Create DB in memory

Author: fsimonis

preciceprofiling/merge.py

@@ -466,19 +466,25 @@ def mergeCommand(files, outfile, align):
     resolved = detectFiles(files)
     sanitized = sanitizeFiles(resolved)
 
+    # Remove the old DB if present
     outfile.unlink(missing_ok=True)
-    con = sqlite3.connect(outfile)
+
+    # We create the db in-memory and safe it to disk later (10% faster)
+    con = sqlite3.connect(":memory:")
 
     loadProfilingOutputs(con, sanitized)
 
     if align:
         alignEvents(con)
 
-    # commit and tidy up
-    con.commit()
     createIndices(con)
-    con.execute("VACUUM")
+    con.commit()
+
+    # Backup the in-memory DB to a blank DB on disk
+    filedb = sqlite3.connect(outfile)
+    con.backup(filedb)
     con.close()
+    filedb.close()
 
     return 0