From 0796a372d0156021a38f239498a666cf23cc046a Mon Sep 17 00:00:00 2001 From: Martin Sumner Date: Mon, 23 Jul 2018 13:59:24 +0100 Subject: [PATCH] Add docs for journal compaction startup options --- docs/STARTUP_OPTIONS.md | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/docs/STARTUP_OPTIONS.md b/docs/STARTUP_OPTIONS.md index 369500a..83f6aff 100644 --- a/docs/STARTUP_OPTIONS.md +++ b/docs/STARTUP_OPTIONS.md @@ -70,3 +70,13 @@ Compression point can be set using `{compression_point, on_receipt|on_compact}`. ## Root Path The root path is the name of the folder in which the database has been (or should be) persisted. + +## Journal Compaction + +The compaction of the Journal, is the process through which the space of replaced (or deleted) objects can be reclaimed from the journal. This is controlled through the following parameters: + +The `compaction_runs_perday` indicates for the leveled store how many times eahc day it will attempt to run a compaction (it is normal for this to be ~= the numbe rof hours per day that compcation is permitted). + +The `compaction_low_hour` and `compaction_high_hour` are the hours of the day which support the compaction window - set to 0 and 23 respectively if compaction is required to be a continuous process. + +The `max_run_length` controls how many files can be compacted in a single compaction run. The scoring of files and runs is controlled through `maxrunlength_compactionpercentage` and `singlefile_compactionpercentage`.