PostgreSQL中用于初始化查询执行计划函数是哪个

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一、数据结构

EState
执行器在调用时的主要工作状态

typedef struct EState
{
    nodeTag     type;//标记

    
    //所有查询类型的基础状态
    ScanDirection es_direction; 
    Snapshot    es_snapshot;    
    Snapshot    es_crosscheck_snapshot; 
    List       *es_range_table; 
    struct RangeTblEntry **es_range_table_array;    
    Index       es_range_table_size;    
    Relation   *es_relations;   
    struct ExecRowMark **es_rowmarks;   
    PlannedStmt *es_plannedstmt;    
    const char *es_sourceText;  

    JunkFilter *es_junkFilter;  

    
    //如查询可以插入/删除元组,这里记录了命令ID
    CommandId   es_output_cid;

    
    //insert/update/delete 目标表信息
    ResultRelInfo *es_result_relations; 
    int         es_num_result_relations;    
    ResultRelInfo *es_result_relation_info; 

    
    ResultRelInfo *es_root_result_relations;    
    int         es_num_root_result_relations;   

    
    List       *es_tuple_routing_result_relations;

    
    //用于触发触发器的信息
    List       *es_trig_target_relations;   
    TupleTableSlot *es_trig_tuple_slot; 
    TupleTableSlot *es_trig_oldtup_slot;    
    TupleTableSlot *es_trig_newtup_slot;    

    
    //参数信息
    ParamListInfo es_param_list_info;   
    ParamExecData *es_param_exec_vals;  

    QueryEnvironment *es_queryEnv;  

    
    //其他工作状态
    MemoryContext es_query_cxt; 

    List       *es_tupleTable;  

    uint64      es_processed;   
    Oid         es_lastoid;     

    int         es_top_eflags;  
    int         es_instrument;  
    bool        es_finished;    

    List       *es_exprcontexts;    

    List       *es_subplanstates;   

    List       *es_auxmodifytables; 

    
    ExprContext *es_per_tuple_exprcontext;

    
    HeapTuple  *es_epQtuple;    
    bool       *es_epqTupleSet; 
    bool       *es_epqScanDone; 

    bool        es_use_parallel_mode;   

    
    //用于并行执行的每个查询共享内存区域。
    struct dsa_area *es_query_dsa;

    
    int         es_jit_flags;
    struct JitContext *es_jit;
    struct JitInstrumentation *es_jit_worker_instr;
} EState;

PlanState
PlanState是所有PlanState-type节点的虚父类(请参照面向对象的虚类)

typedef struct PlanState
{
    NodeTag     type;//节点类型

    Plan       *plan;           

    EState     *state;          

    ExecProcNodeMtd ExecProcNode;   
    ExecProcNodeMtd ExecProcNodeReal;   

    Instrumentation *instrument;    
    WorkerInstrumentation *worker_instrument;   

    
    //worker相应的JIT instrumentation
    struct SharedJitInstrumentation *worker_jit_instrument;

    
    ExprState  *qual;           
    struct PlanState *lefttree; 
    struct PlanState *righttree;

    List       *initPlan;       
    List       *subPlan;        

    
    Bitmapset  *chgParam;       

    
    TupleDesc ps_ResultTupleDesc;   
    TupleTableSlot *ps_ResultTupleSlot; 
    ExprContext *ps_ExprContext;    
    ProjectionInfo *ps_ProjInfo;    

    
    TupleDesc   scandesc;
} PlanState;

二、源码解读

InitPlan函数初始化查询执行计划:打开文件/分配存储空间并启动规则管理器.

static void
InitPlan(QueryDesc *queryDesc, int eflags)
{
    CmdType     operation = queryDesc->operation;//命令类型
    PlannedStmt *plannedstmt = queryDesc->plannedstmt;//已规划的语句指针
    Plan       *plan = plannedstmt->planTree;//计划树
    List       *rangeTable = plannedstmt->rtable;//RTE链表
    EState     *estate = queryDesc->estate;//参见数据结构
    PlanState  *planstate;//参见数据结构
    TupleDesc   tupType;//参见数据结构
    ListCell   *l;
    int         i;

    
    ExecCheckRTPerms(rangeTable, true);

    
    ExecInitRangeTable(estate, rangeTable);

    estate->es_plannedstmt = plannedstmt;

    
    if (plannedstmt->resultRelations)//存在resultRelations
    {
        List       *resultRelations = plannedstmt->resultRelations;//结果Relation链表
        int         numResultRelations = list_length(resultRelations);//链表大小
        ResultRelInfo *resultRelInfos;//ResultRelInfo数组
        ResultRelInfo *resultRelInfo;//ResultRelInfo指针

        resultRelInfos = (ResultRelInfo *)
            palloc(numResultRelations * sizeof(ResultRelInfo));//分配空间
        resultRelInfo = resultRelInfos;//指针赋值
        foreach(l, resultRelations)//遍历链表
        {
            Index       resultRelationIndex = lfirst_int(l);
            Relation    resultRelation;

            resultRelation = ExecGetRangeTableRelation(estate,
                                                       resultRelationIndex);//获取结果Relation
            InitResultRelInfo(resultRelInfo,
                              resultRelation,
                              resultRelationIndex,
                              NULL,
                              estate->es_instrument);//初始化ResultRelInfo
            resultRelInfo++;//处理下一个ResultRelInfo
        }
        estate->es_result_relations = resultRelInfos;//赋值
        estate->es_num_result_relations = numResultRelations;

        
        //设置es_result_relation_info为NULL,除了ModifyTable
        estate->es_result_relation_info = NULL;

        
        if (plannedstmt->rootResultRelations)//存在rootResultRelations(并行处理)
        {
            int         num_roots = list_length(plannedstmt->rootResultRelations);

            resultRelInfos = (ResultRelInfo *)
                palloc(num_roots * sizeof(ResultRelInfo));
            resultRelInfo = resultRelInfos;
            foreach(l, plannedstmt->rootResultRelations)
            {
                Index       resultRelIndex = lfirst_int(l);
                Relation    resultRelDesc;

                resultRelDesc = ExecGetRangeTableRelation(estate,
                                                          resultRelIndex);
                InitResultRelInfo(resultRelInfo,
                                  resultRelDesc,
                                  resultRelIndex,
                                  NULL,
                                  estate->es_instrument);
                resultRelInfo++;
            }

            estate->es_root_result_relations = resultRelInfos;
            estate->es_num_root_result_relations = num_roots;
        }
        else
        {
            estate->es_root_result_relations = NULL;
            estate->es_num_root_result_relations = 0;
        }
    }
    else//不存在resultRelations
    {
        
        estate->es_result_relations = NULL;
        estate->es_num_result_relations = 0;
        estate->es_result_relation_info = NULL;
        estate->es_root_result_relations = NULL;
        estate->es_num_root_result_relations = 0;
    }

    
    if (plannedstmt->rowMarks)//如存在rowMarks
    {
        estate->es_rowmarks = (ExecRowMark **)
            palloc0(estate->es_range_table_size * sizeof(ExecRowMark *));
        foreach(l, plannedstmt->rowMarks)
        {
            PlanRowMark *rc = (PlanRowMark *) lfirst(l);
            Oid         relid;
            Relation    relation;
            ExecRowMark *erm;

            
            if (rc->isParent)
                continue;

            
            relid = exec_rt_fetch(rc->rti, estate)->relid;

            
            switch (rc->markType)
            {
                case ROW_MARK_EXCLUSIVE:
                case ROW_MARK_NOKEYEXCLUSIVE:
                case ROW_MARK_SHARE:
                case ROW_MARK_KEYSHARE:
                case ROW_MARK_REFERENCE:
                    relation = ExecGetRangeTableRelation(estate, rc->rti);
                    break;
                case ROW_MARK_COPY:
                    
                    relation = NULL;
                    break;
                default:
                    elog(ERROR, "unrecognized markType: %d", rc->markType);
                    relation = NULL;    
                    break;
            }

            
            if (relation)
                CheckValidRowMarkRel(relation, rc->markType);

            erm = (ExecRowMark *) palloc(sizeof(ExecRowMark));
            erm->relation = relation;
            erm->relid = relid;
            erm->rti = rc->rti;
            erm->prti = rc->prti;
            erm->rowmarkId = rc->rowmarkId;
            erm->markType = rc->markType;
            erm->strength = rc->strength;
            erm->waitPolicy = rc->waitPolicy;
            erm->erMactive = false;
            ItemPointerSetInvalid(&(erm->curCtid));
            erm->ermExtra = NULL;

            Assert(erm->rti > 0 && erm->rti <= estate->es_range_table_size &&
                   estate->es_rowmarks[erm->rti - 1] == NULL);

            estate->es_rowmarks[erm->rti - 1] = erm;
        }
    }

    
    estate->es_tupleTable = NIL;
    estate->es_trig_tuple_slot = NULL;
    estate->es_trig_oldtup_slot = NULL;
    estate->es_trig_newtup_slot = NULL;

    
    //标记EvalPlanQual为非活动模式
    estate->es_epqTuple = NULL;
    estate->es_epqTupleSet = NULL;
    estate->es_epqScanDone = NULL;

    
    Assert(estate->es_subplanstates == NIL);
    i = 1;                      
    foreach(l, plannedstmt->subplans)//遍历subplans
    {
        Plan       *subplan = (Plan *) lfirst(l);
        PlanState  *subplanstate;
        int         sp_eflags;

        
        sp_eflags = eflags
            & (EXEC_FLAG_EXPLAIN_ONLY | EXEC_FLAG_WITH_NO_DATA);//设置sp_eflags
        if (bms_is_member(i, plannedstmt->rewindPlanIDs))
            sp_eflags |= EXEC_FLAG_REWIND;

        subplanstate = ExecInitNode(subplan, estate, sp_eflags);//执行Plan节点初始化过程

        estate->es_subplanstates = lappend(estate->es_subplanstates,
                                           subplanstate);

        i++;
    }

    
    planstate = ExecInitNode(plan, estate, eflags);//执行Plan节点初始化过程

    
    tupType = ExecGetResultType(planstate);

    
    if (operation == CMD_SELECT)//SELECT命令
    {
        bool        junk_filter_needed = false;
        ListCell   *tlist;

        foreach(tlist, plan->targetlist)//遍历tlist
        {
            TargetEntry *tle = (TargetEntry *) lfirst(tlist);

            if (tle->resjunk)//如需要垃圾过滤器
            {
                junk_filter_needed = true;//设置为T
                break;
            }
        }

        if (junk_filter_needed)
        {
            JunkFilter *j;

            j = ExecInitJunkFilter(planstate->plan->targetlist,
                                   tupType->tdhasoid,
                                   ExecInitExtraTupleSlot(estate, NULL));//初始化
            estate->es_junkFilter = j;

            
            //期望返回已清理的元组类型
            tupType = j->jf_cleanTupType;
        }
    }
    //赋值
    queryDesc->tupDesc = tupType;
    queryDesc->planstate = planstate;
}

三、跟踪分析

测试脚本如下

testdb=# explain select dw.*,grjf.grbh,grjf.xm,grjf.ny,grjf.je 
testdb-# from t_dwxx dw,lateral (select gr.grbh,gr.xm,jf.ny,jf.je 
testdb(#                         from t_grxx gr inner join t_jfxx jf 
testdb(#                                        on gr.dwbh = dw.dwbh 
testdb(#                                           and gr.grbh = jf.grbh) grjf
testdb-# order by dw.dwbh;
                                        QUERY PLAN                                        
------------------------------------------------------------------------------------------
 Sort  (cost=20070.93..20320.93 rows=100000 width=47)
   Sort Key: dw.dwbh
   ->  Hash Join  (cost=3754.00..8689.61 rows=100000 width=47)
         Hash Cond: ((gr.dwbh)::text = (dw.dwbh)::text)
         ->  Hash Join  (cost=3465.00..8138.00 rows=100000 width=31)
               Hash Cond: ((jf.grbh)::text = (gr.grbh)::text)
               ->  Seq Scan on t_jfxx jf  (cost=0.00..1637.00 rows=100000 width=20)
               ->  Hash  (cost=1726.00..1726.00 rows=100000 width=16)
                     ->  Seq Scan on t_grxx gr  (cost=0.00..1726.00 rows=100000 width=16)
         ->  Hash  (cost=164.00..164.00 rows=10000 width=20)
               ->  Seq Scan on t_dwxx dw  (cost=0.00..164.00 rows=10000 width=20)
(11 rows)

启动gdb,设置断点,进入InitPlan

(gdb) b InitPlan
Breakpoint 1 at 0x6d9df2: file execMain.c, line 808.
(gdb) c
Continuing.

Breakpoint 1, InitPlan (queryDesc=0x20838b8, eflags=16) at execMain.c:808
warning: Source file is more recent than executable.
808     CmdType     operation = queryDesc->operation;

输入参数

(gdb) p *queryDesc
$1 = {operation = CMD_SELECT, plannedstmt = 0x207e6c0, 
  sourceText = 0x1f96eb8 "select dw.*,grjf.grbh,grjf.xm,grjf.ny,grjf.je \nfrom t_dwxx dw,lateral (select gr.grbh,gr.xm,jf.ny,jf.je \n", ' ' <repeats 24 times>, "from t_grxx gr inner join t_jfxx jf \n", ' ' <repeats 34 times>..., 
  snapshot = 0x1fba8e0, crosscheck_snapshot = 0x0, dest = 0xf8f280 <donothingDR>, params = 0x0, queryEnv = 0x0, 
  instrument_options = 0, tupDesc = 0x0, estate = 0x207f898, planstate = 0x0, already_executed = false, totaltime = 0x0}
(gdb) p eflags
$2 = 16

变量赋值,PlannedStmt的详细数据结构先前章节已有解释,请参见相关章节.

(gdb) n
809     PlannedStmt *plannedstmt = queryDesc->plannedstmt;
(gdb) 
810     Plan       *plan = plannedstmt->planTree;
(gdb) 
811     List       *rangeTable = plannedstmt->rtable;
(gdb) n
812     EState     *estate = queryDesc->estate;
(gdb) 
821     ExecCheckRTPerms(rangeTable, true);
(gdb) p *plannedstmt
$3 = {type = T_PlannedStmt, commandType = CMD_SELECT, queryId = 0, hasReturning = false, hasModifyinGCTE = false, 
  canSetTag = true, transientPlan = false, dependsOnRole = false, parallelModeNeeded = false, jitFlags = 0, 
  planTree = 0x20788f8, rtable = 0x207c568, resultRelations = 0x0, nonleafResultRelations = 0x0, rootResultRelations = 0x0, 
  subplans = 0x0, rewindPlanIDs = 0x0, rowMarks = 0x0, relationOids = 0x207c5c8, invalItems = 0x0, paramExecTypes = 0x0, 
  utilityStmt = 0x0, stmt_location = 0, stmt_len = 313}
(gdb) p *plan
$4 = {type = T_Sort, startup_cost = 20070.931487218411, total_cost = 20320.931487218411, plan_rows = 100000, 
  plan_width = 47, parallel_aware = false, parallel_safe = true, plan_node_id = 0, targetlist = 0x207cc28, qual = 0x0, 
  lefttree = 0x207c090, righttree = 0x0, initPlan = 0x0, extParam = 0x0, allParam = 0x0}
(gdb) p *estate
$5 = {type = T_EState, es_direction = ForwardScanDirection, es_snapshot = 0x1fba8e0, es_crosscheck_snapshot = 0x0, 
  es_range_table = 0x0, es_plannedstmt = 0x0, 
  es_sourceText = 0x1f96eb8 "select dw.*,grjf.grbh,grjf.xm,grjf.ny,grjf.je \nfrom t_dwxx dw,lateral (select gr.grbh,gr.xm,jf.ny,jf.je \n", ' ' <repeats 24 times>, "from t_grxx gr inner join t_jfxx jf \n", ' ' <repeats 34 times>..., 
  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 = 0x207f780, 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}

RTE链表,一共有5个Item,3个基础关系RTE_RELATION(1/3/4),1个RTE_SUBQUERY(2号),1个RTE_JOIN(5号)

(gdb) n
826     estate->es_range_table = rangeTable;
(gdb) p *rangeTable
$6 = {type = T_List, length = 5, head = 0x207c540, tail = 0x207cb28}
(gdb) p *(RangeTblEntry *)rangeTable->head->data.ptr_value
$9 = {type = T_RangeTblEntry, rtekind = RTE_RELATION, relid = 16734, relkind = 114 'r', tablesample = 0x0, subquery = 0x0, 
  security_barrier = false, jointype = JOIN_INNER, joinaliasvars = 0x0, functions = 0x0, funcordinality = false, 
  tablefunc = 0x0, values_lists = 0x0, ctename = 0x0, ctelevelsup = 0, self_reference = false, coltypes = 0x0, 
  coltypmods = 0x0, colcollations = 0x0, enrname = 0x0, enrtuples = 0, alias = 0x1f98448, eref = 0x1fbdd20, 
  lateral = false, inh = false, inFromCl = true, requiredPerms = 2, checkAsUser = 0, selectedCols = 0x2054de8, 
  insertedCols = 0x0, updatedCols = 0x0, securityQuals = 0x0}
...

没有结果Relation,执行相应的处理逻辑

(gdb) 
835     if (plannedstmt->resultRelations)
(gdb) p plannedstmt->resultRelations
$14 = (List *) 0x0
(gdb) n
922         estate->es_result_relations = NULL;
(gdb) 
923         estate->es_num_result_relations = 0;
(gdb) 
924         estate->es_result_relation_info = NULL;
(gdb) 
925         estate->es_root_result_relations = NULL;
(gdb) 
926         estate->es_num_root_result_relations = 0;

不存在rowMarks(for update)

(gdb) n
939     foreach(l, plannedstmt->rowMarks)
(gdb) p plannedstmt->rowMarks
$15 = (List *) 0x0
(gdb) p plannedstmt->rowMarks
$16 = (List *) 0x0
(gdb) n
1000        estate->es_tupleTable = NIL;

执行赋值

(gdb) n
1001        estate->es_trig_tuple_slot = NULL;
(gdb) 
1002        estate->es_trig_oldtup_slot = NULL;
...

没有subplans

(gdb) n
1017        foreach(l, plannedstmt->subplans)
(gdb) p *plannedstmt->subplans
Cannot access memory at address 0x0
(gdb) n

初始化节点(执行ExecInitNode)和获取TupleType

(gdb) n
1046        planstate = ExecInitNode(plan, estate, eflags);
(gdb) n
1051        tupType = ExecGetResultType(planstate);
(gdb) 
1057        if (operation == CMD_SELECT)
(gdb) p *planstate
$17 = {type = T_SortState, plan = 0x20788f8, state = 0x207f898, ExecProcNode = 0x6e41bb <ExecProcNodeFirst>, 
  ExecProcNodeReal = 0x716144 <ExecSort>, instrument = 0x0, worker_instrument = 0x0, worker_jit_instrument = 0x0, 
  qual = 0x0, lefttree = 0x207fbc8, righttree = 0x0, initPlan = 0x0, subPlan = 0x0, chgParam = 0x0, 
  ps_ResultTupleSlot = 0x2090dc0, ps_ExprContext = 0x0, ps_ProjInfo = 0x0, scandesc = 0x208e920}
(gdb) p tupType
$18 = (TupleDesc) 0x20909a8
(gdb) p *tupType
$19 = {natts = 7, tdtypeid = 2249, tdtypmod = -1, tdhasoid = false, tdrefcount = -1, constr = 0x0, attrs = 0x20909c8}

判断是否需要垃圾过滤器

(gdb) n
1059            bool        junk_filter_needed = false;
(gdb) 
1062            foreach(tlist, plan->targetlist)

不需要junk filter

(gdb) 
1073            if (junk_filter_needed)

赋值,结束调用

(gdb) 
1087        queryDesc->tupDesc = tupType;
(gdb) 
1088        queryDesc->planstate = planstate;
(gdb) 
1089    }
(gdb) 
standard_ExecutorStart (queryDesc=0x20838b8, eflags=16) at execMain.c:267
267     MemoryContextSwitchTo(oldcontext);
(gdb) p *queryDesc
$21 = {operation = CMD_SELECT, plannedstmt = 0x207e6c0, 
  sourceText = 0x1f96eb8 "select dw.*,grjf.grbh,grjf.xm,grjf.ny,grjf.je \nfrom t_dwxx dw,lateral (select gr.grbh,gr.xm,jf.ny,jf.je \n", ' ' <repeats 24 times>, "from t_grxx gr inner join t_jfxx jf \n", ' ' <repeats 34 times>..., 
  snapshot = 0x1fba8e0, crosscheck_snapshot = 0x0, dest = 0xf8f280 <donothingDR>, params = 0x0, queryEnv = 0x0, 
  instrument_options = 0, tupDesc = 0x20909a8, estate = 0x207f898, planstate = 0x207fab0, already_executed = false, 
  totaltime = 0x0}

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