Function XLogRegisterData

src/backend/access/transam/xloginsert.c:338–361

* Add data to the WAL record that's being constructed. * * The data is appended to the "main chunk", available at replay with * XLogRecGetData(). */

 * XLogRecGetData().
 */
void
XLogRegisterData(char *data, int len)
{
	XLogRecData *rdata;

	Assert(begininsert_called);

	if (num_rdatas >= max_rdatas)
		elog(ERROR, "too much WAL data");
	rdata = &rdatas[num_rdatas++];

	rdata->data = data;
	rdata->len = len;

	/*
	 * we use the mainrdata_last pointer to track the end of the chain, so no
	 * need to clear 'next' here.
	 */

	mainrdata_last->next = rdata;
	mainrdata_last = rdata;

	mainrdata_len += len;
}

/*
 * Add buffer-specific data to the WAL record that's being constructed.