Question

I’m currently thinking of using SQLite as db engine for my C# project, but i ran into the following problem: i can’t find any API for memory storage. What i want to achieve is the following:

Upon start of the program i want to load the db file (from HDD) into memory.
During execution of the program i want to use this memory stream as a real db (read,write,insert,select etc).
Upon closing save the stream to the file.

Can anyone point me in the right way or suggest another db engine that would be better suited for this purpose.

Answer 1

You can use SQLite Online Backup API that has ability to copy db file to memory, memory to file.
Native support for SQLite Online Backup API is present in System.Data.SQLite from version 1.0.80.0 (with SQLite 3.7.11).

This is simple example how API can be used in C#:

SQLiteConnection source = new SQLiteConnection("Data Source=c:\\test.db");
source.Open();

using (SQLiteConnection destination = new SQLiteConnection(
  "Data Source=:memory:"))
{
  destination.Open();               

  // copy db file to memory
  source.BackupDatabase(destination, "main", "main",-1, null, 0);
  source.Close();

  // insert, select ,...        
  using (SQLiteCommand command = new SQLiteCommand())
  {
    command.CommandText =
      "INSERT INTO t1 (x) VALUES('some new value');";

    command.Connection = destination;
    command.ExecuteNonQuery();
  }             

  source = new SQLiteConnection("Data Source=c:\\test.db");
  source.Open();

  // save memory db to file
  destination.BackupDatabase(source, "main", "main",-1, null, 0);
  source.Close();               
}