BulkUpdate

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

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

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/>(Auto/Memory/Physical) +<br/>Index on qualifiers"]
    Pseudo --> Stream["VerticaCopyStream<br/>(COPY ... FROM STDIN)"]
    Stream -->|Write| PseudoTable[("Pseudo Table")]
    PseudoTable -->|"UPDATE Target SET ...<br/>FROM Pseudo WHERE qualifiers match<br/>(no INSERT step)"| Table[("Target Table")]
    PseudoTable -->|Drop| Cleanup(["Pseudo Table Dropped"])

Use Case

Use this method to update rows at high speed. It leverages VerticaCopyStream, Vertica.Data’s native COPY ... FROM STDIN streaming API.

For updating 1,000 or more rows, prefer this method over UpdateAll — Vertica’s IsMultiStatementExecutable setting is false, so UpdateAll issues one round trip per row.

A pseudo (staging) table, indexed on the qualifier columns, is created for every call. The library streams into it via a COPY load internally, then cascades the changes to the target table via an UPDATE ... FROM statement with no INSERT step — staged rows with no matching target row are left as-is, not inserted. This reuses the same SQL-generation path as the update half of BulkMerge, so Vertica’s identity-column restrictions apply here too. See Operations (Vertica) 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. Defaults to the primary or identity column if not specified.

mappings (via VerticaBulkInsertMapItem) 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.

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

If every staged field is also a qualifier (nothing left to actually update), the generated UPDATE is skipped and the operation returns 0.

Caveats

This operation creates a pseudo (staging) table for every call — a per-call, uniquely-named TABLE or GLOBAL TEMPORARY TABLE, per pseudoTableType. The database user must have permission to create tables, or a VerticaException will be thrown.

Usability

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

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

To specify a batch size:

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

Dictionary/ExpandoObject

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

DataReader

using (var sourceConnection = new VerticaConnection(sourceConnectionString))
{
    using (var reader = sourceConnection.ExecuteReader("SELECT * FROM \"Person\" WHERE \"Age\" > 18"))
    {
        using (var destinationConnection = new VerticaConnection(destinationConnectionString))
        {
            var rows = destinationConnection.BulkUpdate("\"Person\"", reader);
        }
    }
}

To bulk-update via DataEntityDataReader:

using (var connection = new VerticaConnection(connectionString))
{
    var people = GetPeople(10000);
    using (var reader = new DataEntityDataReader<Person>(people))
    {
        var updatedRows = connection.BulkUpdate("\"Person\"", reader);
    }
}

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 VerticaConnection(connectionString))
{
    var people = GetPeople(10000);
    var updatedRows = connection.BulkUpdate<Person>(people,
        qualifiers: e => new { e.Name });
}

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

Column Mappings

Add column mappings using the VerticaBulkInsertMapItem class.

var mappings = new List<VerticaBulkInsertMapItem>();

// Add the mappings
mappings.Add(new VerticaBulkInsertMapItem("SourceId", "DestinationId"));
mappings.Add(new VerticaBulkInsertMapItem("SourceName", "DestinationName"));
mappings.Add(new VerticaBulkInsertMapItem("SourceAge", "DestinationAge"));
mappings.Add(new VerticaBulkInsertMapItem("SourceCreatedDateUtc", "DestinationCreatedDateUtc"));

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

Async Method

An equivalent BulkUpdateAsync method is also available.

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