Align range and default value for deletes_pct_allowed in merge policy (…

…opensearch-project#7730)

Adjust the range and default value for deletes_pct_allowed in merge policy for more control and optimal disk usage (opensearch-project#7360)

Signed-off-by: Nikhil Kumar <nikhkumn@amazon.com>
Co-authored-by: Nikhil Kumar <nikhkumn@amazon.com>

CHANGELOG.md

@@ -61,6 +61,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Add ZSTD compression for snapshotting ([#2996](https://github.com/opensearch-project/OpenSearch/pull/2996))
 - Change `com.amazonaws.sdk.ec2MetadataServiceEndpointOverride` to `aws.ec2MetadataServiceEndpoint` ([7372](https://github.com/opensearch-project/OpenSearch/pull/7372/))
 - Change `com.amazonaws.sdk.stsEndpointOverride` to `aws.stsEndpointOverride` ([7372](https://github.com/opensearch-project/OpenSearch/pull/7372/))
+- Align range and default value for deletes_pct_allowed in merge policy ([#7730](https://github.com/opensearch-project/OpenSearch/pull/7730))
 
 ### Deprecated
 

server/src/main/java/org/opensearch/index/MergePolicyConfig.java

@@ -94,8 +94,8 @@
  *
  *     Controls the maximum percentage of deleted documents that is tolerated in
  *     the index. Lower values make the index more space efficient at the
- *     expense of increased CPU and I/O activity. Values must be between <code>20</code> and
- *     <code>50</code>. Default value is <code>33</code>.
+ *     expense of increased CPU and I/O activity. Values must be between <code>5</code> and
+ *     <code>50</code>. Default value is <code>20</code>.
  * </ul>
  *
  * <p>
@@ -136,7 +136,7 @@ public final class MergePolicyConfig {
     public static final ByteSizeValue DEFAULT_MAX_MERGED_SEGMENT = new ByteSizeValue(5, ByteSizeUnit.GB);
     public static final double DEFAULT_SEGMENTS_PER_TIER = 10.0d;
     public static final double DEFAULT_RECLAIM_DELETES_WEIGHT = 2.0d;
-    public static final double DEFAULT_DELETES_PCT_ALLOWED = 33.0d;
+    public static final double DEFAULT_DELETES_PCT_ALLOWED = 20.0d;
     public static final Setting<Double> INDEX_COMPOUND_FORMAT_SETTING = new Setting<>(
         "index.compound_format",
         Double.toString(TieredMergePolicy.DEFAULT_NO_CFS_RATIO),
@@ -189,7 +189,7 @@ public final class MergePolicyConfig {
     public static final Setting<Double> INDEX_MERGE_POLICY_DELETES_PCT_ALLOWED_SETTING = Setting.doubleSetting(
         "index.merge.policy.deletes_pct_allowed",
         DEFAULT_DELETES_PCT_ALLOWED,
-        20.0d,
+        5.0d,
         50.0d,
         Property.Dynamic,
         Property.IndexScope