runtime error: division by zero

[tamsky]

Running influxdb-0.6.3-1.x86_64.rpm in a single node configuration.

[2014/05/14 20:09:34 EDT] [INFO] (coordinator.(*CoordinatorImpl).RunQuery:69) Query: db: mondemand, u: root, q: SELECT blank_response.value / request.value FROM blank_response INNER JOIN request LIMIT 10
********************************BUG********************************
Database: mondemand
Query: [select blank_response.value / request.value from blank_response inner join request limit 10]
Error: runtime error: integer divide by zero. Stacktrace: goroutine 3795 [running]:
common.RecoverFunc(0xc218219146, 0x9, 0xc21eb9cb60, 0x67, 0x7faac4f92e78)
        /home/vagrant/influxdb/src/common/recover.go:13 +0x106
runtime.panic(0x889520, 0x100ae7d)
        /home/vagrant/bin/go/src/pkg/runtime/panic.c:248 +0x106
engine.DivideOperator(0xc2157ebd10, 0x2, 0x2, 0xc2200e4100, 0x2, ...)
        /home/vagrant/influxdb/src/engine/arithmetic.go:127 +0x21a
engine.GetValue(0xc214b87550, 0xc2200e4100, 0x2, 0x2, 0xc214dca100, ...)
        /home/vagrant/influxdb/src/engine/arithmetic.go:37 +0x538
engine.func·012(0xc220395af0, 0xc220395af0, 0xc220395af0)
        /home/vagrant/influxdb/src/engine/engine.go:644 +0x376
engine.func·014(0xc220395aa0, 0xc220eefe00, 0x1)
        /home/vagrant/influxdb/src/engine/merge.go:57 +0x8cb
engine.(*mergeState).yieldNextPoints(0xc21c759630, 0xc214b87870, 0x0, 0x0)
        /home/vagrant/influxdb/src/engine/merge.go:193 +0x23d
engine.func·016(0xc218fe78c0, 0x7c9d80, 0xc21c759570)
        /home/vagrant/influxdb/src/engine/merge.go:279 +0x9c
engine.(*QueryEngine).yieldSeriesData(0xc2126dc460, 0xc2
[2014/05/14 20:09:34 EDT] [EROR] (coordinator.(*CoordinatorImpl).readFromResponseChannels:345) Error while executing query: Internal Error
[2014/05/14 20:09:39 EDT] [INFO] (wal.(*WAL).RecoverServerFromRequestNumber:197) /opt/influxdb/shared/data/wal/log.6780002 yielded 10000 requests
[2014/05/14 20:09:39 EDT] [INFO] (wal.(*WAL).RecoverServerFromRequestNumber:191) Replaying from /opt/influxdb/shared/data/wal/log.6790002:-1
[2014/05/14 20:09:39 EDT] [INFO] (wal.(*log).replayFromFileLocation:227) replaying from file location 0
[2014/05/14 20:09:39 EDT] [INFO] (wal.(*WAL).processCommitEntry:344) Deleting /opt/influxdb/shared/data/wal/log.6780002

Possibly related #413 but not sure.

[jvshahid]

It's not really clear whether this is a data issue or a bug. I also don't think it's related to #413, you are doing division in the query which could cause a divide by zero error. You should be able to do select blank_response.value / request.value from blank_response inner join request where request.value <> 0 limit 10 once #524 is fixed. This will filter out 0 values from the denominator

[tamsky]

What math library does influxdb use?

Instead of forcing the query side to work harder,
any chance we can support division-by-zero using IEEE-754 style ±Infinity?

How does influx currently handle

• results that overflow?
• invalid results; eg. sqrt(-1) == ±NaN ?

[jvshahid]

Even if that was possible, json doesn't support infinity or nan, at least not in a standard way

[tamsky]

For the moment, assume I use your approach, filter zero values from the denominator at query time.
Will I see a result for time windows where there is a non-zero numerator and a filtered-away denominator?

Perhaps this could be a configurable command line parameter/value that allows users to declare a (text) substitute for the output of division by zero?

("1.0e5000" would appear to overflow even an implementation that uses 128bit float.) [1]

[1] http://stackoverflow.com/questions/1423081/json-left-out-infinity-and-nan-json-status-in-ecmascript#comment17240692_9356535

[jvshahid]

Closing this issue since #524 is closed. The fix will be included in the next release.

[tamsky]

If my questions are not appropriate to discuss here, a better venue is...

[damm]

@tamsky I think https://groups.google.com/forum/#!forum/influxdb works (or irc)

[tamsky]

@pauldix - Can we output null as the result of division-by-zero ?