The Hydrolix query language is an ANSI-compliant SQL, based on the Yandex ClickHouse SQL language. Queries are passed via the Hydrolix Query API which offers programmatic access to your data.
To query data,
- Ingest some data
- Construct the WHERE clause
- Define the query conditions
- Execute the query against the Query API
When querying Hydrolix, it is important to follow these steps:
- Specify the project name and the table name within the FROM portion of the SELECT statement separated by a period (.).
SELECT …… FROM project_name.table_name WHERE ……
- Specify a view schema
Hydrolix has the notion that a single data set can have different query data structures. The query data structure, or view schema allows for a user's access to a data set to be restricted to a set of columns, but can also be used to set the data type for a column. For example, something that is stored as a number may also need to be operated on as a string sometimes.
If no view is specified and a default view has been defined, the view schema is not required as part of the SQL.
When referencing data in tables, a time specification within a WHERE predicate is required. This predicate should reference the primary datetime column that was specified in the transform schema when the data was ingested.
SELECT count(timestamp) AS count FROM my_first_project.the_table WHERE (timestamp BETWEEN ‘1977-04-25 00:00:00’ AND ‘2010-04-25 23:00:00’)
- Define the rest of the query.
- Execute the query
Queries are sent to Hydrolix via the Query API. The only required parameter is "query" to pass in the query. Query results are returned as JSON.
Updated 4 months ago