Table Statistics and its Effect on Query Plans
2019-12-17
Beginner
20 min.
Create table statistics. Analyze impact of statistics on query plans.
You will learn
- Creating table statistics.
- Analyzing the effect of table statistics on query plans.
Prerequisites
- Tutorials: Compare Prepared and Executed Plan
SAP HANA and Dynamic Tiering relies on statistics in order to help the optimizer choose the most effective access plan. Creating statistics is particularly important for queries involving Dynamic Tiering as they help SAP HANA determine when it is appropriate to use optimizations like joinRelocation
or SemiJoin
rules. These query operators help SAP HANA and Dynamic Tiering minimize the volume of data (# of rows & column values) transferred between the core SAP HANA and Dynamic Tiering nodes.
Step 1: Create Prepared and Executed Query Plans
Step 2: Create Statistics and Opening Prepared and Executed Query Plans After Running Statistics
Step 3: Analyze the Impact of Statistics on Prepared Plans
Step 4: Analyze the Impact of Statistics on Executed Plans
Navigate tutorial steps