Working with Secondary Indexes | CREATE INDEX | Teradata Vantage - Collecting Statistics on a Secondary Index - Analytics Database - Teradata Vantage

SQL Data Definition Language Detailed Topics

Deployment
VantageCloud
VantageCore
Edition
Enterprise
IntelliFlex
VMware
Product
Analytics Database
Teradata Vantage
Release Number
17.20
Published
June 2022
Language
English (United States)
Last Update
2023-07-11
dita:mapPath
vuk1628111288877.ditamap
dita:ditavalPath
qkf1628213546010.ditaval
dita:id
B035-1184
lifecycle
latest
Product Category
Teradata Vantage™

You should collect statistics on your secondary indexes to enable the Optimizer to make the best use of them.

You cannot collect statistics on a UDT column. This includes UDT columns that are components of an index. The Optimizer uses dynamic AMP sampling information for equality predicates on UDT columns and default selectivity for other predicates on UDT indexes for costing. The dynamic AMP sampling provides limited statistics information about the index. For example, it cannot detect nulls or skew. If a UDT index access path does not show any improved performance, you should consider dropping the index to avoid the overhead involved in its storage and maintenance.