Invalid division by zero

[mehdiym]

• What version of Dgraph are you using?
  1.0.10

• Have you tried reproducing the issue with latest release?
  It worked with 1.0.9 but bugs with 1.0.10

• What is the hardware spec (RAM, OS)?
  Linux Debian Testing, 16GoDDR

• Steps to reproduce the issue (command/config used to run Dgraph).
  In a query, I do a division and protect potential 0 value for the divisor with a 'max' function.
  The error only happens with value variables, it works with numeric values.
  I also tried to protect the division with a 'cond' without success.

Here is my query:

{
var(func: uid("0xea61")) {
	ct_thinks as count(thinks)
	knows {
		ct_knows as math(1)
	}
	sum_knows as sum(val(ct_knows))
}
me(func: uid("0xea61")) {
	avg: math(ct_thinks / max(1, sum_knows))
}
}

• Expected behaviour and actual result.
  If sum_knows equals to 0 then avg should be 0.
  If I replace ct_thinks with a literal value, then no more bug.

[mehdiym]

I simplified the query.
The bug disappears if:

• sum_knows is set to math(1) instead of a sum
• ct_thinks is replaced with a number

[srfrog]

Thanks for reporting this. The div0 error is correct but appears to be for the wrong reason.

If I understand correctly, ct_thinks evaluates to zero, and sum_knows also evaluates to zero. so avg should be 0 / 1 == 0. Is this correct?

[mehdiym]

Correct.