大家好，我是考100分的小小码 ，祝大家学习进步，加薪顺利呀。今天说一说PostgreSQL源码学习–执行器#10，11,希望您对编程的造诣更进一步.
本节介绍standard_ExecutorRun和ExecutorRun函数。
standard_ExecutorRun函数
//src/include/execurot/executor.h
extern void standard_ExecutorRun(QueryDesc *queryDesc,
ScanDirection direction, uint64 count, bool execute_once);
代码100分
代码100分//src/backend/executor/execMain.c
Assert(queryDesc != NULL);
estate = queryDesc->estate;
Assert(estate != NULL);
Assert(!(estate->es_top_eflags & EXEC_FLAG_EXPLAIN_ONLY));
/* 切换为每个查询对应的内存上下文 */
oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
/* 视情况开始执行器运行时间统计 */
if (queryDesc->totaltime)
InstrStartNode(queryDesc->totaltime);
operation = queryDesc->operation;
dest = queryDesc->dest;
/* 若要发送元组，启动元组接收器 */
estate->es_processed = 0;
sendTuples = (operation == CMD_SELECT ||
queryDesc->plannedstmt->hasReturning);
if (sendTuples)
dest->rStartup(dest, operation, queryDesc->tupDesc);
/* 执行plan */
if (!ScanDirectionIsNoMovement(direction))
{
if (execute_once && queryDesc->already_executed)
elog(ERROR, "can"t re-execute query flagged for single execution");
queryDesc->already_executed = true;
ExecutePlan(estate,
queryDesc->planstate,
queryDesc->plannedstmt->parallelModeNeeded,
operation,
sendTuples,
count,
direction,
dest,
execute_once);
}
/* 关闭元组接收器 */
if (sendTuples)
dest->rShutdown(dest);
/* 结束执行器计时 */
if (queryDesc->totaltime)
InstrStopNode(queryDesc->totaltime, estate->es_processed);
/* 切回内存上下文 */
MemoryContextSwitchTo(oldcontext);
ExecutorRun函数
void
ExecutorRun(QueryDesc *queryDesc,
ScanDirection direction, uint64 count,
bool execute_once)
{
if (ExecutorRun_hook)
(*ExecutorRun_hook) (queryDesc, direction, count, execute_once);
else
standard_ExecutorRun(queryDesc, direction, count, execute_once);
}
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