In Transaction Trace Viewer, the Tree View shows various methods being called during a transaction trace. They are noted by colored icons, red, yellow and green to indicate how much time they took to call during the transaction trace. The color levels are to show the severity level. So, the longer a call takes to make, it may be noted with a green, yellow or red icon.
When running a transaction trace, it displays the details of transaction like methods, backend calls, webservices, etc. In the details sometimes it shows the 0 ms time for some methods and backend calls. Now if any query is executed in the transaction, there should be some time but not 0ms. Why is this time is 0ms?
All versions of APM
It does not mean that no backends were called, what it means is that the number of backends hit during this end to end transaction trace session made up 0% of the time it took to do the trace. Basically the calls marked with green are very quick (i.e. you're not driving during rush hour), the calls marked with a yellow icon indicate it took some time to make the call (i.e. getting closer to driving in rush hour traffic) and the calls marked in red indicate that it took the most time for the transaction to run (i.e. you're stuck in rush hour traffic).