Configure default LobHandler to use temporary LOBs on Oracle

JdbcOperationsSessionRepository recently introduced validation when inserting new session attributes in order to prevent data integrity violations in highly concurrent environments. This is done by using INSERT INTO ... SELECT statement to verify existence of session record in parent table. Such arrangement causes problems with Oracle if inserted attribute is of size 4 kb or more.

This commit enhances JdbcHttpSessionConfiguration to detect Oracle database is used, and set createTemporaryLob option on default LobHandler to true.

Resolves: #1203
See also: #1031

Author: vpavic

spring-session-jdbc/src/integration-test/java/org/springframework/session/jdbc/AbstractJdbcOperationsSessionRepositoryITests.java

@@ -811,6 +811,21 @@ public void sessionFromStoreResolvesAttributesLazily() {
 						.isEqualTo("value2");
 	}
 
+	@Test // gh-1203
+	public void saveWithLargeAttribute() {
+		String attributeName = "largeAttribute";
+		int arraySize = 4000;
+
+		JdbcOperationsSessionRepository.JdbcSession session = this.repository
+				.createSession();
+		session.setAttribute(attributeName, new byte[arraySize]);
+		this.repository.save(session);
+		session = this.repository.findById(session.getId());
+
+		assertThat(session).isNotNull();
+		assertThat((byte[]) session.getAttribute(attributeName)).hasSize(arraySize);
+	}
+
 	private String getSecurityName() {
 		return this.context.getAuthentication().getName();
 	}

spring-session-jdbc/src/main/java/org/springframework/session/jdbc/config/annotation/web/http/JdbcHttpSessionConfiguration.java

@@ -35,6 +35,9 @@
 import org.springframework.core.serializer.support.SerializingConverter;
 import org.springframework.core.type.AnnotationMetadata;
 import org.springframework.jdbc.core.JdbcTemplate;
+import org.springframework.jdbc.support.JdbcUtils;
+import org.springframework.jdbc.support.MetaDataAccessException;
+import org.springframework.jdbc.support.lob.DefaultLobHandler;
 import org.springframework.jdbc.support.lob.LobHandler;
 import org.springframework.scheduling.annotation.EnableScheduling;
 import org.springframework.scheduling.annotation.SchedulingConfigurer;
@@ -102,6 +105,11 @@ public JdbcOperationsSessionRepository sessionRepository() {
 		if (this.lobHandler != null) {
 			sessionRepository.setLobHandler(this.lobHandler);
 		}
+		else if (requiresTemporaryLob(this.dataSource)) {
+			DefaultLobHandler lobHandler = new DefaultLobHandler();
+			lobHandler.setCreateTemporaryLob(true);
+			sessionRepository.setLobHandler(lobHandler);
+		}
 		if (this.springSessionConversionService != null) {
 			sessionRepository.setConversionService(this.springSessionConversionService);
 		}
@@ -115,6 +123,17 @@ else if (this.conversionService != null) {
 		return sessionRepository;
 	}
 
+	private static boolean requiresTemporaryLob(DataSource dataSource) {
+		try {
+			String productName = JdbcUtils.extractDatabaseMetaData(dataSource,
+					"getDatabaseProductName");
+			return "Oracle".equalsIgnoreCase(JdbcUtils.commonDatabaseName(productName));
+		}
+		catch (MetaDataAccessException ex) {
+			return false;
+		}
+	}
+
 	public void setMaxInactiveIntervalInSeconds(Integer maxInactiveIntervalInSeconds) {
 		this.maxInactiveIntervalInSeconds = maxInactiveIntervalInSeconds;
 	}