本篇内容主要讲解“怎么使用PostgreSQL中ExecInitExprRec函数”，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“怎么使用PostgreSQL中ExecInitExprRec函数”吧!
EEO_XXX宏定义
opcode分发器宏定义
#if defined(EEO_USE_COMPUTED_GOTO)
//--------------- 定义了EEO_USE_COMPUTED_GOTO
//跳转target -> opcode搜索表结构体
typedef struct ExprEvalOpLookup
{
const void *opcode;
ExprEvalOp op;
} ExprEvalOpLookup;
static const void **dispatch_table = NULL;
static ExprEvalOpLookup reverse_dispatch_table[EEOP_LAST];
#define EEO_SWITCH()
#define EEO_CASE(name) CASE_##name:
#define EEO_DISPATCH() goto *((void *) op->opcode)
#define EEO_OPCODE(opcode) ((intptr_t) dispatch_table[opcode])
#else
//--------------- 没有定义EEO_USE_COMPUTED_GOTO
#define EEO_SWITCH() starteval: switch ((ExprEvalOp) op->opcode)
#define EEO_CASE(name) case name:
#define EEO_DISPATCH() goto starteval
#define EEO_OPCODE(opcode) (opcode)
#endif
#define EEO_NEXT() \
do { \
op++; \
EEO_DISPATCH(); \
} while (0)
#define EEO_JUMP(stepno) \
do { \
op = &state->steps[stepno]; \
EEO_DISPATCH(); \
} while (0)ExprState
解析表达式中运行期状态节点
#define EEO_FLAG_IS_QUAL (1 << 0)
typedef struct ExprState
{
//节点tag
Node tag;
//EEO_FLAG_IS_QUAL
uint8 flags;
#define FIELDNO_EXPRSTATE_RESNULL 2
bool resnull;
#define FIELDNO_EXPRSTATE_RESVALUE 3
Datum resvalue;
#define FIELDNO_EXPRSTATE_RESULTSLOT 4
TupleTableSlot *resultslot;
struct ExprEvalStep *steps;
ExprStateEvalFunc evalfunc;
//原始的表达式树,仅用于debugging
Expr *expr;
//evalfunc的私有状态
void *evalfunc_private;
//当前的步数
int steps_len;
//steps数组已分配的长度
int steps_alloc;
//父PlanState节点(如存在)
struct PlanState *parent;
//用于编译PARAM_EXTERN节点
ParamListInfo ext_params;
//
Datum *innermost_caseval;
bool *innermost_casenull;
Datum *innermost_domainval;
bool *innermost_domainnull;
} ExprState;ExprEvalStep
表达式解析步骤结构体
typedef struct ExprEvalStep
{
intptr_t opcode;
//存储该步骤的结果
Datum *resvalue;
bool *resnull;
union
{
//用于EEOP_INNER/OUTER/SCAN_FETCHSOME
struct
{
//获取到的属性编号
int last_var;
TupleDesc known_desc;
} fetch;
struct
{
//attnum是常规VAR的attr number - 1
//对于SYSVAR,该值是常规的attr number
int attnum;
Oid vartype;
} var;
struct
{
Var *var;
bool first;
bool slow;
TupleDesc tupdesc;
JunkFilter *junkFilter;
} wholerow;
struct
{
int resultnum;
int attnum;
} assign_var;
struct
{
int resultnum;
} assign_tmp;
struct
{
Datum value;
bool isnull;
} constval;
//对于EEOP_FUNCEXPR_* / NULLIF / DISTINCT
struct
{
//函数的检索数据
FmgrInfo *finfo;
//参数信息等
FunctionCallInfo fcinfo_data;
//无需额外的指向,更快速的访问
PGFunction fn_addr;
int nargs;
} func;
struct
{
bool *anynull;
int jumpdone;
} boolexpr;
struct
{
int jumpdone;
} qualexpr;
struct
{
int jumpdone;
} jump;
struct
{
TupleDesc argdesc;
} nulltest_row;
struct
{
int paramid;
Oid paramtype;
} param;
struct
{
ExecEvalSubroutine paramfunc;
void *paramarg;
int paramid;
Oid paramtype;
} cparam;
struct
{
Datum *value;
bool *isnull;
} casetest;
struct
{
Datum *value;
bool *isnull;
} make_readonly;
struct
{
FmgrInfo *finfo_out;
FunctionCallInfo fcinfo_data_out;
FmgrInfo *finfo_in;
FunctionCallInfo fcinfo_data_in;
} iocoerce;
struct
{
SQLValueFunction *svf;
} sqlvaluefunction;
//EEOP_NEXTVALUEEXPR
struct
{
Oid seqid;
Oid seqtypid;
} nextvalueexpr;
struct
{
Datum *elemvalues;
bool *elemnulls;
int nelems;
Oid elemtype;
int16 elemlength;
bool elembyval;
char elemalign;
bool multidims;
} arrayexpr;
struct
{
ExprState *elemexprstate;
Oid resultelemtype;
struct ArrayMapState *amstate;
} arraycoerce;
struct
{
TupleDesc tupdesc;
Datum *elemvalues;
bool *elemnulls;
} row;
struct
{
FmgrInfo *finfo;
FunctionCallInfo fcinfo_data;
PGFunction fn_addr;
int jumpnull;
int jumpdone;
} rowcompare_step;
struct
{
RowCompareType rctype;
} rowcompare_final;
struct
{
Datum *values;
bool *nulls;
int nelems;
MinMaxOp op;
FmgrInfo *finfo;
FunctionCallInfo fcinfo_data;
} minmax;
struct
{
AttrNumber fieldnum;
Oid resulttype;
TupleDesc argdesc;
} fieldselect;
struct
{
FieldStore *fstore;
TupleDesc *argdesc;
Datum *values;
bool *nulls;
int ncolumns;
} fieldstore;
struct
{
struct ArrayRefState *state;
int off;
bool isupper;
int jumpdone;
} arrayref_subscript;
struct
{
struct ArrayRefState *state;
} arrayref;
struct
{
char *constraintname;
Datum *checkvalue;
bool *checknull;
Oid resulttype;
} domaincheck;
struct
{
ConvertRowtypeExpr *convert;
TupleDesc indesc;
TupleDesc outdesc;
TupleConversionMap *map;
bool initialized;
} convert_rowtype;
struct
{
Oid element_type;
bool useOr;
int16 typlen;
bool typbyval;
char typalign;
FmgrInfo *finfo;
FunctionCallInfo fcinfo_data;
PGFunction fn_addr;
} scalararrayop;
struct
{
XmlExpr *xexpr;
Datum *named_argvalue;
bool *named_argnull;
Datum *argvalue;
bool *argnull;
} xmlexpr;
struct
{
AggrefExprState *astate;
} aggref;
struct
{
AggState *parent;
List *clauses;
} grouping_func;
struct
{
WindowFuncExprState *wfstate;
} window_func;
struct
{
SubPlanState *sstate;
} subplan;
struct
{
AlternativeSubPlanState *asstate;
} alternative_subplan;
struct
{
AggState *aggstate;
FunctionCallInfo fcinfo_data;
int jumpnull;
} agg_deserialize;
struct
{
bool *nulls;
int nargs;
int jumpnull;
} agg_strict_input_check;
struct
{
AggState *aggstate;
AggStatePerTrans pertrans;
ExprContext *aggcontext;
int setno;
int transno;
int setoff;
int jumpnull;
} agg_init_trans;
struct
{
AggState *aggstate;
int setno;
int transno;
int setoff;
int jumpnull;
} agg_strict_trans_check;
struct
{
AggState *aggstate;
AggStatePerTrans pertrans;
ExprContext *aggcontext;
int setno;
int transno;
int setoff;
} agg_trans;
} d;
} ExprEvalStep;ExprEvalOp
ExprEvalSteps的鉴频器,定义哪个操作将被执行并且联合体ExprEvalStep->d中的哪个struct将被使用.
typedef enum ExprEvalOp
{
//整个表达式已被解析,返回
EEOP_DONE,
//在相应的元组slot上应用了slot_getsomeattrs方法
EEOP_INNER_FETCHSOME,
EEOP_OUTER_FETCHSOME,
EEOP_SCAN_FETCHSOME,
//计算非系统Var变量值
EEOP_INNER_VAR,
EEOP_OUTER_VAR,
EEOP_SCAN_VAR,
//计算系统Var变量值
EEOP_INNER_SYSVAR,
EEOP_OUTER_SYSVAR,
EEOP_SCAN_SYSVAR,
//计算整行Var
EEOP_WHOLEROW,
EEOP_ASSIGN_INNER_VAR,
EEOP_ASSIGN_OUTER_VAR,
EEOP_ASSIGN_SCAN_VAR,
//分配ExprState's resvalue/resnull到该列的resultslot中
EEOP_ASSIGN_TMP,
//同上,应用MakeExpandedObjectReadOnly()
EEOP_ASSIGN_TMP_MAKE_RO,
//解析常量值
EEOP_CONST,
EEOP_FUNCEXPR,
EEOP_FUNCEXPR_STRICT,
EEOP_FUNCEXPR_FUSAGE,
EEOP_FUNCEXPR_STRICT_FUSAGE,
EEOP_BOOL_AND_STEP_FIRST,
EEOP_BOOL_AND_STEP,
EEOP_BOOL_AND_STEP_LAST,
//与布尔OR表达式类似
EEOP_BOOL_OR_STEP_FIRST,
EEOP_BOOL_OR_STEP,
EEOP_BOOL_OR_STEP_LAST,
//解析布尔NOT表达式
EEOP_BOOL_NOT_STEP,
//用于ExecQual()中的BOOL_AND_STEP简化版本
EEOP_QUAL,
//无条件跳转到另外一个步骤
EEOP_JUMP,
//基于当前结果值的条件跳转
EEOP_JUMP_IF_NULL,
EEOP_JUMP_IF_NOT_NULL,
EEOP_JUMP_IF_NOT_TRUE,
//为scalar值执行NULL测试
EEOP_NULLTEST_ISNULL,
EEOP_NULLTEST_ISNOTNULL,
//为行值执行NULL测试
EEOP_NULLTEST_ROWISNULL,
EEOP_NULLTEST_ROWISNOTNULL,
//解析BooleanTest表达式
EEOP_BOOLTEST_IS_TRUE,
EEOP_BOOLTEST_IS_NOT_TRUE,
EEOP_BOOLTEST_IS_FALSE,
EEOP_BOOLTEST_IS_NOT_FALSE,
//解析PARAM_EXEC/EXTERN参数
EEOP_PARAM_EXEC,
EEOP_PARAM_EXTERN,
EEOP_PARAM_CALLBACK,
//返回CaseTestExpr值
EEOP_CASE_TESTVAL,
//对目标值应用MakeExpandedObjectReadOnly()
EEOP_MAKE_READONLY,
//解析各种特殊用途的表达式类型
EEOP_IOCOERCE,
EEOP_DISTINCT,
EEOP_NOT_DISTINCT,
EEOP_NULLIF,
EEOP_SQLVALUEFUNCTION,
EEOP_CURRENTOFEXPR,
EEOP_NEXTVALUEEXPR,
EEOP_ARRAYEXPR,
EEOP_ARRAYCOERCE,
EEOP_ROW,
EEOP_ROWCOMPARE_STEP,
//基于上一步的ROWCOMPARE_STEP操作解析布尔值
EEOP_ROWCOMPARE_FINAL,
//解析GREATEST()和LEAST()
EEOP_MINMAX,
//解析FieldSelect表达式
EEOP_FIELDSELECT,
EEOP_FIELDSTORE_DEFORM,
EEOP_FIELDSTORE_FORM,
//处理数组子脚本.如为NULL则短路表达式为NULL
EEOP_ARRAYREF_SUBSCRIPT,
EEOP_ARRAYREF_OLD,
//为ArrayRef分配118
EEOP_ARRAYREF_ASSIGN,
//为ArrayRef提取表达式计算element/slice
EEOP_ARRAYREF_FETCH,
//为CoerceToDomainValue解析值
EEOP_DOMAIN_TESTVAL,
//解析域 NOT NULL 约束
EEOP_DOMAIN_NOTNULL,
//解析单个域CHECK约束
EEOP_DOMAIN_CHECK,
//解析特殊目的的表达式类型
EEOP_CONVERT_ROWTYPE,
EEOP_SCALARARRAYOP,
EEOP_XMLEXPR,
EEOP_AGGREF,
EEOP_GROUPING_FUNC,
EEOP_WINDOW_FUNC,
EEOP_SUBPLAN,
EEOP_ALTERNATIVE_SUBPLAN,
//聚合相关节点
EEOP_AGG_STRICT_DESERIALIZE,
EEOP_AGG_DESERIALIZE,
EEOP_AGG_STRICT_INPUT_CHECK,
EEOP_AGG_INIT_TRANS,
EEOP_AGG_STRICT_TRANS_CHECK,
EEOP_AGG_PLAIN_TRANS_BYVAL,
EEOP_AGG_PLAIN_TRANS,
EEOP_AGG_ORDERED_TRANS_DATUM,
EEOP_AGG_ORDERED_TRANS_TUPLE,
//不存在的操作,比如用于检测数组长度
EEOP_LAST
} ExprEvalOp;二、源码解读
ExecInitExprRec函数,把表达式解析需要的步骤追加到ExprState->steps中,可能会递归进入到子表达式节点中.
其主要逻辑是根据节点类型,执行相应的处理逻辑,比如节点类型为OpExpr,则其逻辑为:
case T_OpExpr://操作符表达式
{
OpExpr *op = (OpExpr *) node;
ExecInitFunc(&scratch, node,
op->args, op->opfuncid, op->inputcollid,
state);
ExprEvalPushStep(state, &scratch);
break;
}其他节点类型类似,代码虽然很长,但逻辑清晰简单.
static void
ExecInitExprRec(Expr *node, ExprState *state,
Datum *resv, bool *resnull)
{
ExprEvalStep scratch = {0};
//避免出现堆栈溢出
check_stack_depth();
//步骤的输出位置往往是调用者提供给我们的
Assert(resv != NULL && resnull != NULL);
scratch.resvalue = resv;
scratch.resnull = resnull;
//CASE的顺序与NodeTag枚举类型中的顺序一样
switch (nodeTag(node))
{
case T_Var://VAR
{
Var *variable = (Var *) node;
if (variable->varattno == InvalidAttrNumber)
{
ExecInitWholeRowVar(&scratch, variable, state);
}
else if (variable->varattno <= 0)
{
scratch.d.var.attnum = variable->varattno;
scratch.d.var.vartype = variable->vartype;
switch (variable->varno)
{
case INNER_VAR:
scratch.opcode = EEOP_INNER_SYSVAR;
break;
case OUTER_VAR:
scratch.opcode = EEOP_OUTER_SYSVAR;
break;
default:
scratch.opcode = EEOP_SCAN_SYSVAR;
break;
}
}
else
{
scratch.d.var.attnum = variable->varattno - 1;
scratch.d.var.vartype = variable->vartype;
switch (variable->varno)
{
case INNER_VAR:
scratch.opcode = EEOP_INNER_VAR;
break;
case OUTER_VAR:
scratch.opcode = EEOP_OUTER_VAR;
break;
default:
scratch.opcode = EEOP_SCAN_VAR;
break;
}
}
ExprEvalPushStep(state, &scratch);
break;
}
case T_Const://常量
{
Const *con = (Const *) node;
scratch.opcode = EEOP_CONST;
scratch.d.constval.value = con->constvalue;
scratch.d.constval.isnull = con->constisnull;
ExprEvalPushStep(state, &scratch);
break;
}
case T_Param://参数
{
Param *param = (Param *) node;
ParamListInfo params;
switch (param->paramkind)
{
case PARAM_EXEC:
scratch.opcode = EEOP_PARAM_EXEC;
scratch.d.param.paramid = param->paramid;
scratch.d.param.paramtype = param->paramtype;
ExprEvalPushStep(state, &scratch);
break;
case PARAM_EXTERN:
if (state->ext_params)
params = state->ext_params;
else if (state->parent &&
state->parent->state)
params = state->parent->state->es_param_list_info;
else
params = NULL;
if (params && params->paramCompile)
{
params->paramCompile(params, param, state,
resv, resnull);
}
else
{
scratch.opcode = EEOP_PARAM_EXTERN;
scratch.d.param.paramid = param->paramid;
scratch.d.param.paramtype = param->paramtype;
ExprEvalPushStep(state, &scratch);
}
break;
default:
elog(ERROR, "unrecognized paramkind: %d",
(int) param->paramkind);
break;
}
break;
}
case T_Aggref://聚集
{
Aggref *aggref = (Aggref *) node;
AggrefExprState *astate = makeNode(AggrefExprState);
scratch.opcode = EEOP_AGGREF;
scratch.d.aggref.astate = astate;
astate->aggref = aggref;
if (state->parent && IsA(state->parent, AggState))
{
AggState *aggstate = (AggState *) state->parent;
aggstate->aggs = lcons(astate, aggstate->aggs);
aggstate->numaggs++;
}
else
{
elog(ERROR, "Aggref found in non-Agg plan node");
}
ExprEvalPushStep(state, &scratch);
break;
}
case T_GroupingFunc:
{
GroupingFunc *grp_node = (GroupingFunc *) node;
Agg *agg;
if (!state->parent || !IsA(state->parent, AggState) ||
!IsA(state->parent->plan, Agg))
elog(ERROR, "GroupingFunc found in non-Agg plan node");
scratch.opcode = EEOP_GROUPING_FUNC;
scratch.d.grouping_func.parent = (AggState *) state->parent;
agg = (Agg *) (state->parent->plan);
if (agg->groupingSets)
scratch.d.grouping_func.clauses = grp_node->cols;
else
scratch.d.grouping_func.clauses = NIL;
ExprEvalPushStep(state, &scratch);
break;
}
case T_WindowFunc:
{
WindowFunc *wfunc = (WindowFunc *) node;
WindowFuncExprState *wfstate = makeNode(WindowFuncExprState);
wfstate->wfunc = wfunc;
if (state->parent && IsA(state->parent, WindowAggState))
{
WindowAggState *winstate = (WindowAggState *) state->parent;
int nfuncs;
winstate->funcs = lcons(wfstate, winstate->funcs);
nfuncs = ++winstate->numfuncs;
if (wfunc->winagg)
winstate->numaggs++;
wfstate->args = ExecInitExprList(wfunc->args,
state->parent);
wfstate->aggfilter = ExecInitExpr(wfunc->aggfilter,
state->parent);
if (nfuncs != winstate->numfuncs)
ereport(ERROR,
(errcode(ERRCODE_WINDOWING_ERROR),
errmsg("window function calls cannot be nested")));
}
else
{
elog(ERROR, "WindowFunc found in non-WindowAgg plan node");
}
scratch.opcode = EEOP_WINDOW_FUNC;
scratch.d.window_func.wfstate = wfstate;
ExprEvalPushStep(state, &scratch);
break;
}
case T_ArrayRef:
{
ArrayRef *aref = (ArrayRef *) node;
ExecInitArrayRef(&scratch, aref, state, resv, resnull);
break;
}
case T_FuncExpr://函数表达式
{
FuncExpr *func = (FuncExpr *) node;
ExecInitFunc(&scratch, node,
func->args, func->funcid, func->inputcollid,
state);
ExprEvalPushStep(state, &scratch);
break;
}
case T_OpExpr://操作符表达式
{
OpExpr *op = (OpExpr *) node;
ExecInitFunc(&scratch, node,
op->args, op->opfuncid, op->inputcollid,
state);
ExprEvalPushStep(state, &scratch);
break;
}
case T_DistinctExpr:
{
DistinctExpr *op = (DistinctExpr *) node;
ExecInitFunc(&scratch, node,
op->args, op->opfuncid, op->inputcollid,
state);
scratch.opcode = EEOP_DISTINCT;
ExprEvalPushStep(state, &scratch);
break;
}
case T_NullIfExpr:
{
NullIfExpr *op = (NullIfExpr *) node;
ExecInitFunc(&scratch, node,
op->args, op->opfuncid, op->inputcollid,
state);
scratch.opcode = EEOP_NULLIF;
ExprEvalPushStep(state, &scratch);
break;
}
case T_ScalarArrayOpExpr:
{
ScalarArrayOpExpr *opexpr = (ScalarArrayOpExpr *) node;
Expr *scalararg;
Expr *arrayarg;
FmgrInfo *finfo;
FunctionCallInfo fcinfo;
AclResult aclresult;
Assert(list_length(opexpr->args) == 2);
scalararg = (Expr *) linitial(opexpr->args);
arrayarg = (Expr *) lsecond(opexpr->args);
aclresult = pg_proc_aclcheck(opexpr->opfuncid,
GetUserId(),
ACL_EXECUTE);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, OBJECT_FUNCTION,
get_func_name(opexpr->opfuncid));
InvokeFunctionExecuteHook(opexpr->opfuncid);
finfo = palloc0(sizeof(FmgrInfo));
fcinfo = palloc0(sizeof(FunctionCallInfoData));
fmgr_info(opexpr->opfuncid, finfo);
fmgr_info_set_expr((Node *) node, finfo);
InitFunctionCallInfoData(*fcinfo, finfo, 2,
opexpr->inputcollid, NULL, NULL);
ExecInitExprRec(scalararg, state,
&fcinfo->arg[0], &fcinfo->argnull[0]);
ExecInitExprRec(arrayarg, state, resv, resnull);
scratch.opcode = EEOP_SCALARARRAYOP;
scratch.d.scalararrayop.element_type = InvalidOid;
scratch.d.scalararrayop.useOr = opexpr->useOr;
scratch.d.scalararrayop.finfo = finfo;
scratch.d.scalararrayop.fcinfo_data = fcinfo;
scratch.d.scalararrayop.fn_addr = finfo->fn_addr;
ExprEvalPushStep(state, &scratch);
break;
}
case T_BoolExpr:
{
BoolExpr *boolexpr = (BoolExpr *) node;
int nargs = list_length(boolexpr->args);
List *adjust_jumps = NIL;
int off;
ListCell *lc;
if (boolexpr->boolop != NOT_EXPR)
scratch.d.boolexpr.anynull = (bool *) palloc(sizeof(bool));
off = 0;
foreach(lc, boolexpr->args)
{
Expr *arg = (Expr *) lfirst(lc);
ExecInitExprRec(arg, state, resv, resnull);
switch (boolexpr->boolop)
{
case AND_EXPR:
Assert(nargs >= 2);
if (off == 0)
scratch.opcode = EEOP_BOOL_AND_STEP_FIRST;
else if (off + 1 == nargs)
scratch.opcode = EEOP_BOOL_AND_STEP_LAST;
else
scratch.opcode = EEOP_BOOL_AND_STEP;
break;
case OR_EXPR:
Assert(nargs >= 2);
if (off == 0)
scratch.opcode = EEOP_BOOL_OR_STEP_FIRST;
else if (off + 1 == nargs)
scratch.opcode = EEOP_BOOL_OR_STEP_LAST;
else
scratch.opcode = EEOP_BOOL_OR_STEP;
break;
case NOT_EXPR:
Assert(nargs == 1);
scratch.opcode = EEOP_BOOL_NOT_STEP;
break;
default:
elog(ERROR, "unrecognized boolop: %d",
(int) boolexpr->boolop);
break;
}
scratch.d.boolexpr.jumpdone = -1;
ExprEvalPushStep(state, &scratch);
adjust_jumps = lappend_int(adjust_jumps,
state->steps_len - 1);
off++;
}
foreach(lc, adjust_jumps)
{
ExprEvalStep *as = &state->steps[lfirst_int(lc)];
Assert(as->d.boolexpr.jumpdone == -1);
as->d.boolexpr.jumpdone = state->steps_len;
}
break;
}
case T_SubPlan:
{
SubPlan *subplan = (SubPlan *) node;
SubPlanState *sstate;
if (!state->parent)
elog(ERROR, "SubPlan found with no parent plan");
sstate = ExecInitSubPlan(subplan, state->parent);
state->parent->subPlan = lappend(state->parent->subPlan,
sstate);
scratch.opcode = EEOP_SUBPLAN;
scratch.d.subplan.sstate = sstate;
ExprEvalPushStep(state, &scratch);
break;
}
case T_AlternativeSubPlan:
{
AlternativeSubPlan *asplan = (AlternativeSubPlan *) node;
AlternativeSubPlanState *asstate;
if (!state->parent)
elog(ERROR, "AlternativeSubPlan found with no parent plan");
asstate = ExecInitAlternativeSubPlan(asplan, state->parent);
scratch.opcode = EEOP_ALTERNATIVE_SUBPLAN;
scratch.d.alternative_subplan.asstate = asstate;
ExprEvalPushStep(state, &scratch);
break;
}
case T_FieldSelect:
{
FieldSelect *fselect = (FieldSelect *) node;
ExecInitExprRec(fselect->arg, state, resv, resnull);
scratch.opcode = EEOP_FIELDSELECT;
scratch.d.fieldselect.fieldnum = fselect->fieldnum;
scratch.d.fieldselect.resulttype = fselect->resulttype;
scratch.d.fieldselect.argdesc = NULL;
ExprEvalPushStep(state, &scratch);
break;
}
case T_FieldStore:
{
FieldStore *fstore = (FieldStore *) node;
TupleDesc tupDesc;
TupleDesc *descp;
Datum *values;
bool *nulls;
int ncolumns;
ListCell *l1,
*l2;
tupDesc = lookup_rowtype_tupdesc(fstore->resulttype, -1);
ncolumns = tupDesc->natts;
DecrTupleDescRefCount(tupDesc);
values = (Datum *) palloc(sizeof(Datum) * ncolumns);
nulls = (bool *) palloc(sizeof(bool) * ncolumns);
descp = (TupleDesc *) palloc(sizeof(TupleDesc));
*descp = NULL;
ExecInitExprRec(fstore->arg, state, resv, resnull);
scratch.opcode = EEOP_FIELDSTORE_DEFORM;
scratch.d.fieldstore.fstore = fstore;
scratch.d.fieldstore.argdesc = descp;
scratch.d.fieldstore.values = values;
scratch.d.fieldstore.nulls = nulls;
scratch.d.fieldstore.ncolumns = ncolumns;
ExprEvalPushStep(state, &scratch);
forboth(l1, fstore->newvals, l2, fstore->fieldnums)
{
Expr *e = (Expr *) lfirst(l1);
AttrNumber fieldnum = lfirst_int(l2);
Datum *save_innermost_caseval;
bool *save_innermost_casenull;
if (fieldnum <= 0 || fieldnum > ncolumns)
elog(ERROR, "field number %d is out of range in FieldStore",
fieldnum);
save_innermost_caseval = state->innermost_caseval;
save_innermost_casenull = state->innermost_casenull;
state->innermost_caseval = &values[fieldnum - 1];
state->innermost_casenull = &nulls[fieldnum - 1];
ExecInitExprRec(e, state,
&values[fieldnum - 1],
&nulls[fieldnum - 1]);
state->innermost_caseval = save_innermost_caseval;
state->innermost_casenull = save_innermost_casenull;
}
scratch.opcode = EEOP_FIELDSTORE_FORM;
scratch.d.fieldstore.fstore = fstore;
scratch.d.fieldstore.argdesc = descp;
scratch.d.fieldstore.values = values;
scratch.d.fieldstore.nulls = nulls;
scratch.d.fieldstore.ncolumns = ncolumns;
ExprEvalPushStep(state, &scratch);
break;
}
case T_RelabelType:
{
RelabelType *relabel = (RelabelType *) node;
ExecInitExprRec(relabel->arg, state, resv, resnull);
break;
}
case T_CoerceViaIO:
{
CoerceViaIO *iocoerce = (CoerceViaIO *) node;
Oid iofunc;
bool typisvarlena;
Oid typioparam;
FunctionCallInfo fcinfo_in;
ExecInitExprRec(iocoerce->arg, state, resv, resnull);
scratch.opcode = EEOP_IOCOERCE;
scratch.d.iocoerce.finfo_out = palloc0(sizeof(FmgrInfo));
scratch.d.iocoerce.fcinfo_data_out = palloc0(sizeof(FunctionCallInfoData));
getTypeOutputInfo(exprType((Node *) iocoerce->arg),
&iofunc, &typisvarlena);
fmgr_info(iofunc, scratch.d.iocoerce.finfo_out);
fmgr_info_set_expr((Node *) node, scratch.d.iocoerce.finfo_out);
InitFunctionCallInfoData(*scratch.d.iocoerce.fcinfo_data_out,
scratch.d.iocoerce.finfo_out,
1, InvalidOid, NULL, NULL);
scratch.d.iocoerce.finfo_in = palloc0(sizeof(FmgrInfo));
scratch.d.iocoerce.fcinfo_data_in = palloc0(sizeof(FunctionCallInfoData));
getTypeInputInfo(iocoerce->resulttype,
&iofunc, &typioparam);
fmgr_info(iofunc, scratch.d.iocoerce.finfo_in);
fmgr_info_set_expr((Node *) node, scratch.d.iocoerce.finfo_in);
InitFunctionCallInfoData(*scratch.d.iocoerce.fcinfo_data_in,
scratch.d.iocoerce.finfo_in,
3, InvalidOid, NULL, NULL);
fcinfo_in = scratch.d.iocoerce.fcinfo_data_in;
fcinfo_in->arg[1] = ObjectIdGetDatum(typioparam);
fcinfo_in->argnull[1] = false;
fcinfo_in->arg[2] = Int32GetDatum(-1);
fcinfo_in->argnull[2] = false;
ExprEvalPushStep(state, &scratch);
break;
}
case T_ArrayCoerceExpr:
{
ArrayCoerceExpr *acoerce = (ArrayCoerceExpr *) node;
Oid resultelemtype;
ExprState *elemstate;
ExecInitExprRec(acoerce->arg, state, resv, resnull);
resultelemtype = get_element_type(acoerce->resulttype);
if (!OidIsValid(resultelemtype))
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("target type is not an array")));
elemstate = makeNode(ExprState);
elemstate->expr = acoerce->elemexpr;
elemstate->parent = state->parent;
elemstate->ext_params = state->ext_params;
elemstate->innermost_caseval = (Datum *) palloc(sizeof(Datum));
elemstate->innermost_casenull = (bool *) palloc(sizeof(bool));
ExecInitExprRec(acoerce->elemexpr, elemstate,
&elemstate->resvalue, &elemstate->resnull);
if (elemstate->steps_len == 1 &&
elemstate->steps[0].opcode == EEOP_CASE_TESTVAL)
{
elemstate = NULL;
}
else
{
scratch.opcode = EEOP_DONE;
ExprEvalPushStep(elemstate, &scratch);
ExecReadyExpr(elemstate);
}
scratch.opcode = EEOP_ARRAYCOERCE;
scratch.d.arraycoerce.elemexprstate = elemstate;
scratch.d.arraycoerce.resultelemtype = resultelemtype;
if (elemstate)
{
scratch.d.arraycoerce.amstate =
(ArrayMapState *) palloc0(sizeof(ArrayMapState));
}
else
{
scratch.d.arraycoerce.amstate = NULL;
}
ExprEvalPushStep(state, &scratch);
break;
}
case T_ConvertRowtypeExpr:
{
ConvertRowtypeExpr *convert = (ConvertRowtypeExpr *) node;
ExecInitExprRec(convert->arg, state, resv, resnull);
scratch.opcode = EEOP_CONVERT_ROWTYPE;
scratch.d.convert_rowtype.convert = convert;
scratch.d.convert_rowtype.indesc = NULL;
scratch.d.convert_rowtype.outdesc = NULL;
scratch.d.convert_rowtype.map = NULL;
scratch.d.convert_rowtype.initialized = false;
ExprEvalPushStep(state, &scratch);
break;
}
case T_CaseExpr:
{
CaseExpr *caseExpr = (CaseExpr *) node;
List *adjust_jumps = NIL;
Datum *caseval = NULL;
bool *casenull = NULL;
ListCell *lc;
if (caseExpr->arg != NULL)
{
caseval = palloc(sizeof(Datum));
casenull = palloc(sizeof(bool));
ExecInitExprRec(caseExpr->arg, state,
caseval, casenull);
if (get_typlen(exprType((Node *) caseExpr->arg)) == -1)
{
scratch.opcode = EEOP_MAKE_READONLY;
scratch.resvalue = caseval;
scratch.resnull = casenull;
scratch.d.make_readonly.value = caseval;
scratch.d.make_readonly.isnull = casenull;
ExprEvalPushStep(state, &scratch);
scratch.resvalue = resv;
scratch.resnull = resnull;
}
}
foreach(lc, caseExpr->args)
{
CaseWhen *when = (CaseWhen *) lfirst(lc);
Datum *save_innermost_caseval;
bool *save_innermost_casenull;
int whenstep;
save_innermost_caseval = state->innermost_caseval;
save_innermost_casenull = state->innermost_casenull;
state->innermost_caseval = caseval;
state->innermost_casenull = casenull;
ExecInitExprRec(when->expr, state, resv, resnull);
state->innermost_caseval = save_innermost_caseval;
state->innermost_casenull = save_innermost_casenull;
scratch.opcode = EEOP_JUMP_IF_NOT_TRUE;
scratch.d.jump.jumpdone = -1;
ExprEvalPushStep(state, &scratch);
whenstep = state->steps_len - 1;
ExecInitExprRec(when->result, state, resv, resnull);
scratch.opcode = EEOP_JUMP;
scratch.d.jump.jumpdone = -1;
ExprEvalPushStep(state, &scratch);
adjust_jumps = lappend_int(adjust_jumps,
state->steps_len - 1);
state->steps[whenstep].d.jump.jumpdone = state->steps_len;
}
Assert(caseExpr->defresult);
ExecInitExprRec(caseExpr->defresult, state,
resv, resnull);
foreach(lc, adjust_jumps)
{
ExprEvalStep *as = &state->steps[lfirst_int(lc)];
Assert(as->opcode == EEOP_JUMP);
Assert(as->d.jump.jumpdone == -1);
as->d.jump.jumpdone = state->steps_len;
}
break;
}
case T_CaseTestExpr:
{
scratch.opcode = EEOP_CASE_TESTVAL;
scratch.d.casetest.value = state->innermost_caseval;
scratch.d.casetest.isnull = state->innermost_casenull;
ExprEvalPushStep(state, &scratch);
break;
}
case T_ArrayExpr:
{
ArrayExpr *arrayexpr = (ArrayExpr *) node;
int nelems = list_length(arrayexpr->elements);
ListCell *lc;
int elemoff;
scratch.opcode = EEOP_ARRAYEXPR;
scratch.d.arrayexpr.elemvalues =
(Datum *) palloc(sizeof(Datum) * nelems);
scratch.d.arrayexpr.elemnulls =
(bool *) palloc(sizeof(bool) * nelems);
scratch.d.arrayexpr.nelems = nelems;
scratch.d.arrayexpr.multidims = arrayexpr->multidims;
scratch.d.arrayexpr.elemtype = arrayexpr->element_typeid;
get_typlenbyvalalign(arrayexpr->element_typeid,
&scratch.d.arrayexpr.elemlength,
&scratch.d.arrayexpr.elembyval,
&scratch.d.arrayexpr.elemalign);
elemoff = 0;
foreach(lc, arrayexpr->elements)
{
Expr *e = (Expr *) lfirst(lc);
ExecInitExprRec(e, state,
&scratch.d.arrayexpr.elemvalues[elemoff],
&scratch.d.arrayexpr.elemnulls[elemoff]);
elemoff++;
}
ExprEvalPushStep(state, &scratch);
break;
}
case T_RowExpr:
{
RowExpr *rowexpr = (RowExpr *) node;
int nelems = list_length(rowexpr->args);
TupleDesc tupdesc;
int i;
ListCell *l;
if (rowexpr->row_typeid == RECORDOID)
{
tupdesc = ExecTypeFromExprList(rowexpr->args);
}
else
{
tupdesc = lookup_rowtype_tupdesc_copy(rowexpr->row_typeid, -1);
}
ExecTypeSetColNames(tupdesc, rowexpr->colnames);
BlessTupleDesc(tupdesc);
Assert(nelems <= tupdesc->natts);
nelems = Max(nelems, tupdesc->natts);
scratch.opcode = EEOP_ROW;
scratch.d.row.tupdesc = tupdesc;
scratch.d.row.elemvalues =
(Datum *) palloc(sizeof(Datum) * nelems);
scratch.d.row.elemnulls =
(bool *) palloc(sizeof(bool) * nelems);
memset(scratch.d.row.elemnulls, true, sizeof(bool) * nelems);
i = 0;
foreach(l, rowexpr->args)
{
Form_pg_attribute att = TupleDescAttr(tupdesc, i);
Expr *e = (Expr *) lfirst(l);
if (!att->attisdropped)
{
if (exprType((Node *) e) != att->atttypid)
ereport(ERROR,
(errcode(ERRCODE_DATATYPE_MISMATCH),
errmsg("ROW() column has type %s instead of type %s",
format_type_be(exprType((Node *) e)),
format_type_be(att->atttypid))));
}
else
{
e = (Expr *) makeNullConst(INT4OID, -1, InvalidOid);
}
ExecInitExprRec(e, state,
&scratch.d.row.elemvalues[i],
&scratch.d.row.elemnulls[i]);
i++;
}
ExprEvalPushStep(state, &scratch);
break;
}
case T_RowCompareExpr:
{
RowCompareExpr *rcexpr = (RowCompareExpr *) node;
int nopers = list_length(rcexpr->opnos);
List *adjust_jumps = NIL;
ListCell *l_left_expr,
*l_right_expr,
*l_opno,
*l_opfamily,
*l_inputcollid;
ListCell *lc;
int off;
Assert(list_length(rcexpr->largs) == nopers);
Assert(list_length(rcexpr->rargs) == nopers);
Assert(list_length(rcexpr->opfamilies) == nopers);
Assert(list_length(rcexpr->inputcollids) == nopers);
off = 0;
for (off = 0,
l_left_expr = list_head(rcexpr->largs),
l_right_expr = list_head(rcexpr->rargs),
l_opno = list_head(rcexpr->opnos),
l_opfamily = list_head(rcexpr->opfamilies),
l_inputcollid = list_head(rcexpr->inputcollids);
off < nopers;
off++,
l_left_expr = lnext(l_left_expr),
l_right_expr = lnext(l_right_expr),
l_opno = lnext(l_opno),
l_opfamily = lnext(l_opfamily),
l_inputcollid = lnext(l_inputcollid))
{
Expr *left_expr = (Expr *) lfirst(l_left_expr);
Expr *right_expr = (Expr *) lfirst(l_right_expr);
Oid opno = lfirst_oid(l_opno);
Oid opfamily = lfirst_oid(l_opfamily);
Oid inputcollid = lfirst_oid(l_inputcollid);
int strategy;
Oid lefttype;
Oid righttype;
Oid proc;
FmgrInfo *finfo;
FunctionCallInfo fcinfo;
get_op_opfamily_properties(opno, opfamily, false,
&strategy,
&lefttype,
&righttype);
proc = get_opfamily_proc(opfamily,
lefttype,
righttype,
BTORDER_PROC);
if (!OidIsValid(proc))
elog(ERROR, "missing support function %d(%u,%u) in opfamily %u",
BTORDER_PROC, lefttype, righttype, opfamily);
finfo = palloc0(sizeof(FmgrInfo));
fcinfo = palloc0(sizeof(FunctionCallInfoData));
fmgr_info(proc, finfo);
fmgr_info_set_expr((Node *) node, finfo);
InitFunctionCallInfoData(*fcinfo, finfo, 2,
inputcollid, NULL, NULL);
ExecInitExprRec(left_expr, state,
&fcinfo->arg[0], &fcinfo->argnull[0]);
ExecInitExprRec(right_expr, state,
&fcinfo->arg[1], &fcinfo->argnull[1]);
scratch.opcode = EEOP_ROWCOMPARE_STEP;
scratch.d.rowcompare_step.finfo = finfo;
scratch.d.rowcompare_step.fcinfo_data = fcinfo;
scratch.d.rowcompare_step.fn_addr = finfo->fn_addr;
scratch.d.rowcompare_step.jumpnull = -1;
scratch.d.rowcompare_step.jumpdone = -1;
ExprEvalPushStep(state, &scratch);
adjust_jumps = lappend_int(adjust_jumps,
state->steps_len - 1);
}
if (nopers == 0)
{
scratch.opcode = EEOP_CONST;
scratch.d.constval.value = Int32GetDatum(0);
scratch.d.constval.isnull = false;
ExprEvalPushStep(state, &scratch);
}
scratch.opcode = EEOP_ROWCOMPARE_FINAL;
scratch.d.rowcompare_final.rctype = rcexpr->rctype;
ExprEvalPushStep(state, &scratch);
foreach(lc, adjust_jumps)
{
ExprEvalStep *as = &state->steps[lfirst_int(lc)];
Assert(as->opcode == EEOP_ROWCOMPARE_STEP);
Assert(as->d.rowcompare_step.jumpdone == -1);
Assert(as->d.rowcompare_step.jumpnull == -1);
as->d.rowcompare_step.jumpdone = state->steps_len - 1;
as->d.rowcompare_step.jumpnull = state->steps_len;
}
break;
}
case T_CoalesceExpr:
{
CoalesceExpr *coalesce = (CoalesceExpr *) node;
List *adjust_jumps = NIL;
ListCell *lc;
Assert(coalesce->args != NIL);
foreach(lc, coalesce->args)
{
Expr *e = (Expr *) lfirst(lc);
ExecInitExprRec(e, state, resv, resnull);
scratch.opcode = EEOP_JUMP_IF_NOT_NULL;
scratch.d.jump.jumpdone = -1;
ExprEvalPushStep(state, &scratch);
adjust_jumps = lappend_int(adjust_jumps,
state->steps_len - 1);
}
foreach(lc, adjust_jumps)
{
ExprEvalStep *as = &state->steps[lfirst_int(lc)];
Assert(as->opcode == EEOP_JUMP_IF_NOT_NULL);
Assert(as->d.jump.jumpdone == -1);
as->d.jump.jumpdone = state->steps_len;
}
break;
}
case T_MinMaxExpr:
{
MinMaxExpr *minmaxexpr = (MinMaxExpr *) node;
int nelems = list_length(minmaxexpr->args);
TypeCacheEntry *typentry;
FmgrInfo *finfo;
FunctionCallInfo fcinfo;
ListCell *lc;
int off;
typentry = lookup_type_cache(minmaxexpr->minmaxtype,
TYPECACHE_CMP_PROC);
if (!OidIsValid(typentry->cmp_proc))
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_FUNCTION),
errmsg("could not identify a comparison function for type %s",
format_type_be(minmaxexpr->minmaxtype))));
finfo = palloc0(sizeof(FmgrInfo));
fcinfo = palloc0(sizeof(FunctionCallInfoData));
fmgr_info(typentry->cmp_proc, finfo);
fmgr_info_set_expr((Node *) node, finfo);
InitFunctionCallInfoData(*fcinfo, finfo, 2,
minmaxexpr->inputcollid, NULL, NULL);
scratch.opcode = EEOP_MINMAX;
scratch.d.minmax.values =
(Datum *) palloc(sizeof(Datum) * nelems);
scratch.d.minmax.nulls =
(bool *) palloc(sizeof(bool) * nelems);
scratch.d.minmax.nelems = nelems;
scratch.d.minmax.op = minmaxexpr->op;
scratch.d.minmax.finfo = finfo;
scratch.d.minmax.fcinfo_data = fcinfo;
off = 0;
foreach(lc, minmaxexpr->args)
{
Expr *e = (Expr *) lfirst(lc);
ExecInitExprRec(e, state,
&scratch.d.minmax.values[off],
&scratch.d.minmax.nulls[off]);
off++;
}
ExprEvalPushStep(state, &scratch);
break;
}
case T_SQLValueFunction:
{
SQLValueFunction *svf = (SQLValueFunction *) node;
scratch.opcode = EEOP_SQLVALUEFUNCTION;
scratch.d.sqlvaluefunction.svf = svf;
ExprEvalPushStep(state, &scratch);
break;
}
case T_XmlExpr:
{
XmlExpr *xexpr = (XmlExpr *) node;
int nnamed = list_length(xexpr->named_args);
int nargs = list_length(xexpr->args);
int off;
ListCell *arg;
scratch.opcode = EEOP_XMLEXPR;
scratch.d.xmlexpr.xexpr = xexpr;
if (nnamed)
{
scratch.d.xmlexpr.named_argvalue =
(Datum *) palloc(sizeof(Datum) * nnamed);
scratch.d.xmlexpr.named_argnull =
(bool *) palloc(sizeof(bool) * nnamed);
}
else
{
scratch.d.xmlexpr.named_argvalue = NULL;
scratch.d.xmlexpr.named_argnull = NULL;
}
if (nargs)
{
scratch.d.xmlexpr.argvalue =
(Datum *) palloc(sizeof(Datum) * nargs);
scratch.d.xmlexpr.argnull =
(bool *) palloc(sizeof(bool) * nargs);
}
else
{
scratch.d.xmlexpr.argvalue = NULL;
scratch.d.xmlexpr.argnull = NULL;
}
off = 0;
foreach(arg, xexpr->named_args)
{
Expr *e = (Expr *) lfirst(arg);
ExecInitExprRec(e, state,
&scratch.d.xmlexpr.named_argvalue[off],
&scratch.d.xmlexpr.named_argnull[off]);
off++;
}
off = 0;
foreach(arg, xexpr->args)
{
Expr *e = (Expr *) lfirst(arg);
ExecInitExprRec(e, state,
&scratch.d.xmlexpr.argvalue[off],
&scratch.d.xmlexpr.argnull[off]);
off++;
}
ExprEvalPushStep(state, &scratch);
break;
}
case T_NullTest:
{
NullTest *ntest = (NullTest *) node;
if (ntest->nulltesttype == IS_NULL)
{
if (ntest->argisrow)
scratch.opcode = EEOP_NULLTEST_ROWISNULL;
else
scratch.opcode = EEOP_NULLTEST_ISNULL;
}
else if (ntest->nulltesttype == IS_NOT_NULL)
{
if (ntest->argisrow)
scratch.opcode = EEOP_NULLTEST_ROWISNOTNULL;
else
scratch.opcode = EEOP_NULLTEST_ISNOTNULL;
}
else
{
elog(ERROR, "unrecognized nulltesttype: %d",
(int) ntest->nulltesttype);
}
scratch.d.nulltest_row.argdesc = NULL;
ExecInitExprRec(ntest->arg, state,
resv, resnull);
ExprEvalPushStep(state, &scratch);
break;
}
case T_BooleanTest:
{
BooleanTest *btest = (BooleanTest *) node;
ExecInitExprRec(btest->arg, state, resv, resnull);
switch (btest->booltesttype)
{
case IS_TRUE:
scratch.opcode = EEOP_BOOLTEST_IS_TRUE;
break;
case IS_NOT_TRUE:
scratch.opcode = EEOP_BOOLTEST_IS_NOT_TRUE;
break;
case IS_FALSE:
scratch.opcode = EEOP_BOOLTEST_IS_FALSE;
break;
case IS_NOT_FALSE:
scratch.opcode = EEOP_BOOLTEST_IS_NOT_FALSE;
break;
case IS_UNKNOWN:
scratch.opcode = EEOP_NULLTEST_ISNULL;
break;
case IS_NOT_UNKNOWN:
scratch.opcode = EEOP_NULLTEST_ISNOTNULL;
break;
default:
elog(ERROR, "unrecognized booltesttype: %d",
(int) btest->booltesttype);
}
ExprEvalPushStep(state, &scratch);
break;
}
case T_CoerceToDomain:
{
CoerceToDomain *ctest = (CoerceToDomain *) node;
ExecInitCoerceToDomain(&scratch, ctest, state,
resv, resnull);
break;
}
case T_CoerceToDomainValue:
{
scratch.opcode = EEOP_DOMAIN_TESTVAL;
scratch.d.casetest.value = state->innermost_domainval;
scratch.d.casetest.isnull = state->innermost_domainnull;
ExprEvalPushStep(state, &scratch);
break;
}
case T_CurrentOfExpr:
{
scratch.opcode = EEOP_CURRENTOFEXPR;
ExprEvalPushStep(state, &scratch);
break;
}
case T_NextValueExpr:
{
NextValueExpr *nve = (NextValueExpr *) node;
scratch.opcode = EEOP_NEXTVALUEEXPR;
scratch.d.nextvalueexpr.seqid = nve->seqid;
scratch.d.nextvalueexpr.seqtypid = nve->typeId;
ExprEvalPushStep(state, &scratch);
break;
}
default:
elog(ERROR, "unrecognized node type: %d",
(int) nodeTag(node));
break;
}
}
void
ExprEvalPushStep(ExprState *es, const ExprEvalStep *s)
{
if (es->steps_alloc == 0)
{
es->steps_alloc = 16;
es->steps = palloc(sizeof(ExprEvalStep) * es->steps_alloc);
}
else if (es->steps_alloc == es->steps_len)
{
es->steps_alloc *= 2;
es->steps = repalloc(es->steps,
sizeof(ExprEvalStep) * es->steps_alloc);
}
memcpy(&es->steps[es->steps_len++], s, sizeof(ExprEvalStep));
}三、跟踪分析
测试脚本
testdb=# select 1+id,c2 from t_expr where id < 3;进入ExecInitExprRec,Node节点为OpExpr,执行ExprEvalPushStep压入步骤中
(gdb) step
ExecInitExprRec (node=0x1c9a930, state=0x1c8f7d8, resv=0x1c8f7e0, resnull=0x1c8f7dd) at execExpr.c:645
645 ExprEvalStep scratch = {0};
(gdb) n
648 check_stack_depth();
(gdb)
651 Assert(resv != NULL && resnull != NULL);
(gdb)
652 scratch.resvalue = resv;
(gdb)
653 scratch.resnull = resnull;
(gdb)
656 switch (nodeTag(node))
(gdb)
891 OpExpr *op = (OpExpr *) node;
(gdb) p *node
$16 = {type = T_OpExpr}
(gdb) n
893 ExecInitFunc(&scratch, node,
(gdb)
896 ExprEvalPushStep(state, &scratch);
(gdb)
897 break;
(gdb)
2122 }
(gdb)到此，相信大家对“怎么使用PostgreSQL中ExecInitExprRec函数”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！
