[rrd-users] A couple of questions about the 'update' function

[Sam Umbach]

On 4/11/07, David Ball <davidtball at gmail.com> wrote:
>    Hi there.  A couple questions about the 'update' function in 1.2.19:
>
> -what is the maximum number of  timestamp:value  entries that can be
> combined in a single 'update' command?

There doesn't appear to be a fixed limit in the rrdtool source.  You
may still be limited by a maximum command line length or maximum
parameter count in the shell or C library.

> -if a  timestamp:value  pair is sent in an update command, but we
> already have data for that timestamp slot, is the original entry left
> in place, or is it replaced with the new? (note: I'm not using SNMP to
> gather this data, so it is possible, though unlikely, to have
> overlapping entries arise).

Data can only be inserted into an rrd file in order of increasing
timestamps.  If rrdtool encounters an older timestamp than the most
recent update, an error is printed and the command aborts.  If you
expect this to happen, you may not want to combine multiple updates in
the same rrdtool update invocation.

-Sam