parquet.filter2.predicate

Class UserDefinedPredicate<T extends Comparable<T>>

java.lang.Object

parquet.filter2.predicate.UserDefinedPredicate<T>

Type Parameters:

T - The type of the column this predicate is applied to.

public abstract class UserDefinedPredicate<T extends Comparable<T>>
extends Object

A UserDefinedPredicate decides whether a record should be kept or dropped, first by inspecting meta data about a group of records to see if the entire group can be dropped, then by inspecting actual values of a single column. These predicates can be combined into a complex boolean expression via the FilterApi.

Constructor Summary

Constructors

Constructor and Description
UserDefinedPredicate() A udp must have a default constructor.

Method Summary

Methods

Modifier and Type	Method and Description
abstract boolean	canDrop(Statistics<T> statistics) Given information about a group of records (eg, the min and max value) Return true to drop all the records in this group, false to keep them for further inspection.
abstract boolean	inverseCanDrop(Statistics<T> statistics) Same as canDrop(parquet.filter2.predicate.Statistics<T>) except this method describes the logical inverse behavior of this predicate.
abstract boolean	keep(T value) Return true to keep the record with this value, false to drop it.

Methods inherited from class java.lang.Object

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

Constructor Detail

UserDefinedPredicate

public UserDefinedPredicate()

A udp must have a default constructor. The udp passed to FilterApi will not be serialized along with its state. Only its class name will be recorded, it will be instantiated reflectively via the default constructor.

Method Detail

keep

public abstract boolean keep(T value)

Return true to keep the record with this value, false to drop it.

canDrop

public abstract boolean canDrop(Statistics<T> statistics)

Given information about a group of records (eg, the min and max value) Return true to drop all the records in this group, false to keep them for further inspection. Returning false here will cause the records to be loaded and each value will be passed to keep(T) to make the final decision. It is safe to always return false here, if you simply want to visit each record via the keep(T) method, though it is much more efficient to drop entire chunks of records here if you can.

inverseCanDrop

public abstract boolean inverseCanDrop(Statistics<T> statistics)

Same as canDrop(parquet.filter2.predicate.Statistics<T>) except this method describes the logical inverse behavior of this predicate. If this predicate is passed to the not() operator, then inverseCanDrop(parquet.filter2.predicate.Statistics<T>) will be called instead of canDrop(parquet.filter2.predicate.Statistics<T>) It is safe to always return false here, if you simply want to visit each record via the keep(T) method, though it is much more efficient to drop entire chunks of records here if you can. It may be valid to simply return !canDrop(statistics) but that is not always the case. To illustrate, look at this re-implementation of a UDP that checks for values greater than 7: // This is just an example, you should use the built in {@link FilterApi#gt} operator instead of // implementing your own like this. public class IntGreaterThan7UDP extends UserDefinedPredicate {