BulkDelete

This method deletes rows from the database in bulk, matched by the defined qualifiers. It is supported for Oracle. Oracle also has a dedicated BulkDeleteByKey operation for deleting by primary key.

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

Use Case

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

For deleting 1,000 or more rows, prefer this method over DeleteAll.

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

Special Arguments

The qualifiers, bulkCopyTimeout, batchSize 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.

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.

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.

Caveats

This operation creates a pseudo-temporary table internally under a transaction context. The database user must have permission to create tables, or an OracleException will be thrown.

Usability

The following example retrieves all inactive people, then bulk-deletes them from the Person table.

using (var connection = new OracleConnection(connectionString))
{
    var people = connection.Query<Person>(e => e.IsActive == false);
    var deletedRows = connection.BulkDelete<Person>(people);
}

To specify a batch size:

using (var connection = new OracleConnection(connectionString))
{
    var deletedRows = connection.BulkDelete<Person>(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 deletedRows = connection.BulkDelete("Person", table);
}

Dictionary/ExpandoObject

using (var sourceConnection = new OracleConnection(sourceConnectionString))
{
    var result = sourceConnection.QueryAll("Person");
    using (var destinationConnection = new OracleConnection(destinationConnectionString))
    {
        var deletedRows = destinationConnection.BulkDelete("Person", result);
    }
}

DataReader

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

Targeting a Table

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

using (var connection = new OracleConnection(connectionString))
{
    var deletedRows = connection.BulkDelete("Person", people);
}

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 deletedRows = connection.BulkDelete<Person>(people,
        qualifiers: e => new { e.LastName, e.DateOfBirth });
}

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

Async Method

An equivalent BulkDeleteAsync method is also available.

using (var connection = new OracleConnection(connectionString))
{
    var people = connection.Query<Person>(e => e.IsActive == false);
    var deletedRows = await connection.BulkDeleteAsync<Person>(people);
}