Supported SQL Operators and Expressions

This section describes the scope, restrictions, and usage rules of SQL operators and expressions (including data types) supported by the OmniStream Flink Native feature in Flink versions 1.16.3, 1.17.1, and 1.20.0.

Table 2 and Table 3 list the operators, expressions, and functions supported by OmniStream. Symbols are used to indicate whether the operators and expressions are supported. For details about the symbols, see Table 1.

Table 2 and Table 3 display the data types supported by or involved in OmniStream. The data types that are not displayed in the two tables are not supported by OmniStream.
If you use operators and expressions that are not supported by OmniStream, the execution plan will be rolled back to native execution, which deteriorates the performance.
When you use the SQL Client interactive user interface to execute SQL statements, you are advised to export the execution result to the data table whose connector is blackhole. For details, see the execution mode of Nexmark Q0.
Due to memory restrictions, only the Calc and LookupJoin operators are supported by default. To support other operators, set export FLINK_PERFORMANCE to false to enable environment variables.

**Table 1** Meanings of symbols in the operator and expression support tables
Symbol	Description
S	Indicates that the operator or expression is supported.
PS	Indicates that the operator or expression is partially supported, with some restrictions. For details about the restrictions, see Constraints.
NS	Indicates that the operator or expression is not supported.
NA	Indicates that the operator or expression is not involved. This scenario does not exist in open source Flink.
[Blank Cell]	Indicates a scenario that is irrelevant or needs to be confirmed.

**Table 2** Supported operators
Operator	BIGINT	VARCHAR	TIMESTAMP(3)
Calc	S	S	S
Sink	S	S	S
Csv Source	S	S	S
Kafka Source	S	S	S
Kafka Sink	S	S	S
Join	PS	PS	PS
LookupJoin	PS	PS	PS
GroupAggregate	PS	PS	PS
LocalGroupAggregate	PS	PS	PS
GlobalGroupAggregate	PS	PS	PS
IncrementalGroupAggregate	PS	PS	PS
LocalWindowAggregate	PS	PS	PS
GlobalWindowAggregate	PS	PS	PS
GroupWindowAggregate	PS	PS	PS
WindowAggregate	PS	PS	PS
WindowJoin	PS	PS	PS
Deduplicate	PS	PS	PS
Expand	PS	PS	PS
Rank	PS	PS	PS

**Table 3** Supported expressions
Expression	Function Type	BIGINT	VARCHAR	NULL	TIMESTAMP(3)
*	Scalar functions	S	NS	S	S
+	Scalar functions	S	NS	S	S
-	Scalar functions	S	NS	S	S
/	Scalar functions	S	NS	S	S
LOWER	Scalar functions	NA	S	NA	NA
SPLIT_INDEX	Scalar functions	S	S	NA	NA
DATE_FORMAT	Scalar functions	NA	NA	NA	S
COUNT_CHAR	Scalar functions	NA	S	NA	NA
HOUR	Scalar functions	S	NA	NS	S
REGEX_EXTRACT	Scalar functions	NA	S	NS	NA

Parent topic: Using the Feature