Revision 5a2a6483dc23a8854e02984ece3b8d88b783959d authored by Yi Wu on 26 October 2017, 19:19:43 UTC, committed by Facebook Github Bot on 26 October 2017, 19:30:54 UTC
Summary: Adding the `min_blob_size` option to allow storing small values in base db (in LSM tree) together with the key. The goal is to improve performance for small values, while taking advantage of blob db's low write amplification for large values. Also adding expiration timestamp to blob index. It will be useful to evict stale blob indexes in base db by adding a compaction filter. I'll work on the compaction filter in future patches. See blob_index.h for the new blob index format. There are 4 cases when writing a new key: * small value w/o TTL: put in base db as normal value (i.e. ValueType::kTypeValue) * small value w/ TTL: put (type, expiration, value) to base db. * large value w/o TTL: write value to blob log and put (type, file, offset, size, compression) to base db. * large value w/TTL: write value to blob log and put (type, expiration, file, offset, size, compression) to base db. Closes https://github.com/facebook/rocksdb/pull/3066 Differential Revision: D6142115 Pulled By: yiwu-arbug fbshipit-source-id: 9526e76e19f0839310a3f5f2a43772a4ad182cd0
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DUMP_FORMAT.md
## RocksDB dump format
The version 1 RocksDB dump format is fairly simple:
1) The dump starts with the magic 8 byte identifier "ROCKDUMP"
2) The magic is followed by an 8 byte big-endian version which is 0x00000001.
3) Next are arbitrarily sized chunks of bytes prepended by 4 byte little endian number indicating how large each chunk is.
4) The first chunk is special and is a json string indicating some things about the creation of this dump. It contains the following keys:
* database-path: The path of the database this dump was created from.
* hostname: The hostname of the machine where the dump was created.
* creation-time: Unix seconds since epoc when this dump was created.
5) Following the info dump the slices paired into are key/value pairs.
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