Differentiate between single- and multi- props.

impl/memory/datastore_index.go

 // Copyright 2015 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 package memory
 
 import (
         "bytes"
         "fmt"
         "sort"
 
         ds "github.com/luci/gae/service/datastore"
         "github.com/luci/gae/service/datastore/serialize"
         "github.com/luci/gkvlite"
 )
 
 type qIndexSlice []*ds.IndexDefinition
 
 func (s qIndexSlice) Len() int           { return len(s) }
 func (s qIndexSlice) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
 func (s qIndexSlice) Less(i, j int) bool { return s[i].Less(s[j]) }
 
 func defaultIndexes(kind string, pmap ds.PropertyMap) []*ds.IndexDefinition {
         ret := make(qIndexSlice, 0, 2*len(pmap)+1)
         ret = append(ret, &ds.IndexDefinition{Kind: kind})
-        for name, pvals := range pmap {
+        for name := range pmap {
+                pvals := pmap.Slice(name)
                 needsIndex := false
                 for _, v := range pvals {
                         if v.IndexSetting() == ds.ShouldIndex {
                                 needsIndex = true
                                 break
                         }
                 }
                 if !needsIndex {
                         continue
                 }
@@ skipping 223 matching lines @@
         compIdx := []*ds.IndexDefinition{}
         walkCompIdxs(store.Snapshot(), nil, func(i *ds.IndexDefinition) bool {
                 compIdx = append(compIdx, i)
                 return true
         })
 
         mergeIndexes(key.Namespace(), store,
                 indexEntriesWithBuiltins(key, oldEnt, compIdx),
                 indexEntriesWithBuiltins(key, newEnt, compIdx))
 }