To support features like:
Lenses SQL Engine Streaming mode needs to have up-to-date schema information for all structured topics that are used as input
in a given query. In this context, structured means topics that are using complex storage formats like AVRO or JSON.
INSERT INTO daily-item-purchases-stats
, COUNT(*) as dailyPurchases
, AVG(price / quantity) as average_per_unit
WINDOW BY TUMBLE 1d
GROUP BY itemId;
For the above query, for example, the purchases topic will need to have a value set to a structured format and a
valid schema will need to already have been configured in Lenses. In such schema, fields itemId, price and
quantity must be defined, the latter two being of a numerical type.
These requirements ensure the Engine will always in a position to know what kind of data it will be working with,
guaranteeing at the same time that all obvious errors are caught before a query is submitted.
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