Clarify the @lock on String-based queries

Author: mipo256

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/repository/query/StringBasedJdbcQuery.java

@@ -27,6 +27,8 @@
 import java.util.function.Function;
 import java.util.function.Supplier;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
 import org.springframework.beans.BeanInstantiationException;
 import org.springframework.beans.BeanUtils;
 import org.springframework.beans.factory.BeanFactory;
@@ -78,6 +80,8 @@
 public class StringBasedJdbcQuery extends AbstractJdbcQuery {
 
 	private static final String PARAMETER_NEEDS_TO_BE_NAMED = "For queries with named parameters you need to provide names for method parameters; Use @Param for query method parameters, or use the javac flag -parameters";
+	private final static String LOCKING_IS_NOT_SUPPORTED = "Currently, @Lock is supported only on derived queries. In other words, for queries created with @Query, the locking condition specified with @Lock does nothing";
+	private static final Log LOG = LogFactory.getLog(StringBasedJdbcQuery.class);
 	private final JdbcConverter converter;
 	private final RowMapperFactory rowMapperFactory;
 	private final ValueExpressionQueryRewriter.ParsedQuery parsedQuery;
@@ -187,6 +191,10 @@ public StringBasedJdbcQuery(String query, JdbcQueryMethod queryMethod, NamedPara
 				(counter, expression) -> String.format("__$synthetic$__%d", counter + 1), String::concat);
 
 		this.query = query;
+
+		if (queryMethod.hasLockMode()) {
+			LOG.warn(LOCKING_IS_NOT_SUPPORTED);
+		}
 		this.parsedQuery = rewriter.parse(this.query);
 		this.delegate = delegate;
 	}

src/main/antora/modules/ROOT/pages/jdbc/transactions.adoc

@@ -101,6 +101,10 @@ The required value of type `LockMode` offers two values: `PESSIMISTIC_READ` whic
 Some databases do not make this distinction.
 In that cases both modes are equivalent of `PESSIMISTIC_WRITE`.
 
+NOTE: It is worth stating explicitly, that `@Lock` currently is not supported on string-based queries. It means,
+that queries in the repository, created with `@Query`, will ignore the locking information provided by the `@Lock`,
+Using `@Lock` on string-based queries will result in the warning in logs.
+
 .Using @Lock on derived query method
 [source,java]
 ----