![]() For more information on locking, see Locking and row versioning. However, unlike loading data into a rowstore, TABLOCK leads to an X lock on the table rather than a BU (Bulk Update) lock and therefore parallel data load cannot be done. Minimal logging: You can get further reduction in logging if you follow the prerequisites for minimal logging. Since there is no TABLOCK required, you can load the data in parallel. Best practice is to use batchsize >= 102400. This includes any batch sizes that are less than 102,400 rows. Any data that goes to a delta rowgroup is fully logged. For example, if data was compressed 10x, the corresponding transaction log will be roughly 10x smaller without requiring TABLOCK or Bulk-logged/Simple recovery model. Reduced Logging: The data that is directly loaded into compressed row groups leads to significant reduction in the size of the log. Unlike rowstore bulk loads into SQL Server, you don't need to specify TABLOCK because each bulk import thread will load data exclusively into separate rowgroups (compressed or delta rowgroups) with exclusive lock on it. Parallel loads: You can have multiple concurrent bulk loads (bcp or bulk insert) that are each loading a separate data file. The data is never inserted directly into the columnstore index.īulk loading has these built-in performance optimizations: On a rowstore table with a nonclustered columnstore index data, SQL Server always inserts data into the base table. If the batch size It is recommended that you choose a batch size >=102400 for efficient bulk import because you can avoid moving data rows to delta rowgroups before the rows are eventually moved to compressed rowgroups by a background thread, Tuple mover (TM). If the batch size is >= 102400, the rows are directly into the compressed rowgroups.Data is inserted into rowgroups in the order it is received. To perform a bulk load, you can use bcp Utility, Integration Services, or select rows from a staging table. Only rows at the end of a load that don't meet the minimum of 102,400 rows per rowgroup go to the deltastore. Bulk loading fills rowgroups to maximum capacity and compresses them directly into the columnstore. It is the most performant way to move data into a columnstore index because it operates on batches of rows. What is bulk loading?īulk loading refers to the way large numbers of rows are added to a data store. New to columnstore indexes? See Columnstore indexes - overview and Columnstore Index Architecture. Loading data into a columnstore index is an essential part of any data warehousing process because it moves data into the index in preparation for analytics. ![]() Options and recommendations for loading data into a columnstore index by using the standard SQL bulk loading and trickle insert methods. ![]() Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics Analytics Platform System (PDW)
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