Dhruba Borthakur 7632fdb5cb Support taking a configurable number of files from the same level to compact in a single compaction run. ... Summary: The compaction process takes some files from LevelK and merges it into LevelK+1. The number of files it picks from LevelK was capped such a way that the total amount of data picked does not exceed the maxfilesize of that level. This essentially meant that only one file from LevelK is picked for a single compaction. For bulkloads, we would like to take many many file from LevelK and compact them using a single compaction run. This patch introduces a option called the 'source_compaction_factor' (similar to expanded_compaction_factor). It is a multiplier that is multiplied by the maxfilesize of that level to arrive at the limit that is used to throttle the number of source files from LevelK. For bulk loads, set source_compaction_factor to a very high number so that multiple files from the same level are picked for compaction in a single compaction. The default value of source_compaction_factor is 1, so that we can keep backward compatibilty with existing compaction semantics. Test Plan: make clean check Reviewers: emayanke, sheki Reviewed By: emayanke CC: leveldb Differential Revision: https://reviews.facebook.net/D6867		2012-11-21 08:37:03 -08:00
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leveldb	Support taking a configurable number of files from the same level to compact in a single compaction run.	2012-11-21 08:37:03 -08:00