NHibernate 2nd lvl 缓存，自定义查询，sqldialect

Question

我有 NH 和 FNH 的主干版本。当我尝试添加二级缓存时，NHibernate 的某些部分忘记了选择的 sqldialect。

初始配置:

var cfg = Fluently.Configure()
  .Database(MsSqlConfiguration.MsSql2008
    .ConnectionString(connectionString)
    .DefaultSchema("dbo")
    .UseReflectionOptimizer()    
  .Mappings(m => ................);

有罪自定义查询:

var sql = @"with Foo(col1,col2,col3)
              as (select bla bla bla...)
            Select bla bla bla from Foo";

list = Session.CreateSQLQuery(sql)
  .AddEntity("fizz", typeof(Fizz))
  .SomethingUnimportant();

当我将配置更改为:

var cfg = Fluently.Configure()
  .Database(MsSqlConfiguration.MsSql2008
    .ConnectionString(connectionString)
    .DefaultSchema("dbo")
     .UseReflectionOptimizer()
     .Cache(c=>c
       .UseQueryCache()
         .ProviderClass<HashtableCacheProvider>())
       .ShowSql())
     .Mappings(m => ................);

查询抛出错误( WITH 在 mssql2008 中添加子句):

The query should start with 'SELECT' or 'SELECT DISTINCT'

[NotSupportedException: The query should start with 'SELECT' or 'SELECT DISTINCT'] NHibernate.Dialect.MsSql2000Dialect.GetAfterSelectInsertPoint(SqlString sql) +179 NHibernate.Dialect.MsSql2000Dialect.GetLimitString(SqlString querySqlString, Int32 offset, Int32 limit) +119 NHibernate.Dialect.MsSql2005Dialect.GetLimitString(SqlString querySqlString, Int32 offset, Int32 last) +127 NHibernate.Loader.Loader.PrepareQueryCommand(QueryParameters queryParameters, Boolean scroll, ISessionImplementor session) +725 NHibernate.Loader.Loader.DoQuery(ISessionImplementor session, QueryParameters queryParameters, Boolean returnProxies) +352 NHibernate.Loader.Loader.DoQueryAndInitializeNonLazyCollections(ISessionImplementor session, QueryParameters queryParameters, Boolean returnProxies) +114 NHibernate.Loader.Loader.DoList(ISessionImplementor session, QueryParameters queryParameters) +205

任何想法究竟是什么混淆了 nhibernate 以及如何解决它？

有罪的 NHibernate 代码(在 NHibernate/Dialect/MsSql200Dialect.cs 中):

private static int GetAfterSelectInsertPoint(SqlString sql)
{
  if (sql.StartsWithCaseInsensitive("select distinct"))
  {
    return 15;
  }
  else if (sql.StartsWithCaseInsensitive("select"))
  {
    return 6;
  }
  throw new NotSupportedException
    ("The query should start with 'SELECT' or 'SELECT DISTINCT'");
  }
}

看起来 .SetMaxResults(123)导致这个。幸运的是，我可以取消绑定(bind)该查询。

希望这能解决这个问题。

Answer 1

我使用 Alkampfer 的解决方案修复了该错误，但我创建了自己的 SQL 方言，而不是直接修补 NHibernate 源:

public class Sql2008DialectWithBugFixes : MsSql2008Dialect
{
    public override SqlString GetLimitString(SqlString querySqlString, int offset, int last)
    {
        if (offset == 0)
        {
            return querySqlString.Insert(GetAfterSelectInsertPoint(querySqlString), " top " + last);
        }

        return base.GetLimitString(querySqlString, offset, last);
    }

    private static int GetAfterSelectInsertPoint(SqlString sql)
    {
        Int32 selectPosition;

        if ((selectPosition = sql.IndexOfCaseInsensitive("select distinct")) >= 0)
        {
            return selectPosition + 15; // "select distinct".Length;

        }
        if ((selectPosition = sql.IndexOfCaseInsensitive("select")) >= 0)
        {
            return selectPosition + 6; // "select".Length;
        }

        throw new NotSupportedException("The query should start with 'SELECT' or 'SELECT DISTINCT'");
    }
}