BulkMerge

This method merges all rows from the client application into the database in bulk — inserting new rows and updating existing ones based on the defined qualifiers. It is supported for Oracle.

This page documents the Oracle-specific arguments and examples. For the SQL Server implementation, see BulkMerge (SQL Server).

Use Case

Use this method to merge rows at high speed. It leverages the native bulk operation from ODP.NET via the OracleBulkCopy class.

For merging 1,000 or more rows, prefer this method over MergeAll.

A pseudo (staging) table is created under a transaction context. The library writes to it via BulkInsert internally, then cascades the changes to the target table via a MERGE statement — see Operations (Oracle) for the underlying mechanics.

Special Arguments

The qualifiers, mappings, bulkCopyTimeout, batchSize, identityBehavior and pseudoTableType arguments are available for this operation.

qualifiers defines the fields used to match existing rows, corresponding to the WHERE clause. Defaults to the primary column if not specified.

mappings (via OracleBulkInsertMapItem) defines explicit column mappings between the source properties and the destination columns. When omitted, columns are auto-mapped by name (case-insensitive).

bulkCopyTimeout overrides the command timeout, in seconds.

batchSize overrides the number of rows sent to the server per batch. When not set, all items are sent at once.

identityBehavior (via OracleBulkImportIdentityBehavior) controls whether newly generated identity values are set back on the data entities. Disabled by default.

pseudoTableType (via OracleBulkImportPseudoTableType) controls the kind of staging table used internally.

Every pseudoTableType value currently resolves to Physical at runtime — see Operations (Oracle) for details.

The identity column, if any, is always left out of the INSERT column list generated for unmatched rows — a brand-new row’s identity property is typically an unset default (e.g. 0), not a real value meant to be inserted as-is.

Identity Setting Alignment

When identityBehavior is ReturnIdentity, the library adds a __RepoDb_OrderColumn column to the staging table to track each entity’s position in the source IEnumerable. This ensures the identity values returned from the database are assigned back to the correct entity, regardless of ordering during the underlying MERGE.

Usability

Given a list of Person models containing both existing and new rows, the following example bulk-merges them into the Person table.

using (var connection = new OracleConnection(connectionString))
{
    var mergedRows = connection.BulkMerge(people);
}

To specify a batch size:

using (var connection = new OracleConnection(connectionString))
{
    var mergedRows = connection.BulkMerge(people, batchSize: 100);
}

When batchSize is not set, all rows are sent to the server in a single batch.

DataTable

using (var connection = new OracleConnection(connectionString))
{
    var table = ConvertToDataTable(people);
    var mergedRows = connection.BulkMerge("Person", table);
}

Dictionary/ExpandoObject

using (var sourceConnection = new OracleConnection(sourceConnectionString))
{
    var result = sourceConnection.QueryAll("Person");
    using (var destinationConnection = new OracleConnection(destinationConnectionString))
    {
        var mergedRows = destinationConnection.BulkMerge("Person", result,
            qualifiers: Field.From("LastName", "DateOfBirth"));
    }
}

DataReader

using (var sourceConnection = new OracleConnection(sourceConnectionString))
{
    using (var reader = sourceConnection.ExecuteReader("SELECT * FROM Person WHERE (IsActive = 1)"))
    {
        using (var destinationConnection = new OracleConnection(destinationConnectionString))
        {
            var rows = destinationConnection.BulkMerge("Person", reader);
        }
    }
}

To bulk-merge via DataEntityDataReader:

using (var connection = new OracleConnection(connectionString))
{
    var people = GetPeople(10000);
    using (var reader = new DataEntityDataReader<Person>(people))
    {
        var mergedRows = connection.BulkMerge("Person", reader);
    }
}

Field Qualifiers

By default, the primary column is used as the qualifier. To override, pass a list of Field objects in the qualifiers argument.

using (var connection = new OracleConnection(connectionString))
{
    var people = GetPeople(10000);
    var mergedRows = connection.BulkMerge<Person>(people,
        qualifiers: e => new { e.LastName, e.DateOfBirth });
}

Use indexed columns from the target table as qualifiers to maximize performance.

Column Mappings

Add column mappings using the OracleBulkInsertMapItem class.

var mappings = new List<OracleBulkInsertMapItem>();

// Add the mappings
mappings.Add(new OracleBulkInsertMapItem("SourceId", "DestinationId"));
mappings.Add(new OracleBulkInsertMapItem("SourceName", "DestinationName"));
mappings.Add(new OracleBulkInsertMapItem("SourceIsActive", "DestinationIsActive"));
mappings.Add(new OracleBulkInsertMapItem("SourceDateInsertedUtc", "DestinationDateInsertedUtc"));

// Execute
using (var connection = new OracleConnection(connectionString))
{
    var people = GetPeople(10000);
    var mergedRows = connection.BulkMerge(people,
        mappings: mappings);
}

Targeting a Table

To target a specific table, pass the literal table name.

using (var connection = new OracleConnection(connectionString))
{
    var people = GetPeople(10000);
    var mergedRows = connection.BulkMerge("Person", people);
}

Async Method

An equivalent BulkMergeAsync method is also available.

using (var connection = new OracleConnection(connectionString))
{
    var mergedRows = await connection.BulkMergeAsync(people);
}