INSERT

The INSERT keyword can be used to insert new documents into a collection. On a single server, an insert operation is executed transactionally in an all-or-nothing fashion.

If the RocksDB engine is used and intermediate commits are enabled, a query may execute intermediate transaction commits in case the running transaction (AQL query) hits the specified size thresholds. In this case, the query’s operations carried out so far will be committed and not rolled back in case of a later abort/rollback. That behavior can be controlled by adjusting the intermediate commit settings for the RocksDB engine.

For sharded collections, the entire query and/or insert operation may not be transactional, especially if it involves different shards and/or DB-Servers.

Each INSERT operation is restricted to a single collection, and the collection name must not be dynamic. Only a single INSERT statement per collection is allowed per AQL query, and it cannot be followed by read or write operations that access the same collection, by traversal operations, or AQL functions that can read documents.

The syntax for an insert operation is:

INSERT document INTO collection [ OPTIONS options ]

Note: The IN keyword is allowed in place of INTO and has the same meaning.

collection must contain the name of the collection into which the documents should be inserted. document is the document to be inserted, and it may or may not contain a _key attribute. If no _key attribute is provided, ArangoDB will auto-generate a value for _key value. Inserting a document will also auto-generate a document revision number for the document.

FOR i IN 1..100
  INSERT { value: i } INTO numbers

An insert operation can also be performed without a FOR loop to insert a single document:

INSERT { value: 1 } INTO numbers

When inserting into an edge collection, it is mandatory to specify the attributes _from and _to in document:

FOR u IN users
  FOR p IN products
    FILTER u._key == p.recommendedBy
    INSERT { _from: u._id, _to: p._id } INTO recommendations

Setting query options

The OPTIONS keyword followed by an object with query options can optionally be provided in an INSERT operation.

It can be used to suppress query errors that may occur when violating unique key constraints:

FOR i IN 1..1000
  INSERT {
    _key: CONCAT('test', i),
    name: "test",
    foobar: true
  } INTO users OPTIONS { ignoreErrors: true }

To make sure data are durable when an insert query returns, there is the waitForSync query option:

FOR i IN 1..1000
  INSERT {
    _key: CONCAT('test', i),
    name: "test",
    foobar: true
  } INTO users OPTIONS { waitForSync: true }

If you want to replace existing documents with documents having the same key there is the overwrite query option. This will let you safely replace the documents instead of raising a “unique constraint violated error”:

FOR i IN 1..1000
  INSERT {
    _key: CONCAT('test', i),
    name: "test",
    foobar: true
  } INTO users OPTIONS { overwrite: true }

To further control the behavior of INSERT on primary index unique constraint violations, there is the overwriteMode option. It offers the following modes:

  • "ignore": if a document with the specified _key value exists already, nothing will be done and no write operation will be carried out. The insert operation will return success in this case. This mode does not support returning the old document version. Using RETURN OLD will trigger a parse error, as there will be no old version to return. RETURN NEW will only return the document in case it was inserted. In case the document already existed, RETURN NEW will return null.
  • "replace": if a document with the specified _key value exists already, it will be overwritten with the specified document value. This mode will also be used when no overwrite mode is specified but the overwrite flag is set to true.
  • "update": if a document with the specified _key value exists already, it will be patched (partially updated) with the specified document value.
  • "conflict": if a document with the specified _key value exists already, return a unique constraint violation error so that the insert operation fails. This is also the default behavior in case the overwrite mode is not set, and the overwrite flag is false or not set either.

The main use case of inserting documents with overwrite mode ignore is to make sure that certain documents exist in the cheapest possible way. In case the target document already exists, the ignore mode is most efficient, as it will not retrieve the existing document from storage and not write any updates to it.

When using the update overwrite mode, the keepNull and mergeObjects options control how the update is done. See UPDATE operation.

FOR i IN 1..1000
  INSERT {
    _key: CONCAT('test', i),
    name: "test",
    foobar: true
  } INTO users OPTIONS { overwriteMode: "update", keepNull: true, mergeObjects: false }

The RocksDB engine does not require collection-level locks. Different write operations on the same collection do not block each other, as long as there are no write-write conflicts on the same documents. From an application development perspective it can be desired to have exclusive write access on collections, to simplify the development. Note that writes do not block reads in RocksDB. Exclusive access can also speed up modification queries, because we avoid conflict checks.

Use the exclusive option to achieve this effect on a per query basis:

FOR doc IN collection
  INSERT { myval: doc.val + 1 } INTO users 
  OPTIONS { exclusive: true }

Returning the inserted documents

The inserted documents can also be returned by the query. In this case, the INSERT statement can be a RETURN statement (intermediate LET statements are allowed, too). To refer to the inserted documents, the INSERT statement introduces a pseudo-value named NEW.

The documents contained in NEW will contain all attributes, even those auto-generated by the database (e.g. _id, _key, _rev).

INSERT document INTO collection RETURN NEW

Following is an example using a variable named inserted to return the inserted documents. For each inserted document, the document key is returned:

FOR i IN 1..100
  INSERT { value: i }
  INTO users
  LET inserted = NEW
  RETURN inserted._key