private static CloudTableClient GetTableClient(RenameColumnOptions options)
{
if (options.UseDevStorage)
{
return(CloudStorageAccount.DevelopmentStorageAccount.CreateCloudTableClient());
}
else
{
StorageCredentials credentials;
if (!string.IsNullOrEmpty(options.Key))
{
string host = options.TableUri.Host;
string account = host.Substring(0, host.IndexOf('.'));
credentials = new StorageCredentials(account, options.Key);
}
else
{
credentials = new StorageCredentials(options.SasToken);
}
CloudTableClient client = new CloudTableClient(new Uri(options.TableUri.GetLeftPart(UriPartial.Authority)), credentials);
return(client);
}
}
private static async Task <int> RenameTableColumnAsync(RenameColumnOptions options)
{
// get table name
string tableName = options.TableUri.AbsolutePath.Substring(1);
Console.WriteLine($"Renaming {options.From} to {options.To} on table {options.TableUri}.");
// build credentials
CloudTableClient client = GetTableClient(options);
var table = client.GetTableReference(tableName);
if (!await table.ExistsAsync())
{
Console.WriteLine($"Table {tableName} does not exist.");
return(1);
}
string updateMessage = "Updating entities, this could take a while.";
Console.Write(updateMessage);
long updateCount = 0;
TableContinuationToken token = null;
do
{
var queryResult = await table.ExecuteQuerySegmentedAsync(new TableQuery <DynamicTableEntity>(), token);
token = queryResult.ContinuationToken;
// move value to new attribute name
var entities = queryResult.Results;
var entitiesToUpdate = new List <DynamicTableEntity>();
foreach (var entity in entities)
{
if (entity.Properties.ContainsKey(options.From))
{
// TODO: check if options.To already exists
entity[options.To] = entity[options.From];
//entity[options.From] = null;
entity.Properties.Remove(options.From);
entitiesToUpdate.Add(entity);
}
}
// apply updates
// group by partition
var partitionGroups = entitiesToUpdate.ToLookup(e => e.PartitionKey, e => e);
foreach (var partitionGroup in partitionGroups)
{
var batch = new TableBatchOperation();
foreach (var entity in partitionGroup)
{
batch.Add(TableOperation.Replace(entity));
// TODO: check batch size
// limit: "total payload may be no more than 4 MB in size" https://docs.microsoft.com/en-us/rest/api/storageservices/performing-entity-group-transactions
// estimate: https://docs.microsoft.com/en-us/archive/blogs/avkashchauhan/how-the-size-of-an-entity-is-caclulated-in-windows-azure-table-storage
if (batch.Count == 100)
{
bool success = await ExecuteBatchAsync(table, batch);
updateCount += batch.Count;
Console.Write($"\r{updateMessage} {updateCount} rows updated.");
batch.Clear();
}
}
if (batch.Count > 0)
{
bool success = await ExecuteBatchAsync(table, batch);
updateCount += batch.Count;
Console.Write($"\r{updateMessage} {updateCount} rows updated.");
}
}
} while (token != null);
Console.WriteLine("\n\nDone!");
return(0);
}