Find hotspots in your Spanner Omni database

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This document describes how to diagnose hotspots, or queries with high CPU usage, in your Spanner Omni databases. The process for diagnosing hotspots is mostly identical to Spanner hotspot diagnosis, with the following distinctions:

• The Spanner Omni system insights dashboard is available in Grafana. For more information on how to set up this dashboard, see set up Grafana.

• Instead of going to the Google Cloud console to query SPANNER_SYS.* tables, you query your database directly using the Spanner Omni CLI. For example, the following query shows the data splits with the highest CPU usage over the past 5 hours in the database, and ranks them by CPU usage:

  spanner sql \
  --database DATABASE_ID --execute \
  "SELECT * \
  FROM SPANNER_SYS.SPLIT_STATS_TOP_MINUTE \
  WHERE INTERVAL_END > TIMESTAMP_SUB(CURRENT_TIMESTAMP(), \
  INTERVAL 5 HOUR) \
  ORDER BY CPU_USAGE_SCORE DESC"
  

  Replace DATABASE_ID with the database identifier—for example, MY_DATABASE.

Known issues

• If the total compute capacity of your Spanner Omni deployment is less than 3.5 vCPU per server, the split CPU usage scores in the SPANNER_SYS.* tables might be lower than the correct scores on the system insights dashboard. The dashboard shows the correct split CPU usage scores, but you need to query the SPANNER_SYS.* tables to identify the splits that correspond to those scores.