BulkDelete

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

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

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

Call Flow Diagram

The diagram below shows the flow when calling this operation.

flowchart TD
    Client["Client<br/>(RepoDB)"] -->|BulkDelete| Source["Entities /<br/>DataTable /<br/>DbDataReader"]
    Source --> Pseudo["Create Pseudo Table<br/>(deterministic name) +<br/>Index on qualifiers"]
    Pseudo --> Loader["Buffered row-by-row<br/>parameterized INSERT<br/>(qualifier columns only)"]
    Loader -->|Write| PseudoTable[("Pseudo Table")]
    PseudoTable -->|"DELETE FROM Target<br/>WHERE EXISTS (SELECT 1 FROM<br/>Pseudo S WHERE qualifiers match)"| Table[("Target Table")]
    PseudoTable -->|Drop| Cleanup(["Pseudo Table Dropped"])

Use Case

Use this method to delete rows against SAP HANA without hand-rolling the row-by-row loop yourself.

SAP HANA has no native bulk-load API, so writing into the pseudo table is a client-buffered loop of single-row, parameterized INSERT statements — one round trip per row. The cascading DELETE against the real table, however, is a single native statement.

A pseudo (staging) table, containing only the qualifier columns and indexed on them, is created under a deterministic name for every call. The library writes to it row-by-row internally, then cascades the deletions to the target table via a correlated EXISTS subquery — see Operations (SAP HANA) for the underlying mechanics and its concurrency caveat.

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 EXISTS correlation. Defaults to the primary or identity column if not specified.

bulkCopyTimeout overrides the command timeout, in seconds, applied to each row’s INSERT while staging.

batchSize overrides how many rows are buffered client-side between flushes (default 500) — it does not change the number of round trips.

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

Usability

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

using (var connection = new HanaConnection(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 HanaConnection(connectionString))
{
    var deletedRows = connection.BulkDelete<Person>(people, batchSize: 100);
}

batchSize only controls the client-side buffer; each row is still its own round trip.

DataTable

using (var connection = new HanaConnection(connectionString))
{
    var table = ConvertToDataTable(people);
    var deletedRows = connection.BulkDelete("\"Person\"", table);
}

Dictionary/ExpandoObject

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

DataReader

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

Targeting a Table

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

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

Field Qualifiers

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

using (var connection = new HanaConnection(connectionString))
{
    var deletedRows = connection.BulkDelete<Person>(people,
        qualifiers: e => new { e.Name });
}

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