Method: projects.instances.databases.sessions.partitionRead

Creates a set of partition tokens that can be used to execute a read operation in parallel. Each of the returned partition tokens can be used by sessions.streamingRead to specify a subset of the read result to read. The same session and read-only transaction must be used by the PartitionReadRequest used to create the partition tokens and the ReadRequests that use the partition tokens. There are no ordering guarantees on rows returned among the returned partition tokens, or even within each individual sessions.streamingRead call issued with a partitionToken.

Partition tokens become invalid when the session used to create them is deleted, is idle for too long, begins a new transaction, or becomes too old. When any of these happen, it is not possible to resume the read, and the whole operation must be restarted from the beginning.

HTTP request


The URL uses gRPC Transcoding syntax.

Path parameters



Required. The session used to create the partitions.

Authorization requires the following IAM permission on the specified resource session:

  • spanner.databases.partitionRead

Request body

The request body contains data with the following structure:

JSON representation
  "transaction": {
    object (TransactionSelector)
  "table": string,
  "index": string,
  "columns": [
  "keySet": {
    object (KeySet)
  "partitionOptions": {
    object (PartitionOptions)

object (TransactionSelector) only snapshot transactions are supported, read/write and single use transactions are not.



Required. The name of the table in the database to be read.



If non-empty, the name of an index on table. This index is used instead of the table primary key when interpreting keySet and sorting result rows. See keySet for further information.



The columns of table to be returned for each row matching this request.


object (KeySet)

Required. keySet identifies the rows to be yielded. keySet names the primary keys of the rows in table to be yielded, unless index is present. If index is present, then keySet instead names index keys in index.

It is not an error for the keySet to name rows that do not exist in the database. yields nothing for nonexistent rows.


object (PartitionOptions)

Additional options that affect how many partitions are created.

Response body

If successful, the response body contains an instance of PartitionResponse.

Authorization scopes

Requires one of the following OAuth scopes:


For more information, see the Authentication Overview.