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59 lines
2.8 KiB
Markdown
59 lines
2.8 KiB
Markdown
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---
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title: Rocksdb Tuning Advisor
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layout: post
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author: poojam23
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category: blog
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---
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The performance of Rocksdb is contingent on its tuning. However, because
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of the complexity of its underlying technology and a large number of
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configurable parameters, a good configuration is sometimes hard to obtain. The aim of
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the python command-line tool, Rocksdb Advisor, is to automate the process of
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suggesting improvements in the configuration based on advice from Rocksdb
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experts.
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### Overview
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Experts share their wisdom as rules comprising of conditions and suggestions in the INI format (refer
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[rules.ini](https://github.com/facebook/rocksdb/blob/master/tools/advisor/advisor/rules.ini)).
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Users provide the Rocksdb configuration that they want to improve upon (as the
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familiar Rocksdb OPTIONS file —
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[example](https://github.com/facebook/rocksdb/blob/master/examples/rocksdb_option_file_example.ini))
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and the path of the file which contains Rocksdb logs and statistics.
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The [Advisor](https://github.com/facebook/rocksdb/blob/master/tools/advisor/advisor/rule_parser_example.py)
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creates appropriate DataSource objects (for Rocksdb
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[logs](https://github.com/facebook/rocksdb/blob/master/tools/advisor/advisor/db_log_parser.py),
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[options](https://github.com/facebook/rocksdb/blob/master/tools/advisor/advisor/db_options_parser.py),
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[statistics](https://github.com/facebook/rocksdb/blob/master/tools/advisor/advisor/db_stats_fetcher.py) etc.)
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and provides them to the [Rules Engine](https://github.com/facebook/rocksdb/blob/master/tools/advisor/advisor/rule_parser.py).
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The Rules uses rules from experts to parse data-sources and trigger appropriate rules.
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The Advisor's output gives information about which rules were triggered,
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why they were triggered and what each of them suggests. Each suggestion
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provided by a triggered rule advises some action on a Rocksdb
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configuration option, for example, increase CFOptions.write_buffer_size,
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set bloom_bits to 2 etc.
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### Usage
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An example command to run the tool:
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```shell
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cd rocksdb/tools/advisor
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python3 -m advisor.rule_parser_example --rules_spec=advisor/rules.ini --rocksdb_options=test/input_files/OPTIONS-000005 --log_files_path_prefix=test/input_files/LOG-0 --stats_dump_period_sec=20
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```
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Sample output where a Rocksdb log-based rule has been triggered :
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```shell
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Rule: stall-too-many-memtables
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LogCondition: stall-too-many-memtables regex: Stopping writes because we have \d+ immutable memtables \(waiting for flush\), max_write_buffer_number is set to \d+
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Suggestion: inc-bg-flush option : DBOptions.max_background_flushes action : increase suggested_values : ['2']
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Suggestion: inc-write-buffer option : CFOptions.max_write_buffer_number action : increase
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scope: col_fam:
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{'default'}
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```
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### Read more
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For more information, refer to [advisor](https://github.com/facebook/rocksdb/tree/master/tools/advisor/README.md).
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