HTTP interface for Stream Transactions

Stream Transactions allow you to perform a multi-document transaction with individual begin and commit/abort commands

For an introduction to this transaction type, see Stream Transactions.

To use a Stream Transaction, a client first sends the configuration of the transaction to the ArangoDB server.

Contrary to JavaScript Transactions, the definition of Stream Transaction must only contain the collections that are going to be used and (optionally) the various transaction options supported by ArangoDB. No action attribute is supported.

The Stream Transaction API works in conjunction with other APIs in ArangoDB. To use the transaction for a supported operation a client needs to specify the transaction identifier in the x-arango-trx-id HTTP header on each request. This will automatically cause these operations to use the specified transaction.

Supported transactional API operations include:

All operations in the Document API
Get the number of documents via the Collection API
Truncate a collection via the Collection API
Create an AQL cursor via the Cursor API
Handle vertices and edges of managed graphs (General Graph / Gharial API)

Begin a Stream Transaction

POST /_db/{database-name}/_api/transaction/begin

Begin a Stream Transaction that allows clients to call selected APIs over a short period of time, referencing the transaction ID, and have the server execute the operations transactionally.

Committing or aborting a running transaction must be done by the client. It is bad practice to not commit or abort a transaction once you are done using it. It forces the server to keep resources and collection locks until the entire transaction times out.

The transaction description must be passed in the body of the POST request. If the transaction can be started on the server, HTTP 201 will be returned.

For successfully started transactions, the returned JSON object has the following properties:

error: boolean flag to indicate if an error occurred (false in this case)
code: the HTTP status code
result: result containing
- id: the identifier of the transaction
- status: containing the string ‘running’

If the transaction specification is either missing or malformed, the server will respond with HTTP 400 or HTTP 404.

The body of the response will then contain a JSON object with additional error details. The object has the following attributes:

error: boolean flag to indicate that an error occurred (true in this case)
code: the HTTP status code
errorNum: the server error number
errorMessage: a descriptive error message

Path Parameters

database-name* string
The name of the database.

Query Parameters

HTTP Headers

x-arango-allow-dirty-read boolean
Set this header to true to allow the Coordinator to ask any shard replica for the data, not only the shard leader. This may result in “dirty reads”.
This header decides about dirty reads for the entire transaction. Individual read operations, that are performed as part of the transaction, cannot override it.

Request Body application/json object

allowImplicit boolean
Allow reading from undeclared collections.
collections* object
collections must be a JSON object that can have one or all sub-attributes read, write or exclusive, each being an array of collection names or a single collection name as string. Collections that will be written to in the transaction must be declared with the write or exclusive attribute or it will fail, whereas non-declared collections from which is solely read will be added lazily.
lockTimeout integer
an optional numeric value that can be used to set a timeout in seconds for waiting on collection locks. This option is only meaningful when using exclusive locks. If not specified, a default value will be used. Setting lockTimeout to 0 will make ArangoDB not time out waiting for a lock.
maxTransactionSize integer
Transaction size limit in bytes.
skipFastLockRound boolean (default: false)
Whether to disable fast locking for write operations.
Skipping the fast lock round can be faster overall if there are many concurrent Stream Transactions queued that all try to lock the same collection exclusively. It avoids deadlocking and retrying which can occur with the fast locking by guaranteeing a deterministic locking order at the expense of each actual locking operation taking longer.
Fast locking should not be skipped for read-only Stream Transactions because it degrades performance if there are no concurrent transactions that use exclusive locks on the same collection.
waitForSync boolean
an optional boolean flag that, if set, will force the transaction to write all data to disk before returning.

Responses

201 Created
If the transaction is running on the server, HTTP 201 will be returned.
400 Bad Request
If the transaction specification is either missing or malformed, the server will respond with HTTP 400.
404 Not Found
If the transaction specification contains an unknown collection, the server will respond with HTTP 404.

Examples

Executing a transaction on a single collection

curl -X POST --header 'accept: application/json' --data-binary @- --dump - 'http://localhost:8529/_api/transaction/begin' <<'EOF'
{
  "collections": {
    "write": "products"
  }
}
EOF

Show output

Referring to a non-existing collection

curl -X POST --header 'accept: application/json' --data-binary @- --dump - 'http://localhost:8529/_api/transaction/begin' <<'EOF'
{
  "collections": {
    "read": "products"
  }
}
EOF

Show output

Get the status of a Stream Transaction

GET /_db/{database-name}/_api/transaction/{transaction-id}

The result is an object describing the status of the transaction. It has at least the following attributes:

id: the identifier of the transaction
status: the status of the transaction. One of “running”, “committed” or “aborted”.

Path Parameters

database-name* string
The name of the database.
transaction-id* string
The transaction identifier.

Query Parameters

HTTP Headers

Responses

200 OK
If the transaction is fully executed and committed on the server, HTTP 200 will be returned.
400 Bad Request
If the transaction identifier specified is either missing or malformed, the server will respond with HTTP 400.
404 Not Found
If the transaction was not found with the specified identifier, the server will respond with HTTP 404.

Examples

Get transaction status

curl --header 'accept: application/json' --dump - 'http://localhost:8529/_api/transaction/72205'

Show output

Commit a Stream Transaction

PUT /_db/{database-name}/_api/transaction/{transaction-id}

Commit a running server-side transaction. Committing is an idempotent operation. It is not an error to commit a transaction more than once.

If the transaction can be committed, HTTP 200 will be returned. The returned JSON object has the following properties:

error: boolean flag to indicate if an error occurred (false in this case)
code: the HTTP status code
result: result containing
- id: the identifier of the transaction
- status: containing the string ‘committed’

If the transaction cannot be found, committing is not allowed or the transaction was aborted, the server will respond with HTTP 400, HTTP 404 or HTTP 409.

The body of the response will then contain a JSON object with additional error details. The object has the following attributes:

error: boolean flag to indicate that an error occurred (true in this case)
code: the HTTP status code
errorNum: the server error number
errorMessage: a descriptive error message

Path Parameters

database-name* string
The name of the database.
transaction-id* string
The transaction identifier,

Query Parameters

HTTP Headers

Responses

200 OK
If the transaction was committed, HTTP 200 will be returned.
400 Bad Request
If the transaction cannot be committed, the server will respond with HTTP 400.
404 Not Found
If the transaction was not found, the server will respond with HTTP 404.
409 Conflict
If the transaction was already aborted, the server will respond with HTTP 409.

Examples

Committing a transaction:

curl -X PUT --header 'accept: application/json' --dump - 'http://localhost:8529/_api/transaction/72215'

Show output

Abort a Stream Transaction

DELETE /_db/{database-name}/_api/transaction/{transaction-id}

Abort a running server-side transaction. Aborting is an idempotent operation. It is not an error to abort a transaction more than once.

If the transaction can be aborted, HTTP 200 will be returned. The returned JSON object has the following properties:

error: boolean flag to indicate if an error occurred (false in this case)
code: the HTTP status code
result: result containing
- id: the identifier of the transaction
- status: containing the string ‘aborted’

If the transaction cannot be found, aborting is not allowed or the transaction was already committed, the server will respond with HTTP 400, HTTP 404 or HTTP 409.

The body of the response will then contain a JSON object with additional error details. The object has the following attributes:

error: boolean flag to indicate that an error occurred (true in this case)
code: the HTTP status code
errorNum: the server error number
errorMessage: a descriptive error message

Path Parameters

database-name* string
The name of the database.
transaction-id* string
The transaction identifier,

Query Parameters

HTTP Headers

Responses

200 OK
If the transaction was aborted, HTTP 200 will be returned.
400 Bad Request
If the transaction cannot be aborted, the server will respond with HTTP 400.
404 Not Found
If the transaction was not found, the server will respond with HTTP 404.
409 Conflict
If the transaction was already committed, the server will respond with HTTP 409.

Examples

Aborting a transaction:

curl -X DELETE --header 'accept: application/json' --dump - 'http://localhost:8529/_api/transaction/72225'

Show output

List the running Stream Transactions

GET /_db/{database-name}/_api/transaction

The result is an object with the transactions attribute, which contains an array of transactions. In a cluster the array will contain the transactions from all Coordinators.

Each array entry contains an object with the following attributes:

id: the transaction’s id
state: the transaction’s status

Path Parameters

database-name* string
The name of the database.

Query Parameters

HTTP Headers

Responses

200 OK
If the list of transactions can be retrieved successfully, HTTP 200 will be returned.

Examples

Get currently running transactions

curl --header 'accept: application/json' --dump - 'http://localhost:8529/_api/transaction'

Show output