Operations · 4 min read

BulkUpdate

This method updates existing rows in the database in bulk, matched by the defined qualifiers. It is supported for Aurora MySQL.

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/>+ index on qualifiers"]
    Pseudo --> Copy["AuroraDbBulkCopy<br/>(LOAD DATA LOCAL)"]
    Copy -->|Write| PseudoTable[("Pseudo Table")]
    PseudoTable -->|"UPDATE ... INNER JOIN Pseudo<br/>(no unmatched-row insert)"| Table[("Target Table")]
    PseudoTable -->|Drop| Cleanup(["Pseudo Table Dropped"])

Use Case

Use this method to update rows at high speed. It leverages AuroraDbBulkCopy, a LOAD DATA LOCAL INFILE-based bulk writer from RepoDb.Connector.AuroraDb.MySqlConnector.

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

A pseudo (staging) table — with an index on the qualifier columns — is always created first. The library writes to it via AuroraDbBulkCopy internally, then cascades the changes to the target table via MySQL’s multi-table UPDATE ... INNER JOIN syntax — staged rows with no matching target row are left as-is, not inserted. See Operations (AuroraDB MySqlConnector) 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 ON clause. Defaults to the primary column if not specified.

mappings (via AuroraDbBulkInsertMapItem) defines explicit column mappings between the source properties and the destination columns, with an optional AuroraDbType override per mapping. 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.

pseudoTableType (via AuroraDbBulkImportPseudoTableType) is accepted but currently has no effect — every staged call resolves to Physical regardless of the value passed.

Caveats

This operation creates a pseudo table internally. The database user must have permission to create tables, or the underlying exception from Aurora MySQL will surface from the create-table statement.

Usability

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

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

To specify a batch size:

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

Dictionary/ExpandoObject

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

DataReader

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

To bulk-update via DataEntityDataReader:

using (var connection = new AuroraDbConnection(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 AuroraDbConnection(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.

Targeting a Table

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

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

Async Method

An equivalent BulkUpdateAsync method is also available.

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