Introduce Elasticsearch PostingFormat based on Lucene 90 positing for…

…mat using PFOR (elastic#103601) (elastic#103624)

Lucene 9.9 has introduced a new posting format that uses FOR instead of PFOR. Elasticsearch prefers the former 
format, therefore we introduce it as a our own posting format here.

docs/changelog/103601.yaml

@@ -0,0 +1,7 @@
+pr: 103601
+summary: Introduce Elasticsearch `PostingFormat` based on Lucene 90 positing format
+  using PFOR
+area: Search
+type: bug
+issues:
+ - 103002

server/src/main/java/module-info.java

@@ -419,7 +419,8 @@
     provides org.apache.lucene.codecs.PostingsFormat
         with
             org.elasticsearch.index.codec.bloomfilter.ES85BloomFilterPostingsFormat,
-            org.elasticsearch.index.codec.bloomfilter.ES87BloomFilterPostingsFormat;
+            org.elasticsearch.index.codec.bloomfilter.ES87BloomFilterPostingsFormat,
+            org.elasticsearch.index.codec.postings.ES812PostingsFormat;
     provides org.apache.lucene.codecs.DocValuesFormat with ES87TSDBDocValuesFormat;
 
     exports org.elasticsearch.cluster.routing.allocation.shards

server/src/main/java/org/elasticsearch/action/admin/indices/diskusage/IndexDiskUsageAnalyzer.java

@@ -55,6 +55,7 @@
 import org.elasticsearch.common.lucene.Lucene;
 import org.elasticsearch.core.CheckedConsumer;
 import org.elasticsearch.core.IOUtils;
+import org.elasticsearch.index.codec.postings.ES812PostingsFormat;
 import org.elasticsearch.index.shard.ShardId;
 import org.elasticsearch.index.store.LuceneFilesExtensions;
 
@@ -302,6 +303,9 @@ private static void readProximity(Terms terms, PostingsEnum postings) throws IOE
     private static BlockTermState getBlockTermState(TermsEnum termsEnum, BytesRef term) throws IOException {
         if (term != null && termsEnum.seekExact(term)) {
             final TermState termState = termsEnum.termState();
+            if (termState instanceof final ES812PostingsFormat.IntBlockTermState blockTermState) {
+                return new BlockTermState(blockTermState.docStartFP, blockTermState.posStartFP, blockTermState.payStartFP);
+            }
             if (termState instanceof final Lucene99PostingsFormat.IntBlockTermState blockTermState) {
                 return new BlockTermState(blockTermState.docStartFP, blockTermState.posStartFP, blockTermState.payStartFP);
             }

server/src/main/java/org/elasticsearch/index/codec/PerFieldMapperCodec.java

@@ -19,6 +19,7 @@
 import org.elasticsearch.index.IndexMode;
 import org.elasticsearch.index.IndexSettings;
 import org.elasticsearch.index.codec.bloomfilter.ES87BloomFilterPostingsFormat;
+import org.elasticsearch.index.codec.postings.ES812PostingsFormat;
 import org.elasticsearch.index.codec.tsdb.ES87TSDBDocValuesFormat;
 import org.elasticsearch.index.mapper.IdFieldMapper;
 import org.elasticsearch.index.mapper.MappedFieldType;
@@ -44,6 +45,8 @@ public final class PerFieldMapperCodec extends Lucene99Codec {
     private final ES87BloomFilterPostingsFormat bloomFilterPostingsFormat;
     private final ES87TSDBDocValuesFormat tsdbDocValuesFormat;
 
+    private final ES812PostingsFormat es812PostingsFormat;
+
     static {
         assert Codec.forName(Lucene.LATEST_CODEC).getClass().isAssignableFrom(PerFieldMapperCodec.class)
             : "PerFieldMapperCodec must subclass the latest lucene codec: " + Lucene.LATEST_CODEC;
@@ -54,6 +57,7 @@ public PerFieldMapperCodec(Mode compressionMode, MapperService mapperService, Bi
         this.mapperService = mapperService;
         this.bloomFilterPostingsFormat = new ES87BloomFilterPostingsFormat(bigArrays, this::internalGetPostingsFormatForField);
         this.tsdbDocValuesFormat = new ES87TSDBDocValuesFormat();
+        this.es812PostingsFormat = new ES812PostingsFormat();
     }
 
     @Override
@@ -69,7 +73,8 @@ private PostingsFormat internalGetPostingsFormatForField(String field) {
         if (format != null) {
             return format;
         }
-        return super.getPostingsFormatForField(field);
+        // return our own posting format using PFOR
+        return es812PostingsFormat;
     }
 
     boolean useBloomFilter(String field) {