merged = await database.Do.BulkMergeAsync(transactions.ToList(), qualifiers: p => new { p.TransactionID, p.TransactionDate, p.AccountId, p.TransactionTypeID, p.Attribute1, p.Attribute2, p.Attribute3, p.Attribute4 }, hints: SqlServerTableHints.TabLock, bulkCopyTimeout: 0).ConfigureAwait(false);

public class TransactionRaw
    {
        public long Id { get; set; }

        public long TransactionID { get; set; }

        public DateTime TransactionDate { get; set; }

        public DateTime IncidentCreationDate { get; set; }

        public int? AccountId { get; set; }

        public long? ContactID { get; set; }

        public int? SeverityID { get; set; }

        public int? InterfaceID { get; set; }

        public int? DispositionID { get; set; }

        public long? Attribute1 { get; set; }

        public long? Attribute2 { get; set; }

        public long? Attribute3 { get; set; }

        public long? Attribute4 { get; set; }

        public int? QueueID { get; set; }

        public int? TransactionTypeID { get; set; }

        public int? SourceLevel1ID { get; set; }

        public int? SourceLevel2ID { get; set; }

        public int? ProductID { get; set; }

        public int? CountryID { get; set; }

        public int? CustomerTypeID { get; set; }

        public int? CategoryID { get; set; }

        public int? StatusID { get; set; }

        public string PhoneCallUUID { get; set; }

        public int? ChannelID { get; set; }
    }

    public class TransactionComparer : IEqualityComparer<TransactionRaw>
    {
        public bool Equals(TransactionRaw t1, TransactionRaw t2)
        {
            return (t1.TransactionID == t2.TransactionID) && (t1.TransactionDate == t2.TransactionDate) && (t1.Attribute1 == t2.Attribute1) && (t1.Attribute2 == t2.Attribute2) && (t1.Attribute3 == t2.Attribute3) && (t1.Attribute4 == t2.Attribute4) && (t1.AccountId == t2.AccountId);
        }

        public int GetHashCode(TransactionRaw t)
        {
            return $"{t.TransactionID}{t.TransactionDate}{t.AccountId}{t.Attribute1}{t.Attribute2}{t.Attribute3}{t.Attribute4}".GetHashCode();
        }
    }

CREATE TABLE [TransactionsRaw](
	[Id] [bigint] IDENTITY(1,1) NOT NULL,
	[TransactionID] [bigint] NOT NULL,
	[TransactionDate] [datetime] NOT NULL,
	[AccountId] [int] NULL,
	[ProductID] [int] NULL,
	[Attribute1] [bigint] NULL,
	[Attribute2] [bigint] NULL,
	[Attribute3] [bigint] NULL,
	[Attribute4] [bigint] NULL,
	[PhoneCallUUID] [varchar](64) NULL,
	[InterfaceID] [int] NULL,
	[CategoryID] [int] NULL,
	[ContactID] [int] NULL,
	[CountryID] [int] NULL,
	[CustomerTypeID] [int] NULL,
	[QueueID] [int] NULL,
	[IncidentCreationDate] [datetime] NOT NULL,
	[StatusID] [int] NULL,
	[SeverityID] [int] NULL,
	[SourceLevel1ID] [int] NULL,
	[SourceLevel2ID] [int] NULL,
	[DispositionID] [int] NULL,
	[TransactionTypeID] [int] NULL,
	[ChannelID] [int] NULL
) ON [PRIMARY]