No durability guarantee (benchmark is misleading)

[damnever]

I was wondering why nutsdb is so fast, so I did a quick review on your code, and there is no flush/sync call in the code, you should call it to ensure durability and update the benchmark. 💪

Also, the README should mention the byte endianness issue as well, and the isolation level is not clear.

[xujiajun]

@damnever hi ,thanks your advises,

as man2 said about mmap : The file may not actually be updated until msync(2) or munmap(2) is called. Actually i called munmap in this code, so data will be updated.

if you can give me your pr to improve it， it will be better；）

BTW, about the README i will continue to improve.

[damnever]

YES, but nutsdb declares to support ACID, so you should call it in each Commit, without it, the most important part about nutsdb is wrong.

[damnever]

Also, the simple lock cannot fully guarantee the ACID.

[xujiajun]

@damnever ，thanks :)
i have updated the README about transaction in the Caveats & Limitations，and i will rethink your advises , and i will continue to update the README, especially about the transaction.

[damnever]

Still, it is a misleading README, you should remove the benchmark part and all other contents those declares nutsdb is faster than others, if you remove their flush/fsync/fdatasync part, they are fast too! And anyone can write a fast kvstore.

As I mentioned before, you maybe understand the ACID properties, but you implement it wrong, and what is a non-standard transaction?

As a self-learning project is ok, but DO NOT mislead others!

[xujiajun]

@damnever thanks to review my README，i have updated the README about the benchmark part and about declares nutsdb is faster than others.

About a non-standard transaction or a standard transaction, i mean a transactional database like mysql that provides the ACID properties , i can call it a a standard transaction. If a database not completely including ACID properties，like redis ，i call it a non-standard transaction.

if have any question, Welcome to give me advises.

BTW, i never want to mislead others. if have any mistake about README or code etc. Welcome to submit issue and give me PR.

thanks again！

[damnever]

I glad to see you make some changes.

From the context:

Finally i did it and named NutsDB

[xujiajun]

@damnever hi, now the master branch of nutsdb has supports persistence , i have use sync function in my code to ensure durability and update the benchmark,

selected kvstore which is embedded, persistence and support transactions.

benchmark result:

badger 2019/03/11 18:06:05 INFO: All 0 tables opened in 0s
goos: darwin
goarch: amd64
pkg: github.com/xujiajun/kvstore-bench
BenchmarkBadgerDBPutValue64B-8    	   10000	    112382 ns/op	    2374 B/op	      74 allocs/op
BenchmarkBadgerDBPutValue128B-8   	   20000	     94110 ns/op	    2503 B/op	      74 allocs/op
BenchmarkBadgerDBPutValue256B-8   	   20000	     93480 ns/op	    2759 B/op	      74 allocs/op
BenchmarkBadgerDBPutValue512B-8   	   10000	    101407 ns/op	    3271 B/op	      74 allocs/op
BenchmarkBadgerDBGet-8            	 1000000	      1552 ns/op	     416 B/op	       9 allocs/op
BenchmarkBoltDBPutValue64B-8      	   10000	    203128 ns/op	   21231 B/op	      62 allocs/op
BenchmarkBoltDBPutValue128B-8     	    5000	    229568 ns/op	   13716 B/op	      64 allocs/op
BenchmarkBoltDBPutValue256B-8     	   10000	    196513 ns/op	   17974 B/op	      64 allocs/op
BenchmarkBoltDBPutValue512B-8     	   10000	    199805 ns/op	   17064 B/op	      64 allocs/op
BenchmarkBoltDBGet-8              	 1000000	      1122 ns/op	     592 B/op	      10 allocs/op
BenchmarkNutsDBPutValue64B-8      	   30000	     53614 ns/op	     626 B/op	      14 allocs/op
BenchmarkNutsDBPutValue128B-8     	   30000	     51998 ns/op	     664 B/op	      13 allocs/op
BenchmarkNutsDBPutValue256B-8     	   30000	     53958 ns/op	     920 B/op	      13 allocs/op
BenchmarkNutsDBPutValue512B-8     	   30000	     55787 ns/op	    1432 B/op	      13 allocs/op
BenchmarkNutsDBGet-8              	 2000000	       661 ns/op	      88 B/op	       3 allocs/op
BenchmarkNutsDBGetByHintKey-8     	   50000	     27255 ns/op	     840 B/op	      16 allocs/op
PASS
ok  	github.com/xujiajun/kvstore-bench	83.856s

visit https://github.com/xujiajun/nutsdb#benchmarks for detail.

[damnever]

I didn't go into details, as your benchmark shows, nutsdb is the simplest and fastest, it suites for the small projects(with small values?).

Here is a bit of advice, do some setup and clean up work for each benchmark case.

[xujiajun]

@damnever thanks your advice，but i don't know what you mean about doing some setup and cleaning up work for each benchmark case. I have use b.ResetTimer() to reset timer for each benchmark case and remove data before the case begining.

[olekukonko]

@damnever I think you should be less ambiguous and clearly state the issues.

[damnever]

Here is what I mean. :simple_smile:

• https://github.com/xujiajun/gokvstore-bench/blob/801c0e9f172127f44b3831fc240f9e956740eb0e/bench_badgerdb_test.go#L109-L111
• https://github.com/xujiajun/gokvstore-bench/blob/801c0e9f172127f44b3831fc240f9e956740eb0e/bench_nutsdb_test.go#L129-L133

[xujiajun]

@damnever hi, if have no more advises about this issue, i will close it.