Documentation

InfluxQL subqueries

An InfluxQL subquery is a query nested in the FROM clause of an InfluxQL query. The outer query queries results returned by the inner query (subquery).

InfluxQL does not support a HAVING clause, however InfluxQL subqueries offer functionality similar to the SQL HAVING clause.

Syntax

SELECT_clause FROM ( SELECT_statement ) [...]

When using subqueries, InfluxQL performs the inner query first, then performs the outer query.

The outer query requires a SELECT clause and a FROM clause. The inner query is enclosed in parentheses in the outer query’s FROM clause.

InfluxQL supports multiple nested subqueries:

SELECT_clause FROM ( SELECT_clause FROM ( SELECT_statement ) [...] ) [...]

Examples

Sample data

The examples below use the following sample data sets:

Apply an aggregate function to an aggregated result set

Calculate the average difference between two fields

Filter aggregate values based on a threshold

Perform additional aggregate operations on aggregate values

Notable subquery behaviors

Apply time bounds to the outer query to improve performance

To improve the performance of InfluxQL queries that use subqueries and a specified time range, apply the WHERE clause with time-based predicates to the outer query rather than the inner query. For example–the following queries return the same results, but the query with time-based predicate on the outer query is more performant than the query with time-based predicate on the inner query:

Time bounds on the outer query

SELECT
  inner_value AS value
FROM
  (
    SELECT
      raw_value as inner_value
  )
WHERE
  time >= '2022-01-01T08:00:00Z'
  AND time <= '2022-01-01T20:00:00Z'

Time bounds on the inner query

SELECT
  inner_value AS value
FROM
  (
    SELECT
      raw_value as inner_value
    WHERE
      time >= '2022-07-19T08:00:00Z'
      AND time <= '2022-01-01T20:00:00Z'
  )

Cannot use multiple SELECT statements in a subquery

InfluxQL does not support multiple SELECT statements per subquery:

SELECT_clause FROM (SELECT_statement; SELECT_statement) [...]

However, InfluxQL does support multiple nested subqueries per outer query:

SELECT_clause FROM ( SELECT_clause FROM ( SELECT_statement ) [...] ) [...]
                     ------------------   ----------------
                         Subquery 1          Subquery 2

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