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I have a cockroachdb instance running in production and would like to know the settings for the --max-sql-memory and --cache specified when the database was started. I am trying to enhance performance by following this production checklist but I am not able infer the setting either on dashboard or sql console.

Where can I check the values of max-sql-memory and cache value ?

Note: I am able to access the cockroachdb admin console and sql tables.

Anshuman Tiwari
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1 Answers1

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You can find this information in the logs, shortly after node startup:

I190626 10:22:47.714002 1 cli/start.go:1082  CockroachDB CCL v19.1.2 (x86_64-unknown-linux-gnu, built 2019/06/07 17:32:15, go1.11.6)
I190626 10:22:47.815277 1 server/status/recorder.go:610  available memory from cgroups (8.0 EiB) exceeds system memory 31 GiB, using system memory
I190626 10:22:47.815311 1 server/config.go:386  system total memory: 31 GiB
I190626 10:22:47.815411 1 server/config.go:388  server configuration:
max offset             500000000
cache size             7.8 GiB  <====
SQL memory pool size   7.8 GiB  <====
scan interval          10m0s
scan min idle time     10ms
scan max idle time     1s
event log enabled      true

If the logs have been rotated, the value depends on the flags. The defaults for v19.1 are 128MB, with recommended settings being 0.25 (a quarter of system memory).

The settings are not currently logged periodically or exported through metrics.

Marc
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  • So currently, there is no way to check these settings for an already running instance if the logs have been deleted ? – Anshuman Tiwari Jun 26 '19 at 11:52
  • That's correct. Please feel free to file [an issue](https://github.com/cockroachdb/cockroach/issues) to expose those at runtime. That said, looking at the current command line flags for your node should tell you what it is. If you do not have access to the VM running the nodes, you can find the command line invocation on the admin UI: `nodeaddress:8080/debug/metrics`. – Marc Jun 26 '19 at 12:06
  • That solved my problem. Fortunately the logs were still there and I was able to find the required fields. Thanks a ton @Marc :) – Anshuman Tiwari Jun 26 '19 at 14:07