# MyRocks Performance Troubleshooting

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

```sql
SHOW STATUS LIKE 'Rocksdb%'
```

See [MyRocks Status Variables](https://mariadb.com/docs/server/server-usage/storage-engines/myrocks/myrocks-status-variables) for more information.

### SHOW ENGINE ROCKSDB STATUS

This produces a lot of information.

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:

* [INFORMATION\_SCHEMA.ROCKSDB\_PERF\_CONTEXT\_GLOBAL](https://mariadb.com/docs/server/reference/system-tables/information-schema/information-schema-tables/information-schema-myrocks-tables/information-schema-rocksdb_perf_context_global-table) - global counters
* [INFORMATION\_SCHEMA.ROCKSDB\_PERF\_CONTEXT](https://mariadb.com/docs/server/reference/system-tables/information-schema/information-schema-tables/information-schema-myrocks-tables/information-schema-rocksdb_perf_context-table) - Per-table/partition counters

By default statistics are NOT collected. One needs to set [rocksdb\_perf\_context\_level](https://mariadb.com/docs/server/server-usage/storage-engines/myrocks-system-variables#rocksdb_perf_context_level) to some value (e.g. 3) to enable collection.

<sub>*This page is licensed: CC BY-SA / Gnu FDL*</sub>

{% @marketo/form formId="4316" %}


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://mariadb.com/docs/server/server-usage/storage-engines/myrocks/myrocks-performance-troubleshooting.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.