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|
package metricsql
import (
"sort"
"strings"
)
// Optimize optimizes e in order to improve its performance.
//
// It performs the following optimizations:
//
// - Adds missing filters to `foo{filters1} op bar{filters2}`
// according to https://utcc.utoronto.ca/~cks/space/blog/sysadmin/PrometheusLabelNonOptimization
// I.e. such query is converted to `foo{filters1, filters2} op bar{filters1, filters2}`
func Optimize(e Expr) Expr {
switch t := e.(type) {
case *BinaryOpExpr:
// Convert `foo{filters1} op bar{filters2}` to `foo{filters1, filters2} op bar{filters1, filters2}`.
// This should reduce the number of operations
// See https://utcc.utoronto.ca/~cks/space/blog/sysadmin/PrometheusLabelNonOptimization
// for details.
if !canOptimizeBinaryOp(t) {
return optimizeBinaryOpArgs(t)
}
meLeft := getMetricExprForOptimization(t.Left)
if meLeft == nil || !meLeft.hasNonEmptyMetricGroup() {
return optimizeBinaryOpArgs(t)
}
meRight := getMetricExprForOptimization(t.Right)
if meRight == nil || !meRight.hasNonEmptyMetricGroup() {
return optimizeBinaryOpArgs(t)
}
lfs := intersectLabelFilters(meLeft.LabelFilters[1:], meRight.LabelFilters[1:])
meLeft.LabelFilters = append(meLeft.LabelFilters[:1], lfs...)
meRight.LabelFilters = append(meRight.LabelFilters[:1], lfs...)
return t
case *FuncExpr:
for i := range t.Args {
t.Args[i] = Optimize(t.Args[i])
}
return t
case *AggrFuncExpr:
for i := range t.Args {
t.Args[i] = Optimize(t.Args[i])
}
return t
default:
return e
}
}
func canOptimizeBinaryOp(be *BinaryOpExpr) bool {
if be.JoinModifier.Op != "" || be.GroupModifier.Op != "" {
return false
}
switch be.Op {
case "+", "-", "*", "/", "%", "^",
"==", "!=", ">", "<", ">=", "<=",
"and", "if", "ifnot", "default":
return true
default:
return false
}
}
func optimizeBinaryOpArgs(be *BinaryOpExpr) *BinaryOpExpr {
be.Left = Optimize(be.Left)
be.Right = Optimize(be.Right)
return be
}
func getMetricExprForOptimization(e Expr) *MetricExpr {
me, ok := e.(*MetricExpr)
if ok {
// Ordinary metric expression, i.e. `foo{bar="baz"}`
return me
}
be, ok := e.(*BinaryOpExpr)
if ok {
if !canOptimizeBinaryOp(be) {
return nil
}
if me, ok := be.Left.(*MetricExpr); ok && isNumberOrScalar(be.Right) {
// foo{bar="baz"} * num_or_scalar
return me
}
if me, ok := be.Right.(*MetricExpr); ok && isNumberOrScalar(be.Left) {
// num_or_scalar * foo{bar="baz"}
return me
}
return nil
}
fe, ok := e.(*FuncExpr)
if !ok {
return nil
}
if IsRollupFunc(fe.Name) {
for _, arg := range fe.Args {
re, ok := arg.(*RollupExpr)
if !ok {
continue
}
if me, ok := re.Expr.(*MetricExpr); ok {
// rollup_func(foo{bar="baz"}[d])
return me
}
}
return nil
}
if IsTransformFunc(fe.Name) {
switch strings.ToLower(fe.Name) {
case "absent", "histogram_quantile", "label_join", "label_replace", "scalar", "vector",
"label_set", "label_map", "label_uppercase", "label_lowercase", "label_del", "label_keep", "label_copy",
"label_move", "label_transform", "label_value", "label_match", "label_mismatch",
"prometheus_buckets", "buckets_limit", "histogram_share", "union", "":
// metric expressions for these functions cannot be optimized.
return nil
}
for _, arg := range fe.Args {
if me, ok := arg.(*MetricExpr); ok {
// transform_func(foo{bar="baz"})
return me
}
}
return nil
}
return nil
}
func isNumberOrScalar(e Expr) bool {
if _, ok := e.(*NumberExpr); ok {
return true
}
if fe, ok := e.(*FuncExpr); ok && strings.ToLower(fe.Name) == "scalar" {
return true
}
return false
}
func intersectLabelFilters(a, b []LabelFilter) []LabelFilter {
m := make(map[string]LabelFilter, len(a)+len(b))
var buf []byte
for _, lf := range a {
buf = lf.AppendString(buf[:0])
m[string(buf)] = lf
}
for _, lf := range b {
buf = lf.AppendString(buf[:0])
m[string(buf)] = lf
}
ss := make([]string, 0, len(m))
for s := range m {
ss = append(ss, s)
}
sort.Strings(ss)
lfs := make([]LabelFilter, 0, len(ss))
for _, s := range ss {
lfs = append(lfs, m[s])
}
return lfs
}
|
