Method: Elasticsearch::API::Actions#scroll

Defined in:
lib/elasticsearch/api/actions/scroll.rb

#scroll(arguments = {}) ⇒ Object

Efficiently iterate over a large result set.

When using ‘from` and `size` to return a large result sets, performance drops as you “paginate” in the set, and you can’t guarantee the consistency when the index is being updated at the same time.

The “Scroll” API uses a “point in time” snapshot of the index state, which was created via a “Search” API request specifying the ‘scroll` parameter.

Examples:

A basic example


result = client.search index: 'scrollindex',
                       scroll: '5m',
                       body: { query: { match: { title: 'test' } }, sort: '_id' }

result = client.scroll scroll: '5m', scroll_id: result['_scroll_id']

Call the ‘scroll` API until all the documents are returned


# Index 1,000 documents
client.indices.delete index: 'test'
1_000.times do |i| client.index index: 'test', type: 'test', id: i+1, body: {title: "Test #{i}"} end
client.indices.refresh index: 'test'

# Open the "view" of the index by passing the `scroll` parameter
# Sorting by `_doc` makes the operations faster
r = client.search index: 'test', scroll: '1m', body: {sort: ['_doc']}

# Display the initial results
puts "--- BATCH 0 -------------------------------------------------"
puts r['hits']['hits'].map { |d| d['_source']['title'] }.inspect

# Call the `scroll` API until empty results are returned
while r = client.scroll(scroll_id: r['_scroll_id'], scroll: '5m') and not r['hits']['hits'].empty? do
  puts "--- BATCH #{defined?($i) ? $i += 1 : $i = 1} -------------------------------------------------"
  puts r['hits']['hits'].map { |d| d['_source']['title'] }.inspect
  puts
end

Parameters:

  • arguments (Hash) (defaults to: {}) —

    a customizable set of options

Options Hash (arguments):

  • :scroll_id (String) —

    The scroll ID

  • :body (Hash) —

    The scroll ID if not passed by URL or query parameter.

  • :scroll (Duration) —

    Specify how long a consistent view of the index should be maintained for scrolled search

See Also:



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# File 'lib/elasticsearch/api/actions/scroll.rb', line 52

def scroll(arguments={})
  method = HTTP_GET
  path   = "_search/scroll"
  valid_params = [
    :scroll,
    :scroll_id ]

  params = Utils.__validate_and_extract_params arguments, valid_params
  body   = arguments[:body] || params.delete(:scroll_id)

  perform_request(method, path, params, body).body
end