public interface QuerySplitterProvides the ability to split a query into multiple shards.
Methods
getSplits(Query query, PartitionId partition, int numSplits, Datastore datastore)
public abstract List<Query> getSplits(Query query, PartitionId partition, int numSplits, Datastore datastore)Returns a list of sharded Querys for the given query.
This will create up to the desired number of splits, however it may return less splits if the desired number of splits is unavailable. This will happen if the number of split points provided by the underlying Datastore is less than the desired number, which will occur if the number of results for the query is too small.
| Parameters | |
|---|---|
| Name | Description |
query | Querythe query to split. |
partition | PartitionIdthe partition the query is running in. |
numSplits | intthe desired number of splits. |
datastore | Datastorethe datastore to run on. |
| Returns | |
|---|---|
| Type | Description |
List<Query> | |
| Exceptions | |
|---|---|
| Type | Description |
DatastoreException | if there was a datastore error while generating query splits. |
getSplits(Query query, PartitionId partition, int numSplits, Datastore datastore, Timestamp readTime)
public default List<Query> getSplits(Query query, PartitionId partition, int numSplits, Datastore datastore, Timestamp readTime)Same as #getSplits(Query, PartitionId, int, Datastore) but the splits are based on
readTime, and the returned sharded Querys should also be executed with
readTime. Reading from a timestamp is currently a private preview feature in Datastore.
| Parameters | |
|---|---|
| Name | Description |
query | Query |
partition | PartitionId |
numSplits | int |
datastore | Datastore |
readTime | Timestamp |
| Returns | |
|---|---|
| Type | Description |
List<Query> | |
| Exceptions | |
|---|---|
| Type | Description |
DatastoreException | |