Influx database limitations

Influx database use in
FactoryTalk Optix
has specific limitations, which are described in this section.

SQL support

Influx database does not directly support SQL. A parser translates the SQL queries to Influx-based query language. Only specific SQL commands are supported.
SQL and InfluxQL comparison
Feature
SQL
InfluxQL
WHERE clause
Yes
Yes
GROUP BY clause
Yes
not supported
ORDER BY clause
Yes
partial support
HAVING
Yes
not supported
LIMIT and SLIMIT clauses
Yes
Yes
OFFSET and SOFFSET clauses
Yes
Yes
EXTRACT clause
Yes
not supported
CHAR_LENGTH clause
Yes
not supported
Timezone queries
not supported
not supported
Subqueries
Yes
Yes
Regular expressions
not supported
not supported
CREATE statement
partial support
not supported
INSERT statement
not supported
not supported
UPDATE statement
Yes
not supported
DELETE statement
Yes
partial support example
DROP statement
partial support
partial support
Aliases
AS table alias
Yes
not supported
AS column alias
Yes
Yes
JOIN clauses
INNER join
Yes
not supported
OUTER join
Yes
not supported
CROSS join
Yes
not supported
Operators
<, >, =, != (comparison operators)
Yes
Yes
AND, OR (logical operators)
Yes
Yes
not, IN, IS NULL, LIKE, EXISTS
Yes
not supported
BETWEEN
Yes
Yes
Functions
Window functions: ROW_NUMBER, RANK, DENSE_RANK
Yes
not supported
Aggregate functions: COUNT, MIN, MAX, AVG, SUM
Yes
partial support

Other limitations

  • Influx database is sensitive on time data. Time on the source device and on the database device must be synchronized to keep data consistency. Data record with the same timestamp is overwritten by Influx, so you must carefully design data structure of the database side.
  • Influx may not add record for column custom named
    time
    , which is a restricted phrase.
  • STATUS
    variable is not relevant to Influx database, because the connection is active only when data is transferred.
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