diff --git a/go.mod b/go.mod
index 2a5ba356..e67fc5f3 100644
--- a/go.mod
+++ b/go.mod
@@ -16,7 +16,7 @@ require (
 	github.com/peterh/liner v1.2.1
 	github.com/prometheus/client_golang v1.12.1
 	github.com/streadway/amqp v1.0.0
-	github.com/tidwall/btree v1.4.2
+	github.com/tidwall/btree v1.4.3
 	github.com/tidwall/buntdb v1.2.9
 	github.com/tidwall/geojson v1.3.4
 	github.com/tidwall/gjson v1.12.1
@@ -26,7 +26,7 @@ require (
 	github.com/tidwall/redbench v0.1.0
 	github.com/tidwall/redcon v1.4.4
 	github.com/tidwall/resp v0.1.0
-	github.com/tidwall/rtree v1.8.0
+	github.com/tidwall/rtree v1.8.1
 	github.com/tidwall/sjson v1.2.4
 	github.com/xdg/scram v1.0.5
 	github.com/yuin/gopher-lua v0.0.0-20200816102855-ee81675732da
diff --git a/go.sum b/go.sum
index 4427ee24..07ecb2dd 100644
--- a/go.sum
+++ b/go.sum
@@ -350,8 +350,8 @@ github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO
 github.com/tidwall/assert v0.1.0 h1:aWcKyRBUAdLoVebxo95N7+YZVTFF/ASTr7BN4sLP6XI=
 github.com/tidwall/assert v0.1.0/go.mod h1:QLYtGyeqse53vuELQheYl9dngGCJQ+mTtlxcktb+Kj8=
 github.com/tidwall/btree v1.1.0/go.mod h1:TzIRzen6yHbibdSfK6t8QimqbUnoxUSrZfeW7Uob0q4=
-github.com/tidwall/btree v1.4.2 h1:PpkaieETJMUxYNADsjgtNRcERX7mGc/GP2zp/r5FM3g=
-github.com/tidwall/btree v1.4.2/go.mod h1:LGm8L/DZjPLmeWGjv5kFrY8dL4uVhMmzmmLYmsObdKE=
+github.com/tidwall/btree v1.4.3 h1:Lf5U/66bk0ftNppOBjVoy/AIPBrLMkheBp4NnSNiYOo=
+github.com/tidwall/btree v1.4.3/go.mod h1:LGm8L/DZjPLmeWGjv5kFrY8dL4uVhMmzmmLYmsObdKE=
 github.com/tidwall/buntdb v1.2.9 h1:XVz684P7X6HCTrdr385yDZWB1zt/n20ZNG3M1iGyFm4=
 github.com/tidwall/buntdb v1.2.9/go.mod h1:IwyGSvvDg6hnKSIhtdZ0AqhCZGH8ukdtCAzaP8fI1X4=
 github.com/tidwall/cities v0.1.0 h1:CVNkmMf7NEC9Bvokf5GoSsArHCKRMTgLuubRTHnH0mE=
@@ -382,8 +382,8 @@ github.com/tidwall/resp v0.1.0/go.mod h1:18xEj855iMY2bK6tNF2A4x+nZy5gWO1iO7OOl3j
 github.com/tidwall/rtred v0.1.2 h1:exmoQtOLvDoO8ud++6LwVsAMTu0KPzLTUrMln8u1yu8=
 github.com/tidwall/rtred v0.1.2/go.mod h1:hd69WNXQ5RP9vHd7dqekAz+RIdtfBogmglkZSRxCHFQ=
 github.com/tidwall/rtree v1.3.1/go.mod h1:S+JSsqPTI8LfWA4xHBo5eXzie8WJLVFeppAutSegl6M=
-github.com/tidwall/rtree v1.8.0 h1:nYVLh9UKJrd4CZCNawD3WbHNxmI9LYR4j3E2hqO3tjQ=
-github.com/tidwall/rtree v1.8.0/go.mod h1:iDJQ9NBRtbfKkzZu02za+mIlaP+bjYPnunbSNidpbCQ=
+github.com/tidwall/rtree v1.8.1 h1:Hv0gvvznkDI5YwBkJp9pYh8ZEU1L2A9puLwwGPcQ9j4=
+github.com/tidwall/rtree v1.8.1/go.mod h1:iDJQ9NBRtbfKkzZu02za+mIlaP+bjYPnunbSNidpbCQ=
 github.com/tidwall/sjson v1.2.4 h1:cuiLzLnaMeBhRmEv00Lpk3tkYrcxpmbU81tAY4Dw0tc=
 github.com/tidwall/sjson v1.2.4/go.mod h1:098SZ494YoMWPmMO6ct4dcFnqxwj9r/gF0Etp19pSNM=
 github.com/tidwall/tinyqueue v0.1.1 h1:SpNEvEggbpyN5DIReaJ2/1ndroY8iyEGxPYxoSaymYE=
diff --git a/internal/collection/collection.go b/internal/collection/collection.go
index b28550be..60b96fa4 100644
--- a/internal/collection/collection.go
+++ b/internal/collection/collection.go
@@ -789,15 +789,9 @@ func nextStep(step uint64, cursor Cursor, deadline *deadline.Deadline) {
 	}
 }
 
-// Expired returns a list of all objects that have expired.
-func (c *Collection) Expired(now int64, buffer []string) (ids []string) {
-	ids = buffer[:0]
+// ScanExpires returns a list of all objects that have expired.
+func (c *Collection) ScanExpires(iter func(id string, expires int64) bool) {
 	c.expires.Scan(func(item *itemT) bool {
-		if now < item.expires {
-			return false
-		}
-		ids = append(ids, item.id)
-		return true
+		return iter(item.id, item.expires)
 	})
-	return ids
 }
diff --git a/internal/server/aofshrink.go b/internal/server/aofshrink.go
index 66dea327..f467563e 100644
--- a/internal/server/aofshrink.go
+++ b/internal/server/aofshrink.go
@@ -61,15 +61,17 @@ func (s *Server) aofshrink() {
 				func() {
 					s.mu.Lock()
 					defer s.mu.Unlock()
-					s.scanGreaterOrEqual(nextkey, func(key string, col *collection.Collection) bool {
-						if len(keys) == maxkeys {
-							keysdone = false
-							nextkey = key
-							return false
-						}
-						keys = append(keys, key)
-						return true
-					})
+					s.cols.Ascend(nextkey,
+						func(key string, col *collection.Collection) bool {
+							if len(keys) == maxkeys {
+								keysdone = false
+								nextkey = key
+								return false
+							}
+							keys = append(keys, key)
+							return true
+						},
+					)
 				}()
 				continue
 			}
@@ -87,8 +89,8 @@ func (s *Server) aofshrink() {
 					idsdone = true
 					s.mu.Lock()
 					defer s.mu.Unlock()
-					col := s.getCol(keys[0])
-					if col == nil {
+					col, ok := s.cols.Get(keys[0])
+					if !ok {
 						return
 					}
 					var fnames = col.FieldArr()     // reload an array of field names to match each object
diff --git a/internal/server/crud.go b/internal/server/crud.go
index 08bcb164..e1fb64fa 100644
--- a/internal/server/crud.go
+++ b/internal/server/crud.go
@@ -7,11 +7,9 @@ import (
 	"time"
 
 	"github.com/mmcloughlin/geohash"
-	"github.com/tidwall/btree"
 	"github.com/tidwall/geojson"
 	"github.com/tidwall/geojson/geometry"
 	"github.com/tidwall/resp"
-	"github.com/tidwall/rtree"
 	"github.com/tidwall/tile38/internal/collection"
 	"github.com/tidwall/tile38/internal/glob"
 )
@@ -50,7 +48,7 @@ func (s *Server) cmdBounds(msg *Message) (resp.Value, error) {
 		return NOMessage, errInvalidNumberOfArguments
 	}
 
-	col := s.getCol(key)
+	col, _ := s.cols.Get(key)
 	if col == nil {
 		if msg.OutputType == RESP {
 			return resp.NullValue(), nil
@@ -104,7 +102,7 @@ func (s *Server) cmdType(msg *Message) (resp.Value, error) {
 		return NOMessage, errInvalidNumberOfArguments
 	}
 
-	col := s.getCol(key)
+	col, _ := s.cols.Get(key)
 	if col == nil {
 		if msg.OutputType == RESP {
 			return resp.SimpleStringValue("none"), nil
@@ -142,7 +140,7 @@ func (s *Server) cmdGet(msg *Message) (resp.Value, error) {
 		vs = vs[1:]
 	}
 
-	col := s.getCol(key)
+	col, _ := s.cols.Get(key)
 	if col == nil {
 		if msg.OutputType == RESP {
 			return resp.NullValue(), nil
@@ -306,12 +304,12 @@ func (s *Server) cmdDel(msg *Message) (res resp.Value, d commandDetails, err err
 		return
 	}
 	found := false
-	col := s.getCol(d.key)
+	col, _ := s.cols.Get(d.key)
 	if col != nil {
 		d.obj, d.fields, ok = col.Delete(d.id)
 		if ok {
 			if col.Count() == 0 {
-				s.deleteCol(d.key)
+				s.cols.Delete(d.key)
 			}
 			found = true
 		} else if erron404 {
@@ -370,7 +368,7 @@ func (s *Server) cmdPdel(msg *Message) (res resp.Value, d commandDetails, err er
 	}
 
 	var expired int
-	col := s.getCol(d.key)
+	col, _ := s.cols.Get(d.key)
 	if col != nil {
 		g := glob.Parse(d.pattern, false)
 		if g.Limits[0] == "" && g.Limits[1] == "" {
@@ -399,7 +397,7 @@ func (s *Server) cmdPdel(msg *Message) (res resp.Value, d commandDetails, err er
 			d.children = nchildren
 		}
 		if col.Count() == 0 {
-			s.deleteCol(d.key)
+			s.cols.Delete(d.key)
 		}
 	}
 	d.command = "pdel"
@@ -431,9 +429,9 @@ func (s *Server) cmdDrop(msg *Message) (res resp.Value, d commandDetails, err er
 		err = errInvalidNumberOfArguments
 		return
 	}
-	col := s.getCol(d.key)
+	col, _ := s.cols.Get(d.key)
 	if col != nil {
-		s.deleteCol(d.key)
+		s.cols.Delete(d.key)
 		d.updated = true
 	} else {
 		d.key = "" // ignore the details
@@ -472,7 +470,7 @@ func (s *Server) cmdRename(msg *Message) (res resp.Value, d commandDetails, err
 		err = errInvalidNumberOfArguments
 		return
 	}
-	col := s.getCol(d.key)
+	col, _ := s.cols.Get(d.key)
 	if col == nil {
 		err = errKeyNotFound
 		return
@@ -486,18 +484,18 @@ func (s *Server) cmdRename(msg *Message) (res resp.Value, d commandDetails, err
 		return true
 	})
 	d.command = "rename"
-	newCol := s.getCol(d.newKey)
+	newCol, _ := s.cols.Get(d.newKey)
 	if newCol == nil {
 		d.updated = true
 	} else if nx {
 		d.updated = false
 	} else {
-		s.deleteCol(d.newKey)
+		s.cols.Delete(d.newKey)
 		d.updated = true
 	}
 	if d.updated {
-		s.deleteCol(d.key)
-		s.setCol(d.newKey, col)
+		s.cols.Delete(d.key)
+		s.cols.Set(d.newKey, col)
 	}
 	d.timestamp = time.Now()
 	switch msg.OutputType {
@@ -524,14 +522,14 @@ func (s *Server) cmdFlushDB(msg *Message) (res resp.Value, d commandDetails, err
 	}
 
 	// clear the entire database
-	s.cols = btree.NewNonConcurrent(byCollectionKey)
-	s.groupHooks = btree.NewNonConcurrent(byGroupHook)
-	s.groupObjects = btree.NewNonConcurrent(byGroupObject)
-	s.hookExpires = btree.NewNonConcurrent(byHookExpires)
-	s.hooks = btree.NewNonConcurrent(byHookName)
-	s.hooksOut = btree.NewNonConcurrent(byHookName)
-	s.hookTree = &rtree.RTree{}
-	s.hookCross = &rtree.RTree{}
+	s.cols.Clear()
+	s.groupHooks.Clear()
+	s.groupObjects.Clear()
+	s.hookExpires.Clear()
+	s.hooks.Clear()
+	s.hooksOut.Clear()
+	s.hookTree.Clear()
+	s.hookCross.Clear()
 
 	d.command = "flushdb"
 	d.updated = true
@@ -781,13 +779,13 @@ func (s *Server) cmdSet(msg *Message) (res resp.Value, d commandDetails, err err
 	if err != nil {
 		return
 	}
-	col := s.getCol(d.key)
+	col, _ := s.cols.Get(d.key)
 	if col == nil {
 		if xx {
 			goto notok
 		}
 		col = collection.New()
-		s.setCol(d.key, col)
+		s.cols.Set(d.key, col)
 	}
 	if xx || nx {
 		_, _, _, ok := col.Get(d.id)
@@ -890,7 +888,7 @@ func (s *Server) cmdFset(msg *Message) (res resp.Value, d commandDetails, err er
 	var updateCount int
 	d, fields, values, xx, err = s.parseFSetArgs(vs)
 
-	col := s.getCol(d.key)
+	col, _ := s.cols.Get(d.key)
 	if col == nil {
 		err = errKeyNotFound
 		return
@@ -949,7 +947,7 @@ func (s *Server) cmdExpire(msg *Message) (res resp.Value, d commandDetails, err
 		return
 	}
 	ok = false
-	col := s.getCol(key)
+	col, _ := s.cols.Get(key)
 	if col != nil {
 		ex := time.Now().Add(time.Duration(float64(time.Second) * value)).UnixNano()
 		ok = col.SetExpires(id, ex)
@@ -993,7 +991,7 @@ func (s *Server) cmdPersist(msg *Message) (res resp.Value, d commandDetails, err
 	}
 	var cleared bool
 	ok = false
-	col := s.getCol(key)
+	col, _ := s.cols.Get(key)
 	if col != nil {
 		var ex int64
 		_, _, ex, ok = col.Get(id)
@@ -1046,7 +1044,7 @@ func (s *Server) cmdTTL(msg *Message) (res resp.Value, err error) {
 	var v float64
 	ok = false
 	var ok2 bool
-	col := s.getCol(key)
+	col, _ := s.cols.Get(key)
 	if col != nil {
 		var ex int64
 		_, _, ex, ok = col.Get(id)
diff --git a/internal/server/expire.go b/internal/server/expire.go
index 81b88d8a..ede82f1a 100644
--- a/internal/server/expire.go
+++ b/internal/server/expire.go
@@ -3,6 +3,7 @@ package server
 import (
 	"time"
 
+	"github.com/tidwall/tile38/internal/collection"
 	"github.com/tidwall/tile38/internal/log"
 )
 
@@ -28,16 +29,15 @@ func (s *Server) backgroundExpiring() {
 
 func (s *Server) backgroundExpireObjects(now time.Time) {
 	nano := now.UnixNano()
-	var ids []string
 	var msgs []*Message
-	s.cols.Ascend(nil, func(v interface{}) bool {
-		col := v.(*collectionKeyContainer)
-		ids = col.col.Expired(nano, ids[:0])
-		for _, id := range ids {
-			msgs = append(msgs, &Message{
-				Args: []string{"del", col.key, id},
-			})
-		}
+	s.cols.Scan(func(key string, col *collection.Collection) bool {
+		col.ScanExpires(func(id string, expires int64) bool {
+			if nano < expires {
+				return false
+			}
+			msgs = append(msgs, &Message{Args: []string{"del", key, id}})
+			return true
+		})
 		return true
 	})
 	for _, msg := range msgs {
@@ -52,7 +52,6 @@ func (s *Server) backgroundExpireObjects(now time.Time) {
 	if len(msgs) > 0 {
 		log.Debugf("Expired %d objects\n", len(msgs))
 	}
-
 }
 
 func (s *Server) backgroundExpireHooks(now time.Time) {
diff --git a/internal/server/fence.go b/internal/server/fence.go
index 2829fef0..2eb17dec 100644
--- a/internal/server/fence.go
+++ b/internal/server/fence.go
@@ -288,7 +288,7 @@ func extendRoamMessage(
 		math.Floor(match.meters*1000)/1000, 'f', -1, 64)
 	if fence.roam.scan != "" {
 		nmsg = append(nmsg, `,"scan":[`...)
-		col := sw.s.getCol(fence.roam.key)
+		col, _ := sw.s.cols.Get(fence.roam.key)
 		if col != nil {
 			obj, _, _, ok := col.Get(match.id)
 			if ok {
@@ -375,7 +375,7 @@ func fenceMatchNearbys(
 	if obj == nil {
 		return nil
 	}
-	col := s.getCol(fence.roam.key)
+	col, _ := s.cols.Get(fence.roam.key)
 	if col == nil {
 		return nil
 	}
diff --git a/internal/server/json.go b/internal/server/json.go
index 4dad895d..b3a2b9b6 100644
--- a/internal/server/json.go
+++ b/internal/server/json.go
@@ -184,7 +184,7 @@ func (s *Server) cmdJget(msg *Message) (resp.Value, error) {
 			}
 		}
 	}
-	col := s.getCol(key)
+	col, _ := s.cols.Get(key)
 	if col == nil {
 		if msg.OutputType == RESP {
 			return resp.NullValue(), nil
@@ -262,7 +262,7 @@ func (s *Server) cmdJset(msg *Message) (res resp.Value, d commandDetails, err er
 			raw = true
 		}
 	}
-	col := s.getCol(key)
+	col, _ := s.cols.Get(key)
 	var createcol bool
 	if col == nil {
 		col = collection.New()
@@ -293,7 +293,7 @@ func (s *Server) cmdJset(msg *Message) (res resp.Value, d commandDetails, err er
 		return s.cmdSet(&nmsg)
 	}
 	if createcol {
-		s.setCol(key, col)
+		s.cols.Set(key, col)
 	}
 
 	d.key = key
@@ -325,7 +325,7 @@ func (s *Server) cmdJdel(msg *Message) (res resp.Value, d commandDetails, err er
 	id := msg.Args[2]
 	path := msg.Args[3]
 
-	col := s.getCol(key)
+	col, _ := s.cols.Get(key)
 	if col == nil {
 		if msg.OutputType == RESP {
 			return resp.IntegerValue(0), d, nil
diff --git a/internal/server/keys.go b/internal/server/keys.go
index bcdb4721..94eaf199 100644
--- a/internal/server/keys.go
+++ b/internal/server/keys.go
@@ -6,6 +6,7 @@ import (
 	"time"
 
 	"github.com/tidwall/resp"
+	"github.com/tidwall/tile38/internal/collection"
 	"github.com/tidwall/tile38/internal/glob"
 )
 
@@ -36,18 +37,17 @@ func (s *Server) cmdKeys(msg *Message) (res resp.Value, err error) {
 	var greaterPivot string
 	var vals []resp.Value
 
-	iterator := func(v interface{}) bool {
-		vcol := v.(*collectionKeyContainer)
+	iter := func(key string, col *collection.Collection) bool {
 		var match bool
 		if everything {
 			match = true
 		} else if greater {
-			if !strings.HasPrefix(vcol.key, greaterPivot) {
+			if !strings.HasPrefix(key, greaterPivot) {
 				return false
 			}
 			match = true
 		} else {
-			match, _ = glob.Match(pattern, vcol.key)
+			match, _ = glob.Match(pattern, key)
 		}
 		if match {
 			if once {
@@ -59,9 +59,9 @@ func (s *Server) cmdKeys(msg *Message) (res resp.Value, err error) {
 			}
 			switch msg.OutputType {
 			case JSON:
-				wr.WriteString(jsonString(vcol.key))
+				wr.WriteString(jsonString(key))
 			case RESP:
-				vals = append(vals, resp.StringValue(vcol.key))
+				vals = append(vals, resp.StringValue(key))
 			}
 
 			// If no more than one match is expected, stop searching
@@ -75,17 +75,17 @@ func (s *Server) cmdKeys(msg *Message) (res resp.Value, err error) {
 	// TODO: This can be further optimized by using glob.Parse and limits
 	if pattern == "*" {
 		everything = true
-		s.cols.Ascend(nil, iterator)
+		s.cols.Scan(iter)
 	} else if strings.HasSuffix(pattern, "*") {
 		greaterPivot = pattern[:len(pattern)-1]
 		if glob.IsGlob(greaterPivot) {
-			s.cols.Ascend(nil, iterator)
+			s.cols.Scan(iter)
 		} else {
 			greater = true
-			s.cols.Ascend(&collectionKeyContainer{key: greaterPivot}, iterator)
+			s.cols.Ascend(greaterPivot, iter)
 		}
 	} else {
-		s.cols.Ascend(nil, iterator)
+		s.cols.Scan(iter)
 	}
 	if msg.OutputType == JSON {
 		wr.WriteString(`],"elapsed":"` + time.Since(start).String() + "\"}")
diff --git a/internal/server/metrics.go b/internal/server/metrics.go
index 01049481..a5cd4623 100644
--- a/internal/server/metrics.go
+++ b/internal/server/metrics.go
@@ -5,6 +5,7 @@ import (
 	"net/http"
 
 	"github.com/tidwall/tile38/core"
+	"github.com/tidwall/tile38/internal/collection"
 
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/collectors"
@@ -121,31 +122,30 @@ func (s *Server) Collect(ch chan<- prometheus.Metric) {
 	/*
 		add objects/points/strings stats for each collection
 	*/
-	s.cols.Ascend(nil, func(v interface{}) bool {
-		c := v.(*collectionKeyContainer)
+	s.cols.Scan(func(key string, col *collection.Collection) bool {
 		ch <- prometheus.MustNewConstMetric(
 			metricDescriptions["collection_objects"],
 			prometheus.GaugeValue,
-			float64(c.col.Count()),
-			c.key,
+			float64(col.Count()),
+			key,
 		)
 		ch <- prometheus.MustNewConstMetric(
 			metricDescriptions["collection_points"],
 			prometheus.GaugeValue,
-			float64(c.col.PointCount()),
-			c.key,
+			float64(col.PointCount()),
+			key,
 		)
 		ch <- prometheus.MustNewConstMetric(
 			metricDescriptions["collection_strings"],
 			prometheus.GaugeValue,
-			float64(c.col.StringCount()),
-			c.key,
+			float64(col.StringCount()),
+			key,
 		)
 		ch <- prometheus.MustNewConstMetric(
 			metricDescriptions["collection_weight"],
 			prometheus.GaugeValue,
-			float64(c.col.TotalWeight()),
-			c.key,
+			float64(col.TotalWeight()),
+			key,
 		)
 		return true
 	})
diff --git a/internal/server/scanner.go b/internal/server/scanner.go
index bee43272..422df7ba 100644
--- a/internal/server/scanner.go
+++ b/internal/server/scanner.go
@@ -131,7 +131,7 @@ func (sw *scanWriter) loadWheres() {
 	sw.wheres = nil
 	sw.whereins = nil
 	sw.fvals = nil
-	sw.col = sw.s.getCol(sw.key)
+	sw.col, _ = sw.s.cols.Get(sw.key)
 	if sw.col != nil {
 		sw.fmap = sw.col.FieldMap()
 		sw.farr = sw.col.FieldArr()
diff --git a/internal/server/search.go b/internal/server/search.go
index 07974b2c..cce1642f 100644
--- a/internal/server/search.go
+++ b/internal/server/search.go
@@ -373,7 +373,7 @@ func (s *Server) cmdSearchArgs(
 			err = errInvalidNumberOfArguments
 			return
 		}
-		col := s.getCol(key)
+		col, _ := s.cols.Get(key)
 		if col == nil {
 			err = errKeyNotFound
 			return
diff --git a/internal/server/server.go b/internal/server/server.go
index 00306cb4..68ad06c9 100644
--- a/internal/server/server.go
+++ b/internal/server/server.go
@@ -100,13 +100,14 @@ type Server struct {
 	conns   map[int]*Client
 
 	mu       sync.RWMutex
-	aof      *os.File     // active aof file
-	aofdirty int32        // mark the aofbuf as having data
-	aofbuf   []byte       // prewrite buffer
-	aofsz    int          // active size of the aof file
-	qdb      *buntdb.DB   // hook queue log
-	qidx     uint64       // hook queue log last idx
-	cols     *btree.BTree // data collections
+	aof      *os.File   // active aof file
+	aofdirty int32      // mark the aofbuf as having data
+	aofbuf   []byte     // prewrite buffer
+	aofsz    int        // active size of the aof file
+	qdb      *buntdb.DB // hook queue log
+	qidx     uint64     // hook queue log last idx
+
+	cols *btree.Map[string, *collection.Collection] // data collections
 
 	follows      map[*bytes.Buffer]bool
 	fcond        *sync.Cond
@@ -177,7 +178,7 @@ func Serve(opts Options) error {
 		http:      opts.UseHTTP,
 		pubsub:    newPubsub(),
 		monconns:  make(map[net.Conn]bool),
-		cols:      btree.NewNonConcurrent(byCollectionKey),
+		cols:      &btree.Map[string, *collection.Collection]{},
 
 		groupHooks:   btree.NewNonConcurrent(byGroupHook),
 		groupObjects: btree.NewNonConcurrent(byGroupObject),
@@ -673,47 +674,6 @@ func (s *Server) backgroundSyncAOF() {
 	}
 }
 
-// collectionKeyContainer is a wrapper object around a collection that includes
-// the collection and the key. It's needed for support with the btree package,
-// which requires a comparator less function.
-type collectionKeyContainer struct {
-	key string
-	col *collection.Collection
-}
-
-func byCollectionKey(a, b interface{}) bool {
-	return a.(*collectionKeyContainer).key < b.(*collectionKeyContainer).key
-}
-
-func (s *Server) setCol(key string, col *collection.Collection) {
-	s.cols.Set(&collectionKeyContainer{key, col})
-}
-
-func (s *Server) getCol(key string) *collection.Collection {
-	if v := s.cols.Get(&collectionKeyContainer{key: key}); v != nil {
-		return v.(*collectionKeyContainer).col
-	}
-	return nil
-}
-
-func (s *Server) scanGreaterOrEqual(
-	key string, iterator func(key string, col *collection.Collection) bool,
-) {
-	s.cols.Ascend(&collectionKeyContainer{key: key},
-		func(v interface{}) bool {
-			vcol := v.(*collectionKeyContainer)
-			return iterator(vcol.key, vcol.col)
-		},
-	)
-}
-
-func (s *Server) deleteCol(key string) *collection.Collection {
-	if v := s.cols.Delete(&collectionKeyContainer{key: key}); v != nil {
-		return v.(*collectionKeyContainer).col
-	}
-	return nil
-}
-
 func isReservedFieldName(field string) bool {
 	switch field {
 	case "z", "lat", "lon":
@@ -1046,7 +1006,7 @@ func randomKey(n int) string {
 
 func (s *Server) reset() {
 	s.aofsz = 0
-	s.cols = btree.NewNonConcurrent(byCollectionKey)
+	s.cols.Clear()
 }
 
 func (s *Server) command(msg *Message, client *Client) (
diff --git a/internal/server/stats.go b/internal/server/stats.go
index 93f6107e..87238561 100644
--- a/internal/server/stats.go
+++ b/internal/server/stats.go
@@ -16,6 +16,7 @@ import (
 	"github.com/tidwall/buntdb"
 	"github.com/tidwall/resp"
 	"github.com/tidwall/tile38/core"
+	"github.com/tidwall/tile38/internal/collection"
 )
 
 var memStats runtime.MemStats
@@ -60,7 +61,7 @@ func (s *Server) cmdStats(msg *Message) (res resp.Value, err error) {
 		if !ok {
 			break
 		}
-		col := s.getCol(key)
+		col, _ := s.cols.Get(key)
 		if col != nil {
 			m := make(map[string]interface{})
 			m["num_points"] = col.PointCount()
@@ -160,8 +161,7 @@ func (s *Server) basicStats(m map[string]interface{}) {
 	m["num_collections"] = s.cols.Len()
 	m["num_hooks"] = s.hooks.Len()
 	sz := 0
-	s.cols.Ascend(nil, func(v interface{}) bool {
-		col := v.(*collectionKeyContainer).col
+	s.cols.Scan(func(key string, col *collection.Collection) bool {
 		sz += col.TotalWeight()
 		return true
 	})
@@ -169,8 +169,7 @@ func (s *Server) basicStats(m map[string]interface{}) {
 	points := 0
 	objects := 0
 	nstrings := 0
-	s.cols.Ascend(nil, func(v interface{}) bool {
-		col := v.(*collectionKeyContainer).col
+	s.cols.Scan(func(key string, col *collection.Collection) bool {
 		points += col.PointCount()
 		objects += col.Count()
 		nstrings += col.StringCount()
@@ -333,8 +332,7 @@ func (s *Server) extStats(m map[string]interface{}) {
 	points := 0
 	objects := 0
 	strings := 0
-	s.cols.Ascend(nil, func(v interface{}) bool {
-		col := v.(*collectionKeyContainer).col
+	s.cols.Scan(func(key string, col *collection.Collection) bool {
 		points += col.PointCount()
 		objects += col.Count()
 		strings += col.StringCount()
@@ -365,8 +363,7 @@ func (s *Server) extStats(m map[string]interface{}) {
 	m["tile38_avg_point_size"] = avgsz
 
 	sz := 0
-	s.cols.Ascend(nil, func(v interface{}) bool {
-		col := v.(*collectionKeyContainer).col
+	s.cols.Scan(func(key string, col *collection.Collection) bool {
 		sz += col.TotalWeight()
 		return true
 	})
diff --git a/internal/server/test.go b/internal/server/test.go
index 01c7a604..1c9c230f 100644
--- a/internal/server/test.go
+++ b/internal/server/test.go
@@ -273,7 +273,7 @@ func (s *Server) parseArea(ovs []string, doClip bool) (vs []string, o geojson.Ob
 			err = errInvalidNumberOfArguments
 			return
 		}
-		col := s.getCol(key)
+		col, _ := s.cols.Get(key)
 		if col == nil {
 			err = errKeyNotFound
 			return