HTTP interfaces for AQL queries

The HTTP API for AQL queries lets you to execute, track, kill, explain, and validate queries written in ArangoDB’s query language

Cursors

Results of AQL queries are returned as cursors in order to batch the communication between server and client. Each batch contains a number of documents and an indication if the current batch is the final batch. Depending on the query, the total number of documents in the result set may or may not be known in advance.

If the number of documents doesn’t exceed the batch size, the full query result is returned to the client in a single round-trip. If there are more documents, then the first batch is returned to the client and the client needs to use the cursor to retrieve the other batches.

In order to free up server resources, the client should delete a cursor as soon as it is no longer needed.

Single roundtrip

The server only transfers a certain number of result documents back to the client in one roundtrip. This number is controllable by the client by setting the batchSize attribute when issuing the query.

If the complete result can be transferred to the client in one go, the client does not need to issue any further request. The client can check whether it has retrieved the complete result set by checking the hasMore attribute of the result set. If it is set to false, then the client has fetched the complete result set from the server. In this case, no server-side cursor is created.

> curl --data @- -X POST --dump - http://localhost:8529/_api/cursor
{ "query" : "FOR u IN users LIMIT 2 RETURN u", "count" : true, "batchSize" : 2 }

HTTP/1.1 201 Created
Content-type: application/json

{
  "hasMore" : false,
  "error" : false,
  "result" : [
    {
      "name" : "user1",
      "_rev" : "210304551",
      "_key" : "210304551",
      "_id" : "users/210304551"
    },
    {
      "name" : "user2",
      "_rev" : "210304552",
      "_key" : "210304552",
      "_id" : "users/210304552"
    }
  ],
  "code" : 201,
  "count" : 2
}

Using a cursor

If the result set contains more documents than should be transferred in a single roundtrip (i.e. as set via the batchSize attribute), the server returns the first few documents and creates a temporary cursor. The cursor identifier is also returned to the client. The server puts the cursor identifier in the id attribute of the response object. Furthermore, the hasMore attribute of the response object is set to true. This is an indication for the client that there are additional results to fetch from the server.

Examples

Create and extract first batch:

> curl --data @- -X POST --dump - http://localhost:8529/_api/cursor
{ "query" : "FOR u IN users LIMIT 5 RETURN u", "count" : true, "batchSize" : 2 }

HTTP/1.1 201 Created
Content-type: application/json

{
  "hasMore" : true,
  "error" : false,
  "id" : "26011191",
  "result" : [
    {
      "name" : "user1",
      "_rev" : "258801191",
      "_key" : "258801191",
      "_id" : "users/258801191"
    },
    {
      "name" : "user2",
      "_rev" : "258801192",
      "_key" : "258801192",
      "_id" : "users/258801192"
    }
  ],
  "code" : 201,
  "count" : 5
}

Extract next batch, still have more:

> curl -X POST --dump - http://localhost:8529/_api/cursor/26011191

HTTP/1.1 200 OK
Content-type: application/json

{
  "hasMore" : true,
  "error" : false,
  "id" : "26011191",
  "result": [
    {
      "name" : "user3",
      "_rev" : "258801193",
      "_key" : "258801193",
      "_id" : "users/258801193"
    },
    {
      "name" : "user4",
      "_rev" : "258801194",
      "_key" : "258801194",
      "_id" : "users/258801194"
    }
  ],
  "code" : 200,
  "count" : 5
}

Extract next batch, done:

> curl -X POST --dump - http://localhost:8529/_api/cursor/26011191

HTTP/1.1 200 OK
Content-type: application/json

{
  "hasMore" : false,
  "error" : false,
  "result" : [
    {
      "name" : "user5",
      "_rev" : "258801195",
      "_key" : "258801195",
      "_id" : "users/258801195"
    }
  ],
  "code" : 200,
  "count" : 5
}

Do not do this because hasMore now has a value of false:

> curl -X POST --dump - http://localhost:8529/_api/cursor/26011191

HTTP/1.1 404 Not Found
Content-type: application/json

{
  "errorNum": 1600,
  "errorMessage": "cursor not found: disposed or unknown cursor",
  "error": true,
  "code": 404
}

If you are no longer interested in the results of a query, you can call the DELETE /_api/cursor/<cursor-id> endpoint as long as a cursor exists to discard the cursor so that the server doesn’t unnecessarily keep the results until the cursor times out (ttl query option).

curl -X DELETE --dump http://localhost:8529/_api/cursor/26011191

{
  "id":"3517",
  "error":false,
  "code":202
}

Execute AQL queries

Create a cursor

post /_api/cursor

Submits an AQL query for execution in the current database. The server returns a result batch and may indicate that further batches need to be fetched using a cursor identifier.

The query details include the query string plus optional query options and bind parameters. These values need to be passed in a JSON representation in the body of the POST request.

Path Parameters
    Query Parameters
      HTTP Headers
      • 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”.

        The header is ignored if this operation is part of a Stream Transaction (x-arango-trx-id header). The header set when creating the transaction decides about dirty reads for the entire transaction, not the individual read operations.

      • To make this operation a part of a Stream Transaction, set this header to the transaction ID returned by the POST /_api/transaction/begin call.

      Request Body application/json
      • maximum number of result documents to be transferred from the server to the client in one roundtrip. If this attribute is not set, a server-controlled default value will be used. A batchSize value of 0 is disallowed.

      • An object with key/value pairs representing the bind parameters. For a bind variable @var in the query, specify the value using an attribute with the name var. For a collection bind variable @@coll, use @coll as the attribute name. For example: "bindVars": { "var": 42, "@coll": "products" }.

      • flag to determine whether the AQL query results cache shall be used. If set to false, then any query cache lookup will be skipped for the query. If set to true, it will lead to the query cache being checked for the query if the query cache mode is either on or demand.

      • indicates whether the number of documents in the result set should be returned in the “count” attribute of the result. Calculating the “count” attribute might have a performance impact for some queries in the future so this option is turned off by default, and “count” is only returned when requested.

      • the maximum number of memory (measured in bytes) that the query is allowed to use. If set, then the query will fail with error “resource limit exceeded” in case it allocates too much memory. A value of 0 indicates that there is no memory limit.

      • key/value object with extra options for the query.

        • If you set this option to true and execute the query against a cluster deployment, then the Coordinator is allowed to read from any shard replica and not only from the leader.

          You may observe data inconsistencies (dirty reads) when reading from followers, namely obsolete revisions of documents because changes have not yet been replicated to the follower, as well as changes to documents before they are officially committed on the leader.

          This feature is only available in the Enterprise Edition.

        • When set to true, the query will throw an exception and abort instead of producing a warning. This option should be used during development to catch potential issues early. When the attribute is set to false, warnings will not be propagated to exceptions and will be returned with the query result. There is also a server configuration option --query.fail-on-warning for setting the default value for failOnWarning so it does not need to be set on a per-query level.

        • if set to true or not specified, this will make the query store the data it reads via the RocksDB storage engine in the RocksDB block cache. This is usually the desired behavior. The option can be set to false for queries that are known to either read a lot of data which would thrash the block cache, or for queries that read data which are known to be outside of the hot set. By setting the option to false, data read by the query will not make it into the RocksDB block cache if not already in there, thus leaving more room for the actual hot set.

        • if set to true and the query contains a LIMIT clause, then the result will have an extra attribute with the sub-attributes stats and fullCount, { ... , "extra": { "stats": { "fullCount": 123 } } }. The fullCount attribute will contain the number of documents in the result before the last top-level LIMIT in the query was applied. It can be used to count the number of documents that match certain filter criteria, but only return a subset of them, in one go. It is thus similar to MySQL’s SQL_CALC_FOUND_ROWS hint. Note that setting the option will disable a few LIMIT optimizations and may lead to more documents being processed, and thus make queries run longer. Note that the fullCount attribute may only be present in the result if the query has a top-level LIMIT clause and the LIMIT clause is actually used in the query.

        • The maximum number of operations after which an intermediate commit is performed automatically.

        • The maximum total size of operations after which an intermediate commit is performed automatically.

        • The number of execution nodes in the query plan after that stack splitting is performed to avoid a potential stack overflow. Defaults to the configured value of the startup option --query.max-nodes-per-callstack.

          This option is only useful for testing and debugging and normally does not need any adjustment.

        • Limits the maximum number of plans that are created by the AQL query optimizer.

        • The query has to be executed within the given runtime or it is killed. The value is specified in seconds. The default value is 0.0 (no timeout).

        • The transaction size limit in bytes.

        • Limits the maximum number of warnings a query will return. The number of warnings a query will return is limited to 10 by default, but that number can be increased or decreased by setting this attribute.

        • Options related to the query optimizer.

          • A list of to-be-included or to-be-excluded optimizer rules can be put into this attribute, telling the optimizer to include or exclude specific rules. To disable a rule, prefix its name with a -, to enable a rule, prefix it with a +. There is also a pseudo-rule all, which matches all optimizer rules. -all disables all rules.

        • If set to true or 1, then the additional query profiling information is returned in the profile sub-attribute of the extra return attribute, unless the query result is served from the query cache. If set to 2, the query includes execution stats per query plan node in stats.nodes sub-attribute of the extra return attribute. Additionally, the query plan is returned in the extra.plan sub-attribute.

        • This Enterprise Edition parameter allows to configure how long a DB-Server has time to bring the SatelliteCollections involved in the query into sync. The default value is 60.0 seconds. When the maximal time is reached, the query is stopped.

        • Let AQL queries (especially graph traversals) treat collection to which a user has no access rights for as if these collections are empty. Instead of returning a forbidden access error, your queries execute normally. This is intended to help with certain use-cases: A graph contains several collections and different users execute AQL queries on that graph. You can naturally limit the accessible results by changing the access rights of users on collections.

          This feature is only available in the Enterprise Edition.

        • This option allows queries to store intermediate and final results temporarily on disk if the amount of memory used (in bytes) exceeds the specified value. This is used for decreasing the memory usage during the query execution.

          This option only has an effect on queries that use the SORT operation but without a LIMIT, and if you enable the spillover feature by setting a path for the directory to store the temporary data in with the --temp.intermediate-results-path startup option.

          Default value: 128MB.

          Spilling data from RAM onto disk is an experimental feature and is turned off by default. The query results are still built up entirely in RAM on Coordinators and single servers for non-streaming queries. To avoid the buildup of the entire query result in RAM, use a streaming query (see the stream option).

        • This option allows queries to store intermediate and final results temporarily on disk if the number of rows produced by the query exceeds the specified value. This is used for decreasing the memory usage during the query execution. In a query that iterates over a collection that contains documents, each row is a document, and in a query that iterates over temporary values (i.e. FOR i IN 1..100), each row is one of such temporary values.

          This option only has an effect on queries that use the SORT operation but without a LIMIT, and if you enable the spillover feature by setting a path for the directory to store the temporary data in with the --temp.intermediate-results-path startup option.

          Default value: 5000000 rows.

          Spilling data from RAM onto disk is an experimental feature and is turned off by default. The query results are still built up entirely in RAM on Coordinators and single servers for non-streaming queries. To avoid the buildup of the entire query result in RAM, use a streaming query (see the stream option).

        • Can be enabled to execute the query lazily. If set to true, then the query is executed as long as necessary to produce up to batchSize results. These results are returned immediately and the query is suspended until the client asks for the next batch (if there are more results). Depending on the query this can mean that the first results will be available much faster and that less memory is needed because the server only needs to store a subset of results at a time. Read-only queries can benefit the most, unless SORT without index or COLLECT are involved that make it necessary to process all documents before a partial result can be returned. It is advisable to only use this option for queries without exclusive locks.

          Remarks:

          • The query will hold resources until it ends (such as RocksDB snapshots, which prevents compaction to some degree). Writes will be in memory until the query is committed.
          • If existing documents are modified, then write locks are held on these documents and other queries trying to modify the same documents will fail because of this conflict.
          • A streaming query may fail late because of a conflict or for other reasons after some batches were already returned successfully, possibly rendering the results up to that point meaningless.
          • The query options cache, count and fullCount are not supported for streaming queries.
          • Query statistics, profiling data and warnings are delivered as part of the last batch.

          If the stream option is false (default), then the complete result of the query is calculated before any of it is returned to the client. The server stores the full result in memory (on the contacted Coordinator if in a cluster). All other resources are freed immediately (locks, RocksDB snapshots). The query will fail before it returns results in case of a conflict.

      • contains the query string to be executed

      • The time-to-live for the cursor (in seconds). If the result set is small enough (less than or equal to batchSize) then results are returned right away. Otherwise they are stored in memory and will be accessible via the cursor with respect to the ttl. The cursor will be removed on the server automatically after the specified amount of time. This is useful to ensure garbage collection of cursors that are not fully fetched by clients. If not set, a server-defined value will be used (default: 30 seconds).

      Responses
      • is returned if the result set can be created by the server.

          Response Body
        • A boolean flag indicating whether the query result was served from the query cache or not. If the query result is served from the query cache, the extra return attribute will not contain any stats sub-attribute and no profile sub-attribute.

        • The HTTP status code.

        • The total number of result documents available (only available if the query was executed with the count attribute set).

        • A flag to indicate that an error occurred (false in this case).

        • An optional JSON object with extra information about the query result.

          • The execution plan.

            • A list of the collections involved in the query. The list only includes the collections that can statically be determined at query compile time.

              • The collection name.

              • How the collection is used. Can be "read", "write", or "exclusive".

            • The estimated cost of the query.

            • The estimated number of results.

            • Whether the query contains write operations.

            • A nested list of the execution plan nodes.

            • A list with the names of the applied optimizer rules.

            • All of the query variables, including user-created and internal ones.

          • The duration of the different query execution phases in seconds.

          • An object with query statistics.

            • The total number of index entries read from in-memory caches for indexes of type edge or persistent. This value is only non-zero when reading from indexes that have an in-memory cache enabled, and when the query allows using the in-memory cache (i.e. using equality lookups on all index attributes).

            • The total number of cache read attempts for index entries that could not be served from in-memory caches for indexes of type edge or persistent. This value is only non-zero when reading from indexes that have an in-memory cache enabled, the query allows using the in-memory cache (i.e. using equality lookups on all index attributes) and the looked up values are not present in the cache.

            • The total number of cursor objects created during query execution. Cursor objects are created for index lookups.

            • The total number of times an existing cursor object was repurposed. Repurposing an existing cursor object is normally more efficient compared to destroying an existing cursor object and creating a new one from scratch.

            • The query execution time (wall-clock time) in seconds.

            • The total number of documents removed after executing a filter condition in a FilterNode or another node that post-filters data. Note that nodes of the IndexNode type can also filter documents by selecting only the required index range from a collection, and the filtered value only indicates how much filtering was done by a post filter in the IndexNode itself or following FilterNode nodes. Nodes of the EnumerateCollectionNode and TraversalNode types can also apply filter conditions and can report the number of filtered documents.

            • The total number of documents that matched the search condition if the query’s final top-level LIMIT operation were not present. This attribute may only be returned if the fullCount option was set when starting the query and only contains a sensible value if the query contains a LIMIT operation on the top level.

            • The total number of cluster-internal HTTP requests performed.

            • When the query is executed with the profile option set to at least 2, then this attribute contains runtime statistics per query execution node. For a human readable output, you can execute db._profileQuery(<query>, <bind-vars>) in arangosh.

              • The number of calls to this node.

              • The execution node ID to correlate the statistics with the plan returned in the extra attribute.

              • The number of items returned by this node. Items are the temporary results returned at this stage.

              • The execution time of this node in seconds.

            • The maximum memory usage of the query while it was running. In a cluster, the memory accounting is done per shard, and the memory usage reported is the peak memory usage value from the individual shards. Note that to keep things lightweight, the per-query memory usage is tracked on a relatively high level, not including any memory allocator overhead nor any memory used for temporary results calculations (e.g. memory allocated/deallocated inside AQL expressions and function calls).

            • The total number of documents iterated over when scanning a collection without an index. Documents scanned by subqueries are included in the result, but operations triggered by built-in or user-defined AQL functions are not.

            • The total number of documents iterated over when scanning a collection using an index. Documents scanned by subqueries are included in the result, but operations triggered by built-in or user-defined AQL functions are not.

            • The total number of data-modification operations successfully executed.

            • The total number of data-modification operations that were unsuccessful, but have been ignored because of the ignoreErrors query option.

          • A list of query warnings.

            • An error code.

            • A description of the problem.

        • A boolean indicator whether there are more results available for the cursor on the server.

        • The ID of a temporary cursor created on the server for fetching more result batches.

        • An array of result documents (might be empty if query has no results).

      • is returned if the JSON representation is malformed or the query specification is missing from the request.

        If the JSON representation is malformed or the query specification is missing from the request, the server will respond with HTTP 400.

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

          Response Body
        • the HTTP status code

        • boolean flag to indicate that an error occurred (true in this case)

        • A descriptive error message.

          If the query specification is complete, the server will process the query. If an error occurs during query processing, the server will respond with HTTP 400. Again, the body of the response will contain details about the error.

        • the server error number

      • The server will respond with HTTP 404 in case a non-existing collection is accessed in the query.

      • The server will respond with HTTP 405 if an unsupported HTTP method is used.

      • The server will respond with HTTP 410 if a server which processes the query or is the leader for a shard which is used in the query stops responding, but the connection has not been closed.

      • The server will respond with HTTP 503 if a server which processes the query or is the leader for a shard which is used in the query is down, either for going through a restart, a failure or connectivity issues.

      Examples

      Execute a query and extract the result in a single go

      curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/cursor
      {
        "query": "FOR p IN products LIMIT 2 RETURN p",
        "count": true,
        "batchSize": 2
      }
      Show output

      Execute a query and extract a part of the result

      curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/cursor
      {
        "query": "FOR p IN products LIMIT 5 RETURN p",
        "count": true,
        "batchSize": 2
      }
      Show output

      Using the query option “fullCount”

      curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/cursor
      {
        "query": "FOR i IN 1..1000 FILTER i > 500 LIMIT 10 RETURN i",
        "count": true,
        "options": {
          "fullCount": true
        }
      }
      Show output

      Enabling and disabling optimizer rules

      curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/cursor
      {
        "query": "FOR i IN 1..10 LET a = 1 LET b = 2 FILTER a + b == 3 RETURN i",
        "count": true,
        "options": {
          "maxPlans": 1,
          "optimizer": {
            "rules": [
              "-all",
              "+remove-unnecessary-filters"
            ]
          }
        }
      }
      Show output

      Execute instrumented query and return result together with execution plan and profiling information

      curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/cursor
      {
        "query": "LET s = SLEEP(0.25) LET t = SLEEP(0.5) RETURN 1",
        "count": true,
        "options": {
          "profile": 2
        }
      }
      Show output

      Execute a data-modification query and retrieve the number of modified documents

      curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/cursor
      {
        "query": "FOR p IN products REMOVE p IN products"
      }
      Show output

      Execute a data-modification query with option ignoreErrors

      curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/cursor
      {
        "query": "REMOVE 'bar' IN products OPTIONS { ignoreErrors: true }"
      }
      Show output

      The following example appends a value to the array arr of the document with key test in the collection documents. The normal update behavior of the UPDATE operation is to replace the array attribute completely, but using the PUSH() function allows you to append to the array:

      curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/cursor
      {
        "query": "FOR doc IN documents FILTER doc._key == @myKey UPDATE doc._key WITH { arr: PUSH(doc.arr, @value) } IN documents RETURN NEW",
        "bindVars": {
          "myKey": "test",
          "value": 42
        }
      }
      Show output

      To set a memory limit for the query, the memoryLimit option can be passed to the server.

      The memory limit specifies the maximum number of bytes that the query is allowed to use. When a single AQL query reaches the specified limit value, the query is aborted with a resource limit exceeded exception. In a cluster, the memory accounting is done per server, so the limit value is effectively a memory limit per query per server.

      If no memory limit is specified, then the server default value (controlled by startup option --query.memory-limit) is used for restricting the maximum amount of memory the query can use. A memory limit value of 0 means that the maximum amount of memory for the query is not restricted.

      curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/cursor
      {
        "query": "FOR i IN 1..100000 SORT i RETURN i",
        "memoryLimit": 100000
      }
      Show output

      Bad query - Missing body

      curl -X POST --header 'accept: application/json' --dump - http://localhost:8529/_api/cursor
      Show output

      Bad query - Unknown collection

      curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/cursor
      {
        "query": "FOR u IN unknowncoll LIMIT 2 RETURN u",
        "count": true,
        "batchSize": 2
      }
      Show output

      Bad query - Execute a data-modification query that attempts to remove a non-existing document

      curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/cursor
      {
        "query": "REMOVE 'foo' IN products"
      }
      Show output

      Read the next batch from a cursor

      post /_api/cursor/{cursor-identifier}

      If the cursor is still alive, returns an object with the following attributes:

      • id: a cursor-identifier
      • result: a list of documents for the current batch
      • hasMore: false if this was the last batch
      • count: if present the total number of elements
      • code: an HTTP status code
      • error: a boolean flag to indicate whether an error occurred
      • errorNum: a server error number (if error is true)
      • errorMessage: a descriptive error message (if error is true)
      • extra: an object with additional information about the query result, with the nested objects stats and warnings. Only delivered as part of the last batch in case of a cursor with the stream option enabled.

      Note that even if hasMore returns true, the next call might still return no documents. If, however, hasMore is false, then the cursor is exhausted. Once the hasMore attribute has a value of false, the client can stop.

      Path Parameters
      • The name of the cursor

      Query Parameters
        HTTP Headers
          Responses
          • The server will respond with HTTP 200 in case of success.

          • If the cursor identifier is omitted, the server will respond with HTTP 404.

          • If no cursor with the specified identifier can be found, the server will respond with HTTP 404.

          • The server will respond with HTTP 410 if a server which processes the query or is the leader for a shard which is used in the query stops responding, but the connection has not been closed.

          • The server will respond with HTTP 503 if a server which processes the query or is the leader for a shard which is used in the query is down, either for going through a restart, a failure or connectivity issues.

          Examples

          Valid request for next batch

          curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/cursor
          {
            "query": "FOR p IN products LIMIT 5 RETURN p",
            "count": true,
            "batchSize": 2
          }
          
          curl -X POST --header 'accept: application/json' --dump - http://localhost:8529/_api/cursor/71109
          Show output

          Missing identifier

          curl -X POST --header 'accept: application/json' --dump - http://localhost:8529/_api/cursor
          Show output

          Unknown identifier

          curl -X POST --header 'accept: application/json' --dump - http://localhost:8529/_api/cursor/123123
          Show output

          Read the next batch from a cursor (deprecated)

          put /_api/cursor/{cursor-identifier}
          This endpoint is deprecated in favor its functionally equivalent POST counterpart.

          If the cursor is still alive, returns an object with the following attributes:

          • id: a cursor-identifier
          • result: a list of documents for the current batch
          • hasMore: false if this was the last batch
          • count: if present the total number of elements
          • code: an HTTP status code
          • error: a boolean flag to indicate whether an error occurred
          • errorNum: a server error number (if error is true)
          • errorMessage: a descriptive error message (if error is true)
          • extra: an object with additional information about the query result, with the nested objects stats and warnings. Only delivered as part of the last batch in case of a cursor with the stream option enabled.

          Note that even if hasMore returns true, the next call might still return no documents. If, however, hasMore is false, then the cursor is exhausted. Once the hasMore attribute has a value of false, the client can stop.

          Path Parameters
          • The name of the cursor

          Query Parameters
            HTTP Headers
              Responses
              • The server will respond with HTTP 200 in case of success.

              • If the cursor identifier is omitted, the server will respond with HTTP 404.

              • If no cursor with the specified identifier can be found, the server will respond with HTTP 404.

              • The server will respond with HTTP 410 if a server which processes the query or is the leader for a shard which is used in the query stops responding, but the connection has not been closed.

              • The server will respond with HTTP 503 if a server which processes the query or is the leader for a shard which is used in the query is down, either for going through a restart, a failure or connectivity issues.

              Examples

              Valid request for next batch

              curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/cursor
              {
                "query": "FOR p IN products LIMIT 5 RETURN p",
                "count": true,
                "batchSize": 2
              }
              
              curl -X PUT --header 'accept: application/json' --dump - http://localhost:8529/_api/cursor/71128
              Show output

              Missing identifier

              curl -X PUT --header 'accept: application/json' --dump - http://localhost:8529/_api/cursor
              Show output

              Unknown identifier

              curl -X PUT --header 'accept: application/json' --dump - http://localhost:8529/_api/cursor/123123
              Show output

              Delete a cursor

              delete /_api/cursor/{cursor-identifier}

              Deletes the cursor and frees the resources associated with it.

              The cursor will automatically be destroyed on the server when the client has retrieved all documents from it. The client can also explicitly destroy the cursor at any earlier time using an HTTP DELETE request. The cursor id must be included as part of the URL.

              Note: the server will also destroy abandoned cursors automatically after a certain server-controlled timeout to avoid resource leakage.

              Path Parameters
              • The id of the cursor

              Query Parameters
                HTTP Headers
                  Responses
                  • is returned if the server is aware of the cursor.

                  • is returned if the server is not aware of the cursor. It is also returned if a cursor is used after it has been destroyed.

                  Examples

                  curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/cursor
                  {
                    "query": "FOR p IN products LIMIT 5 RETURN p",
                    "count": true,
                    "batchSize": 2
                  }
                  
                  curl -X DELETE --header 'accept: application/json' --dump - http://localhost:8529/_api/cursor/71147
                  Show output

                  Track queries

                  You can track AQL queries by enabling query tracking. This allows you to list all currently executing queries. You can also list slow queries and clear this list.

                  Get the AQL query tracking configuration

                  get /_api/query/properties

                  Returns the current query tracking configuration. The configuration is a JSON object with the following properties:

                  • enabled: if set to true, then queries will be tracked. If set to false, neither queries nor slow queries will be tracked.

                  • trackSlowQueries: if set to true, then slow queries will be tracked in the list of slow queries if their runtime exceeds the value set in slowQueryThreshold. In order for slow queries to be tracked, the enabled property must also be set to true.

                  • trackBindVars: if set to true, then bind variables used in queries will be tracked.

                  • maxSlowQueries: the maximum number of slow queries to keep in the list of slow queries. If the list of slow queries is full, the oldest entry in it will be discarded when additional slow queries occur.

                  • slowQueryThreshold: the threshold value for treating a query as slow. A query with a runtime greater or equal to this threshold value will be put into the list of slow queries when slow query tracking is enabled. The value for slowQueryThreshold is specified in seconds.

                  • maxQueryStringLength: the maximum query string length to keep in the list of queries. Query strings can have arbitrary lengths, and this property can be used to save memory in case very long query strings are used. The value is specified in bytes.

                  Responses
                  • Is returned if properties were retrieved successfully.

                  • The server will respond with HTTP 400 in case of a malformed request,

                  Update the AQL query tracking configuration

                  put /_api/query/properties

                  The properties need to be passed in the attribute properties in the body of the HTTP request. properties needs to be a JSON object.

                  After the properties have been changed, the current set of properties will be returned in the HTTP response.

                  Request Body application/json
                  • If set to true, then queries will be tracked. If set to false, neither queries nor slow queries will be tracked.

                  • The maximum query string length to keep in the list of queries. Query strings can have arbitrary lengths, and this property can be used to save memory in case very long query strings are used. The value is specified in bytes.

                  • The maximum number of slow queries to keep in the list of slow queries. If the list of slow queries is full, the oldest entry in it will be discarded when additional slow queries occur.

                  • The threshold value for treating a query as slow. A query with a runtime greater or equal to this threshold value will be put into the list of slow queries when slow query tracking is enabled. The value for slowQueryThreshold is specified in seconds.

                  • If set to true, then the bind variables used in queries will be tracked along with queries.

                  • If set to true, then slow queries will be tracked in the list of slow queries if their runtime exceeds the value set in slowQueryThreshold. In order for slow queries to be tracked, the enabled property must also be set to true.

                  Responses
                  • Is returned if the properties were changed successfully.

                  • The server will respond with HTTP 400 in case of a malformed request,

                  List the running AQL queries

                  get /_api/query/current

                  Returns an array containing the AQL queries currently running in the selected database. Each query is a JSON object with the following attributes:

                  • id: the query’s id

                  • database: the name of the database the query runs in

                  • user: the name of the user that started the query

                  • query: the query string (potentially truncated)

                  • bindVars: the bind parameter values used by the query

                  • started: the date and time when the query was started

                  • runTime: the query’s run time up to the point the list of queries was queried

                  • state: the query’s current execution state (as a string). One of:

                    • "initializing"
                    • "parsing"
                    • "optimizing ast"
                    • "loading collections"
                    • "instantiating plan"
                    • "optimizing plan"
                    • "executing"
                    • "finalizing"
                    • "finished"
                    • "killed"
                    • "invalid"
                  • stream: whether or not the query uses a streaming cursor

                  Path Parameters
                    Query Parameters
                    • If set to true, will return the currently running queries in all databases, not just the selected one. Using the parameter is only allowed in the system database and with superuser privileges.

                    HTTP Headers
                      Responses
                      • Is returned when the list of queries can be retrieved successfully.

                      • The server will respond with HTTP 400 in case of a malformed request,

                      • HTTP 403 is returned in case the all parameter was used, but the request was made in a different database than _system, or by an non-privileged user.

                      List the slow AQL queries

                      get /_api/query/slow

                      Returns an array containing the last AQL queries that are finished and have exceeded the slow query threshold in the selected database. The maximum amount of queries in the list can be controlled by setting the query tracking property maxSlowQueries. The threshold for treating a query as slow can be adjusted by setting the query tracking property slowQueryThreshold.

                      Each query is a JSON object with the following attributes:

                      • id: the query’s id

                      • database: the name of the database the query runs in

                      • user: the name of the user that started the query

                      • query: the query string (potentially truncated)

                      • bindVars: the bind parameter values used by the query

                      • started: the date and time when the query was started

                      • runTime: the query’s total run time

                      • state: the query’s current execution state (will always be “finished” for the list of slow queries)

                      • stream: whether or not the query uses a streaming cursor

                      Path Parameters
                        Query Parameters
                        • If set to true, will return the slow queries from all databases, not just the selected one. Using the parameter is only allowed in the system database and with superuser privileges.

                        HTTP Headers
                          Responses
                          • Is returned when the list of queries can be retrieved successfully.

                          • The server will respond with HTTP 400 in case of a malformed request,

                          • HTTP 403 is returned in case the all parameter was used, but the request was made in a different database than _system, or by an non-privileged user.

                          Clear the list of slow AQL queries

                          delete /_api/query/slow
                          Clears the list of slow AQL queries for the current database.
                          Path Parameters
                            Query Parameters
                            • If set to true, will clear the slow query history in all databases, not just the selected one. Using the parameter is only allowed in the system database and with superuser privileges.

                            HTTP Headers
                              Responses
                              • The server will respond with HTTP 200 when the list of queries was cleared successfully.

                              • The server will respond with HTTP 400 in case of a malformed request.

                              Kill queries

                              Running AQL queries can be killed on the server. To kill a running query, its ID (as returned for the query in the list of currently running queries) must be specified. The kill flag of the query is then set, and the query is aborted as soon as it reaches a cancelation point.

                              Kill a running AQL query

                              delete /_api/query/{query-id}
                              Kills a running query in the currently selected database. The query will be terminated at the next cancelation point.
                              Path Parameters
                              • The id of the query.

                              Query Parameters
                              • If set to true, will attempt to kill the specified query in all databases, not just the selected one. Using the parameter is only allowed in the system database and with superuser privileges.

                              HTTP Headers
                                Responses
                                • The server will respond with HTTP 200 when the query was still running when the kill request was executed and the query’s kill flag was set.

                                • The server will respond with HTTP 400 in case of a malformed request.

                                • HTTP 403 is returned in case the all parameter was used, but the request was made in a different database than _system, or by an non-privileged user.

                                • The server will respond with HTTP 404 when no query with the specified id was found.

                                Explain and parse AQL queries

                                You can retrieve the execution plan for any valid AQL query, as well as syntactically validate AQL queries. Both functionalities don’t actually execute the supplied AQL query, but only inspect it and return meta information about it.

                                You can also retrieve a list of all query optimizer rules and their properties.

                                Explain an AQL query

                                post /_api/explain

                                To explain how an AQL query would be executed on the server, the query string can be sent to the server via an HTTP POST request. The server will then validate the query and create an execution plan for it. The execution plan will be returned, but the query will not be executed.

                                The execution plan that is returned by the server can be used to estimate the probable performance of the query. Though the actual performance will depend on many different factors, the execution plan normally can provide some rough estimates on the amount of work the server needs to do in order to actually run the query.

                                By default, the explain operation will return the optimal plan as chosen by the query optimizer The optimal plan is the plan with the lowest total estimated cost. The plan will be returned in the attribute plan of the response object. If the option allPlans is specified in the request, the result will contain all plans created by the optimizer. The plans will then be returned in the attribute plans.

                                The result will also contain an attribute warnings, which is an array of warnings that occurred during optimization or execution plan creation. Additionally, a stats attribute is contained in the result with some optimizer statistics. If allPlans is set to false, the result will contain an attribute cacheable that states whether the query results can be cached on the server if the query result cache were used. The cacheable attribute is not present when allPlans is set to true.

                                Each plan in the result is a JSON object with the following attributes:

                                • nodes: the array of execution nodes of the plan.

                                • estimatedCost: the total estimated cost for the plan. If there are multiple plans, the optimizer will choose the plan with the lowest total cost.

                                • collections: an array of collections used in the query

                                • rules: an array of rules the optimizer applied.

                                • variables: array of variables used in the query (note: this may contain internal variables created by the optimizer)

                                Request Body application/json
                                • An object with key/value pairs representing the bind parameters. For a bind variable @var in the query, specify the value using an attribute with the name var. For a collection bind variable @@coll, use @coll as the attribute name. For example: "bindVars": { "var": 42, "@coll": "products" }.

                                • Options for the query

                                  • if set to true, all possible execution plans will be returned. The default is false, meaning only the optimal plan will be returned.

                                  • an optional maximum number of plans that the optimizer is allowed to generate. Setting this attribute to a low value allows to put a cap on the amount of work the optimizer does.

                                  • Options related to the query optimizer.

                                    • A list of to-be-included or to-be-excluded optimizer rules can be put into this attribute, telling the optimizer to include or exclude specific rules. To disable a rule, prefix its name with a -, to enable a rule, prefix it with a +. There is also a pseudo-rule all, which matches all optimizer rules. -all disables all rules.

                                • the query which you want explained; If the query references any bind variables, these must also be passed in the attribute bindVars. Additional options for the query can be passed in the options attribute.

                                Responses
                                • If the query is valid, the server will respond with HTTP 200 and return the optimal execution plan in the plan attribute of the response. If option allPlans was set in the request, an array of plans will be returned in the allPlans attribute instead.

                                • The server will respond with HTTP 400 in case of a malformed request, or if the query contains a parse error. The body of the response will contain the error details embedded in a JSON object. Omitting bind variables if the query references any will also result in an HTTP 400 error.

                                • The server will respond with HTTP 404 in case a non-existing collection is accessed in the query.

                                Examples

                                Valid query

                                curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/explain
                                {
                                  "query": "FOR p IN products RETURN p"
                                }
                                Show output

                                A plan with some optimizer rules applied

                                curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/explain
                                {
                                  "query": "FOR p IN products LET a = p.id FILTER a == 4 LET name = p.name SORT p.id LIMIT 1 RETURN name"
                                }
                                Show output

                                Using some options

                                curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/explain
                                {
                                  "query": "FOR p IN products LET a = p.id FILTER a == 4 LET name = p.name SORT p.id LIMIT 1 RETURN name",
                                  "options": {
                                    "maxNumberOfPlans": 2,
                                    "allPlans": true,
                                    "optimizer": {
                                      "rules": [
                                        "-all",
                                        "+use-index-for-sort",
                                        "+use-index-range"
                                      ]
                                    }
                                  }
                                }
                                Show output

                                Returning all plans

                                curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/explain
                                {
                                  "query": "FOR p IN products FILTER p.id == 25 RETURN p",
                                  "options": {
                                    "allPlans": true
                                  }
                                }
                                Show output

                                A query that produces a warning

                                curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/explain
                                {
                                  "query": "FOR i IN 1..10 RETURN 1 / 0"
                                }
                                Show output

                                Invalid query (missing bind parameter)

                                curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/explain
                                {
                                  "query": "FOR p IN products FILTER p.id == @id LIMIT 2 RETURN p.n"
                                }
                                Show output

                                The data returned in the plan attribute of the result contains one element per AQL top-level statement (i.e. FOR, RETURN, FILTER etc.). If the query optimizer removed some unnecessary statements, the result might also contain less elements than there were top-level statements in the AQL query.

                                The following example shows a query with a non-sensible filter condition that the optimizer has removed so that there are less top-level statements.

                                curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/explain
                                "{ \"query\" : \"FOR i IN [ 1, 2, 3 ] FILTER 1 == 2 RETURN i\" }"
                                Show output

                                Parse an AQL query

                                post /_api/query
                                This endpoint is for query validation only. To actually query the database, see /api/cursor.
                                Request Body application/json
                                • To validate a query string without executing it, the query string can be passed to the server via an HTTP POST request.

                                Responses
                                • If the query is valid, the server will respond with HTTP 200 and return the names of the bind parameters it found in the query (if any) in the bindVars attribute of the response. It will also return an array of the collections used in the query in the collections attribute. If a query can be parsed successfully, the ast attribute of the returned JSON will contain the abstract syntax tree representation of the query. The format of the ast is subject to change in future versions of ArangoDB, but it can be used to inspect how ArangoDB interprets a given query. Note that the abstract syntax tree will be returned without any optimizations applied to it.

                                • The server will respond with HTTP 400 in case of a malformed request, or if the query contains a parse error. The body of the response will contain the error details embedded in a JSON object.

                                Examples

                                a valid query

                                curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/query
                                "{ \"query\" : \"FOR i IN 1..100 FILTER i > 10 LIMIT 2 RETURN i * 3\" }"
                                Show output

                                an invalid query

                                curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/query
                                "{ \"query\" : \"FOR i IN 1..100 FILTER i = 1 LIMIT 2 RETURN i * 3\" }"
                                Show output

                                List all AQL optimizer rules

                                get /_api/query/rules
                                A list of all optimizer rules and their properties.
                                Responses
                                • is returned if the list of optimizer rules can be retrieved successfully.

                                    Response Body
                                  • An array of objects. Each object describes an AQL optimizer rule.

                                    • An object with the properties of the rule.

                                      • Whether users are allowed to disable this rule. A few rules are mandatory.

                                      • Whether this rule may create additional query execution plans.

                                      • Whether the rule is applicable in the cluster deployment mode only.

                                      • Whether the optimizer considers this rule by default.

                                      • Whether the rule is available in the Enterprise Edition only.

                                      • Whether the rule is displayed to users. Internal rules are hidden.

                                    • The name of the optimizer rule as seen in query explain outputs.

                                Examples

                                Retrieve the list of all query optimizer rules:

                                curl --header 'accept: application/json' --dump - http://localhost:8529/_api/query/rules
                                Show output