SQL

This section describes the SQL language supported in SpringQL, including Data Definition Language (DDL), Data Manipulation Language (DML) and Query Language.

Currently, SpringQL supports quite limited subset of SQL standard.

SQL interface

You pass SQLs to SpringQL using the following APIs.

• Rust
  • SpringPipeline::command()
• Other languages
  • spring_command()

SQL execution models

DDL

We currently support CREATE statements for DDL.

CREATE statements modify the pipeline to change the dataflow. It takes effect immediately after the DDL is issued via APIs.

tip

CREATE SOURCE READER statements should be issued after other CREATE statements.

Some source readers may drain data inside foreign sources and the data are just diminished if the downstream pumps and sinks are defined yet.

DML and query

We currently do not support simple DMLs (such as INSERT, UPDATE, and DELETE) and queries (such as SELECT).

However, CREATE PUMP statements includes:

• a SELECT statement to fetch rows from upstreams and process them.
• an INSERT statement to push result rows to downstreams.

While SELECT queries in normal relational databases is executed once to tables, queries in SpringQL (and other stream processors supporting SQL) are registered to continuously run. The registered queries applied to each input row.

Search "CQL" or "Continuous Query" if you have further interests on it.

Transactions

We currently do not support transactions.