在 PostgreSQL 9 上用 C 创建触发器

Question

我在 Ubuntu 10.04 上有一个 PostgreSQL 9.0 服务器，我尝试按照以下链接在 C 代码中创建触发器:

Documentation , Compile

目前，我的代码应该仅显示记录中列的值(并返回“已编辑”记录):

#include "postgres.h"
#include "executor/spi.h"
#include "commands/trigger.h"

#ifdef PG_MODULE_MAGIC
PG_MODULE_MAGIC;
#endif

extern Datum trigger_test(PG_FUNCTION_ARGS);

PG_FUNCTION_INFO_V1(trigger_test);

Datum
trigger_test(PG_FUNCTION_ARGS)
{
  TriggerData *trigdata = (TriggerData *) fcinfo->context;
  TupleDesc   tupdesc;
  HeapTuple   rettuple;

  if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
    rettuple = trigdata->tg_newtuple;
  else
    rettuple = trigdata->tg_trigtuple;

  tupdesc = trigdata->tg_relation->rd_att;

  bool isnull = false;
  int64 att = DatumGetInt64(heap_getattr(rettuple, 2, tupdesc, &isnull));

  elog(INFO,"Value second column is: %d",att);
  return PointerGetDatum(rettuple);
}

该文件与postgres.h同路径，其中有文件:executor/spi.h和commands/trigger.h 。但是，当我运行命令时:

cc -fpic -c trigger_test.c

我收到错误:

In file included from postgres.h:48,
from trigger_test.c:1:
   utils/elog.h:69:28: error: utils/errcodes.h: Not exists the file or directory
In file included from trigger_test.c:2:
  executor/spi.h:16:30: error: nodes/parsenodes.h: Not exists the file or directory
  executor/spi.h:17:26: error: utils/portal.h: Not exists the file or directory
  executor/spi.h:18:28: error: utils/relcache.h: Not exists the file or directory
  executor/spi.h:19:28: error: utils/snapshot.h: Not exists the file or directory
...

所有文件都存在，并且我不想更改文件中的所有包含内容:elog.h、spi.h 等，以免产生可能的后果。有没有人设置了这样的触发器并可以告诉我哪里错了？

提前致谢。

Answer 1

您忘记在函数中包含 fmgr.h header ，因此魔术 block 可以正常工作