diff --git a/lsm/include/lsm/store.h b/lsm/include/lsm/store.h
index d7e2e83..1557dd1 100644
--- a/lsm/include/lsm/store.h
+++ b/lsm/include/lsm/store.h
@@ -44,6 +44,16 @@ bool lsm_entry_attr_present(lsm_entry_handle *handle, lsm_attr_type type);
 lsm_error lsm_entry_attr_get(lsm_str **out, lsm_entry_handle *handle,
                              lsm_attr_type type);
 
+/**
+ * Convenience wrapper around `lsm_entry_attr_get` that can be used if we know
+ * beforehand the attribute value is a 64-bit number.
+ *
+ * @param out where to store attribute data
+ * @param entry entry to search for
+ * @param type type of attribute to return
+ */
+lsm_error lsm_entry_attr_get_num(uint64_t *out, lsm_entry_handle *handle, lsm_attr_type type);
+
 /**
  * Add a new attribute to the entry.
  *
@@ -54,6 +64,16 @@ lsm_error lsm_entry_attr_get(lsm_str **out, lsm_entry_handle *handle,
 lsm_error lsm_entry_attr_insert(lsm_entry_handle *handle, lsm_attr_type type,
                                 lsm_str *data);
 
+/**
+ * Convenience wrapper around `lsm_entry_attr_insert` that can be used if the
+ * data to be stored is a 64-bit number.
+ *
+ * @param entry entry to modify
+ * @param type type of attribute to add
+ * @param data data of attribute
+ */
+lsm_error lsm_entry_attr_insert_num(lsm_entry_handle *handle, lsm_attr_type type, uint64_t data);
+
 /**
  * Remove an atribute from the given entry, if present.
  *
@@ -151,6 +171,16 @@ lsm_error lsm_store_insert(lsm_entry_handle **out, lsm_store *store,
 lsm_error lsm_entry_data_append(lsm_store *store, lsm_entry_handle *handle,
                                 lsm_str *data);
 
+/**
+ * Same as `lsm_entry_data_append`, except that it takes a direct char array.
+ *
+ * @param store store the entry is stored in
+ * @param entry entry to append data to
+ * @param data data to append
+ * @param len length of data array
+ */
+lsm_error lsm_entry_data_append_raw(lsm_store *store, lsm_entry_handle *handle, char *data, uint64_t len);
+
 /**
  * Read a number of bytes from the entry's data field. The position from which
  * data is read is dependent on previous read calls.
@@ -163,4 +193,12 @@ lsm_error lsm_entry_data_append(lsm_store *store, lsm_entry_handle *handle,
 lsm_error lsm_entry_data_read(uint64_t *out, char *buf,
                               lsm_entry_handle *handle, uint64_t len);
 
+/**
+ * Return the length of the entry's data.
+ *
+ * @param handle entry handle to return length for
+ * @return length of the data
+ */
+uint64_t lsm_entry_data_len(lsm_entry_handle *handle);
+
 #endif
diff --git a/lsm/src/store/lsm_store.c b/lsm/src/store/lsm_store.c
index 26e6af7..d056621 100644
--- a/lsm/src/store/lsm_store.c
+++ b/lsm/src/store/lsm_store.c
@@ -153,18 +153,32 @@ lsm_error lsm_store_insert(lsm_entry_handle **out, lsm_store *store,
                            lsm_str *key) {
   // TODO what happens when two inserts to the same key happen at the same time?
   lsm_entry_wrapper *wrapper;
-  LSM_RES(lsm_entry_wrapper_init(&wrapper));
-  pthread_rwlock_wrlock(&wrapper->lock);
 
-  lsm_error res = lsm_trie_insert(store->trie, key, wrapper);
+  // If a key was previously removed from the trie, the wrapper will already be
+  // present in the trie
+  if (lsm_trie_search((void **)&wrapper, store->trie, key) == lsm_error_not_found) {
+    LSM_RES(lsm_entry_wrapper_init(&wrapper));
+    pthread_rwlock_wrlock(&wrapper->lock);
 
-  // Check if entry isn't already present in advance
-  if (res != lsm_error_ok) {
-    lsm_entry_wrapper_free(wrapper);
+    lsm_error res = lsm_trie_insert(store->trie, key, wrapper);
 
-    return res;
+    // Check if entry isn't already present in advance
+    if (res != lsm_error_ok) {
+      lsm_entry_wrapper_free(wrapper);
+
+      return res;
+    }
+  } else {
+    pthread_rwlock_wrlock(&wrapper->lock);
+
+    if (wrapper->entry != NULL) {
+      pthread_rwlock_unlock(&wrapper->lock);
+
+      return lsm_error_already_present;
+    }
   }
 
+
   lsm_entry *entry;
   LSM_RES(lsm_entry_init(&entry));
 
diff --git a/lsm/src/store/lsm_store_entry.c b/lsm/src/store/lsm_store_entry.c
index ffbc138..d7bbc40 100644
--- a/lsm/src/store/lsm_store_entry.c
+++ b/lsm/src/store/lsm_store_entry.c
@@ -5,6 +5,7 @@
 
 #include "lsm.h"
 #include "lsm/store_internal.h"
+#include "lsm/str.h"
 
 lsm_error lsm_entry_init(lsm_entry **ptr) {
   lsm_entry *entry = calloc(1, sizeof(lsm_entry));
@@ -77,6 +78,22 @@ lsm_error lsm_entry_attr_get(lsm_str **out, lsm_entry_handle *handle,
   return lsm_error_ok;
 }
 
+lsm_error lsm_entry_attr_get_num(uint64_t *out, lsm_entry_handle *handle, lsm_attr_type type) {
+  lsm_str *s;
+
+  LSM_RES(lsm_entry_attr_get(&s, handle, type));
+
+  uint64_t num;
+
+  for (uint8_t i = 0; i < sizeof(uint64_t) / sizeof(char); i++) {
+    ((char *)&num)[i] = lsm_str_char(s, i);
+  }
+
+  *out = num;
+
+  return lsm_error_ok;
+}
+
 lsm_error lsm_entry_attr_remove(lsm_str **out, lsm_entry_handle *handle,
                                 lsm_attr_type type) {
   if (!lsm_entry_attr_present(handle, type)) {
@@ -149,3 +166,14 @@ lsm_error lsm_entry_attr_insert(lsm_entry_handle *handle, lsm_attr_type type,
 
   return lsm_error_ok;
 }
+
+lsm_error lsm_entry_attr_insert_num(lsm_entry_handle *handle, lsm_attr_type type, uint64_t data) {
+  lsm_str *s;
+  LSM_RES(lsm_str_init_copy_n(&s, (char *)&data, sizeof(uint64_t) / sizeof(char)));
+
+  return lsm_entry_attr_insert(handle, type, s);
+}
+
+uint64_t lsm_entry_data_len(lsm_entry_handle *handle) {
+  return handle->wrapper->entry->data.len;
+}
diff --git a/lsm/src/str/lsm_str.c b/lsm/src/str/lsm_str.c
index afab724..0cfd571 100644
--- a/lsm/src/str/lsm_str.c
+++ b/lsm/src/str/lsm_str.c
@@ -77,16 +77,16 @@ lsm_error lsm_str_overwrite_copy(lsm_str *str, char *s) {
 }
 
 lsm_error lsm_str_overwrite_copy_n(lsm_str *str, char *s, uint64_t len) {
-  if (str->len <= 8) {
-    memcpy(str->data.val, s, str->len);
+  if (len <= 8) {
+    memcpy(str->data.val, s, len);
   } else {
-    char *buf = malloc(str->len * sizeof(char));
+    char *buf = malloc(len * sizeof(char));
 
     if (buf == NULL) {
       return lsm_error_failed_alloc;
     }
 
-    memcpy(buf, s, str->len);
+    memcpy(buf, s, len);
     str->data.ptr = buf;
   }