Bulk Load and Minimal Logging Dean Savović Bulk Load and Minimal Logging

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Agenda Minimal Logging Defined Minimal Logging Cross Reference Enhancements Methods Delete Update

Minimal Logging Defined Only full page BU Locking Batchsize Enable/disable triggers and constraints Input sort order (clustered target)

Minimal Logging Prereqs Simple or Bulk-logged recovery model TABLOCK (not always) Target table not replicated ALLOW_PAGE_LOCKS „ON” Backup

Minimally Logged Operations Bulk import operations (BCP, BULK INSERT and INSERT..SELECT) SELECT INTO operations TRUNCATE Starting in Sql server 2008 , INSERT SELECT statement can also be handled with minimal logging. Partial updates to large value data types, using the .WRITE clause. CREATE INDEX, ALTER INDEX REBUILD DROP TABLE Partition Switch Merge

Bulk Methods Integration Services Data Destinations BCP BULK INSERT SQL Server Destination OLE DB Destination BCP BULK INSERT INSERT … SELECT SELECT … INTO …

Minimal Logging Heap IsEmpty TABLOCK Locks Logging Concurrent Yes BU-Tab Minimal No IX-Tab Full

Data – minimal index – full Minimal Logging Heap + Non-Clustered Index IsEmpty TABLOCK Locks Logging Concurrent Yes Sch-M Minimal No IX-Tab Full Data – minimal index – full

Minimal Logging Clustered Index IsEmpty TABLOCK Locks Logging Concurrent Yes Sch-M Minimal No IX-Tab X-Tab Full

Minimal Logging Clustered Index + Non-Clustered Index IsEmpty TABLOCK Locks Logging Concurrent Yes Sch-M Depends No IX-Tab

Minimal Logging Columnstore Index 102400 NO TABLOCK

Minimal Logging Memory Optimized Always Fully Logged

Bulk Load Enhancements Select * Into dbo.TargetTable from dbo.SourceTable (SQL Server 2005-) Insert into dbo.TargetTable with (TABLOCK) select * from dbo.SourceTable (SQL Server 2008+) Insert into CI Btree (SQL Server 2008+) Order by Enable TF-610 Bulk insert (SQL Server 2008+) Without TABLOCK

Insert Scenarios

Comparison bulk insert dbo.tTable from 'd:\temp\tHeap.csv’ with ( formatfile = ‘D:\temp\bcp.fmt’ , rows_per_batch = 10000000 )

Heap No Indexes

Heap and Indexes

Clustered

Clustered And Non-Clus Indexes

Memory Optimized

Columnstore (CCI)

Comparison

Deleting a Large Amount of Rows in a Partition or Table in Minimally Logging Mode

Create a Copy of Main Table

Bulk load the rows you want to keep into the temporary partition INSERT INTO Sales_Temp WITH (TABLOCK) SELECT * FROM Sales WHERE OrderDate >=‘20010101’ AND OrderDate <‘20020101’ AND<Keep Criteria>

Switch out and truncate the old data

Rebuild indexes and use SWITCH ALTER TABLE Sales_Temp TO Sales SWITCH PARTITION 1

Drop the temporary table

Updating a Large Part of the Data in a Partition or a Table in Minimally Logged Mode

Write a change log to a temporary table

If the table is partitioned, switch out the partition you want to change ALTER TABLE Sales SWITCH PARTITION 1 TO Sales_Old

Merge the change log with the original table and bulk load to temporary table SELECT o.PrimaryKey ,COALESCE(d.Col1, o.Col1) , COALESCE(d.Col2, o.Col3) ... etc... FROM Sales_Old o LEFT JOIN Sales_Delta d

Delete the change log and original data DROP TABLE Sales_Delta DROP TABLE Sales_Old

SWITCH in the result of the merge ALTER TABLE Sales_New SWITCH TO Sales PARTITION 1 DROP TABLE Sales_New

EXEC [sys]. [sp_tableoption] @TableNamePattern = N'dbo EXEC [sys].[sp_tableoption] @TableNamePattern = N'dbo.BulkLoadTest’, @OptionName = 'table lock on bulk load’, @OptionValue = 'ON'

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