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[英]SqlBulkCopy.WriteToServerAsync() does not write to target SQL Server table, bulkCopy.WriteToServer() does
[英]SqlBulkCopy.WriteToServerAsync does not respect the `await` keyword. Why?
SqlBulkCopy.WriteToServerAsync 不遵守await
關鍵字。 為什么?
這是我的代碼:
public async Task UpdateDBWithXML(Action<Func<DataTable, Task>> readXmlInBatches, string hashKey, string hash)
{
using (var transaction = this.Context.Database.BeginTransaction(IsolationLevel.ReadUncommitted))
using (var bulk = new SqlBulkCopy((SqlConnection)this.Connection, SqlBulkCopyOptions.Default, (SqlTransaction)transaction.UnderlyingTransaction))
{
//this.Context.Database.ExecuteSqlCommand("DELETE FROM [dbo].[LegalContractorTemps]");
bulk.DestinationTableName = "LegalContractorTemps";
readXmlInBatches(async (DataTable table) =>
{
if (bulk.ColumnMappings.Count == 0)
{
foreach (DataColumn column in table.Columns)
{
bulk.ColumnMappings.Add(new SqlBulkCopyColumnMapping(column.ColumnName, column.ColumnName));
}
}
await bulk.WriteToServerAsync(table);
});
await this.Context.Database.ExecuteSqlCommandAsync(
"EXECUTE dbo.LegalContractorsDataSynchronize @hashKey, @hash",
new SqlParameter("@hashKey", hashKey),
new SqlParameter("@hash", hash)
);
transaction.Commit();
}
}
在readXmlInBatches
參數中,我將以下函數作為參數傳遞:
public void ReadXMLInBatches(Func<DataTable, Task> processBatch)
{
int batchSize = 10000;
var table = new DataTable();
foreach (var col in columnNames)
{
table.Columns.Add(col);
}
using (var reader = new StreamReader(pathToXml, Encoding.GetEncoding(encoding)))
using (var xmlReader = XmlReader.Create(reader))
{
string lastElement = null;
DataRow lastRow = null;
while (xmlReader.Read())
{
switch (xmlReader.NodeType)
{
case XmlNodeType.Element:
if (xmlReader.Name == "RECORD")
{
if (table.Rows.Count >= batchSize)
{
processBatch(table);
table.Rows.Clear();
}
lastRow = table.Rows.Add();
}
lastElement = xmlReader.Name;
break;
case XmlNodeType.Text:
ReadMember(lastRow, lastElement, xmlReader.Value);
break;
}
}
if (table.Rows.Count > 0)
{
processBatch(table);
table.Rows.Clear();
}
}
}
我在 XML 中有大約 170 萬條記錄。 在我的程序讀取了幾批后,我收到錯誤消息:
System.Data.RowNotInTableException : '該行已從表中刪除並且沒有任何數據。 BeginEdit() 將允許在此行中創建新數據。
我研究了SqlBulkCopy
的源代碼。 並找到了拋出錯誤的方法:
public Task WriteToServerAsync(DataTable table, DataRowState rowState, CancellationToken cancellationToken) {
Task resultTask = null;
SqlConnection.ExecutePermission.Demand();
if (table == null) {
throw new ArgumentNullException("table");
}
if (_isBulkCopyingInProgress){
throw SQL.BulkLoadPendingOperation();
}
SqlStatistics statistics = Statistics;
try {
statistics = SqlStatistics.StartTimer(Statistics);
_rowStateToSkip = ((rowState == 0) || (rowState == DataRowState.Deleted)) ? DataRowState.Deleted : ~rowState | DataRowState.Deleted;
_rowSource = table;
_SqlDataReaderRowSource = null;
_dataTableSource = table;
_rowSourceType = ValueSourceType.DataTable;
_rowEnumerator = table.Rows.GetEnumerator();
_isAsyncBulkCopy = true;
resultTask = WriteRowSourceToServerAsync(table.Columns.Count, cancellationToken); //It returns Task since _isAsyncBulkCopy = true;
}
finally {
SqlStatistics.StopTimer(statistics);
}
return resultTask;
}
我注意到字段_isBulkCopyingInProgress
並決定在調試時檢查它。 我發現當拋出錯誤時,該字段為true
。 這怎么可能? 我希望批量插入首先發生(在執行繼續之前, WriteToServerAsync
將被第二次調用),因為我在這里添加了await
: await bulk.WriteToServerAsync(table);
.
我可能會錯過什么?
您正在向ReadXMLInBatches
傳遞一個異步函數,但它的執行並未在您的方法內等待,因此ReadXMLInBatches
可能會在對WriteToServerAsync
所有調用完成之前終止。
嘗試以下更改:
public async Task ReadXMLInBatchesAsync(Func<DataTable, Task> processBatch)
{
//...
await processBatch(table);
//...
}
public async Task UpdateDBWithXML(Func<Func<DataTable, Task>, Task> readXmlInBatches, string hashKey, string hash)
{
//...
await readXmlInBatches(async (DataTable table) =>
//...
}
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