AppLib ESTIMATE STATISTICS FOR SCHEMA

From Eigenpedia

Contents 1 Syntax 2 Purpose 3 Parameters 4 Example 5 Source Code

Syntax

CALL APPLIB.ESTIMATE_STATISTICS_FOR_SCHEMA( schemaname )
CALL APPLIB.ESTIMATE_STATISTICS_FOR_SCHEMA( schemaname, samplingrate )

Purpose

Executes 'analyze table' with 'estimate statistics for all columns' for all tables in a schema, with an optional sampling rate. Without a sampling rate, LucidDb automatically chooses an appropriate sampling rate for the number of rows present in each table.

Use caution when providing a sampling rate as it will be applied to all tables in the schema. If the sample size (sampling rate multiplied by row count) for a table is too small, the statistics may be inaccurate. Conversely, high sampling rates negate the performance benefits of estimating, rather than computing, statistics.

Parameters

• schemaname: name of schema containing tables to estimate stats for [VARCHAR(255)]
• samplingrate: percentage of rows in each table to sample [FLOAT]; valid values are greater than 0 and less than, or equal to, 100

Example

CALL APPLIB.ESTIMATE_STATISTICS_FOR_SCHEMA( 'TESTSCHEMA' )
CALL APPLIB.ESTIMATE_STATISTICS_FOR_SCHEMA( 'TESTSCHEMA', 50.0 )

(doesn't return anything)

Source Code

http://p4web.eigenbase.org/open/dev/luciddb/src/com/lucidera/luciddb/applib/analysis/EstimateStatisticsForSchemaUdp.java