The Ultimate Guide to High Availability with MariaDB

MyRocks performance troubleshooting

You are viewing an old version of this article. View the current version here.

MyRocks exposes its performance metrics through several interfaces:

  • Status variables
  • SHOW ENGINE ROCKSDB STATUS
  • RocksDB's perf context

the contents slightly overlap, but each source has its own unique information, so be sure to check all three.

Status variables

Check the output of

SHOW STATUS like 'Rocksdb%'

h2. SHOW ENGINE ROCKSDB STATUS

This produces a lot of infrormation.

One particularly interesting part is compaction statistics. It shows the amount of data on each SST level and other details:

*************************** 4. row ***************************
  Type: CF_COMPACTION
  Name: default
Status: 
** 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) Comp(cnt) Avg(sec) KeyIn KeyDrop
----------------------------------------------------------------------------------------------------------------------------------------------------------
  L0      3/0   30.16 MB   1.0      0.0     0.0      0.0      11.9     11.9       0.0   1.0      0.0     76.6       159       632    0.251       0      0
  L1      5/0   247.54 MB   1.0      0.7     0.2      0.5       0.5      0.0      11.6   2.6     58.5     44.1        12         4    2.926     30M    10M
  L2    112/0    2.41 GB   1.0      0.6     0.0      0.6       0.5     -0.1      11.4  43.4     55.2     45.9        11         1   10.827     21M  3588K
  L3    466/0    8.91 GB   0.4      0.0     0.0      0.0       0.0      0.0       8.9   0.0      0.0      0.0         0         0    0.000       0      0
 Sum    586/0   11.59 GB   0.0      1.3     0.2      1.0      12.8     11.8      32.0   1.1      7.1     72.6       181       637    0.284     52M    13M
 Int      0/0    0.00 KB   0.0      0.9     0.1      0.8       0.8      0.0       0.1  20.5     48.4     45.3        19         6    3.133     33M  3588K

Performance context

RocksDB has an internal mechanism called "perf context". The counter values are exposed through two tables:

By default statistics are NOT collected. One needs to set rocksdb_perf_context_level to some value (e.g. 3) to enable collection.

Comments

Comments loading...
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.