Package org.apache.druid.segment.metadata

Class AbstractSegmentMetadataCache.FirstTypeMergePolicy

java.lang.Object

org.apache.druid.segment.metadata.AbstractSegmentMetadataCache.FirstTypeMergePolicy

All Implemented Interfaces:

AbstractSegmentMetadataCache.ColumnTypeMergePolicy

Enclosing class:

AbstractSegmentMetadataCache<T extends DataSourceInformation>

public static class AbstractSegmentMetadataCache.FirstTypeMergePolicy
extends Object
implements AbstractSegmentMetadataCache.ColumnTypeMergePolicy

Classic logic, we use the first type we encounter. This policy is effectively 'newest first' because we iterated segments starting from the most recent time chunk, so this typically results in the most recently used type being chosen, at least for systems that are continuously updated with 'current' data. Since AbstractSegmentMetadataCache.ColumnTypeMergePolicy are used to compute the SQL schema, at least in systems using SQL schemas which are partially or fully computed by this cache, this merge policy can result in query time errors if incompatible types are mixed if the chosen type is more restrictive than the types of some segments. If data is likely to vary in type across segments, consider using AbstractSegmentMetadataCache.LeastRestrictiveTypeMergePolicy instead.

Field Summary

Fields

Modifier and Type	Field	Description
static String	NAME

Constructor Summary

Constructors

Constructor	Description
FirstTypeMergePolicy()

Method Summary

Modifier and Type	Method	Description
boolean	equals(Object o)
int	hashCode()
org.apache.druid.segment.column.ColumnType	merge(org.apache.druid.segment.column.ColumnType existingType, org.apache.druid.segment.column.ColumnType newType)
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

NAME

public static final String NAME

See Also:

Constant Field Values

Constructor Detail

FirstTypeMergePolicy

public FirstTypeMergePolicy()

Method Detail

merge

public org.apache.druid.segment.column.ColumnType merge(org.apache.druid.segment.column.ColumnType existingType,
                                                        org.apache.druid.segment.column.ColumnType newType)

Specified by:

merge in interface AbstractSegmentMetadataCache.ColumnTypeMergePolicy

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object o)

Overrides:

equals in class Object

toString

public String toString()

Overrides:

toString in class Object