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SAP HANA Performance Guide for Developers Company PUBLIC SAP HANA Platform 2.0 SPS 04 Document Version: 1.1 – 2019-10-31 SAP HANA Performance Guide for Developers company. All rights reserved. All rights company. affiliate THE BEST RUN 2019 SAP SE or an SAP SE or an SAP SAP 2019 © Content 1 SAP HANA Performance Guide for Developers......................................6 2 Disclaimer................................................................. 7 3 Schema Design..............................................................8 3.1 Choosing the Appropriate Table Type...............................................8 3.2 Creating Indexes..............................................................9 Primary Key Indexes........................................................10 Secondary Indexes.........................................................11 Multi-Column Index Types....................................................12 Costs Associated with Indexes.................................................13 When to Create Indexes..................................................... 14 3.3 Partitioning Tables............................................................15 3.4 Query Processing Examples.....................................................16 3.5 Delta Tables and Main Tables....................................................18 3.6 Denormalization.............................................................19 3.7 Additional Recommendations....................................................21 4 Query Execution Engine Overview...............................................22 4.1 New Query Processing Engines.................................................. 24 4.2 ESX Example...............................................................25 4.3 Disabling the ESX and HEX Engines...............................................26 5 SQL Query Performance......................................................28 5.1 SQL Process............................................................... 28 SQL Processing Components.................................................29 5.2 SAP HANA SQL Optimizer......................................................31 Rule-Based Optimization....................................................32 Cost-Based Optimization....................................................36 Decisions Not Subject to the SQL Optimizer.......................................48 Query Optimization Steps: Overview ............................................49 5.3 Analysis Tools.............................................................. 50 SQL Plan Cache...........................................................50 Explain Plan............................................................. 54 Plan Visualizer............................................................60 SQL Trace...............................................................68 SQL Optimization Step Debug Trace............................................70 SQL Optimization Time Debug Trace............................................77 SAP HANA Performance Guide for Developers 2 PUBLIC Content Views and Tables..........................................................82 5.4 Case Studies...............................................................83 Simple Examples..........................................................83 Performance Fluctuation of an SDA Query with UNION ALL............................95 Composite OOM due to Memory Consumed over 40 Gigabytes by a Single Query........... 103 Performance Degradation of a View after an Upgrade Caused by Calculation View Unfolding ..................................................................... 109 5.5 SQL Tuning Guidelines........................................................116 General Guidelines........................................................116 Avoiding Implicit Type Casting in Queries.........................................117 Avoiding Inefficient Predicates in Joins ..........................................118 Avoiding Inefficient Predicates in EXISTS/IN ......................................123 Avoiding Set Operations ....................................................124 Improving Performance for Multiple Column Joins..................................125 Using Hints to Alter a Query Plan..............................................126 Additional Recommendations................................................ 131 6 SQLScript Performance Guidelines.............................................134 6.1 Calling Procedures.......................................................... 134 Passing Named Parameters................................................. 135 Changing the Container Signature.............................................136 Accessing and Assigning Variable Values........................................ 136 Assigning Scalar Variables...................................................138 6.2 Working with Tables and Table Variables........................................... 138 Checking Whether a Table or Table Variable is Empty................................138 Determining the Size of a Table Variable or Table...................................140 Accessing a Specific Table Cell................................................141 Searching for Key-Value Pairs in Table Variables....................................142 Avoiding the No Data Found Exception..........................................144 Inserting Table Variables into Other Table Variables .................................144 Inserting Records into Table Variables.......................................... 145 Updating Individual Records in Table Variables.................................... 147 Deleting Individual Records in Table Variables.....................................148 6.3 Blocking Statement Inlining with the NO_INLINE Hint..................................150 6.4 Skipping Expensive Queries.................................................... 151 6.5 Using Dynamic SQL with SQLScript.............................................. 152 Using Input and Output Parameters............................................153 6.6 Simplifying Application Coding with Parallel Operators.................................154 Map Merge Operator...................................................... 154 Map Reduce Operator......................................................156 6.7 Replacing Row-Based Calculations with Set-Based Calculations.......................... 162 6.8 Avoiding Busy Waiting........................................................165 SAP HANA Performance Guide for Developers Content PUBLIC 3 6.9 Best Practices for Using SQLScript...............................................166 Reduce the Complexity of SQL Statements ...................................... 167 Identify Common Sub-Expressions............................................ 167 Multi-Level Aggregation.....................................................167 Reduce Dependencies..................................................... 168 Avoid Using Cursors.......................................................168 Avoid Using Dynamic SQL...................................................170 7 Optimization Features in Calculation Views.......................................171 7.1 Calculation View Instantiation...................................................172 7.2 Setting Join Cardinality....................................................... 176 Join Cardinality.......................................................... 177 Examples...............................................................178 7.3 Optimizing Join Columns......................................................198 Optimize Join Columns Option............................................... 198 Prerequisites for Pruning Join Columns......................................... 199 Example...............................................................201 7.4 Using Dynamic Joins.........................................................210 Dynamic Join Example..................................................... 211 Workaround for Queries Without Requested Join Attributes...........................217 7.5 Union Node Pruning.........................................................220 Pruning Configuration Table.................................................222 Example with a Pruning Configuration Table......................................222 Example with a Constant Mapping.............................................225 Example Tables..........................................................227 7.6 Influencing the Degree of Parallelization...........................................228 Example: Create the Table.................................................. 229 Example: Create the Model..................................................230 Example: Apply Parallelization Based on Table Partitions.............................233 Example: Apply Parallelization Based on Distinct Entries in a Column....................236 Verifying the Degree of Parallelization.......................................... 238 Constraints.............................................................241 7.7 Using "Execute in SQL Engine" in Calculation Views...................................242 Impact of the "Execute in SQL Engine" Option ....................................243 Checking Whether a Query is Unfolded......................................... 246 Influencing Whether a Query is Unfolded........................................246 7.8 Push Down Filters in Rank Nodes................................................248 7.9 Condensed Performance Suggestions...........................................
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