The following table shows the values that are used when -XX:+UseContainerSupport is set:
Less than 1 GB 50% <size>
1 GB - 2 GB <size> - 512 MB
Greater than 2 GB 75% <size>
The default heap size is capped at 25 GB
The default heap size for containers takes affect only when the following conditions are met:
The application is running in a container environment.
The memory limit for the container is set.
The -XX:+UseContainerSupport option is set, which is the default behavior.
["slug" being an entity attribute]
Spring Data offers an existsBy query method, which we can define in the PostRepository, as follows:
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@Repository
public interface PostRepository
extends JpaRepository<Post, Long> {
boolean existsBySlug(String slug);
}
[another] option to emulate existence is using a CASE WHEN EXISTS native SQL query:
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@Repository
public interface PostRepository
extends JpaRepository<Post, Long> {
@Query(value = """
SELECT
CASE WHEN EXISTS (
SELECT 1
FROM post
WHERE slug = :slug
)
THEN 'true'
ELSE 'false'
END
""",
nativeQuery = true
)
boolean existsBySlugWithCase(@Param("slug") String slug);
}
@Repository
public interface PostRepository extends BaseJpaRepository<Post, Long> {
@Query("""
select p
from Post p
where date(p.createdOn) >= :sinceDate
"""
)
@QueryHints(
@QueryHint(name = AvailableHints.HINT_FETCH_SIZE, value = "25")
)
Stream<Post> streamByCreatedOnSince(@Param("sinceDate") LocalDate sinceDate);
}
The FETCH_SIZE JPA query hint is necessary for PostgreSQL and MySQL to instruct the JDBC Driver to prefetch at most 25 records. Otherwise, the PostgreSQL and MySQL JDBC Drivers would prefetch all the query results prior to traversing the underlying ResultSet.
moving:
to the end of the command: ctrl-e
to the begin of the command: ctrl-a
forward a word: alt-f
backword a word: alt-b
deleting:
from current cursor position to the end of word: ald-d
from current cursor position to the begin of word: clt-w
C. Scholz, J. Illig, M. Atzmueller, and G. Stumme. Proceedings of the 25th ACM Conference on Hypertext and Social Media, page 279--284. Santiago, Chile, ACM, (September 2014)
J. Jardine, and S. Teufel. Proceedings of the 14th Conference of the European Chapter of the Association for Computational Linguistics, page 501--510. Gothenburg, Sweden, Association for Computational Linguistics, (April 2014)
J. Illig, B. Roth, and D. Klakow. Proceedings of the 14th Conference of the European Chapter of the Association for Computational Linguistics, volume 2: Short Papers, page 100--105. Gothenburg, Sweden, Association for Computational Linguistics, (April 2014)