diff --git a/docstore/memdocstore/codec.go b/docstore/memdocstore/codec.go
index 68c4d1db85..c2c5baca59 100644
--- a/docstore/memdocstore/codec.go
+++ b/docstore/memdocstore/codec.go
@@ -104,7 +104,7 @@ func decodeDoc(m storedDoc, ddoc driver.Document, fps [][]string) error {
 		// (We don't need the key field because ddoc must already have it.)
 		m2 = map[string]interface{}{}
 		for _, fp := range fps {
-			val, err := getAtFieldPath(m, fp)
+			val, err := getAtFieldPath(m, fp, false)
 			if err != nil {
 				if gcerrors.Code(err) == gcerrors.NotFound {
 					continue
diff --git a/docstore/memdocstore/mem.go b/docstore/memdocstore/mem.go
index c4ecf83178..0077e76fcc 100644
--- a/docstore/memdocstore/mem.go
+++ b/docstore/memdocstore/mem.go
@@ -68,6 +68,13 @@ type Options struct {
 	// When the collection is closed, its contents are saved to the file.
 	Filename string
 
+	// AllowNestedSliceQueries allows querying into nested slices.
+	// If true queries for a field path which points to a slice will return
+	// true if any element of the slice has a value that validates with the operator.
+	// This makes the memdocstore more compatible with MongoDB,
+	// but other providers may not support this feature.
+	AllowNestedSliceQueries bool
+
 	// Call this function when the collection is closed.
 	// For internal use only.
 	onClose func()
@@ -397,18 +404,44 @@ func (c *collection) checkRevision(arg driver.Document, current storedDoc) error
 	return nil
 }
 
-// getAtFieldPath gets the value of m at fp. It returns an error if fp is invalid
+// getAtFieldPath gets the value of m at fp. It returns an error if fp is invalid.
+// If nested is true compare against all elements of a slice, see AllowNestedSliceQueries
 // (see getParentMap).
-func getAtFieldPath(m map[string]interface{}, fp []string) (interface{}, error) {
-	m2, err := getParentMap(m, fp, false)
-	if err != nil {
-		return nil, err
+func getAtFieldPath(m map[string]any, fp []string, nested bool) (result any, err error) {
+	var get func(m any, name string) any
+	get = func(m any, name string) any {
+		switch m := m.(type) {
+		case map[string]any:
+			return m[name]
+		case []any:
+			if !nested {
+				return nil
+			}
+			var result []any
+			for _, e := range m {
+				next := get(e, name)
+				// If we have slices within slices the compare function does not see the nested slices.
+				// Changing the compare function to be recursive would be more effort than flattening the slices here.
+				sliced, ok := next.([]any)
+				if ok {
+					result = append(result, sliced...)
+				} else {
+					result = append(result, next)
+				}
+			}
+			return result
+		}
+		return nil
 	}
-	v, ok := m2[fp[len(fp)-1]]
-	if ok {
-		return v, nil
+	result = m
+	for _, k := range fp {
+		next := get(result, k)
+		if next == nil {
+			return nil, gcerr.Newf(gcerr.NotFound, nil, "field %s not found", strings.Join(fp, "."))
+		}
+		result = next
 	}
-	return nil, gcerr.Newf(gcerr.NotFound, nil, "field %s not found", fp)
+	return result, nil
 }
 
 // setAtFieldPath sets m's value at fp to val. It creates intermediate maps as
@@ -422,14 +455,6 @@ func setAtFieldPath(m map[string]interface{}, fp []string, val interface{}) erro
 	return nil
 }
 
-// Delete the value from m at the given field path, if it exists.
-func deleteAtFieldPath(m map[string]interface{}, fp []string) {
-	m2, _ := getParentMap(m, fp, false) // ignore error
-	if m2 != nil {
-		delete(m2, fp[len(fp)-1])
-	}
-}
-
 // getParentMap returns the map that directly contains the given field path;
 // that is, the value of m at the field path that excludes the last component
 // of fp. If a non-map is encountered along the way, an InvalidArgument error is
diff --git a/docstore/memdocstore/mem_test.go b/docstore/memdocstore/mem_test.go
index 9a843202d6..3d8d617c94 100644
--- a/docstore/memdocstore/mem_test.go
+++ b/docstore/memdocstore/mem_test.go
@@ -16,6 +16,7 @@ package memdocstore
 
 import (
 	"context"
+	"io"
 	"os"
 	"path/filepath"
 	"testing"
@@ -131,6 +132,141 @@ func TestUpdateAtomic(t *testing.T) {
 	}
 }
 
+func TestQueryNested(t *testing.T) {
+	ctx := context.Background()
+
+	dc, err := newCollection(drivertest.KeyField, nil, &Options{AllowNestedSliceQueries: true})
+	if err != nil {
+		t.Fatal(err)
+	}
+	coll := docstore.NewCollection(dc)
+	defer coll.Close()
+
+	// Set up test documents
+	testDocs := []docmap{{
+		drivertest.KeyField: "TestQueryNested",
+		"list":              []any{docmap{"a": "A"}},
+		"map":               docmap{"b": "B"},
+		"listOfMaps":        []any{docmap{"id": "1"}, docmap{"id": "2"}, docmap{"id": "3"}},
+		"mapOfLists":        docmap{"ids": []any{"1", "2", "3"}},
+		"deep":              []any{docmap{"nesting": []any{docmap{"of": docmap{"elements": "yes"}}}}},
+		"listOfLists":       []any{docmap{"items": []any{docmap{"price": 10}, docmap{"price": 20}}}},
+		dc.RevisionField():  nil,
+	}, {
+		drivertest.KeyField: "CheapItems",
+		"items":             []any{docmap{"price": 10}, docmap{"price": 1}},
+		dc.RevisionField():  nil,
+	}, {
+		drivertest.KeyField: "ExpensiveItems",
+		"items":             []any{docmap{"price": 50}, docmap{"price": 100}},
+		dc.RevisionField():  nil,
+	}}
+
+	for _, testDoc := range testDocs {
+		err = coll.Put(ctx, testDoc)
+		if err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	tests := []struct {
+		name     string
+		where    []any
+		wantKeys []string
+	}{
+		{
+			name:     "list field match",
+			where:    []any{"list.a", "=", "A"},
+			wantKeys: []string{"TestQueryNested"},
+		}, {
+			name:  "list field no match",
+			where: []any{"list.a", "=", "missing"},
+		}, {
+			name:     "map field match",
+			where:    []any{"map.b", "=", "B"},
+			wantKeys: []string{"TestQueryNested"},
+		}, {
+			name:     "list of maps field match",
+			where:    []any{"listOfMaps.id", "=", "2"},
+			wantKeys: []string{"TestQueryNested"},
+		}, {
+			name:     "map of lists field match",
+			where:    []any{"mapOfLists.ids", "=", "1"},
+			wantKeys: []string{"TestQueryNested"},
+		}, {
+			name:     "deep nested field match",
+			where:    []any{"deep.nesting.of.elements", "=", "yes"},
+			wantKeys: []string{"TestQueryNested"},
+		}, {
+			name:     "list of lists exact price 10",
+			where:    []any{"listOfLists.items.price", "=", 10},
+			wantKeys: []string{"TestQueryNested"},
+		}, {
+			name:     "list of lists exact price 20",
+			where:    []any{"listOfLists.items.price", "=", 20},
+			wantKeys: []string{"TestQueryNested"},
+		}, {
+			name:     "list of lists price less than or equal to 20",
+			where:    []any{"listOfLists.items.price", "<=", 20},
+			wantKeys: []string{"TestQueryNested"},
+		}, {
+			name:     "items price equals 1",
+			where:    []any{"items.price", "=", 1},
+			wantKeys: []string{"CheapItems"},
+		}, {
+			name:  "items price equals 5 (no match)",
+			where: []any{"items.price", "=", 5},
+		}, {
+			name:     "items price greater than or equal to 1",
+			where:    []any{"items.price", ">=", 1},
+			wantKeys: []string{"CheapItems", "ExpensiveItems"},
+		}, {
+			name:     "items price greater than or equal to 5",
+			where:    []any{"items.price", ">=", 5},
+			wantKeys: []string{"CheapItems", "ExpensiveItems"},
+		}, {
+			name:     "items price greater than or equal to 10",
+			where:    []any{"items.price", ">=", 10},
+			wantKeys: []string{"CheapItems", "ExpensiveItems"},
+		}, {
+			name:     "items price less than or equal to 50",
+			where:    []any{"items.price", "<=", 50},
+			wantKeys: []string{"CheapItems", "ExpensiveItems"},
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			iter := coll.Query().Where(docstore.FieldPath(tc.where[0].(string)), tc.where[1].(string), tc.where[2]).Get(ctx)
+			var got []docmap
+			for {
+				doc := docmap{}
+				err := iter.Next(ctx, doc)
+				if err != nil {
+					if err == io.EOF {
+						break
+					}
+					t.Fatal(err)
+				}
+				got = append(got, doc)
+			}
+
+			// Extract keys from results
+			var gotKeys []string
+			for _, d := range got {
+				if key, ok := d[drivertest.KeyField].(string); ok {
+					gotKeys = append(gotKeys, key)
+				}
+			}
+
+			diff := cmp.Diff(gotKeys, tc.wantKeys)
+			if diff != "" {
+				t.Errorf("query results mismatch (-got +want):\n%s", diff)
+			}
+		})
+	}
+}
+
 func TestSortDocs(t *testing.T) {
 	newDocs := func() []storedDoc {
 		return []storedDoc{
diff --git a/docstore/memdocstore/query.go b/docstore/memdocstore/query.go
index 419017b993..24830e6ed2 100644
--- a/docstore/memdocstore/query.go
+++ b/docstore/memdocstore/query.go
@@ -37,7 +37,7 @@ func (c *collection) RunGetQuery(_ context.Context, q *driver.Query) (driver.Doc
 
 	var resultDocs []storedDoc
 	for _, doc := range c.docs {
-		if filtersMatch(q.Filters, doc) {
+		if filtersMatch(q.Filters, doc, c.opts.AllowNestedSliceQueries) {
 			resultDocs = append(resultDocs, doc)
 		}
 	}
@@ -74,22 +74,22 @@ func (c *collection) RunGetQuery(_ context.Context, q *driver.Query) (driver.Doc
 	}, nil
 }
 
-func filtersMatch(fs []driver.Filter, doc storedDoc) bool {
+func filtersMatch(fs []driver.Filter, doc storedDoc, nested bool) bool {
 	for _, f := range fs {
-		if !filterMatches(f, doc) {
+		if !filterMatches(f, doc, nested) {
 			return false
 		}
 	}
 	return true
 }
 
-func filterMatches(f driver.Filter, doc storedDoc) bool {
-	docval, err := getAtFieldPath(doc, f.FieldPath)
+func filterMatches(f driver.Filter, doc storedDoc, nested bool) bool {
+	docval, err := getAtFieldPath(doc, f.FieldPath, nested)
 	// missing or bad field path => no match
 	if err != nil {
 		return false
 	}
-	c, ok := compare(docval, f.Value)
+	c, ok := compare(docval, f.Value, f.Op)
 	if !ok {
 		return false
 	}
@@ -120,24 +120,46 @@ func applyComparison(op string, c int) bool {
 	}
 }
 
-func compare(x1, x2 interface{}) (int, bool) {
+func compare(x1, x2 any, op string) (int, bool) {
 	v1 := reflect.ValueOf(x1)
 	v2 := reflect.ValueOf(x2)
-	// this is for in/not-in queries.
-	// return 0 if x1 is in slice x2, -1 if not.
+	// For in/not-in queries. Otherwise this should only be reached with AllowNestedSliceQueries set.
+	// Return 0 if x1 is in slice x2, -1 if not.
 	if v2.Kind() == reflect.Slice {
-		for i := 0; i < v2.Len(); i++ {
-			if c, ok := compare(x1, v2.Index(i).Interface()); ok {
-				if !ok {
-					return 0, false
-				}
+		for i := range v2.Len() {
+			if c, ok := compare(x1, v2.Index(i).Interface(), op); ok {
 				if c == 0 {
 					return 0, true
 				}
+				if op != "in" && op != "not-in" {
+					return c, true
+				}
 			}
 		}
 		return -1, true
 	}
+	// See Options.AllowNestedSliceQueries
+	// When querying for x2 in the document and x1 is a list of values we only need one value to match
+	// the comparison value depends on the operator.
+	if v1.Kind() == reflect.Slice {
+		v2Greater := false
+		v2Less := false
+		for i := range v1.Len() {
+			if c, ok := compare(x2, v1.Index(i).Interface(), op); ok {
+				if c == 0 {
+					return 0, true
+				}
+				v2Greater = v2Greater || c > 0
+				v2Less = v2Less || c < 0
+			}
+		}
+		if op[0] == '>' && v2Less {
+			return 1, true
+		} else if op[0] == '<' && v2Greater {
+			return -1, true
+		}
+		return 0, false
+	}
 	if v1.Kind() == reflect.String && v2.Kind() == reflect.String {
 		return strings.Compare(v1.String(), v2.String()), true
 	}
@@ -160,7 +182,7 @@ func compare(x1, x2 interface{}) (int, bool) {
 
 func sortDocs(docs []storedDoc, field string, asc bool) {
 	sort.Slice(docs, func(i, j int) bool {
-		c, ok := compare(docs[i][field], docs[j][field])
+		c, ok := compare(docs[i][field], docs[j][field], ">")
 		if !ok {
 			return false
 		}
diff --git a/docstore/memdocstore/urls.go b/docstore/memdocstore/urls.go
index 84d3258aeb..5f99a00157 100644
--- a/docstore/memdocstore/urls.go
+++ b/docstore/memdocstore/urls.go
@@ -65,8 +65,9 @@ func (o *URLOpener) OpenCollectionURL(ctx context.Context, u *url.URL) (*docstor
 	}
 
 	options := &Options{
-		RevisionField: q.Get("revision_field"),
-		Filename:      q.Get("filename"),
+		RevisionField:           q.Get("revision_field"),
+		Filename:                q.Get("filename"),
+		AllowNestedSliceQueries: q.Get("allow_nested_slice_queries") == "true",
 		onClose: func() {
 			o.mu.Lock()
 			delete(o.collections, collName)
@@ -75,6 +76,7 @@ func (o *URLOpener) OpenCollectionURL(ctx context.Context, u *url.URL) (*docstor
 	}
 	q.Del("revision_field")
 	q.Del("filename")
+	q.Del("allow_nested_slice_queries")
 	for param := range q {
 		return nil, fmt.Errorf("open collection %v: invalid query parameter %q", u, param)
 	}