Version 5.0 introduced the JDBC MetadataStore (see Metadata Store) implementation. You can use the JdbcMetadataStore to maintain the metadata state across application restarts. This MetadataStore implementation can be used with adapters such as the following:spring-doc.cn

To configure these adapters to use the JdbcMetadataStore, declare a Spring bean by using a bean name of metadataStore. The Feed inbound channel adapter and the feed inbound channel adapter both automatically pick up and use the declared JdbcMetadataStore, as the following example shows:spring-doc.cn

@Bean
public MetadataStore metadataStore(DataSource dataSource) {
    return new JdbcMetadataStore(dataSource);
}

The org.springframework.integration.jdbc package has Database schema scripts for several RDMBS vendors. For example, the following listing shows the H2 DDL for the metadata table:spring-doc.cn

CREATE TABLE INT_METADATA_STORE  (
	METADATA_KEY VARCHAR(255) NOT NULL,
	METADATA_VALUE VARCHAR(4000),
	REGION VARCHAR(100) NOT NULL,
	constraint INT_METADATA_STORE_PK primary key (METADATA_KEY, REGION)
);

You can change the INT_ prefix to match the target database design requirements. You can also configure JdbcMetadataStore to use the custom prefix.spring-doc.cn

The JdbcMetadataStore implements ConcurrentMetadataStore, letting it be reliably shared across multiple application instances, where only one instance can store or modify a key’s value. All of these operations are atomic, thanks to transaction guarantees.spring-doc.cn

Transaction management must use JdbcMetadataStore. Inbound channel adapters can be supplied with a reference to the TransactionManager in the poller configuration. Unlike non-transactional MetadataStore implementations, with JdbcMetadataStore, the entry appears in the target table only after the transaction commits. When a rollback occurs, no entries are added to the INT_METADATA_STORE table.spring-doc.cn

Since version 5.0.7, you can configure the JdbcMetadataStore with the RDBMS vendor-specific lockHint option for lock-based queries on metadata store entries. By default, it is FOR UPDATE and can be configured with an empty string if the target database does not support row locking functionality. Consult with your vendor for particular and possible hints in the SELECT expression for locking rows before updates.spring-doc.cn