Apache Flink SQL Parser for Java
General SQL Parser (GSP) parses Apache Flink SQL with a dedicated, hand-tuned grammar — full AST access, offline syntax validation, formatting, rewriting, and column-level data lineage. One commercial SDK — Apache Flink SQL is available in the Java edition.
Apache Flink SQL that GSP parses
CREATE TABLE orders (
order_id BIGINT,
amount DECIMAL(10, 2),
event_time TIMESTAMP(3),
WATERMARK FOR event_time AS event_time - INTERVAL '5' SECOND
) WITH (
'connector' = 'kafka',
'topic' = 'orders'
);Parse it in Java
import gudusoft.gsqlparser.*;
TGSqlParser parser = new TGSqlParser(EDbVendor.dbvflink);
parser.sqltext = sql; // the Apache Flink SQL above
if (parser.parse() == 0) {
System.out.println(parser.sqlstatements.size() + " statement(s) parsed");
} else {
System.out.println(parser.getErrormessage());
}Java edition only. The .NET library has no Apache Flink SQL grammar, so this dialect cannot be parsed from C# or VB.NET. See the .NET SQL Parser SDK for the dialects it does cover.
What GSP handles in Apache Flink SQL
- CREATE TABLE ... WITH (...) connector definitions
- Watermark definitions
- Windowing table-valued functions
- Streaming and batch pipeline SQL in one grammar
Beyond parsing, the same AST powers table/column extraction, validation, formatting, and column-level lineage for Apache Flink SQL.
Apache Flink SQL resources
- Apache Flink SQL syntax reference — dialect documentation
- Apache Flink SQL keyword compatibility — every keyword, and whether it can be an identifier
- Apache Flink SQL capability data (JSON) — measured construct-by-construct parse coverage, machine-readable
- Java quick start — Maven/Gradle setup and first parse
Common questions
Do I need a live Apache Flink SQL database connection to validate SQL?
No. GSP validates Apache Flink SQL syntax completely offline. You get error line and column positions, the offending token, and a hint — with no server, driver, or credentials involved.
How complete is the Apache Flink SQL grammar?
GSP uses a dedicated hand-tuned grammar for Apache Flink SQL — not a generic SQL grammar with flags. The parser recognizes 312 Apache Flink SQL keywords and knows which 309 of them can also be used as identifiers, which is exactly the kind of edge case that breaks generic parsers.
Can I use the Apache Flink SQL parser from C# / .NET?
Not currently. Apache Flink SQL is a Java-edition dialect — the .NET library ships 15 dedicated grammars and Apache Flink SQL is not one of them, so there is no C# code path for it. Everything else on this page describes the Java SDK. If you need Apache Flink SQL in .NET, email info@sqlparser.com; customer demand is how dialects get prioritized for the .NET port.
Can GSP extract column-level lineage from Apache Flink SQL?
Yes. The built-in DataFlowAnalyzer produces column-level lineage, impact analysis, and call graphs from Apache Flink SQL scripts — it is the engine behind Gudu SQLFlow and the lineage integrations for DataHub and OpenMetadata.