com.facebook.presto.common.plan

Enum PlanCanonicalizationStrategy

java.lang.Object

java.lang.Enum<PlanCanonicalizationStrategy>

com.facebook.presto.common.plan.PlanCanonicalizationStrategy

All Implemented Interfaces:

Serializable, Comparable<PlanCanonicalizationStrategy>

public enum PlanCanonicalizationStrategy
extends Enum<PlanCanonicalizationStrategy>

Enum Constant Summary

Enum Constants

Enum Constant and Description
CONNECTOR CONNECTOR strategy will canonicalize plan according to DEFAULT strategy, and additionally canoncialize `TableScanNode` by giving a connector specific implementation.
DEFAULT DEFAULT strategy is used to canonicalize plans with minimal changes.
REMOVE_SAFE_CONSTANTS REMOVE_SAFE_CONSTANTS strategy is used to canonicalize plan with CONNECTOR strategy and will additionally remove constants from plan which are not bound to have impact on plan statistics.

Method Summary

Modifier and Type	Method and Description
static List<PlanCanonicalizationStrategy>	historyBasedPlanCanonicalizationStrategyList() Creates a list of PlanCanonicalizationStrategy to be used for history based optimizations.
static PlanCanonicalizationStrategy	valueOf(String name) Returns the enum constant of this type with the specified name.
static PlanCanonicalizationStrategy[]	values() Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

DEFAULT

public static final PlanCanonicalizationStrategy DEFAULT

DEFAULT strategy is used to canonicalize plans with minimal changes. It only processes following basic plan nodes: Scan, Filter, Project, Aggregation, Unnest. We remove any unimportant information like source location, make the variable names consistent, and order them. For example: `SELECT * FROM table WHERE id IN (1, 2)` will be equivalent to `SELECT * FROM table WHERE id IN (2, 1)` This is used in context of fragment result caching

CONNECTOR

public static final PlanCanonicalizationStrategy CONNECTOR

CONNECTOR strategy will canonicalize plan according to DEFAULT strategy, and additionally canoncialize `TableScanNode` by giving a connector specific implementation. Unlike DEFAULT strategy, it supports all Plan nodes(like union, join etc.) With this approach, we call ConnectorTableLayoutHandle.getIdentifier() for all `TableScanNode`. Each connector can have a specific implementation to canonicalize table layout handles however they want. For example, Hive connector removes constants from constraints on partition keys: `SELECT * FROM table WHERE ds = '2020-01-01'` will be equivalent to `SELECT * FROM table WHERE ds = '2020-01-02'` where `ds` is a partition column in `table` This is used in context of history based optimizations.

REMOVE_SAFE_CONSTANTS

public static final PlanCanonicalizationStrategy REMOVE_SAFE_CONSTANTS

REMOVE_SAFE_CONSTANTS strategy is used to canonicalize plan with CONNECTOR strategy and will additionally remove constants from plan which are not bound to have impact on plan statistics. This includes removing constants from ProjectNode, but keeps constants in FilterNode since they can have major impact on plan statistics. For example: `SELECT *, 1 FROM table` will be equivalent to `SELECT *, 2 FROM table` `SELECT * FROM table WHERE id > 1` will NOT be equivalent to `SELECT * FROM table WHERE id > 1000` This is used in context of history based optimizations.

Method Detail

values

public static PlanCanonicalizationStrategy[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (PlanCanonicalizationStrategy c : PlanCanonicalizationStrategy.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static PlanCanonicalizationStrategy valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum type has no constant with the specified name

NullPointerException - if the argument is null

historyBasedPlanCanonicalizationStrategyList

public static List<PlanCanonicalizationStrategy> historyBasedPlanCanonicalizationStrategyList()

Creates a list of PlanCanonicalizationStrategy to be used for history based optimizations. Output is ordered by decreasing accuracy of statistics, at benefit of more coverage.