Package org.opensearch.index

Class LogByteSizeMergePolicyProvider

java.lang.Object

org.opensearch.index.LogByteSizeMergePolicyProvider

All Implemented Interfaces:

MergePolicyProvider

public class LogByteSizeMergePolicyProvider
extends Object
implements MergePolicyProvider

The LogByteSizeMergePolicy is an alternative merge policy primarily used here to optimize the merging of segments in scenarios with index with timestamps. While the TieredMergePolicy is the default choice, the LogByteSizeMergePolicy can be configured as the default merge policy for time-index data using the index.datastream_merge.policy setting.

Unlike the TieredMergePolicy, which prioritizes merging segments of equal sizes, the LogByteSizeMergePolicy specializes in merging adjacent segments efficiently. This characteristic makes it particularly well-suited for range queries on time-index data. Typically, adjacent segments in time-index data often contain documents with similar timestamps. When these segments are merged, the resulting segment covers a range of timestamps with reduced overlap compared to the adjacent segments. This reduced overlap remains even as segments grow older and larger, which can significantly benefit range queries on timestamps.

In contrast, the TieredMergePolicy does not honor this timestamp range optimization. It focuses on merging segments of equal sizes and does not consider adjacency. Consequently, as segments grow older and larger, the overlap of timestamp ranges among adjacent segments managed by TieredMergePolicy can increase. This can lead to inefficiencies in range queries on timestamps, as the number of segments to be scanned within a given timestamp range could become high.

Opensearch.internal:

Field Summary

Fields

Modifier and Type	Field	Description
static final org.opensearch.core.common.unit.ByteSizeValue	DEFAULT_MAX_MERGE_SEGMENT_FORCE_MERGE
static final org.opensearch.core.common.unit.ByteSizeValue	DEFAULT_MAX_MERGED_SEGMENT
static final int	DEFAULT_MERGE_FACTOR
static final org.opensearch.core.common.unit.ByteSizeValue	DEFAULT_MIN_MERGE
static final Setting<org.opensearch.core.common.unit.ByteSizeValue>	INDEX_LBS_MAX_MERGE_SEGMENT_FOR_FORCED_MERGE_SETTING
static final Setting<org.opensearch.core.common.unit.ByteSizeValue>	INDEX_LBS_MAX_MERGE_SEGMENT_SETTING
static final Setting<Integer>	INDEX_LBS_MAX_MERGED_DOCS_SETTING
static final Setting<Integer>	INDEX_LBS_MERGE_POLICY_MERGE_FACTOR_SETTING
static final Setting<org.opensearch.core.common.unit.ByteSizeValue>	INDEX_LBS_MERGE_POLICY_MIN_MERGE_SETTING
static final Setting<Double>	INDEX_LBS_NO_CFS_RATIO_SETTING

Fields inherited from interface org.opensearch.index.MergePolicyProvider

INDEX_MERGE_ENABLED

Method Summary

Modifier and Type	Method	Description
org.apache.lucene.index.MergePolicy	getMergePolicy()	Gets the merge policy to be used for index.
String	toString()

Methods inherited from class java.lang.Object

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

Field Details

DEFAULT_MIN_MERGE

public static final org.opensearch.core.common.unit.ByteSizeValue DEFAULT_MIN_MERGE

DEFAULT_MERGE_FACTOR

public static final int DEFAULT_MERGE_FACTOR

See Also:

• Constant Field Values

DEFAULT_MAX_MERGED_SEGMENT

public static final org.opensearch.core.common.unit.ByteSizeValue DEFAULT_MAX_MERGED_SEGMENT

DEFAULT_MAX_MERGE_SEGMENT_FORCE_MERGE

public static final org.opensearch.core.common.unit.ByteSizeValue DEFAULT_MAX_MERGE_SEGMENT_FORCE_MERGE

INDEX_LBS_MERGE_POLICY_MERGE_FACTOR_SETTING

public static final Setting<Integer> INDEX_LBS_MERGE_POLICY_MERGE_FACTOR_SETTING

INDEX_LBS_MERGE_POLICY_MIN_MERGE_SETTING

public static final Setting<org.opensearch.core.common.unit.ByteSizeValue> INDEX_LBS_MERGE_POLICY_MIN_MERGE_SETTING

INDEX_LBS_MAX_MERGE_SEGMENT_SETTING

public static final Setting<org.opensearch.core.common.unit.ByteSizeValue> INDEX_LBS_MAX_MERGE_SEGMENT_SETTING

INDEX_LBS_MAX_MERGE_SEGMENT_FOR_FORCED_MERGE_SETTING

public static final Setting<org.opensearch.core.common.unit.ByteSizeValue> INDEX_LBS_MAX_MERGE_SEGMENT_FOR_FORCED_MERGE_SETTING

INDEX_LBS_MAX_MERGED_DOCS_SETTING

public static final Setting<Integer> INDEX_LBS_MAX_MERGED_DOCS_SETTING

INDEX_LBS_NO_CFS_RATIO_SETTING

public static final Setting<Double> INDEX_LBS_NO_CFS_RATIO_SETTING

Method Details

getMergePolicy

public org.apache.lucene.index.MergePolicy getMergePolicy()

Description copied from interface: MergePolicyProvider

Gets the merge policy to be used for index.

Specified by:

getMergePolicy in interface MergePolicyProvider

Returns:

The merge policy instance.

toString

public String toString()

Overrides:

toString in class Object