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.
Feature | SQL | InfluxQL |
---|---|---|
WHERE clause | ||
GROUP BY clause | not supported | |
ORDER BY clause | partial support | |
HAVING | not supported | |
LIMIT and SLIMIT clauses | ||
OFFSET and SOFFSET clauses | ||
EXTRACT clause | not supported | |
CHAR_LENGTH clause | not supported | |
Timezone queries | not supported | not supported |
Subqueries | ||
Regular expressions | not supported | not supported |
CREATE statement | partial support | not supported |
INSERT statement | not supported | not supported |
UPDATE statement | not supported | |
DELETE statement | partial support example | |
DROP statement | partial support | partial support |
Aliases | ||
AS table alias | not supported | |
AS column alias | ||
JOIN clauses | ||
INNER join | not supported | |
OUTER join | not supported | |
CROSS join | not supported | |
Operators | ||
<, >, =, != (comparison operators) | ||
AND, OR (logical operators) | ||
not, IN, IS NULL, LIKE, EXISTS | not supported | |
BETWEEN | ||
Functions | ||
Window functions: ROW_NUMBER, RANK, DENSE_RANK | not supported | |
Aggregate functions: COUNT, MIN, MAX, AVG, SUM | 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 namedtime, which is a restricted phrase.
- STATUSvariable is not relevant to Influx database, because the connection is active only when data is transferred.
influx
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