StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

PO
primarykey
Id
17462034
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
2
CommunityOwnedDate
CreationDate
2013-07-04T04:46:09.223
FavoriteCount
0
LastActivityDate
2013-07-04T04:46:09.223
LastEditDate
LastEditorUserId
0
OwnerUserId
1392882
ParentId
17461543
PostTypeId
2
Score
0
ViewCount
0
LastEditorDisplayName
text
Body
<p>You could cache an Optional in which you would save Optional.absent() in the first request if the response was empty. You have to invalidate this cache's Optional entity as soon as the associated Id is present in the database, or sooner if you are experiencing memory problems with a ever growing cache.</p> <p>I like the guava's Cache and Optional classes as I think they address most of the possible issues and I'll use them in my example:</p> <pre><code>import java.util.concurrent.Callable; import java.util.concurrent.ExecutionException; import java.util.concurrent.TimeUnit; import com.google.common.base.Optional; import com.google.common.cache.Cache; import com.google.common.cache.CacheBuilder; public class OptionalCacheUsage { private static final Cache<Id, Optional<Entity>> cache = CacheBuilder.newBuilder() .softValues() .expireAfterWrite(5, TimeUnit.MINUTES) .build(); private static final Database db = Databases.getDatabase(); Entity findEntity(final Id requestedId) throws ExecutionException, EntityNotFoundException { final Optional<Entity> optionalEntity = cache.get(requestedId, new Callable<Optional<Entity>>() { @Override public Optional<Entity> call() throws Exception { return Optional.fromNullable(db.getById(requestedId)); }}); if (optionalEntity.isPresent()) { return optionalEntity.get(); } else { throw new EntityNotFoundException(); } } Id saveEntity(final Entity newEntity) { final Id savedId = db.save(newEntity); cache.invalidate(savedId); return savedId; } } </code></pre>
Tags
Title
singulars
PostAcceptedAnswerId
1. This table or related slice is empty.
PostParentId
1. POHow to prevent Cache Breakdown by nonexistent id?
  singulars
  PostTypePostTypeId
  PTQuestion
PostTypePostTypeId
1. PTAnswer
UserLastEditorUserId
1. This table or related slice is empty.
UserOwnerUserId
1. USMiguel
plurals
PostLinksPostIdRelatedPostId
1. This table or related slice is empty.
PostLinksRelatedPostIdPostId
1. This table or related slice is empty.
PostsAcceptedAnswerId
1. This table or related slice is empty.
PostsParentIdCreationDate
1. This table or related slice is empty.
VotesPostIdCreationDate
1. This table or related slice is empty.
CommentsPostId
1. COBut the database has too much data. And if one id just visit once, this solution will not work.
  singulars
  PostPostId
  PO
  UserUserId
  USHesey
2. COYep, it won't. The best way to go, I think, is to limit the possible ids and then use this cache. Something like: I have 1000 entities today, so I'll limit the possible ids in the range 0, 2000. Anything outside that is considered nonexistent without consulting the db and you update that range's maximum value in a regular basis.
  singulars
  PostPostId
  PO
  UserUserId
  USMiguel

Querying!

Guidance

A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.