diff --git a/src/layer/base.rs b/src/layer/base.rs
index 20cb247b..94013dc6 100644
--- a/src/layer/base.rs
+++ b/src/layer/base.rs
@@ -1037,48 +1037,47 @@ pub mod tests {
     use crate::storage::memory::*;
 
     pub fn base_layer_files() -> BaseLayerFiles<MemoryBackedStore> {
-        let files: Vec<_> = (0..21).map(|_| MemoryBackedStore::new()).collect();
         BaseLayerFiles {
             node_dictionary_files: DictionaryFiles {
-                blocks_file: files[0].clone(),
-                offsets_file: files[1].clone(),
+                blocks_file: MemoryBackedStore::new(),
+                offsets_file: MemoryBackedStore::new(),
             },
             predicate_dictionary_files: DictionaryFiles {
-                blocks_file: files[2].clone(),
-                offsets_file: files[3].clone(),
+                blocks_file: MemoryBackedStore::new(),
+                offsets_file: MemoryBackedStore::new(),
             },
             value_dictionary_files: DictionaryFiles {
-                blocks_file: files[4].clone(),
-                offsets_file: files[5].clone(),
+                blocks_file: MemoryBackedStore::new(),
+                offsets_file: MemoryBackedStore::new(),
             },
             s_p_adjacency_list_files: AdjacencyListFiles {
                 bitindex_files: BitIndexFiles {
-                    bits_file: files[6].clone(),
-                    blocks_file: files[7].clone(),
-                    sblocks_file: files[8].clone(),
+                    bits_file: MemoryBackedStore::new(),
+                    blocks_file: MemoryBackedStore::new(),
+                    sblocks_file: MemoryBackedStore::new(),
                 },
-                nums_file: files[9].clone(),
+                nums_file: MemoryBackedStore::new(),
             },
             sp_o_adjacency_list_files: AdjacencyListFiles {
                 bitindex_files: BitIndexFiles {
-                    bits_file: files[10].clone(),
-                    blocks_file: files[11].clone(),
-                    sblocks_file: files[12].clone(),
+                    bits_file: MemoryBackedStore::new(),
+                    blocks_file: MemoryBackedStore::new(),
+                    sblocks_file: MemoryBackedStore::new(),
                 },
-                nums_file: files[13].clone(),
+                nums_file: MemoryBackedStore::new(),
             },
             o_ps_adjacency_list_files: AdjacencyListFiles {
                 bitindex_files: BitIndexFiles {
-                    bits_file: files[14].clone(),
-                    blocks_file: files[15].clone(),
-                    sblocks_file: files[16].clone(),
+                    bits_file: MemoryBackedStore::new(),
+                    blocks_file: MemoryBackedStore::new(),
+                    sblocks_file: MemoryBackedStore::new(),
                 },
-                nums_file: files[17].clone(),
+                nums_file: MemoryBackedStore::new(),
             },
             predicate_wavelet_tree_files: BitIndexFiles {
-                bits_file: files[18].clone(),
-                blocks_file: files[19].clone(),
-                sblocks_file: files[20].clone(),
+                bits_file: MemoryBackedStore::new(),
+                blocks_file: MemoryBackedStore::new(),
+                sblocks_file: MemoryBackedStore::new(),
             },
         }
     }
diff --git a/src/layer/builder.rs b/src/layer/builder.rs
index f0a4c56b..331bda2b 100644
--- a/src/layer/builder.rs
+++ b/src/layer/builder.rs
@@ -296,130 +296,128 @@ mod tests {
     use crate::storage::memory::*;
 
     fn new_base_files() -> BaseLayerFiles<MemoryBackedStore> {
-        let files: Vec<_> = (0..21).map(|_| MemoryBackedStore::new()).collect();
         BaseLayerFiles {
             node_dictionary_files: DictionaryFiles {
-                blocks_file: files[0].clone(),
-                offsets_file: files[1].clone(),
+                blocks_file: MemoryBackedStore::new(),
+                offsets_file: MemoryBackedStore::new(),
             },
             predicate_dictionary_files: DictionaryFiles {
-                blocks_file: files[2].clone(),
-                offsets_file: files[3].clone(),
+                blocks_file: MemoryBackedStore::new(),
+                offsets_file: MemoryBackedStore::new(),
             },
             value_dictionary_files: DictionaryFiles {
-                blocks_file: files[4].clone(),
-                offsets_file: files[5].clone(),
+                blocks_file: MemoryBackedStore::new(),
+                offsets_file: MemoryBackedStore::new(),
             },
             s_p_adjacency_list_files: AdjacencyListFiles {
                 bitindex_files: BitIndexFiles {
-                    bits_file: files[6].clone(),
-                    blocks_file: files[7].clone(),
-                    sblocks_file: files[8].clone(),
+                    bits_file: MemoryBackedStore::new(),
+                    blocks_file: MemoryBackedStore::new(),
+                    sblocks_file: MemoryBackedStore::new(),
                 },
-                nums_file: files[9].clone(),
+                nums_file: MemoryBackedStore::new(),
             },
             sp_o_adjacency_list_files: AdjacencyListFiles {
                 bitindex_files: BitIndexFiles {
-                    bits_file: files[10].clone(),
-                    blocks_file: files[11].clone(),
-                    sblocks_file: files[12].clone(),
+                    bits_file: MemoryBackedStore::new(),
+                    blocks_file: MemoryBackedStore::new(),
+                    sblocks_file: MemoryBackedStore::new(),
                 },
-                nums_file: files[13].clone(),
+                nums_file: MemoryBackedStore::new(),
             },
             o_ps_adjacency_list_files: AdjacencyListFiles {
                 bitindex_files: BitIndexFiles {
-                    bits_file: files[14].clone(),
-                    blocks_file: files[15].clone(),
-                    sblocks_file: files[16].clone(),
+                    bits_file: MemoryBackedStore::new(),
+                    blocks_file: MemoryBackedStore::new(),
+                    sblocks_file: MemoryBackedStore::new(),
                 },
-                nums_file: files[17].clone(),
+                nums_file: MemoryBackedStore::new(),
             },
             predicate_wavelet_tree_files: BitIndexFiles {
-                bits_file: files[18].clone(),
-                blocks_file: files[19].clone(),
-                sblocks_file: files[20].clone(),
+                bits_file: MemoryBackedStore::new(),
+                blocks_file: MemoryBackedStore::new(),
+                sblocks_file: MemoryBackedStore::new(),
             },
         }
     }
 
     fn new_child_files() -> ChildLayerFiles<MemoryBackedStore> {
-        let files: Vec<_> = (0..40).map(|_| MemoryBackedStore::new()).collect();
         ChildLayerFiles {
             node_dictionary_files: DictionaryFiles {
-                blocks_file: files[0].clone(),
-                offsets_file: files[1].clone(),
+                blocks_file: MemoryBackedStore::new(),
+                offsets_file: MemoryBackedStore::new(),
             },
             predicate_dictionary_files: DictionaryFiles {
-                blocks_file: files[2].clone(),
-                offsets_file: files[3].clone(),
+                blocks_file: MemoryBackedStore::new(),
+                offsets_file: MemoryBackedStore::new(),
             },
             value_dictionary_files: DictionaryFiles {
-                blocks_file: files[4].clone(),
-                offsets_file: files[5].clone(),
+                blocks_file: MemoryBackedStore::new(),
+                offsets_file: MemoryBackedStore::new(),
             },
 
-            pos_subjects_file: files[6].clone(),
-            pos_objects_file: files[7].clone(),
-            neg_subjects_file: files[8].clone(),
-            neg_objects_file: files[9].clone(),
+            pos_subjects_file: MemoryBackedStore::new(),
+            pos_objects_file: MemoryBackedStore::new(),
+            neg_subjects_file: MemoryBackedStore::new(),
+            neg_objects_file: MemoryBackedStore::new(),
 
             pos_s_p_adjacency_list_files: AdjacencyListFiles {
                 bitindex_files: BitIndexFiles {
-                    bits_file: files[10].clone(),
-                    blocks_file: files[11].clone(),
-                    sblocks_file: files[12].clone(),
+                    bits_file: MemoryBackedStore::new(),
+                    blocks_file: MemoryBackedStore::new(),
+                    sblocks_file: MemoryBackedStore::new(),
                 },
-                nums_file: files[13].clone(),
+                nums_file: MemoryBackedStore::new(),
             },
             pos_sp_o_adjacency_list_files: AdjacencyListFiles {
                 bitindex_files: BitIndexFiles {
-                    bits_file: files[14].clone(),
-                    blocks_file: files[15].clone(),
-                    sblocks_file: files[16].clone(),
+                    bits_file: MemoryBackedStore::new(),
+                    blocks_file: MemoryBackedStore::new(),
+                    sblocks_file: MemoryBackedStore::new(),
                 },
-                nums_file: files[17].clone(),
+                nums_file: MemoryBackedStore::new(),
             },
             pos_o_ps_adjacency_list_files: AdjacencyListFiles {
                 bitindex_files: BitIndexFiles {
-                    bits_file: files[18].clone(),
-                    blocks_file: files[19].clone(),
-                    sblocks_file: files[20].clone(),
+                    bits_file: MemoryBackedStore::new(),
+                    blocks_file: MemoryBackedStore::new(),
+                    sblocks_file: MemoryBackedStore::new(),
                 },
-                nums_file: files[21].clone(),
+                nums_file: MemoryBackedStore::new(),
             },
             neg_s_p_adjacency_list_files: AdjacencyListFiles {
                 bitindex_files: BitIndexFiles {
-                    bits_file: files[22].clone(),
-                    blocks_file: files[23].clone(),
-                    sblocks_file: files[24].clone(),
+                    bits_file: MemoryBackedStore::new(),
+                    blocks_file: MemoryBackedStore::new(),
+                    sblocks_file: MemoryBackedStore::new(),
                 },
-                nums_file: files[25].clone(),
+                nums_file: MemoryBackedStore::new(),
             },
             neg_sp_o_adjacency_list_files: AdjacencyListFiles {
                 bitindex_files: BitIndexFiles {
-                    bits_file: files[26].clone(),
-                    blocks_file: files[27].clone(),
-                    sblocks_file: files[28].clone(),
+                    bits_file: MemoryBackedStore::new(),
+                    blocks_file: MemoryBackedStore::new(),
+                    sblocks_file: MemoryBackedStore::new(),
                 },
-                nums_file: files[29].clone(),
+                nums_file: MemoryBackedStore::new(),
             },
             neg_o_ps_adjacency_list_files: AdjacencyListFiles {
                 bitindex_files: BitIndexFiles {
-                    bits_file: files[30].clone(),
-                    blocks_file: files[31].clone(),
-                    sblocks_file: files[32].clone(),
+                    bits_file: MemoryBackedStore::new(),
+                    blocks_file: MemoryBackedStore::new(),
+                    sblocks_file: MemoryBackedStore::new(),
                 },
-                nums_file: files[33].clone(),
+                nums_file: MemoryBackedStore::new(),
             },
             pos_predicate_wavelet_tree_files: BitIndexFiles {
-                bits_file: files[34].clone(),
-                blocks_file: files[35].clone(),
-                sblocks_file: files[36].clone(),
+                bits_file: MemoryBackedStore::new(),
+                blocks_file: MemoryBackedStore::new(),
+                sblocks_file: MemoryBackedStore::new(),
             },
             neg_predicate_wavelet_tree_files: BitIndexFiles {
-                bits_file: files[37].clone(),
-                blocks_file: files[38].clone(),
-                sblocks_file: files[39].clone(),
+                bits_file: MemoryBackedStore::new(),
+                blocks_file: MemoryBackedStore::new(),
+                sblocks_file: MemoryBackedStore::new(),
             },
         }
     }
diff --git a/src/layer/child.rs b/src/layer/child.rs
index 22b574b4..c131f20d 100644
--- a/src/layer/child.rs
+++ b/src/layer/child.rs
@@ -1594,84 +1594,82 @@ pub mod tests {
     use crate::layer::base::tests::*;
     use crate::storage::memory::*;
     pub fn child_layer_files() -> ChildLayerFiles<MemoryBackedStore> {
-        let files: Vec<_> = (0..40).map(|_| MemoryBackedStore::new()).collect();
-
         ChildLayerFiles {
             node_dictionary_files: DictionaryFiles {
-                blocks_file: files[0].clone(),
-                offsets_file: files[1].clone(),
+                blocks_file: MemoryBackedStore::new(),
+                offsets_file: MemoryBackedStore::new(),
             },
             predicate_dictionary_files: DictionaryFiles {
-                blocks_file: files[2].clone(),
-                offsets_file: files[3].clone(),
+                blocks_file: MemoryBackedStore::new(),
+                offsets_file: MemoryBackedStore::new(),
             },
             value_dictionary_files: DictionaryFiles {
-                blocks_file: files[4].clone(),
-                offsets_file: files[5].clone(),
+                blocks_file: MemoryBackedStore::new(),
+                offsets_file: MemoryBackedStore::new(),
             },
 
-            pos_subjects_file: files[6].clone(),
-            pos_objects_file: files[7].clone(),
-            neg_subjects_file: files[8].clone(),
-            neg_objects_file: files[9].clone(),
+            pos_subjects_file: MemoryBackedStore::new(),
+            pos_objects_file: MemoryBackedStore::new(),
+            neg_subjects_file: MemoryBackedStore::new(),
+            neg_objects_file: MemoryBackedStore::new(),
 
             pos_s_p_adjacency_list_files: AdjacencyListFiles {
                 bitindex_files: BitIndexFiles {
-                    bits_file: files[10].clone(),
-                    blocks_file: files[11].clone(),
-                    sblocks_file: files[12].clone(),
+                    bits_file: MemoryBackedStore::new(),
+                    blocks_file: MemoryBackedStore::new(),
+                    sblocks_file: MemoryBackedStore::new(),
                 },
-                nums_file: files[13].clone(),
+                nums_file: MemoryBackedStore::new(),
             },
             pos_sp_o_adjacency_list_files: AdjacencyListFiles {
                 bitindex_files: BitIndexFiles {
-                    bits_file: files[14].clone(),
-                    blocks_file: files[15].clone(),
-                    sblocks_file: files[16].clone(),
+                    bits_file: MemoryBackedStore::new(),
+                    blocks_file: MemoryBackedStore::new(),
+                    sblocks_file: MemoryBackedStore::new(),
                 },
-                nums_file: files[17].clone(),
+                nums_file: MemoryBackedStore::new(),
             },
             pos_o_ps_adjacency_list_files: AdjacencyListFiles {
                 bitindex_files: BitIndexFiles {
-                    bits_file: files[18].clone(),
-                    blocks_file: files[19].clone(),
-                    sblocks_file: files[20].clone(),
+                    bits_file: MemoryBackedStore::new(),
+                    blocks_file: MemoryBackedStore::new(),
+                    sblocks_file: MemoryBackedStore::new(),
                 },
-                nums_file: files[21].clone(),
+                nums_file: MemoryBackedStore::new(),
             },
             neg_s_p_adjacency_list_files: AdjacencyListFiles {
                 bitindex_files: BitIndexFiles {
-                    bits_file: files[22].clone(),
-                    blocks_file: files[23].clone(),
-                    sblocks_file: files[24].clone(),
+                    bits_file: MemoryBackedStore::new(),
+                    blocks_file: MemoryBackedStore::new(),
+                    sblocks_file: MemoryBackedStore::new(),
                 },
-                nums_file: files[25].clone(),
+                nums_file: MemoryBackedStore::new(),
             },
             neg_sp_o_adjacency_list_files: AdjacencyListFiles {
                 bitindex_files: BitIndexFiles {
-                    bits_file: files[26].clone(),
-                    blocks_file: files[27].clone(),
-                    sblocks_file: files[28].clone(),
+                    bits_file: MemoryBackedStore::new(),
+                    blocks_file: MemoryBackedStore::new(),
+                    sblocks_file: MemoryBackedStore::new(),
                 },
-                nums_file: files[29].clone(),
+                nums_file: MemoryBackedStore::new(),
             },
             neg_o_ps_adjacency_list_files: AdjacencyListFiles {
                 bitindex_files: BitIndexFiles {
-                    bits_file: files[30].clone(),
-                    blocks_file: files[31].clone(),
-                    sblocks_file: files[32].clone(),
+                    bits_file: MemoryBackedStore::new(),
+                    blocks_file: MemoryBackedStore::new(),
+                    sblocks_file: MemoryBackedStore::new(),
                 },
-                nums_file: files[33].clone(),
+                nums_file: MemoryBackedStore::new(),
             },
             pos_predicate_wavelet_tree_files: BitIndexFiles {
-                bits_file: files[34].clone(),
-                blocks_file: files[35].clone(),
-                sblocks_file: files[36].clone(),
+                bits_file: MemoryBackedStore::new(),
+                blocks_file: MemoryBackedStore::new(),
+                sblocks_file: MemoryBackedStore::new(),
             },
             neg_predicate_wavelet_tree_files: BitIndexFiles {
-                bits_file: files[37].clone(),
-                blocks_file: files[38].clone(),
-                sblocks_file: files[39].clone(),
+                bits_file: MemoryBackedStore::new(),
+                blocks_file: MemoryBackedStore::new(),
+                sblocks_file: MemoryBackedStore::new(),
             },
         }
     }
diff --git a/src/storage/memory.rs b/src/storage/memory.rs
index 1b78343a..0b0fb31e 100644
--- a/src/storage/memory.rs
+++ b/src/storage/memory.rs
@@ -247,49 +247,47 @@ impl LayerStore for MemoryLayerStore {
         &self,
     ) -> Box<dyn Future<Item = Box<dyn LayerBuilder>, Error = io::Error> + Send> {
         let name = rand::random();
-
-        let files: Vec<_> = (0..21).map(|_| MemoryBackedStore::new()).collect();
         let blf = BaseLayerFiles {
             node_dictionary_files: DictionaryFiles {
-                blocks_file: files[0].clone(),
-                offsets_file: files[1].clone(),
+                blocks_file: MemoryBackedStore::new(),
+                offsets_file: MemoryBackedStore::new(),
             },
             predicate_dictionary_files: DictionaryFiles {
-                blocks_file: files[2].clone(),
-                offsets_file: files[3].clone(),
+                blocks_file: MemoryBackedStore::new(),
+                offsets_file: MemoryBackedStore::new(),
             },
             value_dictionary_files: DictionaryFiles {
-                blocks_file: files[4].clone(),
-                offsets_file: files[5].clone(),
+                blocks_file: MemoryBackedStore::new(),
+                offsets_file: MemoryBackedStore::new(),
             },
             s_p_adjacency_list_files: AdjacencyListFiles {
                 bitindex_files: BitIndexFiles {
-                    bits_file: files[6].clone(),
-                    blocks_file: files[7].clone(),
-                    sblocks_file: files[8].clone(),
+                    bits_file: MemoryBackedStore::new(),
+                    blocks_file: MemoryBackedStore::new(),
+                    sblocks_file: MemoryBackedStore::new(),
                 },
-                nums_file: files[9].clone(),
+                nums_file: MemoryBackedStore::new(),
             },
             sp_o_adjacency_list_files: AdjacencyListFiles {
                 bitindex_files: BitIndexFiles {
-                    bits_file: files[10].clone(),
-                    blocks_file: files[11].clone(),
-                    sblocks_file: files[12].clone(),
+                    bits_file: MemoryBackedStore::new(),
+                    blocks_file: MemoryBackedStore::new(),
+                    sblocks_file: MemoryBackedStore::new(),
                 },
-                nums_file: files[13].clone(),
+                nums_file: MemoryBackedStore::new(),
             },
             o_ps_adjacency_list_files: AdjacencyListFiles {
                 bitindex_files: BitIndexFiles {
-                    bits_file: files[14].clone(),
-                    blocks_file: files[15].clone(),
-                    sblocks_file: files[16].clone(),
+                    bits_file: MemoryBackedStore::new(),
+                    blocks_file: MemoryBackedStore::new(),
+                    sblocks_file: MemoryBackedStore::new(),
                 },
-                nums_file: files[17].clone(),
+                nums_file: MemoryBackedStore::new(),
             },
             predicate_wavelet_tree_files: BitIndexFiles {
-                bits_file: files[18].clone(),
-                blocks_file: files[19].clone(),
-                sblocks_file: files[20].clone(),
+                bits_file: MemoryBackedStore::new(),
+                blocks_file: MemoryBackedStore::new(),
+                sblocks_file: MemoryBackedStore::new(),
             },
         };
 
@@ -318,84 +316,82 @@ impl LayerStore for MemoryLayerStore {
                 })
                 .and_then(move |parent_layer| {
                     let name = rand::random();
-                    let files: Vec<_> = (0..40).map(|_| MemoryBackedStore::new()).collect();
-
                     let clf = ChildLayerFiles {
                         node_dictionary_files: DictionaryFiles {
-                            blocks_file: files[0].clone(),
-                            offsets_file: files[1].clone(),
+                            blocks_file: MemoryBackedStore::new(),
+                            offsets_file: MemoryBackedStore::new(),
                         },
                         predicate_dictionary_files: DictionaryFiles {
-                            blocks_file: files[2].clone(),
-                            offsets_file: files[3].clone(),
+                            blocks_file: MemoryBackedStore::new(),
+                            offsets_file: MemoryBackedStore::new(),
                         },
                         value_dictionary_files: DictionaryFiles {
-                            blocks_file: files[4].clone(),
-                            offsets_file: files[5].clone(),
+                            blocks_file: MemoryBackedStore::new(),
+                            offsets_file: MemoryBackedStore::new(),
                         },
 
-                        pos_subjects_file: files[6].clone(),
-                        pos_objects_file: files[7].clone(),
-                        neg_subjects_file: files[8].clone(),
-                        neg_objects_file: files[9].clone(),
+                        pos_subjects_file: MemoryBackedStore::new(),
+                        pos_objects_file: MemoryBackedStore::new(),
+                        neg_subjects_file: MemoryBackedStore::new(),
+                        neg_objects_file: MemoryBackedStore::new(),
 
                         pos_s_p_adjacency_list_files: AdjacencyListFiles {
                             bitindex_files: BitIndexFiles {
-                                bits_file: files[10].clone(),
-                                blocks_file: files[11].clone(),
-                                sblocks_file: files[12].clone(),
+                                bits_file: MemoryBackedStore::new(),
+                                blocks_file: MemoryBackedStore::new(),
+                                sblocks_file: MemoryBackedStore::new(),
                             },
-                            nums_file: files[13].clone(),
+                            nums_file: MemoryBackedStore::new(),
                         },
                         pos_sp_o_adjacency_list_files: AdjacencyListFiles {
                             bitindex_files: BitIndexFiles {
-                                bits_file: files[14].clone(),
-                                blocks_file: files[15].clone(),
-                                sblocks_file: files[16].clone(),
+                                bits_file: MemoryBackedStore::new(),
+                                blocks_file: MemoryBackedStore::new(),
+                                sblocks_file: MemoryBackedStore::new(),
                             },
-                            nums_file: files[17].clone(),
+                            nums_file: MemoryBackedStore::new(),
                         },
                         pos_o_ps_adjacency_list_files: AdjacencyListFiles {
                             bitindex_files: BitIndexFiles {
-                                bits_file: files[18].clone(),
-                                blocks_file: files[19].clone(),
-                                sblocks_file: files[20].clone(),
+                                bits_file: MemoryBackedStore::new(),
+                                blocks_file: MemoryBackedStore::new(),
+                                sblocks_file: MemoryBackedStore::new(),
                             },
-                            nums_file: files[21].clone(),
+                            nums_file: MemoryBackedStore::new(),
                         },
                         neg_s_p_adjacency_list_files: AdjacencyListFiles {
                             bitindex_files: BitIndexFiles {
-                                bits_file: files[22].clone(),
-                                blocks_file: files[23].clone(),
-                                sblocks_file: files[24].clone(),
+                                bits_file: MemoryBackedStore::new(),
+                                blocks_file: MemoryBackedStore::new(),
+                                sblocks_file: MemoryBackedStore::new(),
                             },
-                            nums_file: files[25].clone(),
+                            nums_file: MemoryBackedStore::new(),
                         },
                         neg_sp_o_adjacency_list_files: AdjacencyListFiles {
                             bitindex_files: BitIndexFiles {
-                                bits_file: files[26].clone(),
-                                blocks_file: files[27].clone(),
-                                sblocks_file: files[28].clone(),
+                                bits_file: MemoryBackedStore::new(),
+                                blocks_file: MemoryBackedStore::new(),
+                                sblocks_file: MemoryBackedStore::new(),
                             },
-                            nums_file: files[29].clone(),
+                            nums_file: MemoryBackedStore::new(),
                         },
                         neg_o_ps_adjacency_list_files: AdjacencyListFiles {
                             bitindex_files: BitIndexFiles {
-                                bits_file: files[30].clone(),
-                                blocks_file: files[31].clone(),
-                                sblocks_file: files[32].clone(),
+                                bits_file: MemoryBackedStore::new(),
+                                blocks_file: MemoryBackedStore::new(),
+                                sblocks_file: MemoryBackedStore::new(),
                             },
-                            nums_file: files[33].clone(),
+                            nums_file: MemoryBackedStore::new(),
                         },
                         pos_predicate_wavelet_tree_files: BitIndexFiles {
-                            bits_file: files[34].clone(),
-                            blocks_file: files[35].clone(),
-                            sblocks_file: files[36].clone(),
+                            bits_file: MemoryBackedStore::new(),
+                            blocks_file: MemoryBackedStore::new(),
+                            sblocks_file: MemoryBackedStore::new(),
                         },
                         neg_predicate_wavelet_tree_files: BitIndexFiles {
-                            bits_file: files[37].clone(),
-                            blocks_file: files[38].clone(),
-                            sblocks_file: files[39].clone(),
+                            bits_file: MemoryBackedStore::new(),
+                            blocks_file: MemoryBackedStore::new(),
+                            sblocks_file: MemoryBackedStore::new(),
                         },
                     };