How do you get summary stats in Teradata?
How do you get summary stats in Teradata?
COLLECT SUMMARY STATISTICS ON
How does collect statistics work in Teradata?
Teradata optimizer comes up with an execution strategy for every SQL query. This execution strategy is based on the statistics collected on the tables used within the SQL query. Statistics on the table is collected using COLLECT STATISTICS command.
How do you collect stats on index in Teradata?
What to COLLECT STATISTICS On?
- Primary Index of a Join Index.
- Secondary Indexes defined on any join index.
- Non-indexed columns used in joins.
- The Unique Primary Index of small tables (less than 1,000 rows per AMP)
- All Non-Unique Primary Indexes and All Non-Unique Secondary Indexes.
How do you collect statistics?
Generally, you collect quantitative data through sample surveys, experiments and observational studies. You obtain qualitative data through focus groups, in-depth interviews and case studies. We will discuss each of these data collection methods below and examine their advantages and disadvantages.
Why do we need to collect stats in Teradata?
It is recommended to collect stats on non unique secondary indexes(NUSI) for optimizer to know total number of rows in NUSI subtable and make better decisions regarding the cost savings. It is recommended to collect stats on non-indexed columns that are frequently used in ‘WHERE’ clause and equi-joins.
Can we collect stats on views in Teradata?
The Statistics Collection view lets you collect statistics on table columns and indexes.
How often do you collect statistics in Teradata?
Teradata recommends always collecting full-table statistics on a regular basis unless you specify USING clause sampling or threshold options. In this case, the Optimizer determines whether a request to recollect statistics for a column or index set should be honored.
Why do we collect stats in Teradata?
Can we collect stats on view in Teradata?
The Statistics Collection view lets you collect statistics on table columns and indexes. Collecting statistics on columns or indexes is important to producing query plans.
What is the syntax for collecting statistics in Teradata?
Teradata Collect Statistics Syntax. The syntax to collect statistics as follows. COLLECT [SUMMARY] STATISTICS INDEX(index_name) COLUMN(column_name) ON ; Teradata Collect Statistics Example. The following example collects statistics on the employee table. COLLECT STATISTICS COLUMN(empid) on Teradatapoint.employee; Viewing Statistics
How is the execution strategy of Teradata calculated?
Teradata optimizer comes up with an execution strategy for every SQL query. This execution strategy is based on the statistics collected on the tables used within the SQL query. Statistics on the table is collected using COLLECT STATISTICS command.
How many intervals are there in a Teradata table?
Whenever you collected statistics, Teradata did a full table scan on the values, sorted them, and then placed them into 200 intervals. Now, the default is 250 intervals
How are statistics collected in a SQL query?
This execution strategy is based on the statistics collected on the tables used within the SQL query. Statistics on the table is collected using COLLECT STATISTICS command. Optimizer requires environment information and data demographics to come up with optimal execution strategy. There are three approaches to collect statistics on the table.