两种temporal join方式，首选哪一种

Question

我正在 https://ci.apache.org/projects/flink/flink-docs-release-1.13/docs/dev/table/sql/queries/joins/#processing-time-temporal-join、

读书

它正在使用语法 JOIN ... FOR SYSTEM_TIME AS OF 进行时间连接，如下所示

SELECT
  o.amount, o.currency, r.rate, o.amount * r.rate
FROM
  Orders AS o
  JOIN LatestRates FOR SYSTEM_TIME AS OF o.proctime AS r
  ON r.currency = o.currency

还有另一种方法可以做到 temporal join ，那就是使用 TemporalTableFunction


        val latestRates = rateTable.createTemporalTableFunction("ps", "currency");
        tableEnv.registerFunction("LatestRates ", latestRates );

        val result = tableEnv
                .sqlQuery("""select o.amount, o.currency, r.rate, o.amount * r.rate from  Orders as o Lateral table (LatestRates (o.ps)) d  where o.currency =d.currency""");

我会问哪个是首选，在我看来第一个是首选，因为它遵循 SQL 标准来表达 Temporal table

Answer 1

第一种方法，使用 JOIN ... FOR SYSTEM_TIME AS OF 是首选方法。 Table#createTemporalTableFunction(...) 在 Flink 1.12 中添加了这种更好的方法时被弃用（有关详细信息，请参阅 FLIP-132 Temporal Table DDL and Temporal Table Join）。

两种temporal join方式，首选哪一种

Two ways to do temporal join,which one is preferred

apache-flink