Problem

You need to issue queries that return more than 2,000 records, but the query() call can only return up to 2,000 at a time.

Solution

Use queryMore() to retrieve any additional records in batches of up to 2,000 at a time. The queryMore() call takes a single queryLocator parameter that specifies the index of the last result record that was returned. This queryLocator is created and returned by the previous query() or queryMore() call.

When the query() or queryMore() calls return a result with the isDone flag set to true, there are no more records to process.

For example, the following Java code implements the query()*/queryMore()* pattern when querying leads:

QueryResult queryResult = this.stub.query("Select name From lead");
do {
    for(sObject lead : queryResult.getRecords()) {
        System.out.println(lead.get_any()[0].getValue());
    }
    if(queryResult.isDone()) 
        break;
    queryResult = this.stub.queryMore(queryResult.
                                         getQueryLocator());
} while(true);

This code implements query()*/queryMore()* in VB.NET:

Dim lead As sforce.sObject
Dim i As Integer
Dim qr As sforce.QueryResult = binding.query("select name from lead")
Do
     For i = 0 To qr.records.Length
        lead = qr.records(i)
        Console.WriteLine(lead.Any(0).InnerText)
    Next
        If qr.done Then Exit Do
        qr = binding.queryMore(qr.queryLocator)
Loop

The query()*/queryMore()* batch size defaults to 500 records, but can be as small as 200 or as large as 2000. To change the batch size, use the QueryOptions header.