Details

    • Type: New Feature
    • Status: Done
    • Priority: Medium
    • Resolution: Won't Do
    • Affects Version/s: None
    • Fix Version/s: None
    • Labels:
      None

      Description

      mysql> show engine rocksdb status\G
      *************************** 1. row ***************************
        Type: DBSTATS
        Name: rocksdb
      Status: 
      ** DB Stats **
      Uptime(secs): 89725.6 total, 36.8 interval
      Cumulative writes: 8 writes, 11 keys, 8 commit groups, 0.9 writes per commit group, ingest: 0.00 GB, 0.00 MB/s
      Cumulative WAL: 8 writes, 3 syncs, 2.00 writes per sync, written: 0.00 GB, 0.00 MB/s
      Cumulative stall: 00:00:0.000 H:M:S, 0.0 percent
      Interval writes: 3 writes, 4 keys, 3 commit groups, 0.8 writes per commit group, ingest: 0.00 MB, 0.00 MB/s
      Interval WAL: 3 writes, 0 syncs, 3.00 writes per sync, written: 0.00 MB, 0.00 MB/s
      Interval stall: 00:00:0.000 H:M:S, 0.0 percent
      ** Level 0 read latency histogram (micros):
      Count: 5 Average: 2.2000  StdDev: 2.32
      Min: 0  Median: 0.8333  Max: 5
      Percentiles: P50: 0.83 P75: 4.38 P99: 4.97 P99.9: 5.00 P99.99: 5.00
      ------------------------------------------------------
      [       0,       1 )        3  60.000%  60.000% ############
      [       4,       5 )        2  40.000% 100.000% ########
      
      
      *************************** 2. row ***************************
        Type: CF_COMPACTION
        Name: __system__
      Status: 
      ** Compaction Stats [__system__] **
      Level    Files   Size(MB} Score Read(GB}  Rn(GB} Rnp1(GB} Write(GB} Wnew(GB} Moved(GB} W-Amp Rd(MB/s} Wr(MB/s} Comp(sec} Comp(cnt} Avg(sec} KeyIn KeyDrop
      ----------------------------------------------------------------------------------------------------------------------------------------------------------
        L0      2/0       0.00   0.5      0.0     0.0      0.0       0.0      0.0       0.0   0.0      0.0      0.6         0         1    0.002       0      0
       Sum      2/0       0.00   0.0      0.0     0.0      0.0       0.0      0.0       0.0   1.0      0.0      0.6         0         1    0.002       0      0
       Int      0/0       0.00   0.0      0.0     0.0      0.0       0.0      0.0       0.0   1.0      0.0      0.6         0         1    0.002       0      0
      Uptime(secs): 89725.6 total, 89725.6 interval
      Flush(GB): cumulative 0.000, interval 0.000
      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: 0.00 GB write, 0.00 MB/s write, 0.00 GB read, 0.00 MB/s read, 0.0 seconds
      Interval compaction: 0.00 GB write, 0.00 MB/s write, 0.00 GB read, 0.00 MB/s read, 0.0 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
      
      *************************** 3. row ***************************
        Type: CF_COMPACTION
        Name: default
      Status: 
      ** Compaction Stats [default] **
      Level    Files   Size(MB} Score Read(GB}  Rn(GB} Rnp1(GB} Write(GB} Wnew(GB} Moved(GB} W-Amp Rd(MB/s} Wr(MB/s} Comp(sec} Comp(cnt} Avg(sec} KeyIn KeyDrop
      ----------------------------------------------------------------------------------------------------------------------------------------------------------
        L0      1/0       0.00   0.2      0.0     0.0      0.0       0.0      0.0       0.0   0.0      0.0      0.4         0         1    0.003       0      0
       Sum      1/0       0.00   0.0      0.0     0.0      0.0       0.0      0.0       0.0   1.0      0.0      0.4         0         1    0.003       0      0
       Int      0/0       0.00   0.0      0.0     0.0      0.0       0.0      0.0       0.0   1.0      0.0      0.4         0         1    0.003       0      0
      Uptime(secs): 89725.6 total, 89725.6 interval
      Flush(GB): cumulative 0.000, interval 0.000
      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: 0.00 GB write, 0.00 MB/s write, 0.00 GB read, 0.00 MB/s read, 0.0 seconds
      Interval compaction: 0.00 GB write, 0.00 MB/s write, 0.00 GB read, 0.00 MB/s read, 0.0 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
      
      *************************** 4. row ***************************
        Type: Memory_Stats
        Name: rocksdb
      Status: 
      MemTable Total: 3768
      MemTable Unflushed: 1712
      Table Readers Total: 0
      Cache Total: 450
      Default Cache Capacity: 0
      4 rows in set (0.00 sec)

      DB Stats

      This section provides information on overall statistics of the databases. Most of the fields are self explanatory but are listed here.

      • Uptime - in seconds, the total time the system has been up.
      • Interval refers to the length of the last statistics collection period.
      • Write Status - Total number of write batches, the total number of keys in those batches, the size of the writes and the write throughput are reported.
      • WAL - On a PUT, the record will also be written to Write Ahead Log. Total number of writes to WAL, the throughput and the number of fsync/fdatasync that happened are also reported.
      • Keys - Total number of keys in the RocksDB engine.
      • Ingest - Total Data ingested and ingestion rate in MBytes per second.
      • Average number of Writes per sync for WAL ( this gives a rough idea of how many writes might be lost on a crash ).

      There is information also on stalls encountered in the engine. The above statistics are reported on a cumulative and interval basis

      Read Latency section

      This section lists the latency of reads encountered for the different levels of the LSM in RocksDB (Log Structured Merge Tree).

      Typical latencies can be in the low microseconds, as keys are found in the memtable and block cache, but if there is a cache miss or a key is found in lower levels, the latencies go up. This is because more number of SST files will need to be read, and more binary searches need to be done.

      Column Family Compaction Statistics section.

      There is one set of statistics for each column family, including the system column family. Please refer to RocksDB wiki for more information on LSM and Column Families.

      The first subsection lists the count and size of the files @ each level for the Column family.

      • Rn(GB) - refers to total read at non output level
      • Rnp1(GB) - refers to read volume at output level.

      Followed the levelized output, is general compaction statistics for that column family.

      Memory statistics section

      • MemTable Unflushed - Size of memtable that has not been flushed to SST files.
      • Cache Total - Size of block cache

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                • Assignee:
                  alexey.palazhchenko Alexey Palazhchenko
                  Reporter:
                  michael.coburn@percona.com Michael Coburn
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                    Updated:
                    Resolved: