#include "postgres.h"

#include "fmgr.h"

#ifdef PG_MODULE_MAGIC
PG_MODULE_MAGIC;
#endif

Datum rownum(PG_FUNCTION_ARGS);

PG_FUNCTION_INFO_V1(rownum);

Datum
rownum(PG_FUNCTION_ARGS)
{
	int32	   *ptr;

	ptr = (int32 *) fcinfo->flinfo->fn_extra;
	if (ptr == NULL)
	{
		/* First time through for the current query: allocate storage */
		fcinfo->flinfo->fn_extra = MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
													  sizeof(int32));
		ptr = (int32 *) fcinfo->flinfo->fn_extra;
		/* ... and initialize counter */
		*ptr = 1;
	}
	else
		(*ptr)++;

    PG_RETURN_INT32(*ptr);
}