SQL Server Index and Partition Strategy
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This document discusses index and partitioning strategies in SQL Server. It defines what indexes are, their benefits and overhead. It provides recommendations for designing clustered and non-clustered indexes, including keeping keys narrow and avoiding wide data types. Partitioning tables can improve performance of CRUD operations by allowing indexes to be managed separately on each partition. The document demonstrates creating a partitioned table and indexes.
SQL Server Index and Partition Strategy
- 1. Index and Partition Strategy By: Hamid J. Fard (Data Platform Specialist)
- 2. Session Outlines: What an Index is. The benefits and overhead of an Index. General recommendation for index design. Recommendation for Clustered and non-Clustered Index. Index on Partitioned Table
- 3. What is an Index? An object in SQL Server Database. Affects I/O Physical and Logical Operations. Affects to Performance of Retrieving Data. There are Two Types of Index. It might Change the Table Structure. Contains Several Levels.
- 4. The Benefit of Indexes Clustered Index Improves Modification Performance Clustered Index Changes the Table Structure Clustered Index Sort the Data Physically Non-Clustered Index Improves Query Performance Non-Clustered Index Points at RID or Clustered Index Non-Clustered Index can be Stored on Different I/O Path to Improve the I/O Performance
- 5. The Benefit of Indexes (Cont.) Consider single column table with 27 rows. Initial Layout of 27 Rows Ordered Layout of 27 Rows B-Tree Layout of 27 Rows
- 6. Index Overhead Table with Index needs more Storage and Memory Data Manipulation Queries (CRUD) Take Longer More Processing Time Required to Maintain the Indexes of Constantly Changing Tables Clustered Index has Greater Overhead SQL Server supplies some DMVs for Monitoring Index Performance and Detail Information sys.dm_db_index_operational_stats (Low-Level Information) sys.dm_db_index_usage_stats (Returns Statistics)
- 7. Index Design Recommendation Examine the Where and Join criteria clause Use Narrow Indexes Examine Column Uniqueness Examine the Column Data Type Consider Column Order Consider the Type of Index (Clustered vs. NonClustered)
- 8. Use Narrow Index Avoid Wide Data Type such as CHAR, VARCHAR, NCHAR, NVARCHAR It can Accumulate more Rows in 8KB Index Page. Reduces Storage space for Database Reduces the I/O Operations.
- 9. Clustered Index Recommendations Create Clustered Index First. Keep the Index Key Narrow. Rebuild the Clustered Index in Single Step. Create Clustered Index with Preorder Sort. Do not Create Clustered Index on Frequently Updatable Column. Do not Use Wide Key. Prevent Too Many Concurrent Inserts in Sequential Order.
- 10. Non-Clustered Index Recommendation Can be Used with Wide Key. It Can be on Frequently Updatable Columns. Can be Filtered. Can be Used in Join or Where Criteria Clause. Can be on Low Selectivity Column.
- 11. Covering Indexes It can Improve the Query Performance. It Stores the Covering Columns Next to the RID. It does not Required to Read the Base Table. Reduces I/O Operations. Reduces Execution Time.
- 12. Index Compression Introduced in SQL Server 2008. Available only in Enterprise and Developer Edition. This can lead to Serious Performance Improvement. There will be an Overhead of CPU and Memory. Non-Leaf Pages in an Index Receive no Compression under the Page Type.
- 13. Index on Partitioned Table Different index will be created on every partition. Each index can be rebuilt or reorganized separately. It boost up the CRUD operations performance. SQL Server can manage every index separately on every partition.
- 14. Demo Create Partition Table Retrieve Specific Partition’s Record. Create Index on every Partition. Rebuild the Index on Specific Partition.
- 15. Questions and Answers ? (15 Minutes)