Query Management

With InfluxDB’s query management features, users are able to identify currently-running queries, kill queries that are overloading their system, and prevent and halt the execution of inefficient queries with several configuration settings.

List currently-running queries with SHOW QUERIES

SHOW QUERIES lists the query ID, query text, relevant database, and duration of all currently-running queries on your InfluxDB instance. For InfluxDB Enterprise clusters, the SHOW QUERIES output also includes the TCP host.

Syntax:

SHOW QUERIES

Example:

> SHOW QUERIES
qid query                               database duration status
--- -----                               -------- -------- ------
37  SHOW QUERIES                                 100368u  running
36  SELECT mean(myfield) FROM mymeas    mydb     3s       running

Explanation of the output:

• qid: The ID number of the query.
• query: The query text.
• database: The database targeted by the query.
• duration: The length of time that the query has been running.
• status: Current status of the query when SHOW QUERIES was executed.

See Query Language Reference for an explanation of InfluxDB’s time units.

Stop currently-running queries with KILL QUERY

KILL QUERY tells InfluxDB to stop running the relevant query.

Syntax:

Where qid is the query ID, displayed in the SHOW QUERIES output:

KILL QUERY <qid>

InfluxDB Enterprise clusters: To kill queries on a cluster, you need to specify the query ID (qid) and the TCP host (for example, myhost:8088), available in the SHOW QUERIES output.

KILL QUERY <qid> ON "<host>"

A successful KILL QUERY query returns no results.

Examples:

-- kill query with qid of 36 on the local host
> KILL QUERY 36
>

-- kill query on InfluxDB Enterprise cluster
> KILL QUERY 53 ON "myhost:8088"
>

Configuration settings for query management

The following configuration settings are in the [coordinator] section of the configuration file.

max-concurrent-queries

The maximum number of running queries allowed on your instance. The default setting (0) allows for an unlimited number of queries.

If you exceed max-concurrent-queries, InfluxDB does not execute the query and outputs the following error:

ERR: max concurrent queries reached

query-timeout

The maximum time for which a query can run on your instance before InfluxDB kills the query. The default setting ("0") allows queries to run with no time restrictions. This setting is a duration literal.

If your query exceeds the query timeout, InfluxDB kills the query and outputs the following error:

ERR: query timeout reached

log-queries-after

The maximum time a query can run after which InfluxDB logs the query with a Detected slow query message. The default setting ("0") will never tell InfluxDB to log the query. This setting is a duration literal.

Example log output with log-queries-after set to "1s":

[query] 2016/04/28 14:11:31 Detected slow query: SELECT mean(usage_idle) FROM cpu WHERE time >= 0 GROUP BY time(20s) (qid: 3, database: telegraf, threshold: 1s)

qid is the id number of the query. Use this value with KILL QUERY.

The default location for the log output file is /var/log/influxdb/influxdb.log. However on systems that use systemd (most modern Linux distributions) those logs are output to journalctl. You should be able to view the InfluxDB logs using the following command: journalctl -u influxdb

max-select-point

The maximum number of points that a SELECT statement can process. The default setting (0) allows the SELECT statement to process an unlimited number of points.

If your query exceeds max-select-point, InfluxDB kills the query and outputs the following error:

ERR: max number of points reached

max-select-series

The maximum number of series that a SELECT statement can process. The default setting (0) allows the SELECT statement to process an unlimited number of series.

If your query exceeds max-select-series, InfluxDB does not execute the query and outputs the following error:

ERR: max select series count exceeded: <query_series_count> series

max-select-buckets

The maximum number of GROUP BY time() buckets that a query can process. The default setting (0) allows a query to process an unlimited number of buckets.

If your query exceeds max-select-buckets, InfluxDB does not execute the query and outputs the following error:

ERR: max select bucket count exceeded: <query_bucket_count> buckets