How Can I Optimize Batch Deletes in SQL Server 2008?

Batch Delete Optimization in SQL Server 2008

In SQL Server, bulk operations like bulk copy (bcp) provide efficient data manipulation techniques. However, the question arises about the availability of a similar bulk delete feature.

Query:

Is there any solution for bulk delete in SQL Server?

TRUNCATE cannot be used forselective deletion, prompting the need for WHERE clauses. Is there an alternative to bcp for deleting data in bulk?

Answer:

No, SQL Server does not offer a specialized bulk delete operation. However, there are several approaches to optimize batch deletions:

Batch Deletion using @@ROWCOUNT:

SELECT 'Starting' --sets @@ROWCOUNT
WHILE @@ROWCOUNT <> 0
    DELETE TOP (xxx) MyTable WHERE ...

This query executes DELETE statements in batches of 'xxx' rows until no rows remain.

Truncate and Insert Method:

SELECT col1, col2, ... INTO #Holdingtable
           FROM MyTable WHERE ..opposite condition..
TRUNCATE TABLE MyTable
INSERT MyTable (col1, col2, ...)
           SELECT col1, col2, ... FROM #Holdingtable

This technique is effective when a high percentage of rows need to be deleted. It creates a temporary table with the rows to be retained, truncates the original table, and inserts the retained rows back into the table.

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