c# - How to cache .Count() queries in NHibernate.Linq? -

how cache result of such query:

session.query<entity>().count(e=> e.property == someconstant) 

i cannot place cacheable() after it, , if place before count(), fetch entire result set, wouldnt it?

adding cacheable before count will cause aggregate count results cached. can seen sql generated example below.

domain , mapping code

public class entity {     public virtual long id { get; set; }     public virtual string name { get; set; } }  public class entitymap : classmap<entity> {     public entitymap()     {         id(x => x.id).generatedby.identity();         map(x => x.name);         cache.readonly();     } } 

the test code itself.

using (var session = nhibernatehelper.opensession()) using (var tx = session.begintransaction()) {     session.save(new entity() { name = "smith" });     session.save(new entity() { name = "smithers" });     session.save(new entity() { name = "smithery" });     session.save(new entity() { name = "smith" });     tx.commit(); }  string name_constant = "smith"; using (var session = nhibernatehelper.opensession()) using (var tx = session.begintransaction()) {     var result = session.query<entity>().cacheable().count(e => e.name == name_constant); }  using (var session = nhibernatehelper.opensession()) using (var tx = session.begintransaction()) {     var result = session.query<entity>().cacheable().count(e => e.name == name_constant); } 

the sql generated above code can seen below. can see, there 4 insert statements, 1 each session.save. whereas there 1 select despite 2 queries, each performing under separate session. because result of count has been cached nhibernate.

nhibernate: insert [entity] (name) values (@p0); select scope_identity(); @p0 = 'smith' [type: string (4000)] nhibernate: insert [entity] (name) values (@p0); select scope_identity(); @p0 = 'smithers' [type: string (4000)] nhibernate: insert [entity] (name) values (@p0); select scope_identity(); @p0 = 'smithery' [type: string (4000)] nhibernate: insert [entity] (name) values (@p0); select scope_identity(); @p0 = 'smith' [type: string (4000)] nhibernate: select cast(count(*) int) col_0_0_ [entity] entity0_              entity0_.name=@p0; @p0 = 'smith' [type: string (4000)] 

the possible scenarios cause nhibernate ignore cacheable , go db when:

1. the second level cache not enabled in session factory configuration.
2. the entity has not been marked cacheable.

the other scenario know of cause nhibernate perform 2 select queries when entity has been evicted cache, either explicitly using sessionfactory.evict or cached entity becoming expired between 2 calls.