Regular expressions
Regular expressions are a sequence of characters used to identify patterns in identifiers and string values. InfluxQL supports regular expressions in the following operations:
- Identifying fields and tags to query in the
SELECT
clause. - Identifying measurements to query in the
FROM
clause. - Testing tag values and string field values in the
WHERE
clause. - Identifying tag keys to group by in the
GROUP BY
clause
Query performance
Regular expression comparisons are more computationally intensive than exact string comparisons. Queries with regular expressions are not as performant as those without.
Regular expression syntax
InfluxQL Regular expressions are surrounded by /
characters and use the
Go regular expression syntax.
/regular_expression/
Regular expression flags
Regular expression flags modify the pattern-matching behavior of the expression. InfluxQL supports the following regular expression flags:
Flag | Description |
---|---|
i | case-insensitive |
m | multi-line mode: ^ and $ match begin/end line in addition to begin/end text |
s | let . match \n |
U | ungreedy: swap meaning of x* and x*? , x+ and x+? , etc. |
Include regular expression flags at the beginning of your regular expression
pattern enclosed in parentheses (()
) and preceded by a question mark (?
).
/(?iU)foo*/
Regular expression operators
InfluxQL provides the following regular expression operators that test if a string operand matches a regular expression:
=~
: Returns true if the string matches the regular expression!~
: Returns true if the string does not match the regular expression
InfluxQL regular expression operators are used to test string column values in
the WHERE
clause.
Regular expression examples
The examples below use the following sample data sets:
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