Flink sql-client/sql-gateway 支持multiple insert

[朱广彬 <zh...@gmail.com>]

Hi，Community：

目前sql-client和sql-gateway只能支持单条SQL statement，这样就没法利用multiple insert的优化。如下：

INSERT INTO RubberOrders SELECT product, amount FROM Orders WHERE product LIKE '%Rubber%'
INSERT INTO GlassOrders SELECT product, amount FROM Orders WHERE product LIKE '%Glass%'

两条语句会分别生成两个Job，对Orders表读了两次。如果Orders表是Kafka，消费两次的成本是很大的浪费，是否可以优化下？

一种方案是，在SQL 语法层面上支持，如Hive的multiple insert：

FROM Orders INSERT INTO RubberOrders SELECT product, amount WHERE product LIKE '%Rubber%' INSERT INTO GlassOrders SELECT product, amount WHERE product LIKE '%Glass%'

另一种方案是，让sql-client/sql-gateway支持multiple SQL statement，这样即使语法不支持，两条INSERT语句也可以被优化成一个Job，只scan一次Orders表。


不知道社区后续是否有计划针对这个feature优化？



附：目前Table API 支持multiple insert的优化

// run multiple INSERT queries on the registered source table and emit the result to registered sink tables
StatementSet stmtSet = tEnv.createStatementSet();
// only single INSERT query can be accepted by `addInsertSql` method
stmtSet.addInsertSql(
  "INSERT INTO RubberOrders SELECT product, amount FROM Orders WHERE product LIKE '%Rubber%'");
stmtSet.addInsertSql(
  "INSERT INTO GlassOrders SELECT product, amount FROM Orders WHERE product LIKE '%Glass%'");
// execute all statements together
TableResult tableResult2 = stmtSet.execute();