Function getgpsegmentCount

src/backend/cdb/cdbutil.c:1919–1951

* return the number of total segments for current snapshot of * segments info */

 * segments info
 */
int
getgpsegmentCount(void)
{
	/* 1 represents a singleton postgresql in utility mode */
	int32 numsegments = 1;

	if (Gp_role == GP_ROLE_DISPATCH)
		numsegments = cdbcomponent_getCdbComponents()->total_segments;
	else if (Gp_role == GP_ROLE_EXECUTE)
		numsegments = numsegmentsFromQD;
	/*
	 * If we are in 'Utility & Binary Upgrade' mode, it must be launched
	 * by the pg_upgrade, so we give it an correct numsegments to make
	 * sure the pg_upgrade can run normally.
	 * Only Utility QD process have the entire information in the
	 * gp_segment_configuration, so we count the segments count in this
	 * process.
	 */
	else if (Gp_role == GP_ROLE_UTILITY &&
			 IsBinaryUpgrade &&
			 IS_QUERY_DISPATCHER())
	{
		/*
		 * While upgrading in single node mode, we will get zero total
		 * segment count, which will cause assertion error in makeGpPolicy.
		 *
		 * Segment number should be set to a value not less than 1 anyway.
		 */
		numsegments = Max(cdbcomponent_getCdbComponents()->total_segments, 1);
	}

	return numsegments;
}

/*
 * IsOnConflictUpdate