@SzymonPobiega this is the code. It is an NHibernate IIdConvention
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Common;
using Dialects;
using FluentNHibernate.Conventions;
using FluentNHibernate.Conventions.AcceptanceCriteria;
using FluentNHibernate.Conventions.Inspections;
using FluentNHibernate.Conventions.Instances;
using NHibernate.Cfg;
using NHibernate.Dialect;
using NHibernate.Mapping;
public class CustomIdentityHiLoGeneratorConvention : IIdConvention, IIdConventionAcceptance
{
public const string NextHiValueColumnName = "NextHiValue";
public const string NHibernateHiLoIdentityTableName = "NHibernateHiLoIdentity";
public const string TableColumnName = "Entity";
private static readonly int IdBatchSize = ConfigurationHelpers.GetAppSettingAsInt("NHibernate.HiLoIdBatchSizeOverride") ?? 50;
public void Accept(IAcceptanceCriteria<IIdentityInspector> criteria)
{
criteria.Expect(x => x.Type == typeof(int) || x.Type == typeof(uint) || x.Type == typeof(long) || x.Type == typeof(ulong)).Expect(x => x.Generator.EntityType == null);
}
public void Apply(IIdentityInstance instance)
{
instance.GeneratedBy.HiLo(
NHibernateHiLoIdentityTableName,
NextHiValueColumnName,
IdBatchSize.ToString(),
builder => builder.AddParam("where", $"{TableColumnName} = '{instance.EntityType.Name}'"));
}
public static void CreateHighLowScript(Configuration config, int idBatchSize)
{
var initialHiLoBatchNumber = 1000000 / idBatchSize;
var schemaGroups = config.ClassMappings.Where(PersistentClassIsHilo).GroupBy(x => x.Table.Schema).ToArray();
var script = new StringBuilder();
foreach (var schemaGroup in schemaGroups)
{
CreateHiLoScriptForSchema(script, schemaGroup, initialHiLoBatchNumber);
}
config.AddAuxiliaryDatabaseObject(new SimpleAuxiliaryDatabaseObject(
script.ToString(),
null,
new HashSet<string> { typeof(MsSql2000Dialect).FullName, typeof(MsSql2005Dialect).FullName, typeof(MsSql2008WithFunctionsDialect).FullName }));
}
private static bool PersistentClassIsHilo(PersistentClass persistentClass)
{
var identifier = persistentClass.Identifier as SimpleValue;
if (identifier == null)
{
return false;
}
return identifier.IdentifierGeneratorStrategy == "hilo";
}
private static void CreateHiLoScriptForSchema(StringBuilder script, IGrouping<string, PersistentClass> schemaGroup, int initialHiLoBatchNumber)
{
var fullTableName = schemaGroup.Key == null ? NHibernateHiLoIdentityTableName : $"{schemaGroup.Key}.{NHibernateHiLoIdentityTableName}";
script.AppendFormat("DELETE FROM {0};", fullTableName);
script.AppendLine();
script.AppendFormat("ALTER TABLE {0} ADD {1} VARCHAR(128) NOT NULL;", fullTableName, TableColumnName);
script.AppendLine();
script.AppendFormat("CREATE NONCLUSTERED INDEX IX_{1}_{2} ON {0} (Entity ASC);", fullTableName, NHibernateHiLoIdentityTableName, TableColumnName);
script.AppendLine();
script.AppendLine("GO");
script.AppendLine();
foreach (var tableName in schemaGroup.Select(m => m.Table.Name).Distinct())
{
script.AppendFormat($"INSERT INTO {fullTableName} ({TableColumnName}, {NextHiValueColumnName}) VALUES ('{tableName}',{initialHiLoBatchNumber});");
script.AppendLine();
}
}
}
