Package io.trino.sql.planner.optimizations

Class DeterminePartitionCount

java.lang.Object

io.trino.sql.planner.optimizations.DeterminePartitionCount

All Implemented Interfaces:

PlanOptimizer

public class DeterminePartitionCount
extends Object
implements PlanOptimizer

This rule looks at the amount of data read and processed by the query to determine the value of partition count used for remote exchanges. It helps to increase the concurrency of the engine in the case of large cluster. This rule is also cautious about lack of or incorrect statistics therefore it skips for input multiplying nodes like CROSS JOIN or UNNEST. E.g. 1: Given query: SELECT count(column_a) FROM table_with_stats_a config: MIN_INPUT_SIZE_PER_TASK: 500 MB Input table data size: 1000 MB Estimated partition count: Input table data size / MIN_INPUT_SIZE_PER_TASK => 2 E.g. 2: Given query: SELECT * FROM table_with_stats_a as a JOIN table_with_stats_b as b ON a.column_b = b.column_b config: MIN_INPUT_SIZE_PER_TASK: 500 MB Input tables data size: 1000 MB Join output data size: 5000 MB Estimated partition count: max((Input table data size / MIN_INPUT_SIZE_PER_TASK), (Join output data size / MIN_INPUT_SIZE_PER_TASK)) => 10

Constructor Summary

Constructors

Constructor	Description
DeterminePartitionCount(StatsCalculator statsCalculator)

Method Summary

Modifier and Type	Method	Description
PlanNode	optimize(PlanNode plan, Session session, TypeProvider types, SymbolAllocator symbolAllocator, PlanNodeIdAllocator idAllocator, WarningCollector warningCollector, TableStatsProvider tableStatsProvider)

Methods inherited from class java.lang.Object

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

Constructor Details

DeterminePartitionCount

public DeterminePartitionCount(StatsCalculator statsCalculator)

Method Details

optimize

public PlanNode optimize(PlanNode plan,
 Session session,
 TypeProvider types,
 SymbolAllocator symbolAllocator,
 PlanNodeIdAllocator idAllocator,
 WarningCollector warningCollector,
 TableStatsProvider tableStatsProvider)

Specified by:

optimize in interface PlanOptimizer