diff --git a/README.md b/README.md
index e10cf81..ebf660a 100644
--- a/README.md
+++ b/README.md
@@ -32,12 +32,13 @@ Features
 - In-memory database for [fast reads and writes](#performance)
 - Embeddable with a [simple API](https://godoc.org/github.com/tidwall/buntdb)
 - [Spatial indexing](#spatial-indexes) for up to 20 dimensions; Useful for Geospatial data
+- Index fields inside [JSON](#json-indexes) documents
 - Create [custom indexes](#custom-indexes) for any data type
 - [Built-in types](#built-in-types) that are easy to get up & running; String, Uint, Int, Float
 - Flexible [iteration](#iterating) of data; ascending, descending, and ranges
 - [Durable append-only file](#append-only-file) format for persistence. 
 - Option to evict old items with an [expiration](#data-expiration) TTL
-- Tight codebase, under 1K loc using the `cloc` command
+- Tight codebase, ~1K loc using the `cloc` command
 - ACID semantics with locking [transactions](#transactions) that support rollbacks
 
 Getting Started
@@ -260,7 +261,7 @@ user:1:name 49
 user:4:name 63
 ```
 
-### Spatial Indexes
+## Spatial Indexes
 BuntDB has support for spatial indexes by storing rectangles in an [R-tree](https://en.wikipedia.org/wiki/R-tree). An R-tree is organized in a similar manner as a [B-tree](https://en.wikipedia.org/wiki/B-tree), and both are balanced trees. But, an R-tree is special because it can operate on data that is in multiple dimensions. This is super handy for Geospatial applications.
 
 To create a spatial index use the `CreateSpatialIndex` function:
@@ -296,7 +297,7 @@ db.View(func(tx *buntdb.Tx) error {
 
 This will get all three positions.
 
-#### Spatial bracket syntax
+### Spatial bracket syntax
 
 The bracket syntax `[-117 30],[-112 36]` is unique to BuntDB, and it's how the built-in rectangles are processed. But, you are not limited to this syntax. Whatever Rect function you choose to use during `CreateSpatialIndex` will be used to process the parameter, in this case it's `IndexRect`.
 
@@ -346,9 +347,62 @@ Which will return:
 ```
 
 
+## JSON Indexes
+Indexes can be created on individual fields inside JSON documents.
 
+For example:
 
+```go
+package main
 
+import (
+	"fmt"
+
+	"github.com/tidwall/buntdb"
+)
+
+func main() {
+	db, _ := buntdb.Open(":memory:")
+	db.CreateIndex("last_name", "*", buntdb.IndexJSON("name.last"))
+	db.CreateIndex("age", "*", buntdb.IndexJSON("age"))
+	db.Update(func(tx *buntdb.Tx) error {
+		tx.Set("1", `{"name":{"first":"Tom","last":"Johnson"},"age":38}`, nil)
+		tx.Set("2", `{"name":{"first":"Janet","last":"Prichard"},"age":47}`, nil)
+		tx.Set("3", `{"name":{"first":"Carol","last":"Anderson"},"age":52}`, nil)
+		tx.Set("4", `{"name":{"first":"Alan","last":"Cooper"},"age":28}`, nil)
+		return nil
+	})
+	db.View(func(tx *buntdb.Tx) error {
+		fmt.Println("Order by last name")
+		tx.Ascend("last_name", func(key, value string) bool {
+			fmt.Printf("%s: %s\n", key, value)
+			return true
+		})
+		fmt.Println("Order by age")
+		tx.Ascend("age", func(key, value string) bool {
+			fmt.Printf("%s: %s\n", key, value)
+			return true
+		})
+		return nil
+	})
+}
+```
+
+Results:
+
+```
+Order by last name
+3: {"name":{"first":"Carol","last":"Anderson"},"age":52}
+4: {"name":{"first":"Alan","last":"Cooper"},"age":28}
+1: {"name":{"first":"Tom","last":"Johnson"},"age":38}
+2: {"name":{"first":"Janet","last":"Prichard"},"age":47}
+
+Order by age
+4: {"name":{"first":"Alan","last":"Cooper"},"age":28}
+1: {"name":{"first":"Tom","last":"Johnson"},"age":38}
+2: {"name":{"first":"Janet","last":"Prichard"},"age":47}
+3: {"name":{"first":"Carol","last":"Anderson"},"age":52}
+```
 
 
 ### Data Expiration
diff --git a/buntdb.go b/buntdb.go
index d9eeb82..a53bf94 100644
--- a/buntdb.go
+++ b/buntdb.go
@@ -7,6 +7,7 @@ package buntdb
 import (
 	"bufio"
 	"bytes"
+	"encoding/json"
 	"errors"
 	"io"
 	"os"
@@ -530,6 +531,7 @@ func (db *DB) Shrink() error {
 		return err
 	}
 	db.mu.Unlock()
+	time.Sleep(time.Second / 4) // wait just a bit before starting
 	f, err := os.Create(tmpname)
 	if err != nil {
 		return err
@@ -1530,3 +1532,64 @@ func IndexFloat(a, b string) bool {
 	ib, _ := strconv.ParseFloat(b, 64)
 	return ia < ib
 }
+
+// IndexJSON provides for the ability to create an index on any JSON field.
+// When the field is a string, the comparison will be case-insensitive.
+// It returns a helper function used by CreateIndex.
+func IndexJSON(path string) func(a, b string) bool {
+	return jsonIndex(path, false)
+}
+
+// IndexJSONCaseSensitive provides for the ability to create an index on
+// any JSON field.
+// When the field is a string, the comparison will be case-sensitive.
+// It returns a helper function used by CreateIndex.
+func IndexJSONCaseSensitive(path string) func(a, b string) bool {
+	return jsonIndex(path, true)
+}
+
+func jsonIndex(path string, cs bool) func(a, b string) bool {
+	return func(a, b string) bool {
+		var am, bm map[string]interface{}
+		_ = json.Unmarshal([]byte(a), &am)
+		_ = json.Unmarshal([]byte(b), &bm)
+		parts := strings.Split(path, ".")
+		for i, part := range parts {
+			if am == nil {
+				if bm == nil {
+					return false
+				}
+				return true
+			} else if bm == nil {
+				return false
+			}
+			if i < len(parts)-1 {
+				am, _ = am[part].(map[string]interface{})
+				bm, _ = bm[part].(map[string]interface{})
+				continue
+			}
+			a, b := am[part], bm[part]
+			switch av := a.(type) {
+			case bool:
+				if bv, ok := b.(bool); ok {
+					return !av && bv
+				}
+			case float64:
+				if bv, ok := b.(float64); ok {
+					return av < bv
+				}
+			case string:
+				if bv, ok := b.(string); ok {
+					if cs {
+						return av < bv
+					}
+					return strings.ToLower(av) < strings.ToLower(bv)
+				}
+			case nil:
+				return b != nil
+			}
+			return false
+		}
+		return false
+	}
+}
diff --git a/buntdb_test.go b/buntdb_test.go
index 7a782b5..6a8532f 100644
--- a/buntdb_test.go
+++ b/buntdb_test.go
@@ -10,20 +10,39 @@ import (
 	"os"
 	"strconv"
 	"strings"
+	"sync"
 	"testing"
 	"time"
 )
 
-func TestBackgroudOperations(t *testing.T) {
+func testOpen(t testing.TB) *DB {
 	if err := os.RemoveAll("data.db"); err != nil {
 		t.Fatal(err)
 	}
+	return testReOpen(t, nil)
+}
+
+func testReOpen(t testing.TB, db *DB) *DB {
+	if db != nil {
+		if err := db.Close(); err != nil {
+			t.Fatal(err)
+		}
+	}
 	db, err := Open("data.db")
 	if err != nil {
 		t.Fatal(err)
 	}
-	defer func() { _ = os.RemoveAll("data.db") }()
-	defer func() { _ = db.Close() }()
+	return db
+}
+
+func testClose(db *DB) {
+	_ = db.Close()
+	_ = os.RemoveAll("data.db")
+}
+
+func TestBackgroudOperations(t *testing.T) {
+	db := testOpen(t)
+	defer testClose(db)
 	for i := 0; i < 1000; i++ {
 		if err := db.Update(func(tx *Tx) error {
 			for j := 0; j < 200; j++ {
@@ -40,7 +59,7 @@ func TestBackgroudOperations(t *testing.T) {
 		}
 	}
 	n := 0
-	err = db.View(func(tx *Tx) error {
+	err := db.View(func(tx *Tx) error {
 		var err error
 		n, err = tx.Len()
 		return err
@@ -52,15 +71,8 @@ func TestBackgroudOperations(t *testing.T) {
 		t.Fatalf("expecting '%v', got '%v'", 201, n)
 	}
 	time.Sleep(time.Millisecond * 1500)
-	if err := db.Close(); err != nil {
-		t.Fatal(err)
-	}
-	db, err = Open("data.db")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer func() { _ = os.RemoveAll("data.db") }()
-	defer func() { _ = db.Close() }()
+	db = testReOpen(t, db)
+	defer testClose(db)
 	n = 0
 	err = db.View(func(tx *Tx) error {
 		var err error
@@ -75,15 +87,8 @@ func TestBackgroudOperations(t *testing.T) {
 	}
 }
 func TestVariousTx(t *testing.T) {
-	if err := os.RemoveAll("data.db"); err != nil {
-		t.Fatal(err)
-	}
-	db, err := Open("data.db")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer func() { _ = os.RemoveAll("data.db") }()
-	defer func() { _ = db.Close() }()
+	db := testOpen(t)
+	defer testClose(db)
 	if err := db.Update(func(tx *Tx) error {
 		_, _, err := tx.Set("hello", "planet", nil)
 		return err
@@ -98,7 +103,7 @@ func TestVariousTx(t *testing.T) {
 		t.Fatalf("did not correctly receive the user-defined transaction error.")
 	}
 	var val string
-	err = db.View(func(tx *Tx) error {
+	err := db.View(func(tx *Tx) error {
 		var err error
 		val, err = tx.Get("hello")
 		return err
@@ -419,17 +424,10 @@ func TestNoExpiringItem(t *testing.T) {
 	}
 }
 func TestAutoShrink(t *testing.T) {
-	if err := os.RemoveAll("data.db"); err != nil {
-		t.Fatal(err)
-	}
-	db, err := Open("data.db")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer func() { _ = os.RemoveAll("data.db") }()
-	defer func() { _ = db.Close() }()
+	db := testOpen(t)
+	defer testClose(db)
 	for i := 0; i < 1000; i++ {
-		err = db.Update(func(tx *Tx) error {
+		err := db.Update(func(tx *Tx) error {
 			for i := 0; i < 20; i++ {
 				if _, _, err := tx.Set(fmt.Sprintf("HELLO:%d", i), "WORLD", nil); err != nil {
 					return err
@@ -441,16 +439,11 @@ func TestAutoShrink(t *testing.T) {
 			t.Fatal(err)
 		}
 	}
-	if err := db.Close(); err != nil {
-		t.Fatal(err)
-	}
-	db, err = Open("data.db")
-	if err != nil {
-		t.Fatal(err)
-	}
+	db = testReOpen(t, db)
+	defer testClose(db)
 	db.config.AutoShrinkMinSize = 64 * 1024 // 64K
 	for i := 0; i < 2000; i++ {
-		err = db.Update(func(tx *Tx) error {
+		err := db.Update(func(tx *Tx) error {
 			for i := 0; i < 20; i++ {
 				if _, _, err := tx.Set(fmt.Sprintf("HELLO:%d", i), "WORLD", nil); err != nil {
 					return err
@@ -463,14 +456,9 @@ func TestAutoShrink(t *testing.T) {
 		}
 	}
 	time.Sleep(time.Second * 3)
-	if err := db.Close(); err != nil {
-		t.Fatal(err)
-	}
-	db, err = Open("data.db")
-	if err != nil {
-		t.Fatal(err)
-	}
-	err = db.View(func(tx *Tx) error {
+	db = testReOpen(t, db)
+	defer testClose(db)
+	err := db.View(func(tx *Tx) error {
 		n, err := tx.Len()
 		if err != nil {
 			return err
@@ -501,12 +489,8 @@ func TestDatabaseFormat(t *testing.T) {
 		if err := ioutil.WriteFile("data.db", []byte(resp), 0666); err != nil {
 			t.Fatal(err)
 		}
-		db, err := Open("data.db")
-		if err != nil {
-			t.Fatal(err)
-		}
-		defer func() { _ = os.RemoveAll("data.db") }()
-		defer func() { _ = db.Close() }()
+		db := testOpen(t)
+		defer testClose(db)
 	}()
 	testBadFormat := func(resp string) {
 		if err := os.RemoveAll("data.db"); err != nil {
@@ -544,15 +528,8 @@ func TestDatabaseFormat(t *testing.T) {
 }
 
 func TestInsertsAndDeleted(t *testing.T) {
-	if err := os.RemoveAll("data.db"); err != nil {
-		t.Fatal(err)
-	}
-	db, err := Open("data.db")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer func() { _ = os.RemoveAll("data.db") }()
-	defer func() { _ = db.Close() }()
+	db := testOpen(t)
+	defer testClose(db)
 	if err := db.CreateIndex("any", "*", IndexString); err != nil {
 		t.Fatal(err)
 	}
@@ -700,15 +677,8 @@ func TestOpeningClosedDatabase(t *testing.T) {
 
 // test shrinking a database.
 func TestShrink(t *testing.T) {
-	if err := os.RemoveAll("data.db"); err != nil {
-		t.Fatal(err)
-	}
-	db, err := Open("data.db")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer func() { _ = os.RemoveAll("data.db") }()
-	defer func() { _ = db.Close() }()
+	db := testOpen(t)
+	defer testClose(db)
 	if err := db.Shrink(); err != nil {
 		t.Fatal(err)
 	}
@@ -820,17 +790,10 @@ func TestShrink(t *testing.T) {
 }
 
 func TestVariousIndexOperations(t *testing.T) {
-	if err := os.RemoveAll("data.db"); err != nil {
-		t.Fatal(err)
-	}
-	db, err := Open("data.db")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer func() { _ = os.RemoveAll("data.db") }()
-	defer func() { _ = db.Close() }()
+	db := testOpen(t)
+	defer testClose(db)
 	// test creating an index with no index name.
-	err = db.CreateIndex("", "", nil)
+	err := db.CreateIndex("", "", nil)
 	if err == nil {
 		t.Fatal("should not be able to create an index with no name")
 	}
@@ -939,15 +902,8 @@ func TestPatternMatching(t *testing.T) {
 
 func TestBasic(t *testing.T) {
 	rand.Seed(time.Now().UnixNano())
-	if err := os.RemoveAll("data.db"); err != nil {
-		t.Fatal(err)
-	}
-	db, err := Open("data.db")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer func() { _ = os.RemoveAll("data.db") }()
-	defer func() { _ = db.Close() }()
+	db := testOpen(t)
+	defer testClose(db)
 
 	// create a simple index
 	if err := db.CreateIndex("users", "fun:user:*", IndexString); err != nil {
@@ -1019,8 +975,8 @@ func TestBasic(t *testing.T) {
 	}
 	// verify the data has been created
 	buf := &bytes.Buffer{}
-	err = db.View(func(tx *Tx) error {
-		err = tx.Ascend("users", func(key, val string) bool {
+	err := db.View(func(tx *Tx) error {
+		err := tx.Ascend("users", func(key, val string) bool {
 			fmt.Fprintf(buf, "%s %s\n", key, val)
 			return true
 		})
@@ -1151,16 +1107,9 @@ func TestRectStrings(t *testing.T) {
 }
 
 func TestTTL(t *testing.T) {
-	if err := os.RemoveAll("data.db"); err != nil {
-		t.Fatal(err)
-	}
-	db, err := Open("data.db")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer func() { _ = os.RemoveAll("data.db") }()
-	defer func() { _ = db.Close() }()
-	err = db.Update(func(tx *Tx) error {
+	db := testOpen(t)
+	defer testClose(db)
+	err := db.Update(func(tx *Tx) error {
 		if _, _, err := tx.Set("key1", "val1", &SetOptions{Expires: true, TTL: time.Second}); err != nil {
 			return err
 		}
@@ -1195,17 +1144,10 @@ func TestTTL(t *testing.T) {
 }
 
 func TestConfig(t *testing.T) {
-	if err := os.RemoveAll("data.db"); err != nil {
-		t.Fatal(err)
-	}
-	db, err := Open("data.db")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer func() { _ = os.RemoveAll("data.db") }()
-	defer func() { _ = db.Close() }()
+	db := testOpen(t)
+	defer testClose(db)
 
-	err = db.SetConfig(Config{SyncPolicy: SyncPolicy(-1)})
+	err := db.SetConfig(Config{SyncPolicy: SyncPolicy(-1)})
 	if err == nil {
 		t.Fatal("expecting a config syncpolicy error")
 	}
@@ -1477,3 +1419,128 @@ func Benchmark_Spatial_2D(t *testing.B) {
 
 }
 */
+func TestCoverCloseAlreadyClosed(t *testing.T) {
+	db := testOpen(t)
+	defer testClose(db)
+	_ = db.file.Close()
+	if err := db.Close(); err == nil {
+		t.Fatal("expecting an error")
+	}
+}
+
+func TestCoverConfigClosed(t *testing.T) {
+	db := testOpen(t)
+	defer testClose(db)
+	_ = db.Close()
+	var config Config
+	if err := db.ReadConfig(&config); err != ErrDatabaseClosed {
+		t.Fatal("expecting database closed error")
+	}
+	if err := db.SetConfig(config); err != ErrDatabaseClosed {
+		t.Fatal("expecting database closed error")
+	}
+}
+func TestCoverShrinkShrink(t *testing.T) {
+	db := testOpen(t)
+	defer testClose(db)
+	if err := db.Update(func(tx *Tx) error {
+		for i := 0; i < 10000; i++ {
+			_, _, err := tx.Set(fmt.Sprintf("%d", i), fmt.Sprintf("%d", i), nil)
+			if err != nil {
+				return err
+			}
+		}
+		return nil
+	}); err != nil {
+		t.Fatal(err)
+	}
+	if err := db.Update(func(tx *Tx) error {
+		for i := 250; i < 250+100; i++ {
+			_, err := tx.Delete(fmt.Sprintf("%d", i))
+			if err != nil {
+				return err
+			}
+		}
+		return nil
+	}); err != nil {
+		t.Fatal(err)
+	}
+	var err1, err2 error
+	var wg sync.WaitGroup
+	wg.Add(2)
+	go func() {
+		defer wg.Done()
+		err1 = db.Shrink()
+	}()
+	go func() {
+		defer wg.Done()
+		err2 = db.Shrink()
+	}()
+	wg.Wait()
+	//println(123)
+	//fmt.Printf("%v\n%v\n", err1, err2)
+	if err1 != ErrShrinkInProcess && err2 != ErrShrinkInProcess {
+		t.Fatal("expecting a shrink in process error")
+	}
+	db = testReOpen(t, db)
+	defer testClose(db)
+	if err := db.View(func(tx *Tx) error {
+		n, err := tx.Len()
+		if err != nil {
+			return err
+		}
+		if n != 9900 {
+			t.Fatal("expecting 9900 items")
+		}
+		return nil
+	}); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestJSONIndex(t *testing.T) {
+	db := testOpen(t)
+	defer testClose(db)
+
+	_ = db.CreateIndex("last_name", "*", IndexJSON("name.last"))
+	_ = db.CreateIndex("last_name_cs", "*", IndexJSONCaseSensitive("name.last"))
+	_ = db.CreateIndex("age", "*", IndexJSON("age"))
+	_ = db.CreateIndex("student", "*", IndexJSON("student"))
+	_ = db.Update(func(tx *Tx) error {
+		_, _, _ = tx.Set("1", `{"name":{"first":"Tom","last":"Johnson"},"age":38,"student":false}`, nil)
+		_, _, _ = tx.Set("2", `{"name":{"first":"Janet","last":"Prichard"},"age":47,"student":true}`, nil)
+		_, _, _ = tx.Set("3", `{"name":{"first":"Carol","last":"Anderson"},"age":52,"student":true}`, nil)
+		_, _, _ = tx.Set("4", `{"name":{"first":"Alan","last":"Cooper"},"age":28,"student":false}`, nil)
+		_, _, _ = tx.Set("5", `{"name":{"first":"bill","last":"frank"},"age":21,"student":true}`, nil)
+		_, _, _ = tx.Set("6", `{"name":{"first":"sally","last":"randall"},"age":68,"student":false}`, nil)
+		return nil
+	})
+	var keys []string
+	_ = db.View(func(tx *Tx) error {
+		_ = tx.Ascend("last_name_cs", func(key, value string) bool {
+			//fmt.Printf("%s: %s\n", key, value)
+			keys = append(keys, key)
+			return true
+		})
+		_ = tx.Ascend("last_name", func(key, value string) bool {
+			//fmt.Printf("%s: %s\n", key, value)
+			keys = append(keys, key)
+			return true
+		})
+		_ = tx.Ascend("age", func(key, value string) bool {
+			//fmt.Printf("%s: %s\n", key, value)
+			keys = append(keys, key)
+			return true
+		})
+		_ = tx.Ascend("student", func(key, value string) bool {
+			//fmt.Printf("%s: %s\n", key, value)
+			keys = append(keys, key)
+			return true
+		})
+		return nil
+	})
+	expect := "3,4,1,2,5,6,3,4,5,1,2,6,5,4,1,2,3,6,1,4,6,2,3,5"
+	if strings.Join(keys, ",") != expect {
+		t.Fatalf("expected %v, got %v", expect, strings.Join(keys, ","))
+	}
+}