InfluxDB crashes with text field selected in inner join

[cboggs]

InfluxDB crashes when specifying a text field as a selection either before or after selecting the difference between two fields in an INNER JOIN

When using an INNER JOIN, selecting various component fields works as expected. Likewise, selecting the difference between two fields (eg: select a.value - b.value...) works as expected. Specifying a text field, such as hostname, before or after that type of subtraction value causes InfluxDB to crash.

Crashing queries were submitted via both the web admin UI and curl. Sample included below.

Example queries:
WORKS

SELECT total.value, total.hostname, idle.value, idle.hostname FROM totalThreads AS total INNER JOIN idleThreads AS idle GROUP BY time(15s);

WORKS

SELECT total.value - idle.value FROM totalThreads AS total INNER JOIN idleThreads AS idle GROUP BY time(15s);

CRASHES

SELECT total.value - idle.value, total.hostname FROM totalThreads AS total INNER JOIN idleThreads AS idle GROUP BY time(15s);

CRASHES

SELECT total.hostname, total.value - idle.value FROM totalThreads AS total INNER JOIN idleThreads AS idle GROUP BY time(15s);

CRASHES

curl 'http://influxdb:8086/db/testdb/series?u=root&p=root&q=SELECT%20total.value%20-%20idle.value%2C%20total.hostname%20FROM%20totalThreads%20AS%20total%20INNER%20JOIN%20idleThreads%20AS%20idle%20GROUP%20BY%20time(15s)%3B' -H 'Accept: application/json, text/javascript'

Quick cURL to generate test data:

curl -v -XPOST -d '[ { "name" : "totalThreads", "columns" : ["time", "value", "hostname"], "points" : [ [1405364100, 16, "serverA"], [1405364105, 20, "serverB"], [1405364115, 16, "serverA"], [1405364120, 20, "serverB"], [1405364130, 18, "serverA"], [1405364135, 15, "serverB"], [1405364145, 19, "serverA"], [1405364150, 16, "serverB"] ] }, { "name" : "totalThreads", "columns" : ["time", "value", "hostname"], "points" : [ [1405364100, 12, "serverA"], [1405364105, 9, "serverB"], [1405364115, 13, "serverA"], [1405364120, 12, "serverB"], [1405364130, 8, "serverA"], [1405364135, 13, "serverB"], [1405364145, 2, "serverA"], [1405364150, 13, "serverB"] ]} ]' 'http://influxdb:8086/db/testdb/series?u=testuser&p=testpw&time_precision=s'

Debug log info from test is available if needed, but it simply cuts off after logging what the requested query string is, no indication of error or warning before the process dies.

(To be clear, I did eventually figure out that the way to get what I wanted was to craft something like this:
select difference(value) from totalThreads merge idleThreads group by time(15s), hostname;

Just wanted to point out that doing it incorrectly causes a crash instead of an error message.)