use state store index if possible when filtering list results

nomad/deployment_endpoint.go

@@ -409,6 +409,30 @@ func (d *Deployment) List(args *structs.DeploymentListRequest, reply *structs.De
 			return structs.ErrIncompatibleFiltering
 		}
 
+		// Use state store index if possible.
+		useIndex := false
+		matches := listFilterSimpleEqRegex.FindStringSubmatch(args.Filter)
+
+		if len(matches) == 3 {
+			prop := matches[1]
+			value := matches[2]
+
+			switch prop {
+			case "ID":
+				useIndex = true
+				args.Prefix = value
+			case "Namespace":
+				useIndex = true
+				args.Namespace = value
+			}
+		}
+
+		if useIndex {
+			args.Filter = ""
+		} else {
+			// Use wildcards namespace to apply filter to all evals.
+			args.Namespace = "*"
+		}
 		// Use wildcards namespace to apply filter to all deployments.
 		args.Namespace = "*"
 	}

nomad/eval_endpoint.go

@@ -408,8 +408,30 @@ func (e *Eval) List(args *structs.EvalListRequest,
 			return structs.ErrIncompatibleFiltering
 		}
 
-		// Use wildcards namespace to apply filter to all evals.
-		args.Namespace = "*"
+		// Use state store index if possible.
+		useIndex := false
+		matches := listFilterSimpleEqRegex.FindStringSubmatch(args.Filter)
+
+		if len(matches) == 3 {
+			prop := matches[1]
+			value := matches[2]
+
+			switch prop {
+			case "ID":
+				useIndex = true
+				args.Prefix = value
+			case "Namespace":
+				useIndex = true
+				args.Namespace = value
+			}
+		}
+
+		if useIndex {
+			args.Filter = ""
+		} else {
+			// Use wildcards namespace to apply filter to all evals.
+			args.Namespace = "*"
+		}
 	}
 
 	// Setup the blocking query

nomad/util.go

@@ -6,6 +6,7 @@ import (
 	"net"
 	"os"
 	"path/filepath"
+	"regexp"
 	"strconv"
 
 	memdb "github.com/hashicorp/go-memdb"
@@ -20,6 +21,11 @@ import (
 // in ApplyPlanResultsRequest
 var MinVersionPlanNormalization = version.Must(version.NewVersion("0.9.2"))
 
+// listFilterSimpleEqRegex matches go-bexpr filters with a single equality
+// check of a string value. It is used to determine if a state store index can
+// be used rather than filtering elements individually.
+var listFilterSimpleEqRegex = regexp.MustCompile(`^(.+)\s+==\s+"(.+)"$`)
+
 // ensurePath is used to make sure a path exists
 func ensurePath(path string, dir bool) error {
 	if !dir {