wip

docs/VictoriaLogs/LogsQL.md

@@ -1158,6 +1158,7 @@ LogsQL supports the following pipes:
 - [`filter`](#filter-pipe) applies additional [filters](#filters) to results.
 - [`format`](#format-pipe) formats ouptut field from input [log fields](https://docs.victoriametrics.com/victorialogs/keyconcepts/#data-model).
 - [`limit`](#limit-pipe) limits the number selected logs.
+- [`math`](#math-pipe) performs mathematical calculations over numeric values stored in [log fields](https://docs.victoriametrics.com/victorialogs/keyconcepts/#data-model).
 - [`offset`](#offset-pipe) skips the given number of selected logs.
 - [`pack_json`](#pack_json-pipe) packs [log fields](https://docs.victoriametrics.com/victorialogs/keyconcepts/#data-model) into JSON object.
 - [`rename`](#rename-pipe) renames [log fields](https://docs.victoriametrics.com/victorialogs/keyconcepts/#data-model).
@@ -1269,6 +1270,7 @@ See also:
 - [Conditional extract](#conditional-extract)
 - [`unpack_json` pipe](#unpack_json-pipe)
 - [`unpack_logfmt` pipe](#unpack_logfmt-pipe)
+- [`math` pipe](#math-pipe)
 
 #### Format for extract pipe pattern
 
@@ -1526,6 +1528,50 @@ See also:
 - [`sort` pipe](#sort-pipe)
 - [`offset` pipe](#offset-pipe)
 
+### math pipe
+
+`| math ...` [pipe](#pipes) performs mathematical calculations over numeric values stored in [log fields](https://docs.victoriametrics.com/victorialogs/keyconcepts/#data-model).
+For example, the following query divides `duration_msecs` field value by 1000, then rounds them to integer and stores the result in the `duration_secs` field:
+
+```logsql
+_time:5m | math round(duration_msecs / 1000) as duration_secs
+```
+
+The following mathematical operations are supported by `math` pipe:
+
+- `arg1 + arg2` - returns the sum of `arg1` and `arg2`
+- `arg1 - arg2` - returns the difference between `arg1` and `arg2`
+- `arg1 * arg2` - multiplies `arg1` by `arg2`
+- `arg1 / arg2` - divides `arg1` by `arg2`
+- `arg1 % arg2` - returns the remainder of the division of `arg1` by `arg2`
+- `arg1 ^ arg2` - returns the power of `arg1` by `arg2`
+- `abs(arg)` - returns an absolute values for the given `arg`
+- `max(arg1, ..., argN)` - returns the maximum value among the given `arg1`, ..., `argN`
+- `min(arg1, ..., argN)` - returns the minimum value among the given `arg1`, ..., `argN`
+- `round(arg)` - returns rounded to integer value for the given `arg`. The `round()` accepts optional `nearest` arg, which allows rounding the number to the given `nearest` multiple.
+  For example, `round(temperature, 0.1)` rounds `temperature` field to one decimal digit after the point.
+
+Every `argX` argument in every mathematical operation can contain one of the following values:
+
+- The name of [log field](https://docs.victoriametrics.com/victorialogs/keyconcepts/#data-model). For example, `errors_total / requests_total`.
+- Any [supported numeric value](#numeric-values). For example, `response_size_bytes / 1MiB`.
+- Another mathematical expression. Optionally, it may be put inside `(...)`. For example, `(a + b) * c`.
+
+Multiple distinct results can be calculated in a single `math ...` pipe - just separate them with `,`. For example, the following query calculates the error rate
+and the number of successful requests from `errors`, `warnings` and `requests` [log fields](https://docs.victoriametrics.com/victorialogs/keyconcepts/#data-model):
+
+```logsql
+_time:5m | math
+    (errors / requests) as error_rate,
+    (requests - (errors + warnings)) as success_requests
+```
+
+See also:
+
+- [`stats` pipe](#stats-pipe)
+- [`extract` pipe](#extract-pipe)
+
+
 ### offset pipe
 
 If some selected logs must be skipped after [`sort`](#sort-pipe), then `| offset N` [pipe](#pipes) can be used, where `N` can contain any [supported integer numeric value](#numeric-values).
@@ -1808,6 +1854,7 @@ See also:
 - [stats by IPv4 buckets](#stats-by-ipv4-buckets)
 - [stats with additional filters](#stats-with-additional-filters)
 - [stats pipe functions](#stats-pipe-functions)
+- [`math` pipe](#math-pipe)
 - [`sort` pipe](#sort-pipe)
 
 

lib/logstorage/pipe_math.go

@@ -535,8 +535,8 @@ func parseMathExprRound(lex *lexer) (*mathExpr, error) {
 	if err != nil {
 		return nil, err
 	}
-	if len(me.args) != 2 {
-		return nil, fmt.Errorf("'round' function needs 2 args; got %d args: [%s]", len(me.args), me)
+	if len(me.args) != 1 && len(me.args) != 2 {
+		return nil, fmt.Errorf("'round' function needs 1 or 2 args; got %d args: [%s]", len(me.args), me)
 	}
 	return me, nil
 }
@@ -749,6 +749,15 @@ func mathFuncMin(result []float64, args [][]float64) {
 
 func mathFuncRound(result []float64, args [][]float64) {
 	arg := args[0]
+	if len(args) == 1 {
+		// Round to integer
+		for i := range result {
+			result[i] = math.Round(arg[i])
+		}
+		return
+	}
+
+	// Round to nearest
 	nearest := args[1]
 	var f float64
 	for i := range result {

lib/logstorage/pipe_math_test.go

@@ -20,6 +20,7 @@ func TestParsePipeMathSuccess(t *testing.T) {
 	f(`math (foo / ((bar + baz) * abc) ^ -2) as a`)
 	f(`math (foo + bar / baz - abc) as a`)
 	f(`math min(3, foo, (1 + bar) / baz) as a, max(a, b) as b, (abs(c) + 5) as d`)
+	f(`math round(foo) as x`)
 	f(`math round(foo, 0.1) as y`)
 }
 
@@ -39,7 +40,6 @@ func TestParsePipeMathFailure(t *testing.T) {
 	f(`math max() as x`)
 	f(`math max(a) as x`)
 	f(`math round() as x`)
-	f(`math round(a) as x`)
 	f(`math round(a, b, c) as x`)
 }
 
@@ -134,7 +134,7 @@ func TestPipeMath(t *testing.T) {
 		},
 	})
 
-	f("math abs(-min(a,b)) as min, max(b,c) as max", [][]Field{
+	f("math abs(-min(a,b)) as min, round(max(40*b/30,c)) as max", [][]Field{
 		{
 			{"a", "v1"},
 			{"b", "2"},
@@ -150,7 +150,7 @@ func TestPipeMath(t *testing.T) {
 		},
 	})
 
-	f("math round((2*c + (b%c))/(c-b)^(b-1), 0.001) as a", [][]Field{
+	f("math round((2*c + (b%c))/(c-b)^(b-1), -0.001) as a", [][]Field{
 		{
 			{"a", "v"},
 			{"b", "2"},