c# - NHibernate - first query is painfully slow -

database table (postgresql) containing 10000 rows:

create table test (   id bigserial not null,   text text,   constraint test_pkey primary key (id) ) 

classes:

public class test {     public virtual int id { get; set; }     public virtual string text { get; set; } }  public class testmap : classmap<test> {     public testmap()     {         table("test");         id(x => x.id, "id");         map(x => x.text, "text");     } } 

here how query database:

using (isession session = sessionbuilder.opensession()) {     stopwatch s = new stopwatch();      s.start();     var result = session.queryover<test>().where(test => test.text == "aaa").list();     s.stop();     console.writeline(s.elapsedmilliseconds); // >150ms      s.restart();     var result2 = session.queryover<test>().where(test => test.text == "bbb").list();     s.stop();     console.writeline(s.elapsedmilliseconds); // ~4ms } 

why first query takes long? there way speed up?

quite caching. have no indexes can query, full table scan way either answer. first 1 fill buffers , caches, either db (possibly won't table scan) o/s cache or disk pages. second query benefit pages being cached @ level.

craig's suggestion subtle spin on caching & priming - first time tends incur bit of hit , need find out what. in web apps can bit of priming before app accepts requests. if more of batch thing can't disguise warm-up may have live or ditch nhibernate.

take advice & measure what's going on in hibernate too.