/// <summary>
/// Performs actual dump.
/// </summary>
private void doDumpToFile(string tsvFileName)
{
SqliteConnection dumpConn = null;
SqliteCommand cmdSelAll = null;
try
{
// For the dump, we use a separate connection
// This allows main connection to be safely accessed from other threads while dump is in progress
bool dbExists;
getOpenConn(out dumpConn, out dbExists);
using (SqliteCommand cmdPragma = dumpConn.CreateCommand())
{
// This pragma is a MUST to avoid locking the DB for the duration of the dump
// Without it, concurrent store requests will time out.
cmdPragma.CommandText = "PRAGMA read_uncommitted = 1;";
cmdPragma.ExecuteNonQuery();
}
// Dumping is rare. No need to prepare and reuse this command.
cmdSelAll = dumpConn.CreateCommand();
cmdSelAll.CommandText = sqlSelAll;
cmdSelAll.Prepare();
// Write from reader, straight to output file.
using (FileStream fs = new FileStream(tsvFileName, FileMode.Create, FileAccess.ReadWrite))
using (StreamWriter sw = new StreamWriter(fs))
using (var rdr = cmdSelAll.ExecuteReader())
{
sw.WriteLine(StoredResult.GetTSVHeader());
while (rdr.Read())
{
// uid, country, quiz_ix, survey_ix, score, res_enc, survey_enc
int dateNum = (int)(rdr.GetInt64(0) / 1000000);
int xDay = dateNum % 100; dateNum /= 100;
int xMonth = dateNum % 100; dateNum /= 100;
int xYear = dateNum;
DateTime date = new DateTime(xYear, xMonth, xDay);
StoredResult sr = new StoredResult(rdr.GetString(1), date, rdr.GetInt32(2), rdr.GetInt32(3),
rdr.GetInt32(4), rdr.GetString(5), rdr.GetString(6));
sw.WriteLine(sr.GetTSV());
}
}
dumpConn.Close();
}
finally
{
if (cmdSelAll != null)
{
cmdSelAll.Dispose();
}
if (dumpConn != null)
{
dumpConn.Dispose();
}
}
}
