diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..69557e7
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+databases
diff --git a/shell.nix b/shell.nix
index e2ee9ea..40614cd 100644
--- a/shell.nix
+++ b/shell.nix
@@ -23,7 +23,10 @@ in mkShell {
       pg_ctl start -o "--unix_socket_directories=${data_dir} --listen_addresses='''"
     fi
 
-    psql -d postgres -f ${sql_file}
+    if [ ! -d ${data_dir} ]; then
+      psql -d postgres -f ${sql_file}
+    fi
+
     alias psql='psql -d postgres'
     alias nuke='rm -rf ${data_dir}'