---
title: "POST /v1/{+session}:read"
method: POST
path: "/v1/{+session}:read"
tags: ["projects"]
---

# POST /v1/{+session}:read

`POST /v1/{+session}:read`

Reads rows from the database using key lookups and scans, as a simple key/value style alternative to ExecuteSql. This method can't be used to return a result set larger than 10 MiB; if the read matches more data than that, the read fails with a `FAILED_PRECONDITION` error. Reads inside read-write transactions might return `ABORTED`. If this occurs, the application should restart the transaction from the beginning. See Transaction for more details. Larger result sets can be yielded in streaming fashion by calling StreamingRead instead.

## Path parameters

- `session` string, required

## Request body

- ReadRequest — The request for Read and StreamingRead.
  - `transaction` TransactionSelector — This message is used to select the transaction in which a Read or ExecuteSql call runs. See TransactionOptions for more information about transactions.
    - `singleUse` TransactionOptions — Options to use for transactions.
      - `readWrite` ReadWrite — Message type to initiate a read-write transaction. Currently this transaction type has no options.
        - `readLockMode` 'READ_LOCK_MODE_UNSPECIFIED' | 'PESSIMISTIC' | 'OPTIMISTIC' — The read lock mode for the transaction.
        - `multiplexedSessionPreviousTransactionId` string, byte — Optional. Clients should pass the transaction ID of the previous transaction attempt that was aborted if this transaction is being executed on a multiplexed session.
      - `partitionedDml` PartitionedDml — Message type to initiate a Partitioned DML transaction.
      - `readOnly` ReadOnly — Message type to initiate a read-only transaction.
        - `strong` boolean — Read at a timestamp where all previously committed transactions are visible.
        - `minReadTimestamp` string, google-datetime — Executes all reads at a timestamp >= `min_read_timestamp`. This is useful for requesting fresher data than some previous read, or data that is fresh enough to observe the effects of some previously committed transaction whose timestamp is known. Note that this option can only be used in single-use transactions. A timestamp in RFC3339 UTC \"Zulu\" format, accurate to nanoseconds. Example: `"2014-10-02T15:01:23.045123456Z"`.
        - `maxStaleness` string, google-duration — Read data at a timestamp >= `NOW - max_staleness` seconds. Guarantees that all writes that have committed more than the specified number of seconds ago are visible. Because Cloud Spanner chooses the exact timestamp, this mode works even if the client's local clock is substantially skewed from Cloud Spanner commit timestamps. Useful for reading the freshest data available at a nearby replica, while bounding the possible staleness if the local replica has fallen behind. Note that this option can only be used in single-use transactions.
        - `readTimestamp` string, google-datetime — Executes all reads at the given timestamp. Unlike other modes, reads at a specific timestamp are repeatable; the same read at the same timestamp always returns the same data. If the timestamp is in the future, the read is blocked until the specified timestamp, modulo the read's deadline. Useful for large scale consistent reads such as mapreduces, or for coordinating many reads against a consistent snapshot of the data. A timestamp in RFC3339 UTC \"Zulu\" format, accurate to nanoseconds. Example: `"2014-10-02T15:01:23.045123456Z"`.
        - `exactStaleness` string, google-duration — Executes all reads at a timestamp that is `exact_staleness` old. The timestamp is chosen soon after the read is started. Guarantees that all writes that have committed more than the specified number of seconds ago are visible. Because Cloud Spanner chooses the exact timestamp, this mode works even if the client's local clock is substantially skewed from Cloud Spanner commit timestamps. Useful for reading at nearby replicas without the distributed timestamp negotiation overhead of `max_staleness`.
        - `returnReadTimestamp` boolean — If true, the Cloud Spanner-selected read timestamp is included in the Transaction message that describes the transaction.
      - `excludeTxnFromChangeStreams` boolean — When `exclude_txn_from_change_streams` is set to `true`, it prevents read or write transactions from being tracked in change streams. * If the DDL option `allow_txn_exclusion` is set to `true`, then the updates made within this transaction aren't recorded in the change stream. * If you don't set the DDL option `allow_txn_exclusion` or if it's set to `false`, then the updates made within this transaction are recorded in the change stream. When `exclude_txn_from_change_streams` is set to `false` or not set, modifications from this transaction are recorded in all change streams that are tracking columns modified by these transactions. The `exclude_txn_from_change_streams` option can only be specified for read-write or partitioned DML transactions, otherwise the API returns an `INVALID_ARGUMENT` error.
      - `isolationLevel` 'ISOLATION_LEVEL_UNSPECIFIED' | 'SERIALIZABLE' | 'REPEATABLE_READ' — Isolation level for the transaction.
    - `id` string, byte — Execute the read or SQL query in a previously-started transaction.
    - `begin` TransactionOptions — Options to use for transactions.
      - `readWrite` ReadWrite — Message type to initiate a read-write transaction. Currently this transaction type has no options.
        - `readLockMode` 'READ_LOCK_MODE_UNSPECIFIED' | 'PESSIMISTIC' | 'OPTIMISTIC' — The read lock mode for the transaction.
        - `multiplexedSessionPreviousTransactionId` string, byte — Optional. Clients should pass the transaction ID of the previous transaction attempt that was aborted if this transaction is being executed on a multiplexed session.
      - `partitionedDml` PartitionedDml — Message type to initiate a Partitioned DML transaction.
      - `readOnly` ReadOnly — Message type to initiate a read-only transaction.
        - `strong` boolean — Read at a timestamp where all previously committed transactions are visible.
        - `minReadTimestamp` string, google-datetime — Executes all reads at a timestamp >= `min_read_timestamp`. This is useful for requesting fresher data than some previous read, or data that is fresh enough to observe the effects of some previously committed transaction whose timestamp is known. Note that this option can only be used in single-use transactions. A timestamp in RFC3339 UTC \"Zulu\" format, accurate to nanoseconds. Example: `"2014-10-02T15:01:23.045123456Z"`.
        - `maxStaleness` string, google-duration — Read data at a timestamp >= `NOW - max_staleness` seconds. Guarantees that all writes that have committed more than the specified number of seconds ago are visible. Because Cloud Spanner chooses the exact timestamp, this mode works even if the client's local clock is substantially skewed from Cloud Spanner commit timestamps. Useful for reading the freshest data available at a nearby replica, while bounding the possible staleness if the local replica has fallen behind. Note that this option can only be used in single-use transactions.
        - `readTimestamp` string, google-datetime — Executes all reads at the given timestamp. Unlike other modes, reads at a specific timestamp are repeatable; the same read at the same timestamp always returns the same data. If the timestamp is in the future, the read is blocked until the specified timestamp, modulo the read's deadline. Useful for large scale consistent reads such as mapreduces, or for coordinating many reads against a consistent snapshot of the data. A timestamp in RFC3339 UTC \"Zulu\" format, accurate to nanoseconds. Example: `"2014-10-02T15:01:23.045123456Z"`.
        - `exactStaleness` string, google-duration — Executes all reads at a timestamp that is `exact_staleness` old. The timestamp is chosen soon after the read is started. Guarantees that all writes that have committed more than the specified number of seconds ago are visible. Because Cloud Spanner chooses the exact timestamp, this mode works even if the client's local clock is substantially skewed from Cloud Spanner commit timestamps. Useful for reading at nearby replicas without the distributed timestamp negotiation overhead of `max_staleness`.
        - `returnReadTimestamp` boolean — If true, the Cloud Spanner-selected read timestamp is included in the Transaction message that describes the transaction.
      - `excludeTxnFromChangeStreams` boolean — When `exclude_txn_from_change_streams` is set to `true`, it prevents read or write transactions from being tracked in change streams. * If the DDL option `allow_txn_exclusion` is set to `true`, then the updates made within this transaction aren't recorded in the change stream. * If you don't set the DDL option `allow_txn_exclusion` or if it's set to `false`, then the updates made within this transaction are recorded in the change stream. When `exclude_txn_from_change_streams` is set to `false` or not set, modifications from this transaction are recorded in all change streams that are tracking columns modified by these transactions. The `exclude_txn_from_change_streams` option can only be specified for read-write or partitioned DML transactions, otherwise the API returns an `INVALID_ARGUMENT` error.
      - `isolationLevel` 'ISOLATION_LEVEL_UNSPECIFIED' | 'SERIALIZABLE' | 'REPEATABLE_READ' — Isolation level for the transaction.
  - `table` string — Required. The name of the table in the database to be read.
  - `index` string — If non-empty, the name of an index on table. This index is used instead of the table primary key when interpreting key_set and sorting result rows. See key_set for further information.
  - `columns` string[] — Required. The columns of table to be returned for each row matching this request.
  - `keySet` KeySet — `KeySet` defines a collection of Cloud Spanner keys and/or key ranges. All the keys are expected to be in the same table or index. The keys need not be sorted in any particular way. If the same key is specified multiple times in the set (for example if two ranges, two keys, or a key and a range overlap), Cloud Spanner behaves as if the key were only specified once.
    - `keys` array[] — A list of specific keys. Entries in `keys` should have exactly as many elements as there are columns in the primary or index key with which this `KeySet` is used. Individual key values are encoded as described here.
      - unknown[]
        - unknown
    - `ranges` KeyRange[] — A list of key ranges. See KeyRange for more information about key range specifications.
      - `startClosed` unknown[] — If the start is closed, then the range includes all rows whose first `len(start_closed)` key columns exactly match `start_closed`.
        - unknown
      - `startOpen` unknown[] — If the start is open, then the range excludes rows whose first `len(start_open)` key columns exactly match `start_open`.
        - unknown
      - `endClosed` unknown[] — If the end is closed, then the range includes all rows whose first `len(end_closed)` key columns exactly match `end_closed`.
        - unknown
      - `endOpen` unknown[] — If the end is open, then the range excludes rows whose first `len(end_open)` key columns exactly match `end_open`.
        - unknown
    - `all` boolean — For convenience `all` can be set to `true` to indicate that this `KeySet` matches all keys in the table or index. Note that any keys specified in `keys` or `ranges` are only yielded once.
  - `limit` string, int64 — If greater than zero, only the first `limit` rows are yielded. If `limit` is zero, the default is no limit. A limit can't be specified if `partition_token` is set.
  - `resumeToken` string, byte — If this request is resuming a previously interrupted read, `resume_token` should be copied from the last PartialResultSet yielded before the interruption. Doing this enables the new read to resume where the last read left off. The rest of the request parameters must exactly match the request that yielded this token.
  - `partitionToken` string, byte — If present, results are restricted to the specified partition previously created using `PartitionRead`. There must be an exact match for the values of fields common to this message and the PartitionReadRequest message used to create this partition_token.
  - `requestOptions` RequestOptions — Common request options for various APIs.
    - `priority` 'PRIORITY_UNSPECIFIED' | 'PRIORITY_LOW' | 'PRIORITY_MEDIUM' | 'PRIORITY_HIGH' — Priority for the request.
    - `requestTag` string — A per-request tag which can be applied to queries or reads, used for statistics collection. Both `request_tag` and `transaction_tag` can be specified for a read or query that belongs to a transaction. This field is ignored for requests where it's not applicable (for example, `CommitRequest`). Legal characters for `request_tag` values are all printable characters (ASCII 32 - 126) and the length of a request_tag is limited to 50 characters. Values that exceed this limit are truncated. Any leading underscore (_) characters are removed from the string.
    - `transactionTag` string — A tag used for statistics collection about this transaction. Both `request_tag` and `transaction_tag` can be specified for a read or query that belongs to a transaction. To enable tagging on a transaction, `transaction_tag` must be set to the same value for all requests belonging to the same transaction, including BeginTransaction. If this request doesn't belong to any transaction, `transaction_tag` is ignored. Legal characters for `transaction_tag` values are all printable characters (ASCII 32 - 126) and the length of a `transaction_tag` is limited to 50 characters. Values that exceed this limit are truncated. Any leading underscore (_) characters are removed from the string.
    - `clientContext` ClientContext — Container for various pieces of client-owned context attached to a request.
      - `secureContext` object — Optional. Map of parameter name to value for this request. These values will be returned by any SECURE_CONTEXT() calls invoked by this request (e.g., by queries against Parameterized Secure Views).
  - `directedReadOptions` DirectedReadOptions — The `DirectedReadOptions` can be used to indicate which replicas or regions should be used for non-transactional reads or queries. `DirectedReadOptions` can only be specified for a read-only transaction, otherwise the API returns an `INVALID_ARGUMENT` error.
    - `includeReplicas` IncludeReplicas — An `IncludeReplicas` contains a repeated set of `ReplicaSelection` which indicates the order in which replicas should be considered.
      - `replicaSelections` ReplicaSelection[] — The directed read replica selector.
        - `location` string — The location or region of the serving requests, for example, "us-east1".
        - `type` 'TYPE_UNSPECIFIED' | 'READ_WRITE' | 'READ_ONLY' — The type of replica.
      - `autoFailoverDisabled` boolean — If `true`, Spanner doesn't route requests to a replica outside the <`include_replicas` list when all of the specified replicas are unavailable or unhealthy. Default value is `false`.
    - `excludeReplicas` ExcludeReplicas — An ExcludeReplicas contains a repeated set of ReplicaSelection that should be excluded from serving requests.
      - `replicaSelections` ReplicaSelection[] — The directed read replica selector.
        - `location` string — The location or region of the serving requests, for example, "us-east1".
        - `type` 'TYPE_UNSPECIFIED' | 'READ_WRITE' | 'READ_ONLY' — The type of replica.
  - `dataBoostEnabled` boolean — If this is for a partitioned read and this field is set to `true`, the request is executed with Spanner Data Boost independent compute resources. If the field is set to `true` but the request doesn't set `partition_token`, the API returns an `INVALID_ARGUMENT` error.
  - `orderBy` 'ORDER_BY_UNSPECIFIED' | 'ORDER_BY_PRIMARY_KEY' | 'ORDER_BY_NO_ORDER' — Optional. Order for the returned rows. By default, Spanner returns result rows in primary key order except for PartitionRead requests. For applications that don't require rows to be returned in primary key (`ORDER_BY_PRIMARY_KEY`) order, setting `ORDER_BY_NO_ORDER` option allows Spanner to optimize row retrieval, resulting in lower latencies in certain cases (for example, bulk point lookups).
  - `lockHint` 'LOCK_HINT_UNSPECIFIED' | 'LOCK_HINT_SHARED' | 'LOCK_HINT_EXCLUSIVE' — Optional. Lock Hint for the request, it can only be used with read-write transactions.

## Response `200`

Successful response

---

[API](https://skmtc.net/google/apis/spanner.md) · [All operations](https://skmtc.net/google/apis/spanner/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/google/spanner/versions/4b66067d2622/schema)