Interface QuerySplitter (2.19.0)

public interface QuerySplitter

Provides 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`	`Query` the query to split.
`partition`	`PartitionId` the partition the query is running in.
`numSplits`	`int` the desired number of splits.
`datastore`	`Datastore` the 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`