Get all documents from Elasticsearch index by scroll method

elasticsearch-scroll.js

const elasticsearch = require('elasticsearch');

const esClient = new elasticsearch.Client({
  host: 'YOUR ELASTICSEARCH SERVER'
});

/**
 * Get all documents of an Elasticsearch index by scroll method
 * @param {string} index Index to get documents
 * @param {Object} query Querying object
 * @param {number} size Size of each scroll. Default: 1000
 */
async function getAllDocuments(index, query, size = 1000) {
  let data = [];

  const getNext = async (scrollId) => {
    return await esClient.scroll({
      scroll: '2m',
      scrollId: scrollId
    });
  }

  let result = await esClient.search({
    index: index,
    size: size,
    scroll: '2m',
    body: { query: query }
  });

  console.log('Total hits:', result.hits.total);
  console.log('Page hits count:', result.hits.hits.length);

  while (result.hits.hits.length) {
    console.log('Getting next', result.hits.hits.length);
    data = data.concat(result.hits.hits);
    result = await getNext(result._scroll_id);
  }
  console.log('Done', data.length);

  return data;
}

exports.getAllDocuments = getAllDocuments;