Improved Apply support

Fixed errors when apply used table ref instead of subquery

Author: alex-kulakov

Orm/Xtensive.Orm.Firebird/Sql.Drivers.Firebird/v4_0/ServerInfoProvider.cs

@@ -11,7 +11,7 @@ internal class ServerInfoProvider : v2_5.ServerInfoProvider
     public override QueryInfo GetQueryInfo()
     {
       var info = base.GetQueryInfo();
-      info.Features |= QueryFeatures.CrossApply;
+      info.Features |= QueryFeatures.CrossApplyForSubqueriesOnly;
       return info;
     }
 

Orm/Xtensive.Orm.PostgreSql/Sql.Drivers.PostgreSql/v10_0/ServerInfoProvider.cs

@@ -13,7 +13,7 @@ internal class ServerInfoProvider : v9_0.ServerInfoProvider
     public override QueryInfo GetQueryInfo()
     {
       var info = base.GetQueryInfo();
-      info.Features |= QueryFeatures.CrossApply;
+      info.Features |= QueryFeatures.CrossApplyForSubqueriesOnly;
       return info;
     }
 

Orm/Xtensive.Orm/Orm/Providers/SqlCompiler.cs

@@ -563,7 +563,7 @@ public SqlCompiler(HandlerAccessor handlers, CompilerConfiguration configuration
 
       providerInfo = Handlers.ProviderInfo;
       temporaryTablesSupported = DomainHandler.TemporaryTableManager.Supported;
-      forceApplyViaReference = handlers.ProviderInfo.ProviderName.Equals(WellKnown.Provider.PostgreSql);
+      forceApplyViaReference = Handlers.StorageDriver.ServerInfo.Query.Features.HasFlag(Sql.Info.QueryFeatures.CrossApplyForSubqueriesOnly);
 
       if (!providerInfo.Supports(ProviderFeatures.FullFeaturedBooleanExpressions))
         booleanExpressionConverter = new BooleanExpressionConverter(Driver);

Orm/Xtensive.Orm/Sql/Info/QueryFeatures.cs

@@ -147,6 +147,11 @@ public enum QueryFeatures
     /// </summary>
     DeleteLimit = 1 << 25,
 
+    /// <summary>
+    /// Indicates that RDBMS supports CROSS APPLY and OUTER APPLY operators but only for subqueries.
+    /// </summary>
+    CrossApplyForSubqueriesOnly = CrossApply | (1 << 26),
+
     /// <summary>
     /// Indicates that RDBMS supports paging operators (<see cref="Limit"/> and <see cref="Offset"/>).
     /// </summary>