title: Very fast .NET 4 embedded DB
body: <p>I'm looking for some fast embedded DB for .net 4 (preferably in-memory).</p>
  
  <p>My usual operations are very simple: given one big table with about 50 cols and 30k rows (can be up to 1m), make queries like SELECT AVG(col1) FROM table WHERE col2 IN (?) AND col3 IN (?) AND col4 &lt; ?, SELECT col1 FROM table WHERE [same], etc. Columns are strings or floats.</p>
  
  <p>I've started with simple .net DataTables + LINQ which are quite fast but obviously size-limited (it crashes long before there is no ram left). Also there are no indexes which I thought should increase performance.</p>
  
  <p>Then I've tried SQLite (devart adapter) with SQL queries, which is like 10 times slower than in-memory datatables. I've made indexes on all columns in this table but this didn't help. I thought SQLite is considered one of the fastest embedded DBs so it's quite disappointing.</p>
  
  <p>Is there fast and scalable alternative? E.g. something like DataTable with indexes that could use a lot of memory (e.g. I don't mind that it will eat several gigs of ram).</p>