diff options
| author | Brian S. O'Neill <bronee@gmail.com> | 2008-04-14 03:18:32 +0000 |
|---|---|---|
| committer | Brian S. O'Neill <bronee@gmail.com> | 2008-04-14 03:18:32 +0000 |
| commit | 63ff050e4d48f8b997905e9e0a11d944ea6038a6 (patch) | |
| tree | 64bcea8ed7fcbb56cc6cdd438bfff79a5615f203 /src/main/java/com/amazon/carbonado/Query.java | |
| parent | f6cce60bed5b4d49831058f24c9f46de7a2b0265 (diff) | |
Support query fetch limits.
Diffstat (limited to 'src/main/java/com/amazon/carbonado/Query.java')
| -rw-r--r-- | src/main/java/com/amazon/carbonado/Query.java | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/src/main/java/com/amazon/carbonado/Query.java b/src/main/java/com/amazon/carbonado/Query.java index a729331..d1cebca 100644 --- a/src/main/java/com/amazon/carbonado/Query.java +++ b/src/main/java/com/amazon/carbonado/Query.java @@ -268,6 +268,23 @@ public interface Query<S extends Storable> { Cursor<S> fetch() throws FetchException;
/**
+ * Fetches a slice of results for this query, as defined by a numerical
+ * range. A slice can be used to limit the number of results from a
+ * query. It is strongly recommended that the query be given a total {@link
+ * #orderBy ordering} in order for the slice results to be deterministic.
+ *
+ * @param from zero-based {@code from} record number, inclusive
+ * @param to optional zero-based {@code to} record number, exclusive
+ * @return fetch results
+ * @throws IllegalStateException if any blank parameters in this query
+ * @throws IllegalArgumentException if {@code from} is negative or if
+ * {@code from} is more than {@code to}
+ * @throws FetchException if storage layer throws an exception
+ * @since 1.2
+ */
+ Cursor<S> fetch(long from, Long to) throws FetchException;
+
+ /**
* Fetches results for this query after a given starting point, which is
* useful for re-opening a cursor. This is only effective when query has
* been given an explicit {@link #orderBy ordering}. If not a total
@@ -286,6 +303,31 @@ public interface Query<S extends Storable> { Cursor<S> fetchAfter(S start) throws FetchException;
/**
+ * Fetches a slice of results for this query after a given starting point,
+ * which is useful for re-opening a cursor. This is only effective when
+ * query has been given an explicit {@link #orderBy ordering}. If not a
+ * total ordering, then returned cursor may start at an earlier position.
+ * It is strongly recommended that the query be given a total ordering in
+ * order for the slice results to be deterministic.
+ *
+ * <p>Note: This method can be very expensive to call repeatedly, if the
+ * query needs to perform a sort operation. Ideally, the query ordering
+ * should match the natural ordering of an index or key.
+ *
+ * @param start storable to attempt to start after; if null, fetch all results
+ * @param from zero-based {@code from} record number, inclusive
+ * @param to optional zero-based {@code to} record number, exclusive
+ * @return fetch results
+ * @throws IllegalStateException if any blank parameters in this query
+ * @throws IllegalArgumentException if {@code from} is negative or if
+ * {@code from} is more than {@code to}
+ * @throws FetchException if storage layer throws an exception
+ * @see Repository#enterTransaction(IsolationLevel)
+ * @since 1.2
+ */
+ Cursor<S> fetchAfter(S start, long from, Long to) throws FetchException;
+
+ /**
* Attempts to load exactly one matching object. If the number of matching
* records is zero or exceeds one, then an exception is thrown instead.
*
|