InfluxQL mathematical operators

Mathematical operators follow the standard order of operations. That is, parentheses take precedence to division and multiplication, which takes precedence to addition and subtraction. For example 5 / 2 + 3 * 2 = (5 / 2) + (3 * 2) and 5 + 2 * 3 - 2 = 5 + (2 * 3) - 2.

Content

• Mathematical Operators
  • Addition
  • Subtraction
  • Multiplication
  • Division
  • Modulo
  • Bitwise AND
  • Bitwise OR
  • Bitwise Exclusive-OR
  • Common Issues with Mathematical Operators
• Unsupported Operators

Mathematical Operators

Addition

Perform addition with a constant.

SELECT "A" + 5 FROM "add"

SELECT * FROM "add" WHERE "A" + 5 > 10

Perform addition on two fields.

SELECT "A" + "B" FROM "add"

SELECT * FROM "add" WHERE "A" + "B" >= 10

Subtraction

Perform subtraction with a constant.

SELECT 1 - "A" FROM "sub"

SELECT * FROM "sub" WHERE 1 - "A" <= 3

Perform subtraction with two fields.

SELECT "A" - "B" FROM "sub"

SELECT * FROM "sub" WHERE "A" - "B" <= 1

Multiplication

Perform multiplication with a constant.

SELECT 10 * "A" FROM "mult"

SELECT * FROM "mult" WHERE "A" * 10 >= 20

Perform multiplication with two fields.

SELECT "A" * "B" * "C" FROM "mult"

SELECT * FROM "mult" WHERE "A" * "B" <= 80

Multiplication distributes across other operators.

SELECT 10 * ("A" + "B" + "C") FROM "mult"

SELECT 10 * ("A" - "B" - "C") FROM "mult"

SELECT 10 * ("A" + "B" - "C") FROM "mult"

Division

Perform division with a constant.

SELECT 10 / "A" FROM "div"

SELECT * FROM "div" WHERE "A" / 10 <= 2

Perform division with two fields.

SELECT "A" / "B" FROM "div"

SELECT * FROM "div" WHERE "A" / "B" >= 10

Division distributes across other operators.

SELECT 10 / ("A" + "B" + "C") FROM "mult"

Modulo

Perform modulo arithmetic with a constant.

SELECT "B" % 2 FROM "modulo"

SELECT "B" FROM "modulo" WHERE "B" % 2 = 0

Perform modulo arithmetic on two fields.

SELECT "A" % "B" FROM "modulo"

SELECT "A" FROM "modulo" WHERE "A" % "B" = 0

Bitwise AND

You can use this operator with any integers or Booleans, whether they are fields or constants. It does not work with float or string datatypes, and you cannot mix integers and Booleans.

SELECT "A" & 255 FROM "bitfields"

SELECT "A" & "B" FROM "bitfields"

SELECT * FROM "data" WHERE "bitfield" & 15 > 0

SELECT "A" & "B" FROM "booleans"

SELECT ("A" ^ true) & "B" FROM "booleans"

Bitwise OR

You can use this operator with any integers or Booleans, whether they are fields or constants. It does not work with float or string datatypes, and you cannot mix integers and Booleans.

SELECT "A" | 5 FROM "bitfields"

SELECT "A" | "B" FROM "bitfields"

SELECT * FROM "data" WHERE "bitfield" | 12 = 12

Bitwise Exclusive-OR

You can use this operator with any integers or Booleans, whether they are fields or constants. It does not work with float or string datatypes, and you cannot mix integers and Booleans.

SELECT "A" ^ 255 FROM "bitfields"

SELECT "A" ^ "B" FROM "bitfields"

SELECT * FROM "data" WHERE "bitfield" ^ 6 > 0

Common Issues with Mathematical Operators

Issue 1: Mathematical operators with wildcards and regular expressions

InfluxDB does not support combining mathematical operations with a wildcard (*) or regular expression in the SELECT clause. The following queries are invalid and the system returns an error:

Perform a mathematical operation on a wildcard.

> SELECT * + 2 FROM "nope"
ERR: unsupported expression with wildcard: * + 2

Perform a mathematical operation on a wildcard within a function.

> SELECT COUNT(*) / 2 FROM "nope"
ERR: unsupported expression with wildcard: count(*) / 2

Perform a mathematical operation on a regular expression.

> SELECT /A/ + 2 FROM "nope"
ERR: error parsing query: found +, expected FROM at line 1, char 12

Perform a mathematical operation on a regular expression within a function.

> SELECT COUNT(/A/) + 2 FROM "nope"
ERR: unsupported expression with regex field: count(/A/) + 2

Issue 2: Mathematical operators with functions

The use of mathematical operators inside of function calls is currently unsupported. Note that InfluxDB only allows functions in the SELECT clause.

For example

SELECT 10 * mean("value") FROM "cpu"

will work, however

SELECT mean(10 * "value") FROM "cpu"

will yield a parse error.

InfluxQL supports subqueries which offer similar functionality to using mathematical operators inside a function call. See Data Exploration for more information.

Unsupported Operators

Inequalities

Using any of =,!=,<,>,<=,>=,<> in the SELECT clause yields empty results for all types. See GitHub issue 3525.

Logical Operators

Using any of !|,NAND,XOR,NOR yield a parser error.

Additionally using AND, OR in the SELECT clause of a query will not behave as mathematical operators and simply yield empty results, as they are tokens in InfluxQL. However, you can apply the bitwise operators &, | and ^ to Boolean data.

Bitwise Not

There is no bitwise-not operator, because the results you expect depend on the width of your bitfield. InfluxQL does not know how wide your bitfield is, so cannot implement a suitable bitwise-not operator.

For example, if your bitfield is 8 bits wide, then to you the integer 1 represents the bits 0000 0001. The bitwise-not of this should return the bits 1111 1110, i.e. the integer 254.

However, if your bitfield is 16 bits wide, then the integer 1 represents the bits 0000 0000 0000 0001. The bitwise-not of this should return the bits 1111 1111 1111 1110, i.e. the integer 65534.

Solution

You can implement a bitwise-not operation by using the ^ (bitwise xor) operator together with the number representing all-ones for your word-width:

For 8-bit data:

SELECT "A" ^ 255 FROM "data"

For 16-bit data:

SELECT "A" ^ 65535 FROM "data"

For 32-bit data:

SELECT "A" ^ 4294967295 FROM "data"

In each case the constant you need can be calculated as (2 ** width) - 1.