Elasticsearch

Distributed search and analytics engine for full-text search and logging.

When to Use

• Full-text search implementation
• Log aggregation and analysis
• Real-time analytics
• Geospatial search

Quick Start

// Index a document
await client.index({
  index: "products",
  id: "1",
  body: {
    name: "Laptop",
    description: "High-performance laptop",
    price: 999.99,
    category: "electronics",
  },
});

// Search
const { hits } = await client.search({
  index: "products",
  body: {
    query: { match: { description: "laptop" } },
  },
});

Core Concepts

Mappings

await client.indices.create({
  index: "products",
  body: {
    mappings: {
      properties: {
        name: { type: "text", analyzer: "standard" },
        description: { type: "text" },
        price: { type: "float" },
        category: { type: "keyword" },
        tags: { type: "keyword" },
        created_at: { type: "date" },
      },
    },
  },
});

Search Queries

// Boolean query
const query = {
  bool: {
    must: [{ match: { description: "laptop" } }],
    filter: [
      { term: { category: "electronics" } },
      { range: { price: { lte: 1000 } } },
    ],
    should: [{ term: { featured: true } }],
  },
};

// Full-text with highlighting
const result = await client.search({
  index: "products",
  body: {
    query: { match: { description: "laptop computer" } },
    highlight: { fields: { description: {} } },
    sort: [{ price: "asc" }],
    from: 0,
    size: 10,
  },
});

Common Patterns

Aggregations

const result = await client.search({
  index: "orders",
  body: {
    size: 0,
    aggs: {
      sales_by_category: {
        terms: { field: "category" },
        aggs: {
          total_revenue: { sum: { field: "amount" } },
          avg_order: { avg: { field: "amount" } },
        },
      },
      monthly_sales: {
        date_histogram: {
          field: "created_at",
          calendar_interval: "month",
        },
      },
    },
  },
});

Best Practices

Do:

• Use keyword type for exact matches
• Set appropriate shard count
• Use bulk operations for indexing
• Implement proper mappings upfront

Don’t:

• Use text type for filtering
• Create too many shards
• Skip index lifecycle management
• Store large documents

Troubleshooting

References

• Elasticsearch Documentation
• Elasticsearch Best Practices