Tips for using SQL Server 2008 bulk copy
Use native mode bulk copy whenever possible.
Because native mode bulk copies are generally faster than character mode, you should use native
mode bulk copy whenever possible.
Consider using minimally logged bulk copy whenever possible.
The minimally logged bulk copy is much faster than other bulk copy methods, but to use it you
must provide all the following conditions:
1. The database option 'select into/bulkcopy' is set to true (by the way, using this option
causes the recovery model to be reset to BULK_LOGGED).
2. The target table is not being replicated.
3. The TABLOCK hint is specified.
4. The target table has no indexes, or if the table has indexes, it is empty when the bulk copy starts.
Try to use BULK INSERT command instead of bcp utility or Integration Services
to load data into SQL Server 2008.
The BULK INSERT command is much faster than bcp or the data pump to perform text file import
operations, however, the BULK INSERT statement cannot bulk copy data from SQL Server 2008 to
a data file.
Consider using XML format files to bulk import data into tables or non-partitioned
views and to bulk export data.
SQL Server 2008 supports the XML format file. XML format files are more flexible and powerful
than non-XML format files and easy to understand and create. So, consider using XML format
files instead of non-XML format files.
Specify the number of the first and the last row to bulk copy, if you need to bulk copy
not all the rows from the specified data file.
This can results in good performance benefits, because the total amount of data copied will be less.
Consider increasing the packet_size option of the bcp utility.
The packet_size option specifies the number of bytes per network packet sent to and from the
server. The packet_size can be from 4096 to 65535 bytes with the default of 4096. Increased
packet size can enhance performance of bulk copy operations. Try to set the packet_size option
to 8192 bytes and continue monitoring.
If you create a new table and bulk copy data into it, try to bulk load data first and only after
that create any indexes.
This can significantly improve performance of the bulk copy operation, because data will be loaded
into SQL Server 2008 table without any index pages creation during the bulk copy.
Specify the number of rows per batch of data copied, if the transaction log was filled before
the bulk copy is complete.
Because each batch is copied to the server as one transaction, SQL Server 2008 commits or rolls
back the transaction for every batch. When you bulk copy large data files, the transaction log
can be filled before the bulk copy is complete. In this case, enlarge the transaction log, allow
it to grow automatically or specify the number of rows per batch of data copied.
Use the ORDER hint in the bcp utility and BULK INSERT command, if the clustered index
exists on the table and the data file is sorted according to the clustered index.
This can significantly improve performance of the bulk copy operation, because SQL Server 2008
will load data in the clustered index order without any reorders operations.
If you load data into an empty table with the existing nonclustered indexes, try to drop the
nonclustered indexes, bulk load data and only after that recreate the nonclustered indexes.
This can significantly improve performance of the bulk copy operation, because data will be loaded
into SQL Server 2008 table without any index pages creation during the bulk copy.
Specify the TABLOCK hint, if you bulk copy data into an empty table from a single client.
This can improve performance of the bulk copy operation, because this causes a table-level lock to
be taken for the duration of the bulk copy operation.
If you load data into a nonempty table with the existing clustered and/or nonclustered indexes,
and the amount of data added is large, it can be faster to drop all indexes on the table, perform
the bulk copy operation, and then recreate the indexes after the data is loaded.
Check the time needed to load data with dropping/recreating indexes and without dropping/recreating
indexes on your test server before run bulk copy operation on the production server.
Try to avoid using CHECK_CONSTRAINTS and FIRE_TRIGGERS hints in the bcp utility
and BULK INSERT command.
Using these hints can significantly degrade performance of the bulk copy operation, because for
each row loaded the constraints and insert triggers defined on the destination table will be
executed.
If your SQL Server box has multiple CPUs, try to divide loaded data into two or more sources
and run multiple instances of BCP on separate clients to load data in parallel.
Because SQL Server 2008 allows data to be bulk copied into a single table from multiple clients
in parallel using the bcp utility or BULK INSERT command, try to use parallel data loads whenever
possible. To bulk copy data into SQL Server 2008 in parallel, you must provide all the following
conditions:
1. The database option 'select into/bulkcopy' is set to true.
2. The TABLOCK hint is specified.
3. The target table does not have any indexes.
