Add simple benchmark

benchmark.sh

+#!/bin/bash
+
+n_files=20
+input_files_dir='input_files'
+
+# Cleanup
+rm -rf ${input_files_dir} out*.db dump.sql *.db-journal
+
+# Create input files
+mkdir -p input_files
+for i in $(seq $n_files); do
+    cp template_db/template.db ${input_files_dir}/db${i}.db
+done
+
+# Create a list of input files similar to how Ulf is doing
+# Useful for reference on how to modify the current scripts
+input_files_list=`find ${input_files_dir} -type f -name '*.db'`
+
+echo 'Testing with "ATTACH DATABASE" strategy'
+time ./merge_using_attach.py ${input_files_list} -o output_with_attach.db
+
+echo ''
+echo 'Testing with ".dump" strategy'
+time ./merge_using_dump.sh ${input_files_list}
+
+rm -rf ${input_files_dir} dump.sql *.db-journal
+echo ''
+echo 'Done.'