[GitHub] [james-project] jeantil commented on a change in pull request #476: [PERFORMANCE] Reduce Cassandra chunk length for some read intensive t…

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jeantil commented on a change in pull request #476:
URL: https://github.com/apache/james-project/pull/476#discussion_r647352874



##########
File path: mailbox/cassandra/src/main/java/org/apache/james/mailbox/cassandra/modules/CassandraMailboxModule.java
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@@ -42,7 +42,8 @@
         .comment("Holds the mailboxes information.")
         .options(options -> options
             .caching(SchemaBuilder.KeyCaching.ALL,
-                SchemaBuilder.rows(CassandraConstants.DEFAULT_CACHED_ROW_PER_PARTITION)))
+                SchemaBuilder.rows(CassandraConstants.DEFAULT_CACHED_ROW_PER_PARTITION))
+            .compressionOptions(SchemaBuilder.lz4().withChunkLengthInKb(8)))

Review comment:
       how did you come to choose `8` Kb ? 
   is it based on BufferedReader's defaultCharBufferSize to align with memory page size or is based on the estimated size of a mailbox row ? 
   (https://stackoverflow.com/questions/37404068/why-is-the-default-char-buffer-size-of-bufferedreader-8192)
   
   a comment would be nice :D
   
   (if the answer is size of a mailbox row, the same question applies to all the following `8` that appear in the PR) 




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