Supported PromQL Features

When using labeled metrics, you can display a graph using the PromQL query language. The following PromQL features are supported in Mackerel.

Time series selector

• Vector selector
  • = (equality label matcher)
  • != (inequality label matcher)
  • =~ (regular expression label matcher)
  • !~ (negative regular expression label matcher)
• Range vector selector

Modifiers

• offset
• @

Aggregation operators

• sum()
• avg()
• min()
• max()
• quantile()
• count()
• count_values()

Also, the by and without modifiers for controlling the labels used for aggregation are supported.

Binary operators

Defined in 4 patterns: (vector) x (vector), (vector) x (scalar), (scalar) x (vector), and (scalar) x (scalar).

To perform vector operations, a mechanism called vector matching is implemented. One-to-one correspondence (arithmetic and comparison operators) and many-to-many correspondence (set operators) have already been implemented.

One-to-many correspondence using the group_left and group_right modifiers is not implemented.

Arithmetic operators

• + (addition)
• - (subtraction)
• * (multiplication)
• / (division)
• % (remainder)
• ^ (exponentiation)

Comparison operators

• ==
• !=
• >
• >=
• <
• <=

Logical/set binary operators

• and (intersection)
• or (union)
• unless (difference)

Functions

Counter Caluculation Functions

• irate()
• increase()

<aggregation>_over_time Functions

• avg_over_time()
• sum_over_time()
• count_over_time()
• last_over_time()
• present_over_time()

Label Functions

• label_join()
• label_replace()

Type Conversion Functions

• vector()
• scalar()

Variables

Variables related to the display time range are supported.

Range variables

• $__interval is the interval between points on the graph, determined by the display time range. It can be used with <aggregation>_over_time functions to express calculations between adjacent points.
• $__rate_interval is an interval determined by the display time range. Since it is set to a value greater than or equal to the point interval $__interval, it is useful when combined with irate() or increase().
• $__range is the display time range.

Range variables expand to seconds by default. They can be expanded in milliseconds using the ${<variable name>:milliseconds} syntax.

Time variables

$__from and $__to expand to the UNIX timestamp in seconds representing the start time and end time of the display time range, respectively.