arangodb/Documentation/DocuBlocks/Rest/Indexes/post_api_index_hash.md

@startDocuBlock post_api_index_hash @brief creates a hash index

@RESTHEADER{POST /_api/index#hash, Create hash index, createIndex:hash}

@RESTQUERYPARAMETERS

@RESTQUERYPARAM{collection,string,required} The collection name.

@RESTBODYPARAM{type,string,required,string} must be equal to "hash".

@RESTBODYPARAM{fields,array,required,string} an array of attribute paths.

@RESTBODYPARAM{unique,boolean,required,} if true, then create a unique index.

@RESTBODYPARAM{sparse,boolean,required,} if true, then create a sparse index.

@RESTBODYPARAM{deduplicate,boolean,optional,boolean} if false, the deduplication of array values is turned off.

@RESTDESCRIPTION NOTE Swagger examples won't work due to the anchor.

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.

@RESTRETURNCODES

@RESTRETURNCODE{200} If the index already exists, then a HTTP 200 is returned.

@RESTRETURNCODE{201} If the index does not already exist and could be created, then a HTTP 201 is returned.

@RESTRETURNCODE{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.

@RESTRETURNCODE{404} If the collection-name is unknown, then a HTTP 404 is returned.

@EXAMPLES

Creating an unique constraint

@EXAMPLE_ARANGOSH_RUN{RestIndexCreateNewUniqueConstraint} var cn = "products"; db._drop(cn); db._create(cn);

var url = "/_api/index?collection=" + cn;
var body = { 
  type: "hash", 
  unique: true, 
  fields : [ "a", "b" ] 
};

var response = logCurlRequest('POST', url, body);

assert(response.code === 201);

logJsonResponse(response);

~ db._drop(cn); @END_EXAMPLE_ARANGOSH_RUN

Creating a non-unique hash index

@EXAMPLE_ARANGOSH_RUN{RestIndexCreateNewHashIndex} var cn = "products"; db._drop(cn); db._create(cn);

var url = "/_api/index?collection=" + cn;
var body = { 
  type: "hash", 
  unique: false, 
  fields: [ "a", "b" ] 
};

var response = logCurlRequest('POST', url, body);

assert(response.code === 201);

logJsonResponse(response);

~ db._drop(cn); @END_EXAMPLE_ARANGOSH_RUN

Creating a sparse index

@EXAMPLE_ARANGOSH_RUN{RestIndexCreateSparseHashIndex} var cn = "products"; db._drop(cn); db._create(cn);

var url = "/_api/index?collection=" + cn;
var body = { 
  type: "hash", 
  unique: false, 
  sparse: true, 
  fields: [ "a" ] 
};

var response = logCurlRequest('POST', url, body);

assert(response.code === 201);

logJsonResponse(response);

~ db._drop(cn); @END_EXAMPLE_ARANGOSH_RUN @endDocuBlock