Function prepare_foreign_modify

contrib/postgres_fdw/postgres_fdw.c:4208–4252

* prepare_foreign_modify * Establish a prepared statement for execution of INSERT/UPDATE/DELETE */

 *		Establish a prepared statement for execution of INSERT/UPDATE/DELETE
 */
static void
prepare_foreign_modify(PgFdwModifyState *fmstate)
{
	char		prep_name[NAMEDATALEN];
	char	   *p_name;
	PGresult   *res;

	/*
	 * The caller would already have processed a pending asynchronous request
	 * if any, so no need to do it here.
	 */

	/* Construct name we'll use for the prepared statement. */
	snprintf(prep_name, sizeof(prep_name), "pgsql_fdw_prep_%u",
			 GetPrepStmtNumber(fmstate->conn));
	p_name = pstrdup(prep_name);

	/*
	 * We intentionally do not specify parameter types here, but leave the
	 * remote server to derive them by default.  This avoids possible problems
	 * with the remote server using different type OIDs than we do.  All of
	 * the prepared statements we use in this module are simple enough that
	 * the remote server will make the right choices.
	 */
	if (!PQsendPrepare(fmstate->conn,
					   p_name,
					   fmstate->query,
					   0,
					   NULL))
		pgfdw_report_error(ERROR, NULL, fmstate->conn, false, fmstate->query);

	/*
	 * Get the result, and check for success.
	 *
	 * We don't use a PG_TRY block here, so be careful not to throw error
	 * without releasing the PGresult.
	 */
	res = pgfdw_get_result(fmstate->conn, fmstate->query);
	if (PQresultStatus(res) != PGRES_COMMAND_OK)
		pgfdw_report_error(ERROR, res, fmstate->conn, true, fmstate->query);
	PQclear(res);

	/* This action shows that the prepare has been done. */
	fmstate->p_name = p_name;
}

/*
 * convert_prep_stmt_params