Import range query improvements

[Yuval-Ariel]

Why:
Seek is a commonly used operation with rocksdb. Improving it can significantly improve the overall performance of the application.
improve short seek performance with large amount of levels that don’t have much overlap

What :
Improve the creation of range filters to hold less irrelevant items and reducing the seek times

[ayulas]

to use the spdb range query builder you need to set use_spdb_query_builder to true

[erez-speedb]

No improvements, no degradation.

Short test
https://admin.speedb.io/performance?items=Z11dnyIhlJtJqGjvsfjS&items=eqd36PbjSouloFRQQM2e&colors=%23F06292&colors=%2300796b
Small obj
https://admin.speedb.io/performance?items=v2QiIvfovkv3t6sogZyc&items=efkS8brnN9uNii7vjhTA&colors=%23F06292&colors=%2300796b
Large Obj
https://admin.speedb.io/performance?items=NT67puzyBrSIIBk4MhIp&items=8XHUSwkEKQRY3slFXvWo&colors=%23F06292&colors=%2300796b

[isaac-io]

We need a db_bench scenario to showcase the best case where this might show an improvement (e.g. with universal compaction).

[isaac-io]

Currently some of the unit tests are failing. We want to show a scenario with improvement first before we commit to fixing them.

[Yuval-Ariel]

test plan is as follows:

• compare Import range query improvements #13 (df98b70) with v7.2.2 (f2f26b1)
• achieve IO-bound workload so that additional seeks are noticed in the ops/sec
• do seek combined with writes so that the number of levels (internal iterators) is not constant. (the problem with running seeks without writes is that one run could have 10 internal iterators while the other has 11 throughout the test which would naturally introduce unwanted bias in the results)
• use a setup which has many sorted runs and target seek key is sometimes not in range, since the purpose of the optimization is to save unneeded seeks when the target key is not in the range of the internal iterator. e.g. universal compaction and seek to 10X the num in fillup.

fillup cmd:

./db_bench --benchmarks=fillseq --level0_file_num_compaction_trigger=8 --compression_type=None --level0_slowdown_writes_trigger=20 --level0_stop_writes_trigger=30 --max_background_flushes=4 --max_background_compactions=12 --max_write_buffer_number=4 --db=/data/ --num=150000000 --num_levels=40 --key_size=50 --value_size=1000 --block_size=8192 --verify_checksum=1 --delete_obsolete_files_period_micros=62914560 --max_bytes_for_level_multiplier=8 --memtablerep=skip_list --open_files=-1 --compaction_style=1 --universal_compression_size_percent=80 --universal_min_merge_width=2 --universal_max_merge_width=20 --universal_size_ratio=1 --universal_max_size_amplification_percent=200 --universal_allow_trivial_move=1 --universal_compression_size_percent=-1 --sync=0 --threads=1 --seed=1649982947

1st seek cmd:

./db_bench --benchmarks=seekrandomwhilewriting --compression_type=None –cache_size=10737418240 --delayed_write_rate=536870912 --level0_file_num_compaction_trigger=8 --level0_slowdown_writes_trigger=20 --level0_stop_writes_trigger=30 --max_background_flushes=4 --max_background_compactions=1 --max_write_buffer_number=4 --db=/data/ --num=1500000000 --num_levels=40 --key_size=50 --value_size=1000 --block_size=8192 --write_buffer_size=16777216 --target_file_size_base=16777216 --verify_checksum=1 --delete_obsolete_files_period_micros=62914560 --report_interval_seconds=5 --memtablerep=skip_list --open_files=-1 --compaction_style=1 --universal_compression_size_percent=80 --universal_min_merge_width=2 --universal_max_merge_width=20 --universal_size_ratio=1 --universal_max_size_amplification_percent=200 --universal_allow_trivial_move=1 --universal_compression_size_percent=-1 --use_existing_db=1 --sync=0 --threads=10 --seed=1649982947 -duration=900

results:

1st

13:___ 250.735 micros/op 39880 ops/sec; (375342 of 3604999 found)
base:_ 239.131 micros/op 39492 ops/sec; (389445 of 3699999 found)

2nd

same as 1st seek cmd with modifications --threads=2 -duration=1800
13:___ 222.335 micros/op 8995 ops/sec; (1062929 of 8111999 found)
base:_ 227.083 micros/op 8806 ops/sec; (1030695 of 7948999 found)

3rd

same as 1st seek cmd with modifications --num=4500000000(30X fillup num) -open_files=27000
(open files was set since there was a crash of too many open files (limit is 30000))
13:___ 301.155 micros/op 33202 ops/sec; (168579 of 2998999 found)
base:_ 276.143 micros/op 36209 ops/sec; (178650 of 3246999 found)
8% worse

4rth

repetition of 3rd
13:___ 429.774 micros/op 22918 ops/sec; (121471 of 2080999 found)
base:_ 341.864 micros/op 29246 ops/sec; (153157 of 2634999 found)
21% worse

5th

another rep of 3rd
13:___ 321.832 micros/op 31068 ops/sec; (162358 of 2775999 found)
base:_ 671.295 micros/op 10180 ops/sec; (78182 of 1340999 found)
200% better

6th

another rep but 1hr duration
13:___ 480.577 micros/op 20806 ops/sec; (469218 of 7483999 found)
base:_ 449.047 micros/op 20678 ops/sec; (504404 of 8018999 found)

7th

another rep but 10hr duration with --perf_level=5 --statistics=1
13:___ 1154.879 micros/op 8658 ops/sec; (3330073 of 31190999 found)
base:_ 1299.046 micros/op 7244 ops/sec; (2912547 of 27711999 found)
20% better

perf results:

13 performance.xlsx
the first 3 results (-1 , -2 , -3) are not from the above experiment but from similar ones
the -10hr is the 7th rep from above.
confusing results. the variance in the results is very high in certain metrics and the trend in the 10hr is sometimes in contradiction to the first 3.
we expect seek_child_seek_time and count to be lower in #13 but it doesnt seem to be the case which raises speculation to how efficient the setup was.
one metric which is constant for all 4 tests is db_mutex_lock_nanos which is higher by about 23 % in #13 .

next step

further discussion is required regarding these results

[isaac-io]

Should only be relevant for Hybrid compaction.