From a60dc5759854e259bef3d387bd4fdd8975fd5c8d Mon Sep 17 00:00:00 2001
From: tidwall <joshbaker77@gmail.com>
Date: Fri, 15 Feb 2019 08:26:55 -0700
Subject: [PATCH] Isolated fields type

---
 internal/collection/collection.go      |  86 +++++++--------
 internal/collection/collection_test.go | 141 ++++++++++++++-----------
 internal/collection/fields.go          |  40 +++++++
 internal/collection/item/item.go       |  63 ++++++++---
 internal/collection/item/item_test.go  |  71 +++++++++++--
 internal/server/aofshrink.go           |  12 ++-
 internal/server/crud.go                |  14 ++-
 internal/server/fence.go               |   5 +-
 internal/server/scan.go                |   5 +-
 internal/server/scanner.go             |  50 ++++-----
 internal/server/search.go              |  67 +++++++-----
 internal/server/server.go              |  26 ++---
 12 files changed, 375 insertions(+), 205 deletions(-)
 create mode 100644 internal/collection/fields.go

diff --git a/internal/collection/collection.go b/internal/collection/collection.go
index 5167e70f..0827dcef 100644
--- a/internal/collection/collection.go
+++ b/internal/collection/collection.go
@@ -119,39 +119,39 @@ func (c *Collection) delItem(item *item.Item) {
 func (c *Collection) Set(
 	id string, obj geojson.Object, fields []string, values []float64,
 ) (
-	oldObj geojson.Object, oldFields []float64, newFields []float64,
+	oldObj geojson.Object, oldFields *Fields, newFields *Fields,
 ) {
 	// create the new item
-	item := item.New(id, obj)
+	newItem := item.New(id, obj)
 
 	// add the new item to main btree and remove the old one if needed
-	oldItemV, ok := c.items.Set(item)
+	var oldItem *item.Item
+	oldItemV, ok := c.items.Set(newItem)
 	if ok {
-		oldItem := oldItemV
+		oldItem = oldItemV
 		oldObj = oldItem.Obj()
 
 		// remove old item from indexes
 		c.delItem(oldItem)
-		if len(oldItem.Fields()) > 0 {
+		if oldItem.HasFields() {
 			// merge old and new fields
-			oldFields = oldItem.Fields()
-			item.CopyOverFields(oldFields)
+			newItem.CopyOverFields(oldItem)
 		}
 	}
 
 	if fields == nil && len(values) > 0 {
 		// directly set the field values, from copy
-		item.CopyOverFields(values)
+		newItem.CopyOverFields(values)
 	} else if len(fields) > 0 {
 		// add new field to new item
-		c.setFields(item, fields, values, false)
+		c.setFields(newItem, fields, values, false)
 	}
 
 	// add new item to indexes
-	c.addItem(item)
+	c.addItem(newItem)
 	// fmt.Printf("!!! %#v\n", oldObj)
 
-	return oldObj, oldFields, item.Fields()
+	return oldObj, itemFields(oldItem), itemFields(newItem)
 }
 
 func (c *Collection) setFields(
@@ -192,7 +192,7 @@ func (c *Collection) setField(
 // Delete removes an object and returns it.
 // If the object does not exist then the 'ok' return value will be false.
 func (c *Collection) Delete(id string) (
-	obj geojson.Object, fields []float64, ok bool,
+	obj geojson.Object, fields *Fields, ok bool,
 ) {
 	oldItemV, ok := c.items.Delete(id)
 	if !ok {
@@ -202,13 +202,13 @@ func (c *Collection) Delete(id string) (
 
 	c.delItem(oldItem)
 
-	return oldItem.Obj(), oldItem.Fields(), true
+	return oldItem.Obj(), itemFields(oldItem), true
 }
 
 // Get returns an object.
 // If the object does not exist then the 'ok' return value will be false.
 func (c *Collection) Get(id string) (
-	obj geojson.Object, fields []float64, ok bool,
+	obj geojson.Object, fields *Fields, ok bool,
 ) {
 	itemV, ok := c.items.Get(id)
 	if !ok {
@@ -216,13 +216,13 @@ func (c *Collection) Get(id string) (
 	}
 	item := itemV
 
-	return item.Obj(), item.Fields(), true
+	return item.Obj(), itemFields(item), true
 }
 
 // SetField set a field value for an object and returns that object.
 // If the object does not exist then the 'ok' return value will be false.
 func (c *Collection) SetField(id, fieldName string, fieldValue float64) (
-	obj geojson.Object, fields []float64, updated bool, ok bool,
+	obj geojson.Object, fields *Fields, updated bool, ok bool,
 ) {
 	itemV, ok := c.items.Get(id)
 	if !ok {
@@ -230,13 +230,13 @@ func (c *Collection) SetField(id, fieldName string, fieldValue float64) (
 	}
 	item := itemV
 	updated = c.setField(item, fieldName, fieldValue, true)
-	return item.Obj(), item.Fields(), updated, true
+	return item.Obj(), itemFields(item), updated, true
 }
 
 // SetFields is similar to SetField, just setting multiple fields at once
 func (c *Collection) SetFields(
 	id string, fieldNames []string, fieldValues []float64,
-) (obj geojson.Object, fields []float64, updatedCount int, ok bool) {
+) (obj geojson.Object, fields *Fields, updatedCount int, ok bool) {
 	itemV, ok := c.items.Get(id)
 	if !ok {
 		return nil, nil, 0, false
@@ -245,7 +245,7 @@ func (c *Collection) SetFields(
 
 	updatedCount = c.setFields(item, fieldNames, fieldValues, true)
 
-	return item.Obj(), item.Fields(), updatedCount, true
+	return item.Obj(), itemFields(item), updatedCount, true
 }
 
 // FieldMap return a maps of the field names.
@@ -264,7 +264,7 @@ func (c *Collection) FieldArr() []string {
 
 // Scan iterates though the collection ids.
 func (c *Collection) Scan(desc bool, cursor Cursor,
-	iterator func(id string, obj geojson.Object, fields []float64) bool,
+	iterator func(id string, obj geojson.Object, fields *Fields) bool,
 ) bool {
 	var keepon = true
 	var count uint64
@@ -281,7 +281,7 @@ func (c *Collection) Scan(desc bool, cursor Cursor,
 		if cursor != nil {
 			cursor.Step(1)
 		}
-		keepon = iterator(item.ID(), item.Obj(), item.Fields())
+		keepon = iterator(item.ID(), item.Obj(), itemFields(item))
 		return keepon
 	}
 	if desc {
@@ -294,7 +294,7 @@ func (c *Collection) Scan(desc bool, cursor Cursor,
 
 // ScanRange iterates though the collection starting with specified id.
 func (c *Collection) ScanRange(start, end string, desc bool, cursor Cursor,
-	iterator func(id string, obj geojson.Object, fields []float64) bool,
+	iterator func(id string, obj geojson.Object, fields *Fields) bool,
 ) bool {
 	var keepon = true
 	var count uint64
@@ -320,7 +320,7 @@ func (c *Collection) ScanRange(start, end string, desc bool, cursor Cursor,
 				return false
 			}
 		}
-		keepon = iterator(item.ID(), item.Obj(), item.Fields())
+		keepon = iterator(item.ID(), item.Obj(), itemFields(item))
 		return keepon
 	}
 
@@ -334,7 +334,7 @@ func (c *Collection) ScanRange(start, end string, desc bool, cursor Cursor,
 
 // SearchValues iterates though the collection values.
 func (c *Collection) SearchValues(desc bool, cursor Cursor,
-	iterator func(id string, obj geojson.Object, fields []float64) bool,
+	iterator func(id string, obj geojson.Object, fields *Fields) bool,
 ) bool {
 	var keepon = true
 	var count uint64
@@ -352,7 +352,7 @@ func (c *Collection) SearchValues(desc bool, cursor Cursor,
 			cursor.Step(1)
 		}
 		iitm := v.(*item.Item)
-		keepon = iterator(iitm.ID(), iitm.Obj(), iitm.Fields())
+		keepon = iterator(iitm.ID(), iitm.Obj(), itemFields(iitm))
 		return keepon
 	}
 	if desc {
@@ -366,7 +366,7 @@ func (c *Collection) SearchValues(desc bool, cursor Cursor,
 // SearchValuesRange iterates though the collection values.
 func (c *Collection) SearchValuesRange(start, end string, desc bool,
 	cursor Cursor,
-	iterator func(id string, obj geojson.Object, fields []float64) bool,
+	iterator func(id string, obj geojson.Object, fields *Fields) bool,
 ) bool {
 	var keepon = true
 	var count uint64
@@ -384,7 +384,7 @@ func (c *Collection) SearchValuesRange(start, end string, desc bool,
 			cursor.Step(1)
 		}
 		iitm := v.(*item.Item)
-		keepon = iterator(iitm.ID(), iitm.Obj(), iitm.Fields())
+		keepon = iterator(iitm.ID(), iitm.Obj(), itemFields(iitm))
 		return keepon
 	}
 	if desc {
@@ -402,7 +402,7 @@ func (c *Collection) SearchValuesRange(start, end string, desc bool,
 // ScanGreaterOrEqual iterates though the collection starting with specified id.
 func (c *Collection) ScanGreaterOrEqual(id string, desc bool,
 	cursor Cursor,
-	iterator func(id string, obj geojson.Object, fields []float64) bool,
+	iterator func(id string, obj geojson.Object, fields *Fields) bool,
 ) bool {
 	var keepon = true
 	var count uint64
@@ -419,7 +419,7 @@ func (c *Collection) ScanGreaterOrEqual(id string, desc bool,
 		if cursor != nil {
 			cursor.Step(1)
 		}
-		keepon = iterator(item.ID(), item.Obj(), item.Fields())
+		keepon = iterator(item.ID(), item.Obj(), itemFields(item))
 		return keepon
 	}
 	if desc {
@@ -432,7 +432,7 @@ func (c *Collection) ScanGreaterOrEqual(id string, desc bool,
 
 func (c *Collection) geoSearch(
 	rect geometry.Rect,
-	iter func(id string, obj geojson.Object, fields []float64) bool,
+	iter func(id string, obj geojson.Object, fields *Fields) bool,
 ) bool {
 	alive := true
 	c.index.Search(
@@ -440,7 +440,7 @@ func (c *Collection) geoSearch(
 		[]float64{rect.Max.X, rect.Max.Y},
 		func(_, _ []float64, itemv *item.Item) bool {
 			item := itemv
-			alive = iter(item.ID(), item.Obj(), item.Fields())
+			alive = iter(item.ID(), item.Obj(), itemFields(item))
 			return alive
 		},
 	)
@@ -449,12 +449,12 @@ func (c *Collection) geoSearch(
 
 func (c *Collection) geoSparse(
 	obj geojson.Object, sparse uint8,
-	iter func(id string, obj geojson.Object, fields []float64) (match, ok bool),
+	iter func(id string, obj geojson.Object, fields *Fields) (match, ok bool),
 ) bool {
 	matches := make(map[string]bool)
 	alive := true
 	c.geoSparseInner(obj.Rect(), sparse,
-		func(id string, o geojson.Object, fields []float64) (
+		func(id string, o geojson.Object, fields *Fields) (
 			match, ok bool,
 		) {
 			ok = true
@@ -471,7 +471,7 @@ func (c *Collection) geoSparse(
 }
 func (c *Collection) geoSparseInner(
 	rect geometry.Rect, sparse uint8,
-	iter func(id string, obj geojson.Object, fields []float64) (match, ok bool),
+	iter func(id string, obj geojson.Object, fields *Fields) (match, ok bool),
 ) bool {
 	if sparse > 0 {
 		w := rect.Max.X - rect.Min.X
@@ -503,7 +503,7 @@ func (c *Collection) geoSparseInner(
 	}
 	alive := true
 	c.geoSearch(rect,
-		func(id string, obj geojson.Object, fields []float64) bool {
+		func(id string, obj geojson.Object, fields *Fields) bool {
 			match, ok := iter(id, obj, fields)
 			if !ok {
 				alive = false
@@ -521,7 +521,7 @@ func (c *Collection) Within(
 	obj geojson.Object,
 	sparse uint8,
 	cursor Cursor,
-	iter func(id string, obj geojson.Object, fields []float64) bool,
+	iter func(id string, obj geojson.Object, fields *Fields) bool,
 ) bool {
 	var count uint64
 	var offset uint64
@@ -531,7 +531,7 @@ func (c *Collection) Within(
 	}
 	if sparse > 0 {
 		return c.geoSparse(obj, sparse,
-			func(id string, o geojson.Object, fields []float64) (
+			func(id string, o geojson.Object, fields *Fields) (
 				match, ok bool,
 			) {
 				count++
@@ -549,7 +549,7 @@ func (c *Collection) Within(
 		)
 	}
 	return c.geoSearch(obj.Rect(),
-		func(id string, o geojson.Object, fields []float64) bool {
+		func(id string, o geojson.Object, fields *Fields) bool {
 			count++
 			if count <= offset {
 				return true
@@ -571,7 +571,7 @@ func (c *Collection) Intersects(
 	obj geojson.Object,
 	sparse uint8,
 	cursor Cursor,
-	iter func(id string, obj geojson.Object, fields []float64) bool,
+	iter func(id string, obj geojson.Object, fields *Fields) bool,
 ) bool {
 	var count uint64
 	var offset uint64
@@ -581,7 +581,7 @@ func (c *Collection) Intersects(
 	}
 	if sparse > 0 {
 		return c.geoSparse(obj, sparse,
-			func(id string, o geojson.Object, fields []float64) (
+			func(id string, o geojson.Object, fields *Fields) (
 				match, ok bool,
 			) {
 				count++
@@ -599,7 +599,7 @@ func (c *Collection) Intersects(
 		)
 	}
 	return c.geoSearch(obj.Rect(),
-		func(id string, o geojson.Object, fields []float64) bool {
+		func(id string, o geojson.Object, fields *Fields) bool {
 			count++
 			if count <= offset {
 				return true
@@ -619,7 +619,7 @@ func (c *Collection) Intersects(
 func (c *Collection) Nearby(
 	target geojson.Object,
 	cursor Cursor,
-	iter func(id string, obj geojson.Object, fields []float64) bool,
+	iter func(id string, obj geojson.Object, fields *Fields) bool,
 ) bool {
 	// First look to see if there's at least one candidate in the circle's
 	// outer rectangle. This is a fast-fail operation.
@@ -665,7 +665,7 @@ func (c *Collection) Nearby(
 				cursor.Step(1)
 			}
 			item := itemv
-			alive = iter(item.ID(), item.Obj(), item.Fields())
+			alive = iter(item.ID(), item.Obj(), itemFields(item))
 			return alive
 		},
 	)
diff --git a/internal/collection/collection_test.go b/internal/collection/collection_test.go
index 6627bde1..54539df0 100644
--- a/internal/collection/collection_test.go
+++ b/internal/collection/collection_test.go
@@ -104,7 +104,7 @@ func TestCollectionNewCollection(t *testing.T) {
 		Min: geometry.Point{X: -180, Y: -90},
 		Max: geometry.Point{X: 180, Y: 90},
 	}
-	c.geoSearch(bbox, func(id string, obj geojson.Object, field []float64) bool {
+	c.geoSearch(bbox, func(id string, obj geojson.Object, field *Fields) bool {
 		count++
 		return true
 	})
@@ -124,8 +124,8 @@ func TestCollectionSet(t *testing.T) {
 		str1 := String("hello")
 		oldObject, oldFields, newFields := c.Set("str", str1, nil, nil)
 		expect(t, oldObject == nil)
-		expect(t, len(oldFields) == 0)
-		expect(t, len(newFields) == 0)
+		expect(t, fieldLen(oldFields) == 0)
+		expect(t, fieldLen(newFields) == 0)
 	})
 	t.Run("UpdateString", func(t *testing.T) {
 		c := New()
@@ -133,20 +133,20 @@ func TestCollectionSet(t *testing.T) {
 		str2 := String("world")
 		oldObject, oldFields, newFields := c.Set("str", str1, nil, nil)
 		expect(t, oldObject == nil)
-		expect(t, len(oldFields) == 0)
-		expect(t, len(newFields) == 0)
+		expect(t, fieldLen(oldFields) == 0)
+		expect(t, fieldLen(newFields) == 0)
 		oldObject, oldFields, newFields = c.Set("str", str2, nil, nil)
 		expect(t, oldObject == str1)
-		expect(t, len(oldFields) == 0)
-		expect(t, len(newFields) == 0)
+		expect(t, fieldLen(oldFields) == 0)
+		expect(t, fieldLen(newFields) == 0)
 	})
 	t.Run("AddPoint", func(t *testing.T) {
 		c := New()
 		point1 := PO(-112.1, 33.1)
 		oldObject, oldFields, newFields := c.Set("point", point1, nil, nil)
 		expect(t, oldObject == nil)
-		expect(t, len(oldFields) == 0)
-		expect(t, len(newFields) == 0)
+		expect(t, fieldLen(oldFields) == 0)
+		expect(t, fieldLen(newFields) == 0)
 	})
 	t.Run("UpdatePoint", func(t *testing.T) {
 		c := New()
@@ -154,12 +154,12 @@ func TestCollectionSet(t *testing.T) {
 		point2 := PO(-112.2, 33.2)
 		oldObject, oldFields, newFields := c.Set("point", point1, nil, nil)
 		expect(t, oldObject == nil)
-		expect(t, len(oldFields) == 0)
-		expect(t, len(newFields) == 0)
+		expect(t, fieldLen(oldFields) == 0)
+		expect(t, fieldLen(newFields) == 0)
 		oldObject, oldFields, newFields = c.Set("point", point2, nil, nil)
 		expect(t, oldObject == point1)
-		expect(t, len(oldFields) == 0)
-		expect(t, len(newFields) == 0)
+		expect(t, fieldLen(oldFields) == 0)
+		expect(t, fieldLen(newFields) == 0)
 	})
 	t.Run("Fields", func(t *testing.T) {
 		c := New()
@@ -170,23 +170,23 @@ func TestCollectionSet(t *testing.T) {
 			fValues := []float64{1, 2, 3}
 			oldObj, oldFlds, newFlds := c.Set("str", str1, fNames, fValues)
 			expect(t, oldObj == nil)
-			expect(t, len(oldFlds) == 0)
-			expect(t, reflect.DeepEqual(newFlds, fValues))
+			expect(t, fieldLen(oldFlds) == 0)
+			expect(t, fieldIterEquals(newFlds, fValues))
 		}
 		{
 			fNames := []string{"d", "e", "f"}
 			fValues := []float64{4, 5, 6}
 			oldObj, oldFlds, newFlds := c.Set("str", str2, fNames, fValues)
 			expect(t, oldObj == str1)
-			expect(t, reflect.DeepEqual(oldFlds, []float64{1, 2, 3}))
-			expect(t, reflect.DeepEqual(newFlds, []float64{1, 2, 3, 4, 5, 6}))
+			expect(t, fieldIterEquals(oldFlds, []float64{1, 2, 3}))
+			expect(t, fieldIterEquals(newFlds, []float64{1, 2, 3, 4, 5, 6}))
 		}
 		{
 			fValues := []float64{7, 8, 9, 10, 11, 12}
 			oldObj, oldFlds, newFlds := c.Set("str", str1, nil, fValues)
 			expect(t, oldObj == str2)
-			expect(t, reflect.DeepEqual(oldFlds, []float64{1, 2, 3, 4, 5, 6}))
-			expect(t, reflect.DeepEqual(newFlds, []float64{7, 8, 9, 10, 11, 12}))
+			expect(t, fieldIterEquals(oldFlds, []float64{1, 2, 3, 4, 5, 6}))
+			expect(t, fieldIterEquals(newFlds, []float64{7, 8, 9, 10, 11, 12}))
 		}
 	})
 	t.Run("Delete", func(t *testing.T) {
@@ -204,7 +204,7 @@ func TestCollectionSet(t *testing.T) {
 			Max: geometry.Point{X: 1, Y: 2}})
 		var v geojson.Object
 		var ok bool
-		var flds []float64
+		var flds *Fields
 		var updated bool
 		var updateCount int
 
@@ -226,24 +226,24 @@ func TestCollectionSet(t *testing.T) {
 
 		v, flds, updated, ok = c.SetField("3", "hello", 123)
 		expect(t, ok)
-		expect(t, reflect.DeepEqual(flds, []float64{123}))
+		expect(t, fieldIterEquals(flds, []float64{123}))
 		expect(t, updated)
 		expect(t, c.FieldMap()["hello"] == 0)
 
 		v, flds, updated, ok = c.SetField("3", "hello", 1234)
 		expect(t, ok)
-		expect(t, reflect.DeepEqual(flds, []float64{1234}))
+		expect(t, fieldIterEquals(flds, []float64{1234}))
 		expect(t, updated)
 
 		v, flds, updated, ok = c.SetField("3", "hello", 1234)
 		expect(t, ok)
-		expect(t, reflect.DeepEqual(flds, []float64{1234}))
+		expect(t, fieldIterEquals(flds, []float64{1234}))
 		expect(t, !updated)
 
 		v, flds, updateCount, ok = c.SetFields("3",
 			[]string{"planet", "world"}, []float64{55, 66})
 		expect(t, ok)
-		expect(t, reflect.DeepEqual(flds, []float64{1234, 55, 66}))
+		expect(t, fieldIterEquals(flds, []float64{1234, 55, 66}))
 		expect(t, updateCount == 2)
 		expect(t, c.FieldMap()["hello"] == 0)
 		expect(t, c.FieldMap()["planet"] == 1)
@@ -277,6 +277,29 @@ func TestCollectionSet(t *testing.T) {
 	})
 }
 
+func fieldLen(fields *Fields) int {
+	var idx int
+	fields.ForEach(-1, func(value float64) bool {
+		idx++
+		return true
+	})
+	return idx
+}
+
+func fieldIterEquals(fields *Fields, values []float64) bool {
+	ok := true
+	var idx int
+	fields.ForEach(len(values), func(value float64) bool {
+		if value != values[idx] {
+			ok = false
+			return false
+		}
+		idx++
+		return true
+	})
+	return ok
+}
+
 func TestCollectionScan(t *testing.T) {
 	N := 256
 	c := New()
@@ -286,22 +309,22 @@ func TestCollectionScan(t *testing.T) {
 	}
 	var n int
 	var prevID string
-	c.Scan(false, nil, func(id string, obj geojson.Object, fields []float64) bool {
+	c.Scan(false, nil, func(id string, obj geojson.Object, fields *Fields) bool {
 		if n > 0 {
 			expect(t, id > prevID)
 		}
-		expect(t, id == fmt.Sprintf("%04d", int(fields[0])))
+		expect(t, id == fmt.Sprintf("%04d", int(fields.Get(0))))
 		n++
 		prevID = id
 		return true
 	})
 	expect(t, n == c.Count())
 	n = 0
-	c.Scan(true, nil, func(id string, obj geojson.Object, fields []float64) bool {
+	c.Scan(true, nil, func(id string, obj geojson.Object, fields *Fields) bool {
 		if n > 0 {
 			expect(t, id < prevID)
 		}
-		expect(t, id == fmt.Sprintf("%04d", int(fields[0])))
+		expect(t, id == fmt.Sprintf("%04d", int(fields.Get(0))))
 		n++
 		prevID = id
 		return true
@@ -310,11 +333,11 @@ func TestCollectionScan(t *testing.T) {
 
 	n = 0
 	c.ScanRange("0060", "0070", false, nil,
-		func(id string, obj geojson.Object, fields []float64) bool {
+		func(id string, obj geojson.Object, fields *Fields) bool {
 			if n > 0 {
 				expect(t, id > prevID)
 			}
-			expect(t, id == fmt.Sprintf("%04d", int(fields[0])))
+			expect(t, id == fmt.Sprintf("%04d", int(fields.Get(0))))
 			n++
 			prevID = id
 			return true
@@ -323,11 +346,11 @@ func TestCollectionScan(t *testing.T) {
 
 	n = 0
 	c.ScanRange("0070", "0060", true, nil,
-		func(id string, obj geojson.Object, fields []float64) bool {
+		func(id string, obj geojson.Object, fields *Fields) bool {
 			if n > 0 {
 				expect(t, id < prevID)
 			}
-			expect(t, id == fmt.Sprintf("%04d", int(fields[0])))
+			expect(t, id == fmt.Sprintf("%04d", int(fields.Get(0))))
 			n++
 			prevID = id
 			return true
@@ -336,11 +359,11 @@ func TestCollectionScan(t *testing.T) {
 
 	n = 0
 	c.ScanGreaterOrEqual("0070", true, nil,
-		func(id string, obj geojson.Object, fields []float64) bool {
+		func(id string, obj geojson.Object, fields *Fields) bool {
 			if n > 0 {
 				expect(t, id < prevID)
 			}
-			expect(t, id == fmt.Sprintf("%04d", int(fields[0])))
+			expect(t, id == fmt.Sprintf("%04d", int(fields.Get(0))))
 			n++
 			prevID = id
 			return true
@@ -349,11 +372,11 @@ func TestCollectionScan(t *testing.T) {
 
 	n = 0
 	c.ScanGreaterOrEqual("0070", false, nil,
-		func(id string, obj geojson.Object, fields []float64) bool {
+		func(id string, obj geojson.Object, fields *Fields) bool {
 			if n > 0 {
 				expect(t, id > prevID)
 			}
-			expect(t, id == fmt.Sprintf("%04d", int(fields[0])))
+			expect(t, id == fmt.Sprintf("%04d", int(fields.Get(0))))
 			n++
 			prevID = id
 			return true
@@ -373,22 +396,22 @@ func TestCollectionSearch(t *testing.T) {
 	}
 	var n int
 	var prevValue string
-	c.SearchValues(false, nil, func(id string, obj geojson.Object, fields []float64) bool {
+	c.SearchValues(false, nil, func(id string, obj geojson.Object, fields *Fields) bool {
 		if n > 0 {
 			expect(t, obj.String() > prevValue)
 		}
-		expect(t, id == fmt.Sprintf("%04d", int(fields[1])))
+		expect(t, id == fmt.Sprintf("%04d", int(fields.Get(1))))
 		n++
 		prevValue = obj.String()
 		return true
 	})
 	expect(t, n == c.Count())
 	n = 0
-	c.SearchValues(true, nil, func(id string, obj geojson.Object, fields []float64) bool {
+	c.SearchValues(true, nil, func(id string, obj geojson.Object, fields *Fields) bool {
 		if n > 0 {
 			expect(t, obj.String() < prevValue)
 		}
-		expect(t, id == fmt.Sprintf("%04d", int(fields[1])))
+		expect(t, id == fmt.Sprintf("%04d", int(fields.Get(1))))
 		n++
 		prevValue = obj.String()
 		return true
@@ -397,11 +420,11 @@ func TestCollectionSearch(t *testing.T) {
 
 	n = 0
 	c.SearchValuesRange("0060", "0070", false, nil,
-		func(id string, obj geojson.Object, fields []float64) bool {
+		func(id string, obj geojson.Object, fields *Fields) bool {
 			if n > 0 {
 				expect(t, obj.String() > prevValue)
 			}
-			expect(t, id == fmt.Sprintf("%04d", int(fields[1])))
+			expect(t, id == fmt.Sprintf("%04d", int(fields.Get(1))))
 			n++
 			prevValue = obj.String()
 			return true
@@ -410,11 +433,11 @@ func TestCollectionSearch(t *testing.T) {
 
 	n = 0
 	c.SearchValuesRange("0070", "0060", true, nil,
-		func(id string, obj geojson.Object, fields []float64) bool {
+		func(id string, obj geojson.Object, fields *Fields) bool {
 			if n > 0 {
 				expect(t, obj.String() < prevValue)
 			}
-			expect(t, id == fmt.Sprintf("%04d", int(fields[1])))
+			expect(t, id == fmt.Sprintf("%04d", int(fields.Get(1))))
 			n++
 			prevValue = obj.String()
 			return true
@@ -493,7 +516,7 @@ func TestSpatialSearch(t *testing.T) {
 
 	n = 0
 	c.Within(q1, 0, nil,
-		func(id string, obj geojson.Object, fields []float64) bool {
+		func(id string, obj geojson.Object, fields *Fields) bool {
 			n++
 			return true
 		},
@@ -502,7 +525,7 @@ func TestSpatialSearch(t *testing.T) {
 
 	n = 0
 	c.Within(q2, 0, nil,
-		func(id string, obj geojson.Object, fields []float64) bool {
+		func(id string, obj geojson.Object, fields *Fields) bool {
 			n++
 			return true
 		},
@@ -511,7 +534,7 @@ func TestSpatialSearch(t *testing.T) {
 
 	n = 0
 	c.Within(q3, 0, nil,
-		func(id string, obj geojson.Object, fields []float64) bool {
+		func(id string, obj geojson.Object, fields *Fields) bool {
 			n++
 			return true
 		},
@@ -520,7 +543,7 @@ func TestSpatialSearch(t *testing.T) {
 
 	n = 0
 	c.Intersects(q1, 0, nil,
-		func(_ string, _ geojson.Object, _ []float64) bool {
+		func(_ string, _ geojson.Object, _ *Fields) bool {
 			n++
 			return true
 		},
@@ -529,7 +552,7 @@ func TestSpatialSearch(t *testing.T) {
 
 	n = 0
 	c.Intersects(q2, 0, nil,
-		func(_ string, _ geojson.Object, _ []float64) bool {
+		func(_ string, _ geojson.Object, _ *Fields) bool {
 			n++
 			return true
 		},
@@ -538,7 +561,7 @@ func TestSpatialSearch(t *testing.T) {
 
 	n = 0
 	c.Intersects(q3, 0, nil,
-		func(_ string, _ geojson.Object, _ []float64) bool {
+		func(_ string, _ geojson.Object, _ *Fields) bool {
 			n++
 			return true
 		},
@@ -547,7 +570,7 @@ func TestSpatialSearch(t *testing.T) {
 
 	n = 0
 	c.Intersects(q3, 0, nil,
-		func(_ string, _ geojson.Object, _ []float64) bool {
+		func(_ string, _ geojson.Object, _ *Fields) bool {
 			n++
 			return n <= 1
 		},
@@ -559,7 +582,7 @@ func TestSpatialSearch(t *testing.T) {
 		r2, p1, p4, r1, p3, r3, p2,
 	}
 	c.Nearby(q4, nil,
-		func(id string, obj geojson.Object, fields []float64) bool {
+		func(id string, obj geojson.Object, fields *Fields) bool {
 			items = append(items, obj)
 			return true
 		},
@@ -585,7 +608,7 @@ func TestCollectionSparse(t *testing.T) {
 	var n int
 	n = 0
 	c.Within(rect, 1, nil,
-		func(id string, obj geojson.Object, fields []float64) bool {
+		func(id string, obj geojson.Object, fields *Fields) bool {
 			n++
 			return true
 		},
@@ -594,7 +617,7 @@ func TestCollectionSparse(t *testing.T) {
 
 	n = 0
 	c.Within(rect, 2, nil,
-		func(id string, obj geojson.Object, fields []float64) bool {
+		func(id string, obj geojson.Object, fields *Fields) bool {
 			n++
 			return true
 		},
@@ -603,7 +626,7 @@ func TestCollectionSparse(t *testing.T) {
 
 	n = 0
 	c.Within(rect, 3, nil,
-		func(id string, obj geojson.Object, fields []float64) bool {
+		func(id string, obj geojson.Object, fields *Fields) bool {
 			n++
 			return true
 		},
@@ -612,7 +635,7 @@ func TestCollectionSparse(t *testing.T) {
 
 	n = 0
 	c.Within(rect, 3, nil,
-		func(id string, obj geojson.Object, fields []float64) bool {
+		func(id string, obj geojson.Object, fields *Fields) bool {
 			n++
 			return n <= 30
 		},
@@ -621,7 +644,7 @@ func TestCollectionSparse(t *testing.T) {
 
 	n = 0
 	c.Intersects(rect, 3, nil,
-		func(id string, _ geojson.Object, _ []float64) bool {
+		func(id string, _ geojson.Object, _ *Fields) bool {
 			n++
 			return true
 		},
@@ -630,7 +653,7 @@ func TestCollectionSparse(t *testing.T) {
 
 	n = 0
 	c.Intersects(rect, 3, nil,
-		func(id string, _ geojson.Object, _ []float64) bool {
+		func(id string, _ geojson.Object, _ *Fields) bool {
 			n++
 			return n <= 30
 		},
@@ -683,7 +706,7 @@ func TestManyCollections(t *testing.T) {
 		Min: geometry.Point{X: -180, Y: 30},
 		Max: geometry.Point{X: 34, Y: 100},
 	}
-	col.geoSearch(bbox, func(id string, obj geojson.Object, fields []float64) bool {
+	col.geoSearch(bbox, func(id string, obj geojson.Object, fields *Fields) bool {
 		//println(id)
 		return true
 	})
diff --git a/internal/collection/fields.go b/internal/collection/fields.go
new file mode 100644
index 00000000..c4871e39
--- /dev/null
+++ b/internal/collection/fields.go
@@ -0,0 +1,40 @@
+package collection
+
+import "github.com/tidwall/tile38/internal/collection/item"
+
+// // FieldIter ...
+// type FieldIter interface {
+// 	ForEachField(count int, iter func(value float64) bool)
+// 	GetField(index int) float64
+// 	HasFields() bool
+// }
+
+// Fields ...
+type Fields struct {
+	item *item.Item
+}
+
+// ForEach iterates over each field. The count param is the number of
+// iterations. When count is less than zero, then all fields are returns.
+func (fields *Fields) ForEach(count int, iter func(value float64) bool) {
+	if fields == nil || fields.item == nil {
+		return
+	}
+	fields.item.ForEachField(count, iter)
+}
+
+// Get returns the value for a field at index. If there is no field at index,
+// then zero is returned.
+func (fields *Fields) Get(index int) float64 {
+	if fields == nil || fields.item == nil {
+		return 0
+	}
+	return fields.item.GetField(index)
+}
+
+func itemFields(item *item.Item) *Fields {
+	if item == nil || !item.HasFields() {
+		return nil
+	}
+	return &Fields{item: item}
+}
diff --git a/internal/collection/item/item.go b/internal/collection/item/item.go
index 8177da46..5463d8a6 100644
--- a/internal/collection/item/item.go
+++ b/internal/collection/item/item.go
@@ -39,7 +39,7 @@ func (item *Item) ID() string {
 }
 
 // Fields returns the field values
-func (item *Item) Fields() []float64 {
+func (item *Item) fields() []float64 {
 	return *(*[]float64)((unsafe.Pointer)(&reflect.SliceHeader{
 		Data: uintptr(unsafe.Pointer(item.data)),
 		Len:  int(item.fieldsLen) / 8,
@@ -104,8 +104,15 @@ func (item *Item) Less(other btree.Item, ctx interface{}) bool {
 	return item.ID() < other.(*Item).ID()
 }
 
-// CopyOverFields overwriting previous fields
-func (item *Item) CopyOverFields(values []float64) {
+// CopyOverFields overwriting previous fields. Accepts an *Item or []float64
+func (item *Item) CopyOverFields(from interface{}) {
+	var values []float64
+	switch from := from.(type) {
+	case *Item:
+		values = from.fields()
+	case []float64:
+		values = from
+	}
 	fieldBytes := floatsToBytes(values)
 	oldData := item.dataBytes()
 	newData := make([]byte, len(fieldBytes)+int(item.idLen))
@@ -153,15 +160,6 @@ func (item *Item) SetField(index int, value float64) (updated bool) {
 	return true
 }
 
-// GetField returns the value for a field at index.
-func (item *Item) GetField(index int) float64 {
-	numFields := int(item.fieldsLen / 8)
-	if index < numFields {
-		return getFieldAt(item.data, index)
-	}
-	return 0
-}
-
 func (item *Item) dataBytes() []byte {
 	return *(*[]byte)((unsafe.Pointer)(&reflect.SliceHeader{
 		Data: uintptr(unsafe.Pointer(item.data)),
@@ -177,3 +175,44 @@ func floatsToBytes(f []float64) []byte {
 		Cap:  len(f) * 8,
 	}))
 }
+
+// ForEachField iterates over each field. The count param is the number of
+// iterations. When count is less than zero, then all fields are returns.
+func (item *Item) ForEachField(count int, iter func(value float64) bool) {
+	if item == nil {
+		return
+	}
+	fields := item.fields()
+	var n int
+	if count < 0 {
+		n = len(fields)
+	} else {
+		n = count
+	}
+	for i := 0; i < n; i++ {
+		var field float64
+		if i < len(fields) {
+			field = fields[i]
+		}
+		if !iter(field) {
+			return
+		}
+	}
+}
+
+// GetField returns the value for a field at index.
+func (item *Item) GetField(index int) float64 {
+	if item == nil {
+		return 0
+	}
+	numFields := int(item.fieldsLen / 8)
+	if index < numFields {
+		return getFieldAt(item.data, index)
+	}
+	return 0
+}
+
+// HasFields returns true when item has fields
+func (item *Item) HasFields() bool {
+	return item != nil && item.fieldsLen > 0
+}
diff --git a/internal/collection/item/item_test.go b/internal/collection/item/item_test.go
index 6160dde6..f0237a54 100644
--- a/internal/collection/item/item_test.go
+++ b/internal/collection/item/item_test.go
@@ -19,7 +19,12 @@ func testRandItem(t *testing.T) {
 	for i := range values {
 		values[i] = rand.Float64()
 	}
-	item := New(key, geojson.NewPoint(geometry.Point{X: 1, Y: 2}))
+	var item *Item
+	if rand.Int()%2 == 0 {
+		item = New(key, geojson.NewSimplePoint(geometry.Point{X: 1, Y: 2}))
+	} else {
+		item = New(key, geojson.NewPoint(geometry.Point{X: 1, Y: 2}))
+	}
 	if item.ID() != key {
 		t.Fatalf("expected '%v', got '%v'", key, item.ID())
 	}
@@ -38,7 +43,7 @@ func testRandItem(t *testing.T) {
 				t.Fatalf("expected '%v', got '%v'", values[i], item.GetField(i))
 			}
 		}
-		fields := item.Fields()
+		fields := item.fields()
 		for i := 0; i < len(fields); i++ {
 			for _, j := range setValues {
 				if i == j {
@@ -65,6 +70,42 @@ func testRandItem(t *testing.T) {
 			t.Fatal("expected false")
 		}
 	}
+	var fvalues []float64
+	item.ForEachField(len(values), func(value float64) bool {
+		fvalues = append(fvalues, value)
+		return true
+	})
+	if !reflect.DeepEqual(values, fvalues) {
+		t.Fatalf("expected '%v', got  '%v'", values, fvalues)
+	}
+
+	fvalues = nil
+	item.ForEachField(len(values), func(value float64) bool {
+		if len(fvalues) == 1 {
+			return false
+		}
+		fvalues = append(fvalues, value)
+		return true
+	})
+	if len(values) > 0 && len(fvalues) != 1 {
+		t.Fatalf("expected '%v', got '%v'", 1, len(fvalues))
+	}
+
+	fvalues = nil
+	item.ForEachField(-1, func(value float64) bool {
+		fvalues = append(fvalues, value)
+		return true
+	})
+	if !reflect.DeepEqual(values, fvalues) {
+		t.Fatalf("expected '%v', got '%v'", 1, len(fvalues))
+	}
+
+	// should not fail, must allow nil receiver
+	(*Item)(nil).ForEachField(1, nil)
+	if (*Item)(nil).GetField(1) != 0 {
+		t.Fatalf("expected '%v', got '%v'", 0, (*Item)(nil).GetField(1))
+	}
+
 	if item.ID() != key {
 		t.Fatalf("expected '%v', got '%v'", key, item.ID())
 	}
@@ -79,8 +120,22 @@ func testRandItem(t *testing.T) {
 	if points != 1 {
 		t.Fatalf("expected '%v', got '%v'", 1, points)
 	}
-	if !reflect.DeepEqual(item.Fields(), values) {
-		t.Fatalf("expected '%v', got '%v'", values, item.Fields())
+	if !reflect.DeepEqual(item.fields(), values) {
+		t.Fatalf("expected '%v', got '%v'", values, item.fields())
+	}
+	item.CopyOverFields(item)
+	weight, points = item.WeightAndPoints()
+	if weight != len(values)*8+len(key)+points*16 {
+		t.Fatalf("expected '%v', got '%v'", len(values)*8+len(key)+points*16, weight)
+	}
+	if points != 1 {
+		t.Fatalf("expected '%v', got '%v'", 1, points)
+	}
+	if !reflect.DeepEqual(item.fields(), values) {
+		t.Fatalf("expected '%v', got '%v'", values, item.fields())
+	}
+	if !item.HasFields() {
+		t.Fatal("expected true")
 	}
 
 	item.CopyOverFields(nil)
@@ -91,12 +146,16 @@ func testRandItem(t *testing.T) {
 	if points != 1 {
 		t.Fatalf("expected '%v', got '%v'", 1, points)
 	}
-	if len(item.Fields()) != 0 {
-		t.Fatalf("expected '%#v', got '%#v'", 0, len(item.Fields()))
+	if len(item.fields()) != 0 {
+		t.Fatalf("expected '%#v', got '%#v'", 0, len(item.fields()))
 	}
 	if item.ID() != key {
 		t.Fatalf("expected '%v', got '%v'", key, item.ID())
 	}
+	if item.HasFields() {
+		t.Fatal("expected false")
+	}
+
 }
 
 func TestItem(t *testing.T) {
diff --git a/internal/server/aofshrink.go b/internal/server/aofshrink.go
index efc1c1c1..03ca574f 100644
--- a/internal/server/aofshrink.go
+++ b/internal/server/aofshrink.go
@@ -96,8 +96,9 @@ func (server *Server) aofshrink() {
 					var exm = server.expires[keys[0]] // the expiration map
 					var now = time.Now()              // used for expiration
 					var count = 0                     // the object count
+
 					col.ScanGreaterOrEqual(nextid, false, nil,
-						func(id string, obj geojson.Object, fields []float64) bool {
+						func(id string, obj geojson.Object, fields *collection.Fields) bool {
 							if count == maxids {
 								// we reached the max number of ids for one batch
 								nextid = id
@@ -110,13 +111,16 @@ func (server *Server) aofshrink() {
 							values = append(values, "set")
 							values = append(values, keys[0])
 							values = append(values, id)
-							for i, fvalue := range fields {
+							var fidx int
+							fields.ForEach(len(fnames), func(fvalue float64) bool {
 								if fvalue != 0 {
 									values = append(values, "field")
-									values = append(values, fnames[i])
+									values = append(values, fnames[fidx])
 									values = append(values, strconv.FormatFloat(fvalue, 'f', -1, 64))
 								}
-							}
+								fidx++
+								return true
+							})
 							if exm != nil {
 								at, ok := exm[id]
 								if ok {
diff --git a/internal/server/crud.go b/internal/server/crud.go
index e7aa5b03..ad680ab5 100644
--- a/internal/server/crud.go
+++ b/internal/server/crud.go
@@ -34,16 +34,14 @@ func (a byField) Swap(i, j int) {
 	a[i], a[j] = a[j], a[i]
 }
 
-func orderFields(fmap map[string]int, fields []float64) []fvt {
+func orderFields(fmap map[string]int, fields *collection.Fields) []fvt {
 	var fv fvt
 	fvs := make([]fvt, 0, len(fmap))
 	for field, idx := range fmap {
-		if idx < len(fields) {
-			fv.field = field
-			fv.value = fields[idx]
-			if fv.value != 0 {
-				fvs = append(fvs, fv)
-			}
+		fv.field = field
+		fv.value = fields.Get(idx)
+		if fv.value != 0 {
+			fvs = append(fvs, fv)
 		}
 	}
 	sort.Sort(byField(fvs))
@@ -352,7 +350,7 @@ func (server *Server) cmdPdel(msg *Message) (res resp.Value, d commandDetails, e
 		return
 	}
 	now := time.Now()
-	iter := func(id string, o geojson.Object, fields []float64) bool {
+	iter := func(id string, o geojson.Object, fields *collection.Fields) bool {
 		if match, _ := glob.Match(d.pattern, id); match {
 			d.children = append(d.children, &commandDetails{
 				command:   "del",
diff --git a/internal/server/fence.go b/internal/server/fence.go
index 67c041a0..e5d514a2 100644
--- a/internal/server/fence.go
+++ b/internal/server/fence.go
@@ -9,6 +9,7 @@ import (
 	"github.com/tidwall/geojson/geo"
 	"github.com/tidwall/geojson/geometry"
 	"github.com/tidwall/gjson"
+	"github.com/tidwall/tile38/internal/collection"
 	"github.com/tidwall/tile38/internal/glob"
 )
 
@@ -284,7 +285,7 @@ func extendRoamMessage(
 			}
 			pattern := match.id + fence.roam.scan
 			iterator := func(
-				oid string, o geojson.Object, fields []float64,
+				oid string, o geojson.Object, fields *collection.Fields,
 			) bool {
 				if oid == match.id {
 					return true
@@ -371,7 +372,7 @@ func fenceMatchRoam(
 		Max: geometry.Point{X: maxLon, Y: maxLat},
 	}
 	col.Intersects(geojson.NewRect(rect), 0, nil, func(
-		id string, obj2 geojson.Object, fields []float64,
+		id string, obj2 geojson.Object, fields *collection.Fields,
 	) bool {
 		if c.hasExpired(fence.roam.key, id) {
 			return true
diff --git a/internal/server/scan.go b/internal/server/scan.go
index c19894b2..33bd4fc0 100644
--- a/internal/server/scan.go
+++ b/internal/server/scan.go
@@ -7,6 +7,7 @@ import (
 
 	"github.com/tidwall/geojson"
 	"github.com/tidwall/resp"
+	"github.com/tidwall/tile38/internal/collection"
 	"github.com/tidwall/tile38/internal/glob"
 )
 
@@ -67,7 +68,7 @@ func (c *Server) cmdScan(msg *Message) (res resp.Value, err error) {
 			g := glob.Parse(sw.globPattern, s.desc)
 			if g.Limits[0] == "" && g.Limits[1] == "" {
 				sw.col.Scan(s.desc, sw,
-					func(id string, o geojson.Object, fields []float64) bool {
+					func(id string, o geojson.Object, fields *collection.Fields) bool {
 						return sw.writeObject(ScanWriterParams{
 							id:     id,
 							o:      o,
@@ -77,7 +78,7 @@ func (c *Server) cmdScan(msg *Message) (res resp.Value, err error) {
 				)
 			} else {
 				sw.col.ScanRange(g.Limits[0], g.Limits[1], s.desc, sw,
-					func(id string, o geojson.Object, fields []float64) bool {
+					func(id string, o geojson.Object, fields *collection.Fields) bool {
 						return sw.writeObject(ScanWriterParams{
 							id:     id,
 							o:      o,
diff --git a/internal/server/scanner.go b/internal/server/scanner.go
index 7aa4434e..2ecb6c3b 100644
--- a/internal/server/scanner.go
+++ b/internal/server/scanner.go
@@ -64,7 +64,7 @@ type scanWriter struct {
 type ScanWriterParams struct {
 	id              string
 	o               geojson.Object
-	fields          []float64
+	fields          *collection.Fields
 	distance        float64
 	noLock          bool
 	ignoreGlobMatch bool
@@ -194,7 +194,9 @@ func (sw *scanWriter) writeFoot() {
 	}
 }
 
-func (sw *scanWriter) fieldMatch(fields []float64, o geojson.Object) (fvals []float64, match bool) {
+func (sw *scanWriter) fieldMatch(
+	fields *collection.Fields, o geojson.Object,
+) (fvals []float64, match bool) {
 	var z float64
 	var gotz bool
 	fvals = sw.fvals
@@ -212,9 +214,7 @@ func (sw *scanWriter) fieldMatch(fields []float64, o geojson.Object) (fvals []fl
 			var value float64
 			idx, ok := sw.fmap[where.field]
 			if ok {
-				if len(fields) > idx {
-					value = fields[idx]
-				}
+				value = fields.Get(idx)
 			}
 			if !where.match(value) {
 				return
@@ -224,9 +224,7 @@ func (sw *scanWriter) fieldMatch(fields []float64, o geojson.Object) (fvals []fl
 			var value float64
 			idx, ok := sw.fmap[wherein.field]
 			if ok {
-				if len(fields) > idx {
-					value = fields[idx]
-				}
+				value = fields.Get(idx)
 			}
 			if !wherein.match(value) {
 				return
@@ -235,11 +233,7 @@ func (sw *scanWriter) fieldMatch(fields []float64, o geojson.Object) (fvals []fl
 		for _, whereval := range sw.whereevals {
 			fieldsWithNames := make(map[string]float64)
 			for field, idx := range sw.fmap {
-				if idx < len(fields) {
-					fieldsWithNames[field] = fields[idx]
-				} else {
-					fieldsWithNames[field] = 0
-				}
+				fieldsWithNames[field] = fields.Get(idx)
 			}
 			if !whereval.match(fieldsWithNames) {
 				return
@@ -247,11 +241,7 @@ func (sw *scanWriter) fieldMatch(fields []float64, o geojson.Object) (fvals []fl
 		}
 	} else {
 		for idx := range sw.farr {
-			var value float64
-			if len(fields) > idx {
-				value = fields[idx]
-			}
-			sw.fvals[idx] = value
+			sw.fvals[idx] = fields.Get(idx)
 		}
 		for _, where := range sw.wheres {
 			if where.field == "z" {
@@ -285,11 +275,7 @@ func (sw *scanWriter) fieldMatch(fields []float64, o geojson.Object) (fvals []fl
 		for _, whereval := range sw.whereevals {
 			fieldsWithNames := make(map[string]float64)
 			for field, idx := range sw.fmap {
-				if idx < len(fields) {
-					fieldsWithNames[field] = fields[idx]
-				} else {
-					fieldsWithNames[field] = 0
-				}
+				fieldsWithNames[field] = fields.Get(idx)
 			}
 			if !whereval.match(fieldsWithNames) {
 				return
@@ -333,7 +319,10 @@ func (sw *scanWriter) Step(n uint64) {
 
 // ok is whether the object passes the test and should be written
 // keepGoing is whether there could be more objects to test
-func (sw *scanWriter) testObject(id string, o geojson.Object, fields []float64, ignoreGlobMatch bool) (
+func (sw *scanWriter) testObject(
+	id string, o geojson.Object,
+	fields *collection.Fields, ignoreGlobMatch bool,
+) (
 	ok, keepGoing bool, fieldVals []float64) {
 	if !ignoreGlobMatch {
 		match, kg := sw.globMatch(id, o)
@@ -384,14 +373,13 @@ func (sw *scanWriter) writeObject(opts ScanWriterParams) bool {
 					jsfields = `,"fields":{`
 					var i int
 					for field, idx := range sw.fmap {
-						if len(opts.fields) > idx {
-							if opts.fields[idx] != 0 {
-								if i > 0 {
-									jsfields += `,`
-								}
-								jsfields += jsonString(field) + ":" + strconv.FormatFloat(opts.fields[idx], 'f', -1, 64)
-								i++
+						fvalue := opts.fields.Get(idx)
+						if fvalue != 0 {
+							if i > 0 {
+								jsfields += `,`
 							}
+							jsfields += jsonString(field) + ":" + strconv.FormatFloat(fvalue, 'f', -1, 64)
+							i++
 						}
 					}
 					jsfields += `}`
diff --git a/internal/server/search.go b/internal/server/search.go
index 9315d77a..88646e8a 100644
--- a/internal/server/search.go
+++ b/internal/server/search.go
@@ -14,6 +14,7 @@ import (
 	"github.com/tidwall/geojson/geometry"
 	"github.com/tidwall/resp"
 	"github.com/tidwall/tile38/internal/bing"
+	"github.com/tidwall/tile38/internal/collection"
 	"github.com/tidwall/tile38/internal/glob"
 )
 
@@ -370,7 +371,12 @@ func (server *Server) cmdNearby(msg *Message) (res resp.Value, err error) {
 	}
 	sw.writeHead()
 	if sw.col != nil {
-		iter := func(id string, o geojson.Object, fields []float64, dist float64) bool {
+		iter := func(
+			id string,
+			o geojson.Object,
+			fields *collection.Fields,
+			dist float64,
+		) bool {
 			meters := 0.0
 			if s.distance {
 				meters = geo.DistanceFromHaversine(dist)
@@ -398,35 +404,38 @@ func (server *Server) cmdNearby(msg *Message) (res resp.Value, err error) {
 type iterItem struct {
 	id     string
 	o      geojson.Object
-	fields []float64
+	fields *collection.Fields
 	dist   float64
 }
 
 func (server *Server) nearestNeighbors(
 	s *liveFenceSwitches, sw *scanWriter, target *geojson.Circle,
-	iter func(id string, o geojson.Object, fields []float64, dist float64,
+	iter func(
+		id string, o geojson.Object, fields *collection.Fields, dist float64,
 	) bool) {
 	maxDist := target.Haversine()
 	limit := int(sw.limit)
 	var items []iterItem
-	sw.col.Nearby(target, sw, func(id string, o geojson.Object, fields []float64) bool {
-		if server.hasExpired(s.key, id) {
-			return true
-		}
-		ok, keepGoing, _ := sw.testObject(id, o, fields, true)
-		if !ok {
-			return true
-		}
-		dist := target.HaversineTo(o.Center())
-		if maxDist > 0 && dist > maxDist {
-			return false
-		}
-		items = append(items, iterItem{id: id, o: o, fields: fields, dist: dist})
-		if !keepGoing {
-			return false
-		}
-		return len(items) < limit
-	})
+	sw.col.Nearby(
+		target, sw,
+		func(id string, o geojson.Object, fields *collection.Fields) bool {
+			if server.hasExpired(s.key, id) {
+				return true
+			}
+			ok, keepGoing, _ := sw.testObject(id, o, fields, true)
+			if !ok {
+				return true
+			}
+			dist := target.HaversineTo(o.Center())
+			if maxDist > 0 && dist > maxDist {
+				return false
+			}
+			items = append(items, iterItem{id: id, o: o, fields: fields, dist: dist})
+			if !keepGoing {
+				return false
+			}
+			return len(items) < limit
+		})
 	sort.Slice(items, func(i, j int) bool {
 		return items[i].dist < items[j].dist
 	})
@@ -481,7 +490,7 @@ func (server *Server) cmdWithinOrIntersects(cmd string, msg *Message) (res resp.
 	if sw.col != nil {
 		if cmd == "within" {
 			sw.col.Within(s.obj, s.sparse, sw, func(
-				id string, o geojson.Object, fields []float64,
+				id string, o geojson.Object, fields *collection.Fields,
 			) bool {
 				if server.hasExpired(s.key, id) {
 					return true
@@ -497,7 +506,7 @@ func (server *Server) cmdWithinOrIntersects(cmd string, msg *Message) (res resp.
 			sw.col.Intersects(s.obj, s.sparse, sw, func(
 				id string,
 				o geojson.Object,
-				fields []float64,
+				fields *collection.Fields,
 			) bool {
 				if server.hasExpired(s.key, id) {
 					return true
@@ -579,7 +588,11 @@ func (server *Server) cmdSearch(msg *Message) (res resp.Value, err error) {
 			g := glob.Parse(sw.globPattern, s.desc)
 			if g.Limits[0] == "" && g.Limits[1] == "" {
 				sw.col.SearchValues(s.desc, sw,
-					func(id string, o geojson.Object, fields []float64) bool {
+					func(
+						id string,
+						o geojson.Object,
+						fields *collection.Fields,
+					) bool {
 						return sw.writeObject(ScanWriterParams{
 							id:     id,
 							o:      o,
@@ -593,7 +606,11 @@ func (server *Server) cmdSearch(msg *Message) (res resp.Value, err error) {
 				// globSingle is only for ID matches, not values.
 				sw.globSingle = false
 				sw.col.SearchValuesRange(g.Limits[0], g.Limits[1], s.desc, sw,
-					func(id string, o geojson.Object, fields []float64) bool {
+					func(
+						id string,
+						o geojson.Object,
+						fields *collection.Fields,
+					) bool {
 						return sw.writeObject(ScanWriterParams{
 							id:     id,
 							o:      o,
diff --git a/internal/server/server.go b/internal/server/server.go
index a31140a9..08fa1468 100644
--- a/internal/server/server.go
+++ b/internal/server/server.go
@@ -47,19 +47,19 @@ const (
 // commandDetails is detailed information about a mutable command. It's used
 // for geofence formulas.
 type commandDetails struct {
-	command   string            // client command, like "SET" or "DEL"
-	key, id   string            // collection key and object id of object
-	newKey    string            // new key, for RENAME command
-	fmap      map[string]int    // map of field names to value indexes
-	obj       geojson.Object    // new object
-	fields    []float64         // array of field values
-	oldObj    geojson.Object    // previous object, if any
-	oldFields []float64         // previous object field values
-	updated   bool              // object was updated
-	timestamp time.Time         // timestamp when the update occured
-	parent    bool              // when true, only children are forwarded
-	pattern   string            // PDEL key pattern
-	children  []*commandDetails // for multi actions such as "PDEL"
+	command   string             // client command, like "SET" or "DEL"
+	key, id   string             // collection key and object id of object
+	newKey    string             // new key, for RENAME command
+	obj       geojson.Object     // new object
+	fmap      map[string]int     // map of field names to value indexes
+	fields    *collection.Fields // array of field values
+	oldObj    geojson.Object     // previous object, if any
+	oldFields *collection.Fields // previous object field values
+	updated   bool               // object was updated
+	timestamp time.Time          // timestamp when the update occured
+	parent    bool               // when true, only children are forwarded
+	pattern   string             // PDEL key pattern
+	children  []*commandDetails  // for multi actions such as "PDEL"
 }
 
 // Server is a tile38 controller