使用Dapper删除2100行(按ID)的正确方法 [英] Correct method of deleting over 2100 rows (by ID) with Dapper
问题描述
我正在尝试使用 Dapper 为我的数据访问提供支持服务器应用.
I am trying to use Dapper support my data access for my server app.
我的服务器应用程序还有另一个应用程序,该应用程序以每分钟400的速度将记录滴入我的数据库中.
My server app has another application that drops records into my database at a rate of 400 per minute.
我的应用程序批量提取它们,对其进行处理,然后将其从数据库中删除.
My app pulls them out in batches, processes them, and then deletes them from the database.
由于在我处理过程中数据继续流入数据库,所以我没有一个很好的方式来表达delete from myTable where allProcessed = true
.
Since data continues to flow into the database while I am processing, I don't have a good way to say delete from myTable where allProcessed = true
.
但是,我确实知道要删除的行的PK值.所以我想做一个delete from myTable where Id in @listToDelete
However, I do know the PK value of the rows to delete. So I want to do a delete from myTable where Id in @listToDelete
问题是,如果我的服务器宕机了6分钟,那么我有2100多行要删除.
Problem is that if my server goes down for even 6 mintues, then I have over 2100 rows to delete.
由于Dapper使用了我的@listToDelete并将每个参数都变成了一个参数,因此我的delete调用失败. (导致我的数据清除工作进一步落后.)
Since Dapper takes my @listToDelete and turns each one into a parameter, my call to delete fails. (Causing my data purging to get even further behind.)
在Dapper中处理此问题的最佳方法是什么?
What is the best way to deal with this in Dapper?
注意: 我看过表值参数,但从我的看到,它们不是非常性能.我的体系结构的这一部分是系统的瓶颈,我需要非常快非常.
NOTES: I have looked at Tabled Valued Parameters but from what I can see, they are not very performant. This piece of my architecture is the bottle neck of my system and I need to be very very fast.
推荐答案
一种选择是在服务器上创建一个临时表,然后使用批量加载功能一次将所有ID上载到该表中.然后使用join,EXISTS或IN子句仅删除您上传到临时表中的记录.
One option is to create a temp table on the server and then use the bulk load facility to upload all the IDs into that table at once. Then use a join, EXISTS or IN clause to delete only the records that you uploaded into your temp table.
批量加载是SQL Server中经过优化的路径,并且应该非常快.
Bulk loads are a well-optimized path in SQL Server and it should be very fast.
例如:
- 执行语句
CREATE TABLE #RowsToDelete(ID INT PRIMARY KEY)
- 使用批量加载将密钥插入
#RowsToDelete
- 执行
DELETE FROM myTable where Id IN (SELECT ID FROM #RowsToDelete)
- 执行
DROP TABLE #RowsToDelte
(如果您关闭会话,该表也会被自动删除)
- Execute the statement
CREATE TABLE #RowsToDelete(ID INT PRIMARY KEY)
- Use a bulk load to insert keys into
#RowsToDelete
- Execute
DELETE FROM myTable where Id IN (SELECT ID FROM #RowsToDelete)
- Execute
DROP TABLE #RowsToDelte
(the table will also be automatically dropped if you close the session)
(假设Dapper)代码示例:
(Assuming Dapper) code example:
conn.Open();
var columnName = "ID";
conn.Execute(string.Format("CREATE TABLE #{0}s({0} INT PRIMARY KEY)", columnName));
using (var bulkCopy = new SqlBulkCopy(conn))
{
bulkCopy.BatchSize = ids.Count;
bulkCopy.DestinationTableName = string.Format("#{0}s", columnName);
var table = new DataTable();
table.Columns.Add(columnName, typeof (int));
bulkCopy.ColumnMappings.Add(columnName, columnName);
foreach (var id in ids)
{
table.Rows.Add(id);
}
bulkCopy.WriteToServer(table);
}
//or do other things with your table instead of deleting here
conn.Execute(string.Format(@"DELETE FROM myTable where Id IN
(SELECT {0} FROM #{0}s", columnName));
conn.Execute(string.Format("DROP TABLE #{0}s", columnName));
这篇关于使用Dapper删除2100行(按ID)的正确方法的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!