public int GetTableEstimate(TableType tableType, int threshold)
{
TableEstimate tableEstimate;
lock (estimate)
if (!estimate.TryGetValue(tableType, out tableEstimate))
{
tableEstimate = new TableEstimate();
estimate.Add(tableType, tableEstimate);
}
lock (tableEstimate)
{
if (tableEstimate.count == tableEstimate.threshold || tableEstimate.threshold < threshold)
{
DataProviderHelper helper = new DataProviderHelper(tableType);
DbConnection connection = DataProviderHelper.CreateDbConnection(tableType.DataSource.ProviderInvariantName);
connection.ConnectionString = tableType.DataSource.ConnectionString;
connection.Open();
try
{
DbCommand command = connection.CreateCommand();
command.CommandText = helper.GetEstimateRowCountQuery(tableType.ToString(helper), threshold);
tableEstimate.count = Convert.ToInt32(command.ExecuteScalar());
tableEstimate.threshold = threshold;
}
finally
{
connection.Close();
}
}
return tableEstimate.count;
}
}
