Working with Hash Indexes

If a suitable hash index exists, then /_api/simple/by-example will use this index to execute a query-by-example.

Create hash index

creates a hash index

POST /_api/index#hash

Query Parameters

collection (required): The collection name.

A JSON object with these properties is required:

type: must be equal to “hash”.
fields: an array of attribute paths.
unique: if true, then create a unique index.
sparse: if true, then create a sparse index.
deduplicate: if false, the deduplication of array values is turned off.

Creates a hash index for the collection collection-name if it does not already exist. The call expects an object containing the index details.

In a sparse index all documents will be excluded from the index that do not contain at least one of the specified index attributes (i.e. fields) or that have a value of null in any of the specified index attributes. Such documents will not be indexed, and not be taken into account for uniqueness checks if the unique flag is set.

In a non-sparse index, these documents will be indexed (for non-present indexed attributes, a value of null will be used) and will be taken into account for uniqueness checks if the unique flag is set.

Note: unique indexes on non-shard keys are not supported in a cluster.

Return codes

200: If the index already exists, then a HTTP 200 is returned.
201: If the index does not already exist and could be created, then a HTTP 201 is returned.
400: If the collection already contains documents and you try to create a unique hash index in such a way that there are documents violating the uniqueness, then a HTTP 400 is returned.
404: If the collection-name is unknown, then a HTTP 404 is returned.

Examples

Creating an unique constraint

shell> curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/index?collection=products <<EOF
{ 
  "type" : "hash", 
  "unique" : true, 
  "fields" : [ 
    "a", 
    "b" 
  ] 
}
EOF

HTTP/1.1 201 Created
content-type: application/json
connection: Keep-Alive
content-length: 225
server: ArangoDB
x-content-type-options: nosniff

{ 
  "deduplicate" : true, 
  "estimates" : true, 
  "fields" : [ 
    "a", 
    "b" 
  ], 
  "id" : "products/67641", 
  "isNewlyCreated" : true, 
  "name" : "idx_1707084115697729536", 
  "selectivityEstimate" : 1, 
  "sparse" : false, 
  "type" : "hash", 
  "unique" : true, 
  "error" : false, 
  "code" : 201 
}

Hide response body

shell> curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/index?collection=products <<EOF
{ 
  "type" : "hash", 
  "unique" : true, 
  "fields" : [ 
    "a", 
    "b" 
  ] 
}
EOF

HTTP/1.1 201 Created
content-type: application/json
connection: Keep-Alive
content-length: 225
server: ArangoDB
x-content-type-options: nosniff

Show response body

Creating a non-unique hash index

shell> curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/index?collection=products <<EOF
{ 
  "type" : "hash", 
  "unique" : false, 
  "fields" : [ 
    "a", 
    "b" 
  ] 
}
EOF

HTTP/1.1 201 Created
content-type: application/json
connection: Keep-Alive
content-length: 226
server: ArangoDB
x-content-type-options: nosniff

{ 
  "deduplicate" : true, 
  "estimates" : true, 
  "fields" : [ 
    "a", 
    "b" 
  ], 
  "id" : "products/67597", 
  "isNewlyCreated" : true, 
  "name" : "idx_1707084115676758017", 
  "selectivityEstimate" : 1, 
  "sparse" : false, 
  "type" : "hash", 
  "unique" : false, 
  "error" : false, 
  "code" : 201 
}

Hide response body

shell> curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/index?collection=products <<EOF
{ 
  "type" : "hash", 
  "unique" : false, 
  "fields" : [ 
    "a", 
    "b" 
  ] 
}
EOF

HTTP/1.1 201 Created
content-type: application/json
connection: Keep-Alive
content-length: 226
server: ArangoDB
x-content-type-options: nosniff

Show response body

Creating a sparse index

shell> curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/index?collection=products <<EOF
{ 
  "type" : "hash", 
  "unique" : false, 
  "sparse" : true, 
  "fields" : [ 
    "a" 
  ] 
}
EOF

HTTP/1.1 201 Created
content-type: application/json
connection: Keep-Alive
content-length: 221
server: ArangoDB
x-content-type-options: nosniff

{ 
  "deduplicate" : true, 
  "estimates" : true, 
  "fields" : [ 
    "a" 
  ], 
  "id" : "products/67652", 
  "isNewlyCreated" : true, 
  "name" : "idx_1707084115704020992", 
  "selectivityEstimate" : 1, 
  "sparse" : true, 
  "type" : "hash", 
  "unique" : false, 
  "error" : false, 
  "code" : 201 
}

Hide response body

shell> curl -X POST --header 'accept: application/json' --data-binary @- --dump - http://localhost:8529/_api/index?collection=products <<EOF
{ 
  "type" : "hash", 
  "unique" : false, 
  "sparse" : true, 
  "fields" : [ 
    "a" 
  ] 
}
EOF

HTTP/1.1 201 Created
content-type: application/json
connection: Keep-Alive
content-length: 221
server: ArangoDB
x-content-type-options: nosniff

Show response body

❮ Working with Indexes Skiplist ❯