fork of https://github.com/oxigraph/rocksdb and https://github.com/facebook/rocksdb for nextgraph and oxigraph

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Tomislav Novak 88edfd90ae SkipListRep::LookaheadIterator ... Summary: This diff introduces the `lookahead` argument to `SkipListFactory()`. This is an optimization for the tailing use case which includes many seeks. E.g. consider the following operations on a skip list iterator: Seek(x), Next(), Next(), Seek(x+2), Next(), Seek(x+3), Next(), Next(), ... If `lookahead` is positive, `SkipListRep` will return an iterator which also keeps track of the previously visited node. Seek() then first does a linear search starting from that node (up to `lookahead` steps). As in the tailing example above, this may require fewer than ~log(n) comparisons as with regular skip list search. Test Plan: Added a new benchmark (`fillseekseq`) which simulates the usage pattern. It first writes N records (with consecutive keys), then measures how much time it takes to read them by calling `Seek()` and `Next()`. $ time ./db_bench -num 10000000 -benchmarks fillseekseq -prefix_size 1 \ -key_size 8 -write_buffer_size $[1024*1024*1024] -value_size 50 \ -seekseq_next 2 -skip_list_lookahead=0 [...] DB path: [/dev/shm/rocksdbtest/dbbench] fillseekseq : 0.389 micros/op 2569047 ops/sec; real 0m21.806s user 0m12.106s sys 0m9.672s $ time ./db_bench [...] -skip_list_lookahead=2 [...] DB path: [/dev/shm/rocksdbtest/dbbench] fillseekseq : 0.153 micros/op 6540684 ops/sec; real 0m19.469s user 0m10.192s sys 0m9.252s Reviewers: ljin, sdong, igor Reviewed By: igor Subscribers: dhruba, leveldb, march, lovro Differential Revision: https://reviews.facebook.net/D23997		10 years ago
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utilities	WriteBatchWithIndex to allow different Comparators for different column families	10 years ago
c.h	Remove allow_thread_local	10 years ago
cache.h	Remove unused member(s)	10 years ago
compaction_filter.h	Add missing include to use std::unique_ptr	10 years ago
comparator.h	Built-in comparator(s) in RocksJava	10 years ago
db.h	SetOptions() for memtable related options	10 years ago
env.h	Allow env_posix to lower background thread IO priority	10 years ago
filter_policy.h	Implement full filter for block based table.	10 years ago
flush_block_policy.h	move block based table related options BlockBasedTableOptions	10 years ago
immutable_options.h	make compaction related options changeable	10 years ago
iostats_context.h	Fix ios compile	10 years ago
iterator.h	Add License message to public header files.	11 years ago
ldb_tool.h	[RocksDB] allow LDB tool to have customized key formatter	11 years ago
memtablerep.h	SkipListRep::LookaheadIterator	10 years ago
merge_operator.h	Enhance partial merge to support multiple arguments	11 years ago
options.h	Remove allow_thread_local	10 years ago
perf_context.h	Add a function to return current perf level	10 years ago
rate_limiter.h	expose RateLimiter definition	10 years ago
slice.h	JSON (Document) API sketch	10 years ago
slice_transform.h	Add License message to public header files.	11 years ago
statistics.h	Push- instead of pull-model for managing Write stalls	10 years ago
status.h	fix dropping column family bug	10 years ago
table.h	improve memory efficiency of cuckoo reader	10 years ago
table_properties.h	TablePropertiesCollectorFactory	11 years ago
transaction_log.h	Revert "Fix bad merge of D16791 and D16767"	11 years ago
types.h	Add License message to public header files.	11 years ago
universal_compaction.h	Support Multiple DB paths (without having an interface to expose to users)	11 years ago
version.h	Don't keep managing two rocksdb version	10 years ago
write_batch.h	WriteBatchWithIndex: a wrapper of WriteBatch, with a searchable index	10 years ago