Query with math returns field with no name

[jwilder]

Using math on a field returns a field with an empty name. If this used used in a continuous query or select into, it the points can't be inserted and causes some of the issues seen in #5697.

To repro:

> select value from cpu
name: cpu
---------
time            value
1455686412499134533 1
1455686413602752226 2
1455686415066866003 3

> select value * 10 from cpu
name: cpu
---------
time
1455686412499134533 10
1455686413602752226 20
1455686415066866003 30

Notice the second example is missing a value column header.

Selecting multiple columns doesn't fix it.

> select value * 10, value * 2 from cpu
name: cpu
---------
time
1455686412499134533 10  2
1455686413602752226 20  4
1455686415066866003 30  6

Using an as alias does work though:

> select value * 10 as scaled from cpu
name: cpu
---------
time            scaled
1455686412499134533 10
1455686413602752226 20
1455686415066866003 30

[jwilder]

@jsternberg

[jsternberg]

I found where the error is coming from. What should the column name be where there are multiple fields in the binary expression?

[jwilder]

For something like?

select user / total from cpu

Maybe concatenate the fields w/ _? So that query would return user_total.

[jsternberg]

Sure! Should we remove duplicates? If we have SELECT (user + total) / total FROM cpu should it be user_total_total, total_user, or maybe user_total?

[jwilder]

I would probably go with user_total_total or user_total since they are in the order that they were defined in the query. No strong opinion though.

[jsternberg]

I'll go with user_total_total for now since the implementation is much easier.