docs-v2/content/influxdb/clustered/query-data/troubleshoot-and-optimize/troubleshoot.md

title	description	weight	menu	influxdb/clustered/tags	related	aliases
Troubleshoot queries	Troubleshoot SQL and InfluxQL queries in InfluxDB.	201	influxdb_clustered name parent Troubleshoot queries Troubleshoot and optimize queries	query performance observability errors sql influxql	/influxdb/clustered/query-data/sql/ /influxdb/clustered/query-data/influxql/ /influxdb/clustered/reference/client-libraries/v3/	/influxdb/clustered/query-data/execute-queries/troubleshoot/

Troubleshoot SQL and InfluxQL queries that return unexpected results.

• Why doesn't my query return data?
• Optimize slow or expensive queries

Why doesn't my query return data?

If a query doesn't return any data, it might be due to the following:

• Your data falls outside the time range (or other conditions) in the query--for example, the InfluxQL SHOW TAG VALUES command uses a default time range of 1 day.

• The query (InfluxDB server) timed out.

• The query client timed out.

• The query return type is not supported by the client library. For example, array or list types may not be supported. In this case, use array_to_string() to convert the array value to a string--for example:

  SELECT array_to_string(array_agg([1, 2, 3]), ', ')
  

If a query times out or returns an error, it might be due to the following:

• a bad request
• a server or network problem
• it queries too much data

Understand Arrow Flight responses and error messages for queries.

Optimize slow or expensive queries

If a query is slow or uses too many compute resources, limit the amount of data that it queries.

See how to optimize queries and use tools to view runtime metrics, identify bottlenecks, and debug queries.