Package org.apache.calcite.statistic

Class QuerySqlStatisticProvider

java.lang.Object

org.apache.calcite.statistic.QuerySqlStatisticProvider

All Implemented Interfaces:

SqlStatisticProvider

public class QuerySqlStatisticProvider
extends Object
implements SqlStatisticProvider

Implementation of SqlStatisticProvider that generates and executes SQL queries.

Field Summary

Fields

Modifier and Type	Field	Description
static final SqlStatisticProvider	SILENT_CACHING_INSTANCE	Instance that uses SQL to compute statistics, does not log SQL statements, and caches up to 1,024 results for up to 30 minutes.
static final SqlStatisticProvider	VERBOSE_CACHING_INSTANCE	As SILENT_CACHING_INSTANCE but prints SQL statements to System.out.

Constructor Summary

Constructors

Constructor	Description
QuerySqlStatisticProvider(Consumer<String> sqlConsumer)	Creates a QuerySqlStatisticProvider.

Method Summary

Modifier and Type	Method	Description
boolean	isForeignKey(RelOptTable fromTable, List<Integer> fromColumns, RelOptTable toTable, List<Integer> toColumns)	Returns whether a join is a foreign key; that is, whether every row in the referencing table is matched by at least one row in the referenced table.
boolean	isKey(RelOptTable table, List<Integer> columns)	Returns whether a collection of columns is a unique (or primary) key.
double	tableCardinality(RelOptTable table)	Returns an estimate of the number of rows in table.
protected String	toSql(RelNode rel, SqlDialect dialect)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

SILENT_CACHING_INSTANCE

public static final SqlStatisticProvider SILENT_CACHING_INSTANCE

Instance that uses SQL to compute statistics, does not log SQL statements, and caches up to 1,024 results for up to 30 minutes. (That period should be sufficient for the duration of Calcite's tests, and many other purposes.)

VERBOSE_CACHING_INSTANCE

public static final SqlStatisticProvider VERBOSE_CACHING_INSTANCE

As SILENT_CACHING_INSTANCE but prints SQL statements to System.out.

Constructor Details

QuerySqlStatisticProvider

public QuerySqlStatisticProvider(Consumer<String> sqlConsumer)

Creates a QuerySqlStatisticProvider.

Parameters:

sqlConsumer - Called when each SQL statement is generated

Method Details

tableCardinality

public double tableCardinality(RelOptTable table)

Description copied from interface: SqlStatisticProvider

Returns an estimate of the number of rows in table.

Specified by:

tableCardinality in interface SqlStatisticProvider

isForeignKey

public boolean isForeignKey(RelOptTable fromTable,
 List<Integer> fromColumns,
 RelOptTable toTable,
 List<Integer> toColumns)

Description copied from interface: SqlStatisticProvider

Returns whether a join is a foreign key; that is, whether every row in the referencing table is matched by at least one row in the referenced table.

For example, isForeignKey(EMP, [DEPTNO], DEPT, [DEPTNO]) returns true.

To change "at least one" to "exactly one", you also need to call SqlStatisticProvider.isKey(org.apache.calcite.plan.RelOptTable, java.util.List<java.lang.Integer>).

Specified by:

isForeignKey in interface SqlStatisticProvider

isKey

public boolean isKey(RelOptTable table,
 List<Integer> columns)

Description copied from interface: SqlStatisticProvider

Returns whether a collection of columns is a unique (or primary) key.

For example, isKey(EMP, [DEPTNO] returns true; isKey(DEPT, [DEPTNO] returns false.

Specified by:

isKey in interface SqlStatisticProvider

toSql

protected String toSql(RelNode rel,
 SqlDialect dialect)