mondrian.spi

Interface StatisticsProvider

All Known Implementing Classes:

BasicQueryTest.MyJdbcStatisticsProvider, JdbcStatisticsProvider, SqlStatisticsProvider

public interface StatisticsProvider

Provides estimates of the number of rows in a database.

Mondrian generally finds statistics providers via the Dialect.getStatisticsProviders() method on the dialect object for the current connection. The default implementation of that method looks first at the "mondrian.statistics.providers.DATABASE" property (substituting the current database name, e.g. MYSQL or ORACLE, for DATABASE), then at the "mondrian.statistics.providers" property.

See Also:

JdbcStatisticsProvider, SqlStatisticsProvider

Method Summary

Modifier and Type	Method and Description
int	getColumnCardinality(Dialect dialect, DataSource dataSource, String catalog, String schema, String table, String column, Execution execution) Returns an estimate of the number of rows in a table.
int	getQueryCardinality(Dialect dialect, DataSource dataSource, String sql, Execution execution) Returns an estimate of the number of rows returned by a query.
int	getTableCardinality(Dialect dialect, DataSource dataSource, String catalog, String schema, String table, Execution execution) Returns an estimate of the number of rows in a table.

Method Detail

getTableCardinality

int getTableCardinality(Dialect dialect,
                        DataSource dataSource,
                        String catalog,
                        String schema,
                        String table,
                        Execution execution)

Returns an estimate of the number of rows in a table.

Parameters:

dialect - Dialect

dataSource - Data source

catalog - Catalog name

schema - Schema name

table - Table name

execution - Execution

Returns:

Estimated number of rows in table, or -1 if there is no estimate

getQueryCardinality

int getQueryCardinality(Dialect dialect,
                        DataSource dataSource,
                        String sql,
                        Execution execution)

Returns an estimate of the number of rows returned by a query.

Parameters:

dialect - Dialect

dataSource - Data source

sql - Query, e.g. "select * from customers where age < 20"

execution - Execution

Returns:

Estimated number of rows returned by query, or -1 if there is no estimate

getColumnCardinality

int getColumnCardinality(Dialect dialect,
                         DataSource dataSource,
                         String catalog,
                         String schema,
                         String table,
                         String column,
                         Execution execution)

Returns an estimate of the number of rows in a table.

Parameters:

dialect - Dialect

dataSource - Data source

catalog - Catalog name

schema - Schema name

table - Table name

column - Column name

execution - Execution

Returns:

Estimated number of rows in table, or -1 if there is no estimate