(sizeof(AggStatePerGroupData)
* numaggs);
}
aggstate->pergroups = pergroups;
pergroups += numGroupingSets;
}
if (use_hashing)
{
//指针数组,但不是结构体
aggstate->hash_pergroup = pergroups;
find_hash_columns(aggstate);
build_hash_table(aggstate);
aggstate->table_filled = false;
}
if (node->aggstrategy == AGG_HASHED)
{
//Hashing
aggstate->current_phase = 0;
initialize_phase(aggstate, 0);
select_current_set(aggstate, 0, true);
}
else
{
//非Hashing
aggstate->current_phase = 1;
initialize_phase(aggstate, 1);
select_current_set(aggstate, 0, false);
}
aggno = -1;
transno = -1;
foreach(l, aggstate->aggs)
{
AggrefExprState *aggrefstate = (AggrefExprState *) lfirst(l);
Aggref *aggref = aggrefstate->aggref;
AggStatePerAgg peragg;
AggStatePerTrans pertrans;
int existing_aggno;
int existing_transno;
List *same_input_transnos;
Oid inputTypes[FUNC_MAX_ARGS];
int numArguments;
int numDirectArgs;
HeapTuple aggTuple;
Form_pg_aggregate aggform;
AclResult aclresult;
Oid transfn_oid,
finalfn_oid;
bool shareable;
Oid serialfn_oid,
deserialfn_oid;
Expr *finalfnexpr;
Oid aggtranstype;
Datum textInitVal;
Datum initValue;
bool initValueIsNull;
//规划器已为聚合分配了合适的层次
Assert(aggref->agglevelsup == 0);
//拆分模式需要匹配
Assert(aggref->aggsplit == aggstate->aggsplit);
// 1.检查已完成的aggs是否可以重用.
existing_aggno = find_compatible_peragg(aggref, aggstate, aggno,
&same_input_transnos);
if (existing_aggno != -1)
{
aggrefstate->aggno = existing_aggno;
continue;
}
//为Aggref状态节点分配结果数组中的位置索引
peragg = &peraggs[++aggno];
peragg->aggref = aggref;
aggrefstate->aggno = aggno;
//提前pg_aggregate中的行(获取聚合函数信息)
aggTuple = SearchSysCache1(AGGFNOID,
ObjectIdGetDatum(aggref->aggfnoid));
if (!HeapTupleIsValid(aggTuple))
elog(ERROR, "cache lookup failed for aggregate %u",
aggref->aggfnoid);
//转换为相应的数据结构
aggform = (Form_pg_aggregate) GETSTRUCT(aggTuple);
//检查访问权限
aclresult = pg_proc_aclcheck(aggref->aggfnoid, GetUserId(),
ACL_EXECUTE);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, OBJECT_AGGREGATE,
get_func_name(aggref->aggfnoid));
//调用InvokeFunctionExecuteHook
InvokeFunctionExecuteHook(aggref->aggfnoid);
//规划器在Aggref中记录转换状态类型
aggtranstype = aggref->aggtranstype;
Assert(OidIsValid(aggtranstype));
if (DO_AGGSPLIT_COMBINE(aggstate->aggsplit))
{
transfn_oid = aggform->aggcombinefn;
//如果没有设置,会报错
if (!OidIsValid(transfn_oid))
elog(ERROR, "combinefn not set for aggregate function");
}
else
transfn_oid = aggform->aggtransfn;
//在最后处理聚合时才需要Final function
if (DO_AGGSPLIT_SKIPFINAL(aggstate->aggsplit))
peragg->finalfn_oid = finalfn_oid = InvalidOid;
else
peragg->finalfn_oid = finalfn_oid = aggform->aggfinalfn;
shareable = (aggform->aggfinalmodify != AGGMODIFY_READ_WRITE) ||
(finalfn_oid == InvalidOid);
peragg->shareable = shareable;
serialfn_oid = InvalidOid;
deserialfn_oid = InvalidOid;
if (aggtranstype == INTERNALOID)
{
if (DO_AGGSPLIT_SERIALIZE(aggstate->aggsplit))
{
//在没有运行finalfn的情况下序列化才有效
Assert(DO_AGGSPLIT_SKIPFINAL(aggstate->aggsplit));
if (!OidIsValid(aggform->aggserialfn))
elog(ERROR, "serialfunc not provided for serialization aggregation");
serialfn_oid = aggform->aggserialfn;
}
//反序列化
if (DO_AGGSPLIT_DESERIALIZE(aggstate->aggsplit))
{
//在组合状态时才有效
Assert(DO_AGGSPLIT_COMBINE(aggstate->aggsplit));
if (!OidIsValid(aggform->aggdeserialfn))
elog(ERROR, "deserialfunc not provided for deserialization aggregation");
deserialfn_oid = aggform->aggdeserialfn;
}
}
//检查聚合宿主有权限调用相应的函数
{
HeapTuple procTuple;
Oid aggOwner;
procTuple = SearchSysCache1(PROCOID,
ObjectIdGetDatum(aggref->aggfnoid));
if (!HeapTupleIsValid(procTuple))
elog(ERROR, "cache lookup failed for function %u",
aggref->aggfnoid);
aggOwner = ((Form_pg_proc) GETSTRUCT(procTuple))->proowner;
ReleaseSysCache(procTuple);
aclresult = pg_proc_aclcheck(transfn_oid, aggOwner,
ACL_EXECUTE);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, OBJECT_FUNCTION,
get_func_name(transfn_oid));
InvokeFunctionExecuteHook(transfn_oid);
if (OidIsValid(finalfn_oid))
{
aclresult = pg_proc_aclcheck(finalfn_oid, aggOwner,
ACL_EXECUTE);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, OBJECT_FUNCTION,
get_func_name(finalfn_oid));
InvokeFunctionExecuteHook(finalfn_oid);
}
if (OidIsValid(serialfn_oid))
{
aclresult = pg_proc_aclcheck(serialfn_oid, aggOwner,
ACL_EXECUTE);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, OBJECT_FUNCTION,
get_func_name(serialfn_oid));
InvokeFunctionExecuteHook(serialfn_oid);
}
if (OidIsValid(deserialfn_oid))
{
aclresult = pg_proc_aclcheck(deserialfn_oid, aggOwner,
ACL_EXECUTE);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, OBJECT_FUNCTION,
get_func_name(deserialfn_oid));
InvokeFunctionExecuteHook(deserialfn_oid);
}
}
numArguments = get_aggregate_argtypes(aggref, inputTypes);
//计算"direct"参数类型
numDirectArgs = list_length(aggref->aggdirectargs);
//检查有多少参数传递给finalfn
if (aggform->aggfinalextra)
peragg->numFinalArgs = numArguments + 1;
else
peragg->numFinalArgs = numDirectArgs + 1;
//初始化所有直接参数表达式
peragg->aggdirectargs = ExecInitExprList(aggref->aggdirectargs,
(PlanState *) aggstate);
if (OidIsValid(finalfn_oid))
{
build_aggregate_finalfn_expr(inputTypes,
peragg->numFinalArgs,
aggtranstype,
aggref->aggtype,
aggref->inputcollid,
finalfn_oid,
&finalfnexpr);
fmgr_info(finalfn_oid, &peragg->finalfn);
fmgr_info_set_expr((Node *) finalfnexpr, &peragg->finalfn);
}
//获取输出值数据类型的相关信息.
get_typlenbyval(aggref->aggtype,
&peragg->resulttypeLen,
&peragg->resulttypeByVal);
textInitVal = SysCacheGetAttr(AGGFNOID, aggTuple,
Anum_pg_aggregate_agginitval,
&initValueIsNull);
if (initValueIsNull)
initValue = (Datum) 0;
else
initValue = GetAggInitVal(textInitVal, aggtranstype);
existing_transno = find_compatible_pertrans(aggstate, aggref,
shareable,
transfn_oid, aggtranstype,
serialfn_oid, deserialfn_oid,
initValue, initValueIsNull,
same_input_transnos);
if (existing_transno != -1)
{
pertrans = &pertransstates[existing_transno];
pertrans->aggshared = true;
peragg->transno = existing_transno;
}
else
{
pertrans = &pertransstates[++transno];
build_pertrans_for_aggref(pertrans, aggstate, estate,
aggref, transfn_oid, aggtranstype,
serialfn_oid, deserialfn_oid,
initValue, initValueIsNull,
inputTypes, numArguments);
peragg->transno = transno;
}
ReleaseSysCache(aggTuple);
}
aggstate->numaggs = aggno + 1;
aggstate->numtrans = transno + 1;
if (numaggs != list_length(aggstate->aggs))
ereport(ERROR,
(errcode(ERRCODE_GROUPING_ERROR),
errmsg("aggregate function calls cannot be nested")));
for (phaseidx = 0; phaseidx < aggstate->numphases; phaseidx++)
{
AggStatePerPhase phase = &aggstate->phases[phaseidx];
bool dohash = false;
bool dosort = false;
//第一阶段可能不存在
if (!phase->aggnode)
continue;
if (aggstate->aggstrategy == AGG_MIXED && phaseidx == 1)
{
dohash = true;
dosort = true;
}
else if (aggstate->aggstrategy == AGG_MIXED && phaseidx == 0)
{
continue;
}
else if (phase->aggstrategy == AGG_PLAIN ||
phase->aggstrategy == AGG_SORTED)
{
dohash = false;
dosort = true;
}
else if (phase->aggstrategy == AGG_HASHED)
{
dohash = true;
dosort = false;
}
else
Assert(false);
phase->evaltrans = ExecBuildAggTrans(aggstate, phase, dosort, dohash);
}
return aggstate;
}
三、跟踪分析
测试脚本
//禁用并行
testdb=# set max_parallel_workers_per_gather=0;
SET
testdb=# explain verbose select bh,avg(c1),min(c1),max(c2) from t_agg group by bh;
QUERY PLAN
---------------------------------------------------------------------------
HashAggregate (cost=13677.00..13677.06 rows=5 width=45)
Output: bh, avg(c1), min(c1), max(c2)
Group Key: t_agg.bh
-> Seq Scan on public.t_agg (cost=0.00..8677.00 rows=500000 width=13)
Output: bh, c1, c2, c3, c4, c5, c6
(5 rows)
跟踪分析
(gdb) b ExecInitAgg
Breakpoint 1 at 0x6eefc9: file nodeAgg.c, line 2096.
(gdb) c
Continuing.
Breakpoint 1, ExecInitAgg (node=0x2d903a0, estate=0x2d52428, eflags=16) at nodeAgg.c:2096
2096 Bitmapset *all_grouped_cols = NULL;
(gdb)
输入参数
(gdb) p *node
$1 = {plan = {type = T_Agg, startup_cost = 13677, total_cost = 13677.0625, plan_rows = 5, plan_width = 45,
parallel_aware = false, parallel_safe = false, plan_node_id = 0, targetlist = 0x2d631f8, qual = 0x0,
lefttree = 0x2d62cb8, righttree = 0x0, initPlan = 0x0, extParam = 0x0, allParam = 0x0}, aggstrategy = AGG_HASHED,
aggsplit = AGGSPLIT_SIMPLE, numCols = 1, grpColIdx = 0x2d62fa8, grpOperators = 0x2d62f88, numGroups = 5, aggParams = 0x0,
groupingSets = 0x0, chain = 0x0}
(gdb) p *estate
$2 = {type = T_EState, es_direction = ForwardScanDirection, es_snapshot = 0x2d00b80, es_crosscheck_snapshot = 0x0,
es_range_table = 0x2d62ff0, es_plannedstmt = 0x2c72530,
es_sourceText = 0x2c70d78 "select bh,avg(c1),min(c1),max(c2) from t_agg group by bh;", es_junkFilter = 0x0,
es_output_cid = 0, es_result_relations = 0x0, es_num_result_relations = 0, es_result_relation_info = 0x0,
es_root_result_relations = 0x0, es_num_root_result_relations = 0, es_tuple_routing_result_relations = 0x0,
es_trig_target_relations = 0x0, es_trig_tuple_slot = 0x0, es_trig_oldtup_slot = 0x0, es_trig_newtup_slot = 0x0,
es_param_list_info = 0x0, es_param_exec_vals = 0x0, es_queryEnv = 0x0, es_query_cxt = 0x2d52310, es_tupleTable = 0x0,
es_rowMarks = 0x0, es_processed = 0, es_lastoid = 0, es_top_eflags = 16, es_instrument = 0, es_finished = false,
es_exprcontexts = 0x0, es_subplanstates = 0x0, es_auxmodifytables = 0x0, es_per_tuple_exprcontext = 0x0,
es_epqTuple = 0x0, es_epqTupleSet = 0x0, es_epqScanDone = 0x0, es_use_parallel_mode = false, es_query_dsa = 0x0,
es_jit_flags = 0, es_jit = 0x0, es_jit_worker_instr = 0x0}
(gdb)
使用Hash算法计算
(gdb) n
2097 int numGroupingSets = 1;
(gdb)
2100 int i = 0;
(gdb)
2101 int j = 0;
(gdb)
2102 bool use_hashing = (node->aggstrategy == AGG_HASHED ||
(gdb)
2106 Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
(gdb) p use_hashing
$3 = true
(gdb)
1.初始化AggState结构体
(gdb) n
2111 aggstate = makeNode(AggState);
(gdb)
2112 aggstate->ss.ps.plan = (Plan *) node;
(gdb)
2113 aggstate->ss.ps.state = estate;
(gdb)
2114 aggstate->ss.ps.ExecProcNode = ExecAgg;
(gdb)
2116 aggstate->aggs = NIL;
(gdb)
2117 aggstate->numaggs = 0;
(gdb)
2118 aggstate->numtrans = 0;
(gdb)
2119 aggstate->aggstrategy = node->aggstrategy;
(gdb)
2120 aggstate->aggsplit = node->aggsplit;
(gdb)
2121 aggstate->maxsets = 0;
(gdb)
2122 aggstate->projected_set = -1;
(gdb)
2123 aggstate->current_set = 0;
(gdb)
2124 aggstate->peragg = NULL;
(gdb)
2125 aggstate->pertrans = NULL;
(gdb)
2126 aggstate->curperagg = NULL;
(gdb)
2127 aggstate->curpertrans = NULL;
(gdb)
2128 aggstate->input_done = false;
(gdb)
2129 aggstate->agg_done = false;
(gdb)
2130 aggstate->pergroups = NULL;
(gdb)
2131 aggstate->grp_firstTuple = NULL;
(gdb)
2132 aggstate->sort_in = NULL;
(gdb)
2133 aggstate->sort_out = NULL;
(gdb)
(gdb) p *aggstate
$4 = {ss = {ps = {type = T_AggState, plan = 0x2d903a0, state = 0x2d52428, ExecProcNode = 0x6ee438 <ExecAgg>,
ExecProcNodeReal = 0x0, instrument = 0x0, worker_instrument = 0x0, worker_jit_instrument = 0x0, qual = 0x0,
lefttree = 0x0, righttree = 0x0, initPlan = 0x0, subPlan = 0x0, chgParam = 0x0, ps_ResultTupleSlot = 0x0,
ps_ExprContext = 0x0, ps_ProjInfo = 0x0, scandesc = 0x0}, ss_currentRelation = 0x0, ss_currentScanDesc = 0x0,
ss_ScanTupleSlot = 0x0}, aggs = 0x0, numaggs = 0, numtrans = 0, aggstrategy = AGG_HASHED, aggsplit = AGGSPLIT_SIMPLE,
phase = 0x0, numphases = 0, current_phase = 0, peragg = 0x0, pertrans = 0x0, hashcontext = 0x0, aggcontexts = 0x0,
tmpcontext = 0x0, curaggcontext = 0x0, curperagg = 0x0, curpertrans = 0x0, input_done = false, agg_done = false,
projected_set = -1, current_set = 0, grouped_cols = 0x0, all_grouped_cols = 0x0, maxsets = 0, phases = 0x0,
sort_in = 0x0, sort_out = 0x0, sort_slot = 0x0, pergroups = 0x0, grp_firstTuple = 0x0, table_filled = false,
num_hashes = 0, perhash = 0x0, hash_pergroup = 0x0, all_pergroups = 0x0, combinedproj = 0x0}
(gdb)
2.计算分为几个阶段(Hash vs Group)
(gdb)
2138 numPhases = (use_hashing ? 1 : 2);
(gdb) p numPhases
$5 = 1
(gdb) p numHashes
$6 = 1
(gdb)
Hash只需要一个阶段,执行Hash
3.如存在grouping set,则初始化相关信息
(gdb) n
2168 aggstate->maxsets = numGroupingSets;
这里没有grouping set,不需要初始化相关信息
4.分配内存上下文
(gdb)
2169 aggstate->numphases = numPhases;
(gdb)
2172 palloc0(sizeof(ExprContext *) * numGroupingSets);
(gdb)
2171 aggstate->aggcontexts = (ExprContext **)
(gdb)
2188 ExecAssignExprContext(estate, &aggstate->ss.ps);
(gdb)
2189 aggstate->tmpcontext = aggstate->ss.ps.ps_ExprContext;
(gdb)
2191 for (i = 0; i < numGroupingSets; ++i)
(gdb)
2193 ExecAssignExprContext(estate, &aggstate->ss.ps);
(gdb)
2194 aggstate->aggcontexts[i] = aggstate->ss.ps.ps_ExprContext;
(gdb)
2191 for (i = 0; i < numGroupingSets; ++i)
(gdb)
2197 if (use_hashing)
(gdb)
2199 ExecAssignExprContext(estate, &aggstate->ss.ps);
(gdb)
2200 aggstate->hashcontext = aggstate->ss.ps.ps_ExprContext;
(gdb)
2203 ExecAssignExprContext(estate, &aggstate->ss.ps);
(gdb)
2211 if (node->aggstrategy == AGG_HASHED)
(gdb)
2212 eflags &= ~EXEC_FLAG_REWIND;
(gdb)
5.初始化outer plan子节点
(gdb)
2213 outerPlan = outerPlan(node);
(gdb) n
2214 outerPlanState(aggstate) = ExecInitNode(outerPlan, estate, eflags);
(gdb) p *outerPlan
$7 = {type = T_SeqScan, startup_cost = 0, total_cost = 8677, plan_rows = 500000, plan_width = 13, parallel_aware = false,
parallel_safe = false, plan_node_id = 1, targetlist = 0x2d62770, qual = 0x0, lefttree = 0x0, righttree = 0x0,
initPlan = 0x0, extParam = 0x0, allParam = 0x0}
outer(左树)节点为SeqScan,顺序全表扫描.
6.初始化结果类型,slot和投影
(gdb) n
2219 ExecCreateScanSlotFromOuterPlan(estate, &aggstate->ss);
(gdb) n
2220 scanDesc = aggstate->ss.ss_ScanTupleSlot->tts_tupleDescriptor;
(gdb) n
2221 if (node->chain)
(gdb) p *aggstate
$8 = {ss = {ps = {type = T_AggState, plan = 0x2d903a0, state = 0x2d52428, ExecProcNode = 0x6ee438 <ExecAgg>,
ExecProcNodeReal = 0x0, instrument = 0x0, worker_instrument = 0x0, worker_jit_instrument = 0x0, qual = 0x0,
lefttree = 0x2d52bb0, righttree = 0x0, initPlan = 0x0, subPlan = 0x0, chgParam = 0x0, ps_ResultTupleSlot = 0x0,
ps_ExprContext = 0x2d52af0, ps_ProjInfo = 0x0, scandesc = 0x2d52f00}, ss_currentRelation = 0x0,
ss_currentScanDesc = 0x0, ss_ScanTupleSlot = 0x2d53458}, aggs = 0x0, numaggs = 0, numtrans = 0,
aggstrategy = AGG_HASHED, aggsplit = AGGSPLIT_SIMPLE, phase = 0x0, numphases = 1, current_phase = 0, peragg = 0x0,
pertrans = 0x0, hashcontext = 0x2d52a30, aggcontexts = 0x2d52858, tmpcontext = 0x2d52878, curaggcontext = 0x0,
curperagg = 0x0, curpertrans = 0x0, input_done = false, agg_done = false, projected_set = -1, current_set = 0,
grouped_cols = 0x0, all_grouped_cols = 0x0, maxsets = 1, phases = 0x0, sort_in = 0x0, sort_out = 0x0, sort_slot = 0x0,
pergroups = 0x0, grp_firstTuple = 0x0, table_filled = false, num_hashes = 0, perhash = 0x0, hash_pergroup = 0x0,
all_pergroups = 0x0, combinedproj = 0x0}
(gdb)
(gdb) p *scanDesc
$9 = {natts = 7, tdtypeid = 2249, tdtypmod = -1, tdhasoid = false, tdrefcount = -1, constr = 0x0, attrs = 0x2d52f20}
(gdb) p *aggstate->ss.ps.scandesc
$10 = {natts = 7, tdtypeid = 2249, tdtypmod = -1, tdhasoid = false, tdrefcount = -1, constr = 0x0, attrs = 0x2d52f20}
(gdb)
(gdb) n
2227 ExecInitResultTupleSlotTL(estate, &aggstate->ss.ps);
(gdb)
2228 ExecAssignProjectionInfo(&aggstate->ss.ps, NULL);
(gdb)
2244 ExecInitQual(node->plan.qual, (PlanState *) aggstate);
(gdb) p *aggstate
$11 = {ss = {ps = {type = T_AggState, plan = 0x2d903a0, state = 0x2d52428, ExecProcNode = 0x6ee438 <ExecAgg>,
ExecProcNodeReal = 0x0, instrument = 0x0, worker_instrument = 0x0, worker_jit_instrument = 0x0, qual = 0x0,
lefttree = 0x2d52bb0, righttree = 0x0, initPlan = 0x0, subPlan = 0x0, chgParam = 0x0, ps_ResultTupleSlot = 0x2d537b0,
ps_ExprContext = 0x2d52af0, ps_ProjInfo = 0x2d538f0, scandesc = 0x2d52f00}, ss_currentRelation = 0x0,
ss_currentScanDesc = 0x0, ss_ScanTupleSlot = 0x2d53458}, aggs = 0x2d53e00, numaggs = 3, numtrans = 0,
aggstrategy = AGG_HASHED, aggsplit = AGGSPLIT_SIMPLE, phase = 0x0, numphases = 1, current_phase = 0, peragg = 0x0,
pertrans = 0x0, hashcontext = 0x2d52a30, aggcontexts = 0x2d52858, tmpcontext = 0x2d52878, curaggcontext = 0x0,
curperagg = 0x0, curpertrans = 0x0, input_done = false, agg_done = false, projected_set = -1, current_set = 0,
grouped_cols = 0x0, all_grouped_cols = 0x0, maxsets = 1, phases = 0x0, sort_in = 0x0, sort_out = 0x0, sort_slot = 0x0,
pergroups = 0x0, grp_firstTuple = 0x0, table_filled = false, num_hashes = 0, perhash = 0x0, hash_pergroup = 0x0,
all_pergroups = 0x0, combinedproj = 0x0}
(gdb) p *aggstate->ss.ps.scandesc
$12 = {natts = 7, tdtypeid = 2249, tdtypmod = -1, tdhasoid = false, tdrefcount = -1, constr = 0x0, attrs = 0x2d52f20}
#### 结果元组Slot
(gdb) p *aggstate->ss.ps.ps_ResultTupleSlot
$13 = {type = T_TupleTableSlot, tts_isempty = true, tts_shouldFree = false, tts_shouldFreeMin = false, tts_slow = false,
tts_tuple = 0x0, tts_tupleDescriptor = 0x2d53598, tts_mcxt = 0x2d52310, tts_buffer = 0, tts_nvalid = 0,
tts_values = 0x2d53810, tts_isnull = 0x2d53830, tts_mintuple = 0x0, tts_minhdr = {t_len = 0, t_self = {ip_blkid = {
bi_hi = 0, bi_lo = 0}, ip_posid = 0}, t_tableOid = 0, t_data = 0x0}, tts_off = 0, tts_fixedTupleDescriptor = true}
### 投影信息
(gdb) p *aggstate->ss.ps.ps_ProjInfo
$14 = {type = T_ProjectionInfo, pi_state = {tag = {type = T_ExprState}, flags = 6 '\006', resnull = false, resvalue = 0,
resultslot = 0x2d537b0, steps = 0x2d53988, evalfunc = 0x6cd882 <ExecInterpExprStillValid>, expr = 0x2d631f8,
evalfunc_private = 0x6cb43e <ExecInterpExpr>, steps_len = 9, steps_alloc = 16, parent = 0x2d52640, ext_params = 0x0,
innermost_caseval = 0x0, innermost_casenull = 0x0, innermost_domainval = 0x0, innermost_domainnull = 0x0},
pi_exprContext = 0x2d52af0}
(gdb)
7.初始化子表达式
(gdb) n
2243 aggstate->ss.ps.qual =
(gdb)
2249 numaggs = aggstate->numaggs;
(gdb) p *aggstate->ss.ps.qual
Cannot access memory at address 0x0
(gdb)
(gdb) n
2250 Assert(numaggs == list_length(aggstate->aggs));
(gdb) p aggstate->numaggs
$16 = 3
表达式为NULL,一共有3个聚合函数
8.为AggStatePerPhaseData/AggStatePerHashData等结构体分配内存
(gdb) n
2256 aggstate->phases = palloc0(numPhases * sizeof(AggStatePerPhaseData));
(gdb)
2258 aggstate->num_hashes = numHashes;
(gdb)
2259 if (numHashes)
(gdb)
2261 aggstate->perhash = palloc0(sizeof(AggStatePerHashData) * numHashes);
(gdb)
2262 aggstate->phases[0].numsets = 0;
(gdb)
2263 aggstate->phases[0].gset_lengths = palloc(numHashes * sizeof(int));
(gdb) n
2264 aggstate->phases[0].grouped_cols = palloc(numHashes * sizeof(Bitmapset *));
(gdb)
2267 phase = 0;
(gdb)
(gdb) p aggstate->phases[0]
$17 = {aggstrategy = AGG_PLAIN, numsets = 0, gset_lengths = 0x2d5
9.循环遍历各个阶段
9.1计算分组列,存储在phasedata->grouped_cols数组和all_grouped_cols中
9.2初始化AggState->phases数组(数组元素对应的结构体为AggStatePerPhase)
9.3初始化AggState->perhash数组(对应的结构体为AggStatePerHash)
(gdb) n
2268 for (phaseidx = 0; phaseidx <= list_length(node->chain); ++phaseidx)
(gdb) p list_length(node->chain)
$18 = 0
(gdb) n
2273 if (phaseidx > 0)
(gdb)
2280 aggnode = node;
(gdb) p *node
$19 = {plan = {type = T_Agg, startup_cost = 13677, total_cost = 13677.0625, plan_rows = 5, plan_width = 45,
parallel_aware = false, parallel_safe = false, plan_node_id = 0, targetlist = 0x2d631f8, qual = 0x0,
lefttree = 0x2d62cb8, righttree = 0x0, initPlan = 0x0, extParam = 0x0, allParam = 0x0}, aggstrategy = AGG_HASHED,
aggsplit = AGGSPLIT_SIMPLE, numCols = 1, grpColIdx = 0x2d62fa8, grpOperators = 0x2d62f88, numGroups = 5, aggParams = 0x0,
groupingSets = 0x0, chain = 0x0}
(gdb) n
2281 sortnode = NULL;
(gdb)
2284 Assert(phase <= 1 || sortnode);
(gdb)
2286 if (aggnode->aggstrategy == AGG_HASHED
(gdb)
2289 AggStatePerPhase phasedata = &aggstate->phases[0];
(gdb)
2291 Bitmapset *cols = NULL;
(gdb)
2293 Assert(phase == 0);
(gdb)
2294 i = phasedata->numsets++;
(gdb)
2295 perhash = &aggstate->perhash[i];
(gdb)
2298 phasedata->aggnode = node;
(gdb) p *phasedata
$20 = {aggstrategy = AGG_PLAIN, numsets = 1, gset_lengths = 0x2d53fe8, grouped_cols = 0x2d54008, eqfunctions = 0x0,
aggnode = 0x0, sortnode = 0x0, evaltrans = 0x0}
(gdb) p i
$21 = 0
(gdb) n
2299 phasedata->aggstrategy = node->aggstrategy;
(gdb)
2302 perhash->aggnode = aggnode;
(gdb)
2304 phasedata->gset_lengths[i] = perhash->numCols = aggnode->numCols;
(gdb)
2306 for (j = 0; j < aggnode->numCols; ++j)
(gdb) p aggnode->numCols
$22 = 1
(gdb) n
2307 cols = bms_add_member(cols, aggnode->grpColIdx[j]);
(gdb)
2306 for (j = 0; j < aggnode->numCols; ++j)
(gdb)
2309 phasedata->grouped_cols[i] = cols;
(gdb) p cols
$23 = (Bitmapset *) 0x2d54028
(gdb) p *cols
$24 = {nwords = 1, words = 0x2d5402c}
(gdb) p *cols->words
$25 = 2
(gdb) n
2311 all_grouped_cols = bms_add_members(all_grouped_cols, cols);
(gdb)
2312 continue;
(gdb) p all_grouped_cols
$26 = (Bitmapset *) 0x2d54048
(gdb) p *all_grouped_cols
$27 = {nwords = 1, words = 0x2d5404c}
(gdb) p *all_grouped_cols->words
$28 = 2
(gdb) n
2268 for (phaseidx = 0; phaseidx <= list_length(node->chain); ++phaseidx)
(gdb)
2406 i = -1;
10.转换all_grouped_cols为倒序链表
2407 while ((i = bms_next_member(all_grouped_cols, i)) >= 0)
(gdb) p *all_grouped_cols
$29 = {nwords = 1, words = 0x2d5404c}
(gdb) n
2408 aggstate->all_grouped_cols = lcons_int(i, aggstate->all_grouped_cols);
(gdb)
2407 while ((i = bms_next_member(all_grouped_cols, i)) >= 0)
(gdb)
11.在输出expr上下文中设置aggregate-result存储,同时分配私有per-agg工作存储
(gdb)
2414 econtext = aggstate->ss.ps.ps_ExprContext;
(gdb)
2415 econtext->ecxt_aggvalues = (Datum *) palloc0(sizeof(Datum) * numaggs);
(gdb)
2416 econtext->ecxt_aggnulls = (bool *) palloc0(sizeof(bool) * numaggs);
(gdb)
2418 peraggs = (AggStatePerAgg) palloc0(sizeof(AggStatePerAggData) * numaggs);
(gdb)
2419 pertransstates = (AggStatePerTrans) palloc0(sizeof(AggStatePerTransData) * numaggs);
(gdb)
2421 aggstate->peragg = peraggs;
(gdb)
2422 aggstate->pertrans = pertransstates;
(gdb)
2427 * (numGroupingSets + numHashes));
(gdb)
2426 (AggStatePerGroup *) palloc0(sizeof(AggStatePerGroup)
(gdb)
2425 aggstate->all_pergroups =
(gdb)
2428 pergroups = aggstate->all_pergroups;
(gdb)
2430 if (node->aggstrategy != AGG_HASHED)
(gdb)
12.如使用Hash算法,则调用find_hash_columns和build_hash_table方法初始化相关数据
(gdb)
2445 if (use_hashing)
(gdb)
2448 aggstate->hash_pergroup = pergroups;
(gdb)
2450 find_hash_columns(aggstate);
(gdb)
2451 build_hash_table(aggstate);
(gdb)
2452 aggstate->table_filled = false;
(gdb)
2461 if (node->aggstrategy == AGG_HASHED)
(gdb) p *aggstate
$30 = {ss = {ps = {type = T_AggState, plan = 0x2d903a0, state = 0x2d52428, ExecProcNode = 0x6ee438 <ExecAgg>,
ExecProcNodeReal = 0x0, instrument = 0x0, worker_instrument = 0x0, worker_jit_instrument = 0x0, qual = 0x0,
lefttree = 0x2d52bb0, righttree = 0x0, initPlan = 0x0, subPlan = 0x0, chgParam = 0x0, ps_ResultTupleSlot = 0x2d537b0,
ps_ExprContext = 0x2d52af0, ps_ProjInfo = 0x2d538f0, scandesc = 0x2d52f00}, ss_currentRelation = 0x0,
ss_currentScanDesc = 0x0, ss_ScanTupleSlot = 0x2d53458}, aggs = 0x2d53e00, numaggs = 3, numtrans = 0,
aggstrategy = AGG_HASHED, aggsplit = AGGSPLIT_SIMPLE, phase = 0x0, numphases = 1, current_phase = 0, peragg = 0x2d54770,
pertrans = 0x2d56780, hashcontext = 0x2d52a30, aggcontexts = 0x2d52858, tmpcontext = 0x2d52878, curaggcontext = 0x0,
curperagg = 0x0, curpertrans = 0x0, input_done = false, agg_done = false, projected_set = -1, current_set = 0,
grouped_cols = 0x0, all_grouped_cols = 0x2d54090, maxsets = 1, phases = 0x2d53ef8, sort_in = 0x0, sort_out = 0x0,
sort_slot = 0x0, pergroups = 0x0, grp_firstTuple = 0x0, table_filled = false, num_hashes = 1, perhash = 0x2d53f50,
hash_pergroup = 0x2d54988, all_pergroups = 0x2d54988, combinedproj = 0x0}
(gdb) p *aggstate->perhash
$31 = {hashtable = 0x2d54ad8, hashiter = {cur = 0, end = 0, done = false}, hashslot = 0x2d54238, hashfunctions = 0x2d542d0,
eqfuncoids = 0x2d54a90, numCols = 1, numhashGrpCols = 1, largestGrpColIdx = 1, hashGrpColIdxInput = 0x2d549f0,
hashGrpColIdxHash = 0x2d54a10, aggnode = 0x2d903a0}
(gdb) p *aggstate->hash_pergroup
$32 = (AggStatePerGroup) 0x0
(gdb) p *aggstate->all_pergroups
$33 = (AggStatePerGroup) 0x0
(gdb) p *aggstate->phases
$34 = {aggstrategy = AGG_HASHED, numsets = 1, gset_lengths = 0x2d53fe8, grouped_cols = 0x2d54008, eqfunctions = 0x0,
aggnode = 0x2d903a0, sortnode = 0x0, evaltrans = 0x0}
(gdb)
13.调用initialize_phase/select_current_set初始化阶段数据
(gdb) n
2463 aggstate->current_phase = 0;
(gdb)
2464 initialize_phase(aggstate, 0);
(gdb)
2465 select_current_set(aggstate, 0, true);
(gdb)
2510 aggno = -1;
(gdb) p *aggstate->phases
$35 = {aggstrategy = AGG_HASHED, numsets = 1, gset_lengths = 0x2d53fe8, grouped_cols = 0x2d54008, eqfunctions = 0x0,
aggnode = 0x2d903a0, sortnode = 0x0, evaltrans = 0x0}
(gdb)
14.检索聚合函数信息,初始化per-agg和per-trans数据不可变字段
(gdb) n
2463 aggstate->current_phase = 0;
(gdb)
2464 initialize_phase(aggstate, 0);
(gdb)
2465 select_current_set(aggstate, 0, true);
(gdb)
2510 aggno = -1;
(gdb) p *aggstate->phases
$35 = {aggstrategy = AGG_HASHED, numsets = 1, gset_lengths = 0x2d53fe8, grouped_cols = 0x2d54008, eqfunctions = 0x0,
aggnode = 0x2d903a0, sortnode = 0x0, evaltrans = 0x0}
(gdb) n
2511 transno = -1;
(gdb)
2512 foreach(l, aggstate->aggs)
(gdb)
2514 AggrefExprState *aggrefstate = (AggrefExprState *) lfirst(l);
(gdb)
2515 Aggref *aggref = aggrefstate->aggref;
(gdb)
2539 Assert(aggref->agglevelsup == 0);
(gdb) p aggstate->aggs
$36 = (List *) 0x2d53e00
(gdb) p *aggstate->aggs
$37 = {type = T_List, length = 3, head = 0x2d53ed0, tail = 0x2d53dd8}
(gdb) n
2541 Assert(aggref->aggsplit == aggstate->aggsplit);
(gdb)
2544 existing_aggno = find_compatible_peragg(aggref, aggstate, aggno,
(gdb)
2546 if (existing_aggno != -1)
(gdb)
2557 peragg = &peraggs[++aggno];
(gdb)
2558 peragg->aggref = aggref;
(gdb)
2559 aggrefstate->aggno = aggno;
(gdb)
2563 ObjectIdGetDatum(aggref->aggfnoid));
(gdb)
2562 aggTuple = SearchSysCache1(AGGFNOID,
(gdb) p aggref->aggfnoid
$38 = 2116
(gdb) n
2564 if (!HeapTupleIsValid(aggTuple))
(gdb) p *aggTuple
$39 = {t_len = 96, t_self = {ip_blkid = {bi_hi = 0, bi_lo = 0}, ip_posid = 17}, t_tableOid = 2600, t_data = 0x7fa0c01f1630}
(gdb) p *aggTuple->t_data
$40 = {t_choice = {t_heap = {t_xmin = 1, t_xmax = 0, t_field3 = {t_cid = 0, t_xvac = 0}}, t_datum = {datum_len_ = 1,
datum_typmod = 0, datum_typeid = 0}}, t_ctid = {ip_blkid = {bi_hi = 0, bi_lo = 0}, ip_posid = 17}, t_infomask2 = 22,
t_infomask = 2305, t_hoff = 32 ' ', t_bits = 0x7fa0c01f1647 "\377\377\017"}
(gdb) n
2567 aggform = (Form_pg_aggregate) GETSTRUCT(aggTuple);
(gdb)
2570 aclresult = pg_proc_aclcheck(aggref->aggfnoid, GetUserId(),
(gdb) p *aggform
$41 = {aggfnoid = 2116, aggkind = 110 'n', aggnumdirectargs = 0, aggtransfn = 768, aggfinalfn = 0, aggcombinefn = 768,
aggserialfn = 0, aggdeserialfn = 0, aggmtransfn = 0, aggminvtransfn = 0, aggmfinalfn = 0, aggfinalextra = false,
aggmfinalextra = false, aggfinalmodify = 114 'r', aggmfinalmodify = 114 'r', aggsortop = 521, aggtranstype = 23,
aggtransspace = 0, aggmtranstype = 0, aggmtransspace = 0}
(gdb) n
2572 if (aclresult != ACLCHECK_OK)
(gdb)
2575 InvokeFunctionExecuteHook(aggref->aggfnoid);
(gdb)
2578 aggtranstype = aggref->aggtranstype;
(gdb)
2579 Assert(OidIsValid(aggtranstype));
(gdb)
2585 if (DO_AGGSPLIT_COMBINE(aggstate->aggsplit))
(gdb)
2594 transfn_oid = aggform->aggtransfn;
(gdb)
2597 if (DO_AGGSPLIT_SKIPFINAL(aggstate->aggsplit))
(gdb) p transfn_oid
$42 = 768
(gdb) n
2600 peragg->finalfn_oid = finalfn_oid = aggform->aggfinalfn;
(gdb)
2607 shareable = (aggform->aggfinalmodify != AGGMODIFY_READ_WRITE) ||
(gdb) p aggform->aggfinalfn
$43 = 0
(gdb) n
2609 peragg->shareable = shareable;
(gdb)
2611 serialfn_oid = InvalidOid;
(gdb) p shareable
$44 = true
(gdb) n
2612 deserialfn_oid = InvalidOid;
(gdb)
2618 if (aggtranstype == INTERNALOID)
(gdb)
2653 ObjectIdGetDatum(aggref->aggfnoid));
(gdb)
2652 procTuple = SearchSysCache1(PROCOID,
(gdb)
2654 if (!HeapTupleIsValid(procTuple))
(gdb)
2657 aggOwner = ((Form_pg_proc) GETSTRUCT(procTuple))->proowner;
(gdb)
2658 ReleaseSysCache(procTuple);
(gdb)
2660 aclresult = pg_proc_aclcheck(transfn_oid, aggOwner,
(gdb)
2662 if (aclresult != ACLCHECK_OK)
(gdb)
2665 InvokeFunctionExecuteHook(transfn_oid);
(gdb)
2666 if (OidIsValid(finalfn_oid))
(gdb)
2675 if (OidIsValid(serialfn_oid))
(gdb)
2684 if (OidIsValid(deserialfn_oid))
(gdb)
2700 numArguments = get_aggregate_argtypes(aggref, inputTypes);
(gdb)
2703 numDirectArgs = list_length(aggref->aggdirectargs);
(gdb)
2706 if (aggform->aggfinalextra)
(gdb)
2709 peragg->numFinalArgs = numDirectArgs + 1;
(gdb)
2712 peragg->aggdirectargs = ExecInitExprList(aggref->aggdirectargs,
(gdb)
2719 if (OidIsValid(finalfn_oid))
(gdb)
2733 get_typlenbyval(aggref->aggtype,
(gdb)
2741 textInitVal = SysCacheGetAttr(AGGFNOID, aggTuple,
(gdb)
2744 if (initValueIsNull)
(gdb)
2745 initValue = (Datum) 0;
(gdb)
2757 existing_transno = find_compatible_pertrans(aggstate, aggref,
(gdb)
2763 if (existing_transno != -1)
(gdb)
2775 pertrans = &pertransstates[++transno];
(gdb)
2776 build_pertrans_for_aggref(pertrans, aggstate, estate,
(gdb)
2781 peragg->transno = transno;
(gdb)
2783 ReleaseSysCache(aggTuple);
(gdb)
2512 foreach(l, aggstate->aggs)
(gdb)
########
testdb=# select oid,proname from pg_proc where oid in (2116,768);
oid | proname
------+------------
768 | int4larger
2116 | max
(2 rows)
########
下一个循环
...
(gdb) p *aggref
$45 = {xpr = {type = T_Aggref}, aggfnoid = 2132, aggtype = 23, aggcollid = 0, inputcollid = 0, aggtranstype = 23,
aggargtypes = 0x2d63578, aggdirectargs = 0x0, args = 0x2d63688, aggorder = 0x0, aggdistinct = 0x0, aggfilter = 0x0,
aggstar = false, aggvariadic = false, aggkind = 110 'n', agglevelsup = 0, aggsplit = AGGSPLIT_SIMPLE, location = 18}
...
(gdb) p transfn_oid
$49 = 769
...
testdb=# select oid,proname from pg_proc where oid in (2132,769);
oid | proname
------+-------------
769 | int4smaller
2132 | min
(2 rows)
第3遍循环
...
(gdb) p *aggref
$50 = {xpr = {type = T_Aggref}, aggfnoid = 2101, aggtype = 1700, aggcollid = 0, inputcollid = 0, aggtranstype = 1016,
aggargtypes = 0x2d632f0, aggdirectargs = 0x0, args = 0x2d63400, aggorder = 0x0, aggdistinct = 0x0, aggfilter = 0x0,
aggstar = false, aggvariadic = false, aggkind = 110 'n', agglevelsup = 0, aggsplit = AGGSPLIT_SIMPLE, location = 10}
...
(gdb) p transfn_oid
$51 = 1963
...
2512 foreach(l, aggstate->aggs)
(gdb)
#####
testdb=# select oid,proname from pg_proc where oid in (2101,1963);
oid | proname
------+----------------
1963 | int4_avg_accum
2101 | avg
(2 rows)
#####
15.构建一次就完成所有转换工作的表达式.
(gdb)
2790 aggstate->numaggs = aggno + 1;
(gdb)
2791 aggstate->numtrans = transno + 1;
(gdb)
2803 if (numaggs != list_length(aggstate->aggs))
(gdb)
2815 for (phaseidx = 0; phaseidx < aggstate->numphases; phaseidx++)
(gdb)
2817 AggStatePerPhase phase = &aggstate->phases[phaseidx];
(gdb)
2818 bool dohash = false;
(gdb)
2819 bool dosort = false;
(gdb)
2822 if (!phase->aggnode)
(gdb)
2825 if (aggstate->aggstrategy == AGG_MIXED && phaseidx == 1)
(gdb)
2834 else if (aggstate->aggstrategy == AGG_MIXED && phaseidx == 0)
(gdb)
2843 else if (phase->aggstrategy == AGG_PLAIN ||
(gdb)
2844 phase->aggstrategy == AGG_SORTED)
(gdb)
2843 else if (phase->aggstrategy == AGG_PLAIN ||
(gdb)
2849 else if (phase->aggstrategy == AGG_HASHED)
(gdb)
2851 dohash = true;
(gdb)
2852 dosort = false;
(gdb)
2857 phase->evaltrans = ExecBuildAggTrans(aggstate, phase, dosort, dohash);
(gdb)
2815 for (phaseidx = 0; phaseidx < aggstate->numphases; phaseidx++)
(gdb)
2861 return aggstate;
(gdb)
最终结果
AggState结构体
(gdb) p *aggstate
$52 = {ss = {ps = {type = T_AggState, plan = 0x2d903a0, state = 0x2d52428, ExecProcNode = 0x6ee438 <ExecAgg>,
ExecProcNodeReal = 0x0, instrument = 0x0, worker_instrument = 0x0, worker_jit_instrument = 0x0, qual = 0x0,
lefttree = 0x2d52bb0, righttree = 0x0, initPlan = 0x0, subPlan = 0x0, chgParam = 0x0, ps_ResultTupleSlot = 0x2d537b0,
ps_ExprContext = 0x2d52af0, ps_ProjInfo = 0x2d538f0, scandesc = 0x2d52f00}, ss_currentRelation = 0x0,
ss_currentScanDesc = 0x0, ss_ScanTupleSlot = 0x2d53458}, aggs = 0x2d53e00, numaggs = 3, numtrans = 3,
aggstrategy = AGG_HASHED, aggsplit = AGGSPLIT_SIMPLE, phase = 0x2d53ef8, numphases = 1, current_phase = 0,
peragg = 0x2d54770, pertrans = 0x2d56780, hashcontext = 0x2d52a30, aggcontexts = 0x2d52858, tmpcontext = 0x2d52878,
curaggcontext = 0x2d52a30, curperagg = 0x0, curpertrans = 0x0, input_done = false, agg_done = false, projected_set = -1,
current_set = 0, grouped_cols = 0x0, all_grouped_cols = 0x2d54090, maxsets = 1, phases = 0x2d53ef8, sort_in = 0x0,
sort_out = 0x0, sort_slot = 0x0, pergroups = 0x0, grp_firstTuple = 0x0, table_filled = false, num_hashes = 1,
perhash = 0x2d53f50, hash_pergroup = 0x2d54988, all_pergroups = 0x2d54988, combinedproj = 0x0}
AggState->phase
(gdb) p *aggstate->phase
$53 = {aggstrategy = AGG_HASHED, numsets = 1, gset_lengths = 0x2d53fe8, grouped_cols = 0x2d54008, eqfunctions = 0x0,
aggnode = 0x2d903a0, sortnode = 0x0, evaltrans = 0x2d55e78}
AggState->peragg
(gdb) p *aggstate->peragg
$54 = {aggref = 0x2d63740, transno = 0, finalfn_oid = 0, finalfn = {fn_addr = 0x0, fn_oid = 0, fn_nargs = 0,
fn_strict = false, fn_retset = false, fn_stats = 0 '\000', fn_extra = 0x0, fn_mcxt = 0x0, fn_expr = 0x0},
numFinalArgs = 1, aggdirectargs = 0x0, resulttypeLen = 4, resulttypeByVal = true, shareable = true}
(gdb) p *aggstate->peragg->aggref
$55 = {xpr = {type = T_Aggref}, aggfnoid = 2116, aggtype = 23, aggcollid = 0, inputcollid = 0, aggtranstype = 23,
aggargtypes = 0x2d63800, aggdirectargs = 0x0, args = 0x2d63910, aggorder = 0x0, aggdistinct = 0x0, aggfilter = 0x0,
aggstar = false, aggvariadic = false, aggkind = 110 'n', agglevelsup = 0, aggsplit = AGGSPLIT_SIMPLE, location = 26}
(gdb) p aggstate->peragg[1]
$56 = {aggref = 0x2d634b8, transno = 1, finalfn_oid = 0, finalfn = {fn_addr = 0x0, fn_oid = 0, fn_nargs = 0,
fn_strict = false, fn_retset = false, fn_stats = 0 '\000', fn_extra = 0x0, fn_mcxt = 0x0, fn_expr = 0x0},
numFinalArgs = 1, aggdirectargs = 0x0, resulttypeLen = 4, resulttypeByVal = true, shareable = true}
(gdb) p *aggstate->peragg[1]->aggref
$57 = {xpr = {type = T_Aggref}, aggfnoid = 2132, aggtype = 23, aggcollid = 0, inputcollid = 0, aggtranstype = 23,
aggargtypes = 0x2d63578, aggdirectargs = 0x0, args = 0x2d63688, aggorder = 0x0, aggdistinct = 0x0, aggfilter = 0x0,
aggstar = false, aggvariadic = false, aggkind = 110 'n', agglevelsup = 0, aggsplit = AGGSPLIT_SIMPLE, location = 18}
(gdb) p aggstate->peragg[2]
$58 = {aggref = 0x2d63230, transno = 2, finalfn_oid = 1964, finalfn = {fn_addr = 0x978251 <int8_avg>, fn_oid = 1964,
fn_nargs = 1, fn_strict = true, fn_retset = false, fn_stats = 2 '\002', fn_extra = 0x0, fn_mcxt = 0x2d52310,
fn_expr = 0x2d55b80}, numFinalArgs = 1, aggdirectargs = 0x0, resulttypeLen = -1, resulttypeByVal = false,
shareable = true}
(gdb) p *aggstate->peragg[2]->aggref
$59 = {xpr = {type = T_Aggref}, aggfnoid = 2101, aggtype = 1700, aggcollid = 0, inputcollid = 0, aggtranstype = 1016,
aggargtypes = 0x2d632f0, aggdirectargs = 0x0, args = 0x2d63400, aggorder = 0x0, aggdistinct = 0x0, aggfilter = 0x0,
aggstar = false, aggvariadic = false, aggkind = 110 'n', agglevelsup = 0, aggsplit = AGGSPLIT_SIMPLE, location = 10}
AggState->pertrans
(gdb) p aggstate->pertrans[0]
$60 = {aggref = 0x2d63740, aggshared = false, numInputs = 1, numTransInputs = 1, transfn_oid = 768, serialfn_oid = 0,
deserialfn_oid = 0, aggtranstype = 23, transfn = {fn_addr = 0x93e877 <int4larger>, fn_oid = 768, fn_nargs = 2,
fn_strict = true, fn_retset = false, fn_stats = 2 '\002', fn_extra = 0x0, fn_mcxt = 0x2d52310, fn_expr = 0x2d55940},
serialfn = {fn_addr = 0x0, fn_oid = 0, fn_nargs = 0, fn_strict = false, fn_retset = false, fn_stats = 0 '\000',
fn_extra = 0x0, fn_mcxt = 0x0, fn_expr = 0x0}, deserialfn = {fn_addr = 0x0, fn_oid = 0, fn_nargs = 0,
fn_strict = false, fn_retset = false, fn_stats = 0 '\000', fn_extra = 0x0, fn_mcxt = 0x0, fn_expr = 0x0},
aggCollation = 0, numSortCols = 0, numDistinctCols = 0, sortColIdx = 0x0, sortOperators = 0x0, sortCollations = 0x0,
sortNullsFirst = 0x0, equalfnOne = {fn_addr = 0x0, fn_oid = 0, fn_nargs = 0, fn_strict = false, fn_retset = false,
fn_stats = 0 '\000', fn_extra = 0x0, fn_mcxt = 0x0, fn_expr = 0x0}, equalfnMulti = 0x0, initValue = 0,
initValueIsNull = true, inputtypeLen = 0, transtypeLen = 4, inputtypeByVal = false, transtypeByVal = true,
sortslot = 0x0, uniqslot = 0x0, sortdesc = 0x0, sortstates = 0x2d549b0, transfn_fcinfo = {flinfo = 0x2d567a8,
context = 0x2d52640, resultinfo = 0x0, fncollation = 0, isnull = false, nargs = 2, arg = {0 <repeats 100 times>},
argnull = {false <repeats 100 times>}}, serialfn_fcinfo = {flinfo = 0x0, context = 0x0, resultinfo = 0x0,
fncollation = 0, isnull = false, nargs = 0, arg = {0 <repeats 100 times>}, argnull = {false <repeats 100 times>}},
deserialfn_fcinfo = {flinfo = 0x0, context = 0x0, resultinfo = 0x0, fncollation = 0, isnull = false, nargs = 0, arg = {
0 <repeats 100 times>}, argnull = {false <repeats 100 times>}}}
(gdb) p aggstate->pertrans[1]
$61 = {aggref = 0x2d634b8, aggshared = false, numInputs = 1, numTransInputs = 1, transfn_oid = 769, serialfn_oid = 0,
deserialfn_oid = 0, aggtranstype = 23, transfn = {fn_addr = 0x93e8a3 <int4smaller>, fn_oid = 769, fn_nargs = 2,
fn_strict = true, fn_retset = false, fn_stats = 2 '\002', fn_extra = 0x0, fn_mcxt = 0x2d52310, fn_expr = 0x2d55a90},
serialfn = {fn_addr = 0x0, fn_oid = 0, fn_nargs = 0, fn_strict = false, fn_retset = false, fn_stats = 0 '\000',
fn_extra = 0x0, fn_mcxt = 0x0, fn_expr = 0x0}, deserialfn = {fn_addr = 0x0, fn_oid = 0, fn_nargs = 0,
fn_strict = false, fn_retset = false, fn_stats = 0 '\000', fn_extra = 0x0, fn_mcxt = 0x0, fn_expr = 0x0},
aggCollation = 0, numSortCols = 0, numDistinctCols = 0, sortColIdx = 0x0, sortOperators = 0x0, sortCollations = 0x0,
sortNullsFirst = 0x0, equalfnOne = {fn_addr = 0x0, fn_oid = 0, fn_nargs = 0, fn_strict = false, fn_retset = false,
fn_stats = 0 '\000', fn_extra = 0x0, fn_mcxt = 0x0, fn_expr = 0x0}, equalfnMulti = 0x0, initValue = 0,
initValueIsNull = true, inputtypeLen = 0, transtypeLen = 4, inputtypeByVal = false, transtypeByVal = true,
sortslot = 0x0, uniqslot = 0x0, sortdesc = 0x0, sortstates = 0x2d549d0, transfn_fcinfo = {flinfo = 0x2d573f0,
context = 0x2d52640, resultinfo = 0x0, fncollation = 0, isnull = false, nargs = 2, arg = {0 <repeats 100 times>},
argnull = {false <repeats 100 times>}}, serialfn_fcinfo = {flinfo = 0x0, context = 0x0, resultinfo = 0x0,
fncollation = 0, isnull = false, nargs = 0, arg = {0 <repeats 100 times>}, argnull = {false <repeats 100 times>}},
deserialfn_fcinfo = {flinfo = 0x0, context = 0x0, resultinfo = 0x0, fncollation = 0, isnull = false, nargs = 0, arg = {
0 <repeats 100 times>}, argnull = {false <repeats 100 times>}}}
(gdb) p aggstate->pertrans[2]
$62 = {aggref = 0x2d63230, aggshared = false, numInputs = 1, numTransInputs = 1, transfn_oid = 1963, serialfn_oid = 0,
deserialfn_oid = 0, aggtranstype = 1016, transfn = {fn_addr = 0x977d8f <int4_avg_accum>, fn_oid = 1963, fn_nargs = 2,
fn_strict = true, fn_retset = false, fn_stats = 2 '\002', fn_extra = 0x0, fn_mcxt = 0x2d52310, fn_expr = 0x2d55e20},
serialfn = {fn_addr = 0x0, fn_oid = 0, fn_nargs = 0, fn_strict = false, fn_retset = false, fn_stats = 0 '\000',
fn_extra = 0x0, fn_mcxt = 0x0, fn_expr = 0x0}, deserialfn = {fn_addr = 0x0, fn_oid = 0, fn_nargs = 0,
fn_strict = false, fn_retset = false, fn_stats = 0 '\000', fn_extra = 0x0, fn_mcxt = 0x0, fn_expr = 0x0},
aggCollation = 0, numSortCols = 0, numDistinctCols = 0, sortColIdx = 0x0, sortOperators = 0x0, sortCollations = 0x0,
sortNullsFirst = 0x0, equalfnOne = {fn_addr = 0x0, fn_oid = 0, fn_nargs = 0, fn_strict = false, fn_retset = false,
fn_stats = 0 '\000', fn_extra = 0x0, fn_mcxt = 0x0, fn_expr = 0x0}, equalfnMulti = 0x0, initValue = 47537400,
initValueIsNull = false, inputtypeLen = 0, transtypeLen = -1, inputtypeByVal = false, transtypeByVal = false,
sortslot = 0x0, uniqslot = 0x0, sortdesc = 0x0, sortstates = 0x2d55bd8, transfn_fcinfo = {flinfo = 0x2d58038,
context = 0x2d52640, resultinfo = 0x0, fncollation = 0, isnull = false, nargs = 2, arg = {0 <repeats 100 times>},
argnull = {false <repeats 100 times>}}, serialfn_fcinfo = {flinfo = 0x0, context = 0x0, resultinfo = 0x0,
fncollation = 0, isnull = false, nargs = 0, arg = {0 <repeats 100 times>}, argnull = {false <repeats 100 times>}},
deserialfn_fcinfo = {flinfo = 0x0, context = 0x0, resultinfo = 0x0, fncollation = 0, isnull = false, nargs = 0, arg = {
0 <repeats 100 times>}, argnull = {false <repeats 100 times>}}}
AggState->groups相关
(gdb) p *aggstate->pergroups
Cannot access memory at address 0x0
(gdb) p *aggstate->hash_pergroup
$65 = (AggStatePerGroup) 0x0
(gdb) p *aggstate->all_pergroups
$66 = (AggStatePerGroup) 0x0
AggState->perhash
(gdb) p *aggstate->perhash
$67 = {hashtable = 0x2d54ad8, hashiter = {cur = 0, end = 0, done = false}, hashslot = 0x2d54238, hashfunctions = 0x2d542d0,
eqfuncoids = 0x2d54a90, numCols = 1, numhashGrpCols = 1, largestGrpColIdx = 1, hashGrpColIdxInput = 0x2d549f0,
hashGrpColIdxHash = 0x2d54a10, aggnode = 0x2d903a0}
(gdb) p *aggstate->perhash->hashtable
$68 = {hashtab = 0x2d54b70, numCols = 1, keyColIdx = 0x2d54a10, tab_hash_funcs = 0x2d542d0, tab_eq_func = 0x2d54e90,
tablecxt = 0x2d7c450, tempcxt = 0x2d90a00, entrysize = 24, tableslot = 0x2d54df8, inputslot = 0x0, in_hash_funcs = 0x0,
cur_eq_func = 0x0, hash_iv = 0, exprcontext = 0x2d557b0}
(gdb) p *aggstate->perhash->hashfunctions
$69 = {fn_addr = 0x4c8a31 <hashtext>, fn_oid = 400, fn_nargs = 1, fn_strict = true, fn_retset = false, fn_stats = 2 '\002',
fn_extra = 0x0, fn_mcxt = 0x2d52310, fn_expr = 0x0}
DONE!
尚有不少细节需要整理
四、参考资料
N/A
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