BulkUpdate

This method updates existing rows in the database in bulk, matched by the defined qualifiers. It is supported for RepoDb.MySql.BulkOperations, targeting the MySql.Data driver.

This page documents the MySql.Data-specific arguments and examples. For the MySqlConnector implementation, see BulkUpdate (MySqlConnector); for SQL Server, see BulkUpdate (SQL Server); for Oracle, see BulkUpdate (Oracle).

Call Flow Diagram

The diagram below shows the flow when calling this operation.

flowchart TD
    Client["Client<br/>(RepoDB)"] -->|BulkUpdate| Source["Entities /<br/>DataTable /<br/>DbDataReader"]
    Source --> Pseudo["Create Pseudo Table<br/>(Physical)"]
    Pseudo --> BulkCopy["MySqlBulkCopy<br/>(LOAD DATA LOCAL INFILE)"]
    BulkCopy -->|Write| PseudoTable[("Pseudo Table")]
    PseudoTable -->|"UPDATE ... INNER JOIN<br/>ON qualifiers<br/>(no anti-join insert)"| Table[("Target Table")]
    PseudoTable -->|Drop| Cleanup(["Pseudo Table Dropped"])

Use Case

Use this method to update rows at high speed. It leverages this package’s internal MySqlBulkCopy class (LOAD DATA LOCAL INFILE-based, see Operations (MySQL)).

For updating 1,000 or more rows, prefer this method over UpdateAll.

A pseudo (staging) table is created for the call. The library writes to it via its internal MySqlBulkCopy, then cascades the changes to the target table via a single UPDATE ... INNER JOIN statement — unlike BulkMerge, staged rows with no matching target row are left as-is, not inserted. See Operations (MySQL) for the underlying mechanics.

Special Arguments

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

qualifiers defines the fields used to match existing rows, corresponding to the join’s ON clause. Defaults to the primary column if not specified.

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

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 MySqlBulkImportPseudoTableType) controls the kind of staging table used internally.

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

There are no identity-related arguments — this operation never generates or reads back identity values.

Caveats

This operation creates a pseudo-temporary table for each call. The database user must have permission to create tables, or a MySqlException will be thrown. Because CREATE TABLE/DROP TABLE are DDL, each call implicitly commits any other pending work on the connection — see The Staging Table Lifecycle.

Usability

Given a list of Person models, the following example bulk-updates rows in the Person table.

using (var connection = new MySqlConnection(connectionString))
{
    var updatedRows = connection.BulkUpdate(people);
}

To specify a batch size:

using (var connection = new MySqlConnection(connectionString))
{
    var updatedRows = connection.BulkUpdate(people, batchSize: 100);
}

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

DataTable

using (var connection = new MySqlConnection(connectionString))
{
    var table = ConvertToDataTable(people);
    var updatedRows = connection.BulkUpdate("Person", table);
}

Dictionary/ExpandoObject

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

DataReader

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

To bulk-update via DataEntityDataReader:

using (var connection = new MySqlConnection(connectionString))
{
    var people = GetPeople(10000);
    using (var reader = new DataEntityDataReader<Person>(people))
    {
        var updatedRows = connection.BulkUpdate("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 MySqlConnection(connectionString))
{
    var people = GetPeople(10000);
    var updatedRows = connection.BulkUpdate<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 MySqlBulkInsertMapItem class.

var mappings = new List<MySqlBulkInsertMapItem>();

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

// Execute
using (var connection = new MySqlConnection(connectionString))
{
    var people = GetPeople(10000);
    var updatedRows = connection.BulkUpdate(people,
        mappings: mappings);
}

Targeting a Table

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

using (var connection = new MySqlConnection(connectionString))
{
    var people = GetPeople(10000);
    var updatedRows = connection.BulkUpdate("Person", people);
}

Async Method

An equivalent BulkUpdateAsync method is also available.

using (var connection = new MySqlConnection(connectionString))
{
    var updatedRows = await connection.BulkUpdateAsync(people);
}