Struct rocksdb::UniversalCompactOptions

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pub struct UniversalCompactOptions { /* private fields */ }

Implementations

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impl UniversalCompactOptions

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pub fn set_size_ratio(&mut self, ratio: c_int)

Sets the percentage flexibility while comparing file size. If the candidate file(s) size is 1% smaller than the next file’s size, then include next file into this candidate set.

Default: 1

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pub fn set_min_merge_width(&mut self, num: c_int)

Sets the minimum number of files in a single compaction run.

Default: 2

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pub fn set_max_merge_width(&mut self, num: c_int)

Sets the maximum number of files in a single compaction run.

Default: UINT_MAX

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pub fn set_max_size_amplification_percent(&mut self, v: c_int)

sets the size amplification.

It is defined as the amount (in percentage) of additional storage needed to store a single byte of data in the database. For example, a size amplification of 2% means that a database that contains 100 bytes of user-data may occupy upto 102 bytes of physical storage. By this definition, a fully compacted database has a size amplification of 0%. Rocksdb uses the following heuristic to calculate size amplification: it assumes that all files excluding the earliest file contribute to the size amplification.

Default: 200, which means that a 100 byte database could require upto 300 bytes of storage.

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pub fn set_compression_size_percent(&mut self, v: c_int)

Sets the percentage of compression size.

If this option is set to be -1, all the output files will follow compression type specified.

If this option is not negative, we will try to make sure compressed size is just above this value. In normal cases, at least this percentage of data will be compressed. When we are compacting to a new file, here is the criteria whether it needs to be compressed: assuming here are the list of files sorted by generation time: A1…An B1…Bm C1…Ct where A1 is the newest and Ct is the oldest, and we are going to compact B1…Bm, we calculate the total size of all the files as total_size, as well as the total size of C1…Ct as total_C, the compaction output file will be compressed iff total_C / total_size < this percentage

Default: -1

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