The interval datatype can go to microsecond precision though currently
the smallest unit is seconds. Microseconds are represented as decimal
places, eg 5 microseconds is 0.000005 seconds.
To insert microseconds I have to use the following line, ($1*0.000001 ||
' seconds')::interval
Being able to specify microseconds as a unit would avoid hacks like this
and improve support for sub-second intervals.
David