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Version: 0.14

Window join

In this page, you will see how to write window join in SELECT statements. See window to understand the concept around windowing in SpringQL.

Understanding on [INNER | OUTER] JOIN in standard SQL is also required, so learn a bit about it before writing SpringQL's queries.

Inner join​

Currently unsupported.

Outer join​

Currently, only left-outer join is supported.

Left-outer join
SELECT STREAM
    <expression> [AS <alias>]source_trade.ts,
    <, ...>*
FROM <stream name>
LEFT OUTER JOIN <stream name>
    ON <expression resulted in BOOLEAN>
[FIXED | SLIDING] WINDOW <time-based width in DURATION>, <allowed latency in DURATION>;
Example (10-sec fixed window; 1-sec allowed latency)
SELECT STREAM
    source_trade.ts,
    source_trade.amount,
    source_city_temperature.temperature
FROM source_trade
LEFT OUTER JOIN source_city_temperature
    ON source_trade.ts = source_city_temperature.ts
FIXED WINDOW DURATION_SECS(10), DURATION_SECS(1);