From 3662c2976a74d140c589066480ee53171882f624 Mon Sep 17 00:00:00 2001 From: heyongqiang Date: Mon, 17 Sep 2012 15:16:49 -0700 Subject: [PATCH] improve comments about target_file_size_base, target_file_size_multiplier, max_bytes_for_level_base, max_bytes_for_level_multiplier Summary: Summary: as subject Test Plan: compile Reviewers: MarkCallaghan, dhruba Differential Revision: https://reviews.facebook.net/D5499 --- include/leveldb/options.h | 32 +++++++++++++++++++++++--------- 1 file changed, 23 insertions(+), 9 deletions(-) diff --git a/include/leveldb/options.h b/include/leveldb/options.h index f49f833ae..95a22e6b5 100644 --- a/include/leveldb/options.h +++ b/include/leveldb/options.h @@ -163,20 +163,34 @@ struct Options { // space if the same key space is being repeatedly overwritten. int max_mem_compaction_level; - // Target file size for compaction. Target file size for level L is - // (target_file_size_base)^(target_file_size_multiplier). - // For example, if target_file_size_base is 20MB and - // target_file_size_multiplier is 2^10, then target file size on level 1 - // will be 200MB, and wiil be 2GB on level 2. - + // Target file size for compaction. + // target_file_size_base is per-file size for level-1. + // Target file size for level L can be calculated by + // target_file_size_base * (target_file_size_multiplier ^ (L-1)) + // For example, if target_file_size_base is 2MB and + // target_file_size_multiplier is 10, then each file on level-1 will + // be 2MB, and each file on level 2 will be 20MB, + // and each file on level-3 will be 200MB. + + // by default target_file_size_base is 2MB. int target_file_size_base; + // by default target_file_size_multiplier is 1, which means + // by default files in different levels will have similar size. int target_file_size_multiplier; - // Control maximum number of bytes in all compacted files for one level. - // Maximum number of bytes for level L is - // (max_bytes_for_level_base)^(max_bytes_for_level_multiplier). + // Control maximum total data size for a level. + // max_bytes_for_level_base is the max total for level-1. + // Maximum number of bytes for level L can be calculated as + // (max_bytes_for_level_base) * (max_bytes_for_level_multiplier ^ (L-1)) + // For example, if max_bytes_for_level_base is 20MB, and if + // max_bytes_for_level_multiplier is 10, total data size for level-1 + // will be 20MB, total file size for level-2 will be 200MB, + // and total file size for level-3 will be 2GB. + + // by default 'max_bytes_for_level_base' is 10MB. int max_bytes_for_level_base; + // by default 'max_bytes_for_level_base' is 10. int max_bytes_for_level_multiplier; // Maximum number of bytes in all compacted files. We avoid expanding -- GitLab