Revision 8ea087ad16c853ab24af2f73a9b6a0c9ae04a6e8 authored by Zhichao Cao on 06 November 2019, 20:50:33 UTC, committed by Facebook Github Bot on 06 November 2019, 21:02:20 UTC
Summary: In the previous PR https://github.com/facebook/rocksdb/issues/4788, user can use db_bench mix_graph option to generate the workload that is from the social graph. The key is generated based on the key access hotness. In this PR, user can further model the key-range hotness and fit those to two-term-exponential distribution. First, user cuts the whole key space into small key ranges (e.g., key-ranges are the same size and the key-range number is the number of SST files). Then, user calculates the average access count per key of each key-range as the key-range hotness. Next, user fits the key-range hotness to two-term-exponential distribution (f(x) = f(x) = a*exp(b*x) + c*exp(d*x)) and generate the value of a, b, c, and d. They are the parameters in db_bench: prefix_dist_a, prefix_dist_b, prefix_dist_c, and prefix_dist_d. Finally, user can run db_bench by specify the parameters. For example: `./db_bench --benchmarks="mixgraph" -use_direct_io_for_flush_and_compaction=true -use_direct_reads=true -cache_size=268435456 -key_dist_a=0.002312 -key_dist_b=0.3467 -keyrange_dist_a=14.18 -keyrange_dist_b=-2.917 -keyrange_dist_c=0.0164 -keyrange_dist_d=-0.08082 -keyrange_num=30 -value_k=0.2615 -value_sigma=25.45 -iter_k=2.517 -iter_sigma=14.236 -mix_get_ratio=0.85 -mix_put_ratio=0.14 -mix_seek_ratio=0.01 -sine_mix_rate_interval_milliseconds=5000 -sine_a=350 -sine_b=0.0105 -sine_d=50000 --perf_level=2 -reads=1000000 -num=5000000 -key_size=48` Pull Request resolved: https://github.com/facebook/rocksdb/pull/5953 Test Plan: run db_bench with different parameters and checked the results. Differential Revision: D18053527 Pulled By: zhichao-cao fbshipit-source-id: 171f8b3142bd76462f1967c58345ad7e4f84bab7
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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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