gistfile1.txt

# Compression changes from L1 (no compression) to L2 (lz4). So trivial move is not done from 
# L1 to L2. But it starts again for L2 to L3 because both use lz4. However this is more complex
# because the tree starts with data in L0, then grows and uses L0,L1 then grows and uses L0,L1,L2.
# Describing that with physical names for the levels it starts with L0, then grows into L0,L6 and
# then grows into L0,L5,L6 and finally reaches L0,L4,L5,L6.

# Note that I used --min_level_compress=2. So when there is data in L0,L5,L6 then L6 (physical)
# is L2 (logical) and so L6 is compressed while L5 & L0 are not. At that point compaction from
# L0 to L5 can use trivial move (both levels have same compression type) but compacton from L5 to L6
# cannot (different compression types).

# This is why there is a mix of trivial move and proper compaction for L6.

# Above I use logical names for the levels while compaction IO stats below uses the physical
# names. This is a source of confusion because of the way that dynamic leveled compaction adds
# levels as the LSM tree grows. It starts with L0, then adds Lmax, then adds Lmax-1, ... and
# below there is data in L0, L4, L5, L6 where L6=Lmax.

M1=$(( 1024 * 1024 )); ./db_bench --benchmarks=fillseq,stats \
 --db_write_buffer_size=$(( $M1 * 8 )) \
 --target_file_size_base=$(( $M1 * 8 )) \
 --max_bytes_for_level_base=$(( $M1 * 32 )) \
 --level0_file_num_compaction_trigger=4 \
 --level0_slowdown_writes_trigger=20 \
 --level0_stop_writes_trigger=30 \
 --level_compaction_dynamic_level_bytes=true \
 --num=$(( $M1 * 16 )) \
 --min_level_to_compress=2 \
 --compression_type=lz4

Set seed to 1648995247827258 because --seed was 0
Initializing RocksDB Options from the specified file
Initializing RocksDB Options from command-line flags
RocksDB:    version 7.1
Date:       Sun Apr  3 07:14:07 2022
CPU:        32 * Intel Xeon Processor (Skylake)
CPUCache:   16384 KB
Keys:       16 bytes each (+ 0 bytes user-defined timestamp)
Values:     100 bytes each (50 bytes after compression)
Entries:    16777216
Prefix:    0 bytes
Keys per prefix:    0
RawSize:    1856.0 MB (estimated)
FileSize:   1056.0 MB (estimated)
Write rate: 0 bytes/second
Read rate: 0 ops/second
Compression: LZ4
Compression sampling rate: 0
Memtablerep: SkipListFactory
Perf Level: 1
------------------------------------------------
Initializing RocksDB Options from the specified file
Initializing RocksDB Options from command-line flags
DB path: [/tmp/rocksdbtest-2260/dbbench]
fillseq      :       4.018 micros/op 248882 ops/sec;   27.5 MB/s


** Compaction Stats [default] **
Level    Files   Size     Score Read(GB)  Rn(GB) Rnp1(GB) Write(GB) Wnew(GB) Moved(GB) W-Amp Rd(MB/s) Wr(MB/s) Comp(sec) CompMergeCPU(sec) Comp(cnt) Avg(sec) KeyIn KeyDrop Rblob(GB) Wblob(GB)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  L0      3/0   15.13 MB   0.8      0.0     0.0      0.0       1.9      1.9       0.0   1.0      0.0    152.0     12.80              6.59       386    0.033       0      0       0.0       0.0
  L4      6/0   30.25 MB   0.9      0.0     0.0      0.0       0.0      0.0       1.3   0.0      0.0      0.0      0.00              0.00         0    0.000       0      0       0.0       0.0
  L5     35/0   92.30 MB   1.0      1.3     1.3      0.0       0.7      0.7       0.6   0.5    139.4     72.9      9.26              8.63       256    0.036     11M      0       0.0       0.0
  L6    342/0   933.15 MB   0.0      0.5     0.5      0.0       0.3      0.3       0.6   0.5    137.8     72.1      3.95              3.66       108    0.037   4684K      0       0.0       0.0
 Sum    386/0    1.05 GB   0.0      1.8     1.8      0.0       2.8      2.8       2.5   1.5     70.6    111.7     26.01             18.89       750    0.035     15M      0       0.0       0.0
 Int      0/0    0.00 KB   0.0      1.8     1.8      0.0       2.8      2.8       2.4   1.5     72.2    111.1     25.42             18.60       734    0.035     15M      0       0.0       0.0

** Compaction Stats [default] **
Priority    Files   Size     Score Read(GB)  Rn(GB) Rnp1(GB) Write(GB) Wnew(GB) Moved(GB) W-Amp Rd(MB/s) Wr(MB/s) Comp(sec) CompMergeCPU(sec) Comp(cnt) Avg(sec) KeyIn KeyDrop Rblob(GB) Wblob(GB)
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Low      0/0    0.00 KB   0.0      1.8     1.8      0.0       0.9      0.9       0.0   0.0    139.0     72.7     13.21             12.30       364    0.036     15M      0       0.0       0.0
High      0/0    0.00 KB   0.0      0.0     0.0      0.0       1.9      1.9       0.0   0.0      0.0    152.0     12.80              6.59       386    0.033       0      0       0.0       0.0

Blob file count: 0, total size: 0.0 GB, garbage size: 0.0 GB, space amp: 0.0

Uptime(secs): 67.4 total, 64.4 interval
Flush(GB): cumulative 1.901, interval 1.822
AddFile(GB): cumulative 0.000, interval 0.000
AddFile(Total Files): cumulative 0, interval 0
AddFile(L0 Files): cumulative 0, interval 0
AddFile(Keys): cumulative 0, interval 0
Cumulative compaction: 2.84 GB write, 43.11 MB/s write, 1.79 GB read, 27.22 MB/s read, 26.0 seconds
Interval compaction: 2.76 GB write, 43.87 MB/s write, 1.79 GB read, 28.50 MB/s read, 25.4 seconds
Stalls(count): 0 level0_slowdown, 0 level0_slowdown_with_compaction, 0 level0_numfiles, 0 level0_numfiles_with_compaction, 0 stop for pending_compaction_bytes, 0 slowdown for pending_compaction_bytes, 0 memtable_compaction, 0 memtable_slowdown, interval 0 total count
Block cache LRUCache@0x7f8fdba29290#2356776 capacity: 8.00 MB collections: 1 last_copies: 1 last_secs: 0.000101 secs_since: 67
Block cache entry stats(count,size,portion): WriteBuffer(1,256.00 KB,3.125%) Misc(1,0.00 KB,0%)

** File Read Latency Histogram By Level [default] **

** DB Stats **
Uptime(secs): 67.4 total, 64.4 interval
Cumulative writes: 16M writes, 16M keys, 16M commit groups, 1.0 writes per commit group, ingest: 2.05 GB, 31.09 MB/s
Cumulative WAL: 16M writes, 0 syncs, 16777216.00 writes per sync, written: 2.05 GB, 31.09 MB/s
Cumulative stall: 00:00:0.000 H:M:S, 0.0 percent
Interval writes: 16M writes, 16M keys, 16M commit groups, 1.0 writes per commit group, ingest: 2003.85 MB, 31.11 MB/s
Interval WAL: 16M writes, 0 syncs, 16039640.00 writes per sync, written: 1.96 GB, 31.11 MB/s
Interval stall: 00:00:0.000 H:M:S, 0.0 percent