AutoGineer
Generated banner for Elasticsearch Index Design
Generated logo for Elasticsearch Index Design

Elasticsearch Index Design

ElasticOfficialCreated by elastic

  • Skill
  • Tool integration
  • Data and AI
  • Apache-2.0
  • No issues found
Download ZIP

From the author

Design and review Elasticsearch index mappings for stated access patterns: correct field types, text+keyword multi-fields, doc_values tuning, mapping-explosion avoidance, and explicit shard settings. Use when creating a new index, reviewing a mapping for storage or query performance, fixing wrong field types, or when the user asks which type to use for search, filter, sort, or aggregation on a field.
— the description by elastic

AutoGineer summary

Written by AutoGineer from the skill’s own files, not by the author

This skill provides a structured process for designing and reviewing Elasticsearch index mappings. It emphasizes aligning field types with actual access patterns—such as full-text search, filtering, sorting, or aggregation—to optimize storage and query performance. The skill guides users through defining explicit mappings, implementing multi-field patterns, and applying storage optimizations like doc_values tuning and flattened types. It also provides a clear path for remediating existing indices by creating new, optimized mappings and performing a reindex operation, as Elasticsearch does not support in-place type changes.

What it does

  • Analyzes field usage patterns to determine optimal Elasticsearch data types.
  • Provides templates for explicit index mappings to avoid dynamic mapping pitfalls.
  • Identifies and mitigates risks like mapping explosion and storage bloat.
  • Recommends storage optimizations such as disabling doc_values for retrieve-only fields.
  • Outlines the procedure for migrating data to a new index when mapping changes are required.
  • Maps high-level design requirements to specific Elasticsearch CLI operations.

When to use it

  • When creating a new Elasticsearch index and defining its initial schema.
  • When reviewing an existing index to improve query performance or reduce storage costs.
  • When encountering mapping explosion or performance issues due to incorrect field types.
  • When you need to change a field type on a live index that requires a reindex operation.
  • When you are unsure whether to use text, keyword, or other types for specific search or aggregation needs.

Advantages

  • Prevents common performance anti-patterns like fielddata usage or mapping explosion.
  • Reduces disk storage footprint through targeted type selection and doc_values tuning.
  • Ensures search relevance and aggregation accuracy by using correct field types.
  • Provides a safe, repeatable workflow for updating production index schemas.
  • Promotes the use of explicit mappings over dynamic ones for production stability.

Usage examples

“I have a product index. Users search by name, but I also need to sort and aggregate by name. How should I map this?”
The agent will recommend using a text field with a keyword multi-field, providing the JSON structure to map 'name' as text and 'name.keyword' as keyword.
“My index is growing too large and I have a field for labels that contains many different keys. How do I fix this?”
The agent will suggest replacing the dynamic object mapping for 'labels' with the 'flattened' type to prevent mapping explosion.
“I need to change a field from text to keyword to fix my aggregations. How do I do this?”
The agent will explain that in-place changes are not possible, then guide you through creating a new index with the correct mapping and using the reindex command.

Install

  1. Download the skill as a ZIP:

    https://mp-staging.autogineer.com/agent-skills/elastic/elasticsearch-index-design/download

  2. Unzip it into the cross-client skills folder of your project:

    mkdir -p .agents/skills && unzip elasticsearch-index-design.zip -d .agents/skills

Documentation by elastic

Elasticsearch Index Design

Design explicit index mappings from access patterns, review existing mappings for type and storage mistakes, and apply corrections through a new index plus reindex when field types must change.

<!-- begin-partial: preamble -->

Environment Configuration

This skill executes Elasticsearch operations through the elastic CLI. If the elastic CLI is not installed, tell the user what it is needed for. Do not guess credentials, call the HTTP API directly, or attempt other workarounds.

This skill references operations in HTTP-shorthand form (e.g., GET /, GET /_cat/indices, GET /{index}/_mapping, GET /{index}/_settings/index.mode, POST /_query). The Operations table at the end of this document maps each shorthand to the equivalent elastic CLI command — always use the CLI rather than calling the HTTP API directly.

<!-- end-partial: preamble -->

Process

  1. Gather access patterns per field. Before choosing types, list how each field is used. For every field capture:

    • Search — full-text match, phrase, relevance scoring?

    • Filter — exact term, terms set, prefix?

    • Aggregate — terms, cardinality, histogram, stats?

    • Sort — ascending/d descending in result sets?

    • Retrieve only — returned in _source but never queried?

    The decision: classify each field into one primary access pattern (search, exact, numeric metric, date, boolean, structured object, or retrieve-only). Missing access-pattern data is a blocker — ask the user rather than guessing. Call GET / to confirm connectivity; when reviewing an existing index, call GET /{index}/_mapping to ground the discussion in the current mapping.

  2. Choose field types from access patterns. Map each field to the minimal type set that satisfies its pattern. Read Field Type Decisions and Multi-Field Patterns before proposing mappings.

    Key judgments:

    PatternMapping
    Full-text search onlytext (no keyword sub-field)
    Filter / agg / sort onlykeyword (not text)
    Full-text search and sort or aggregationtext with fields.keyword multi-field
    Decimal price or metricdouble, float, or scaled_float — not text or integer
    Timestampdate
    True/false flagboolean
    Free-form key/value map with many distinct keysflattened — not dynamic object

    Multi-field rule: When a field must be searchable and sortable/aggregatable (e.g. product name), map it as text with a keyword sub-field — search on name, sort and aggregate on name.keyword. Mapping as only text or only keyword is wrong for that combined pattern.

    Explicit mapping rule: For new indices, always define mappings explicitly with PUT /{index}. Do not rely on dynamic mapping for production indices — the first document can lock in wrong types (strings as text, ambiguous numbers as keyword).

    Index settings: Set deliberate number_of_shards and number_of_replicas in the same PUT /{index} request when the deployment allows it (Self-Managed / Elastic Cloud Hosted). On Serverless, omit shard and replica counts (Elastic manages them); still supply explicit mappings. State chosen values or document that defaults apply.

    Example — products index optimized for search plus sort/agg on name:

    {
  "settings": {
    "number_of_shards": 1,
    "number_of_replicas": 1
  },
  "mappings": {
    "properties": {
      "name": {
        "type": "text",
        "fields": {
          "keyword": { "type": "keyword", "ignore_above": 256 }
        }
      },
      "price": { "type": "double" },
      "created": { "type": "date" },
      "in_stock": { "type": "boolean" }
    }
  }
}

    Create with PUT /products passing the settings and mappings blocks. Verify with GET /products/_mapping.

  3. Guard against mapping explosion and storage bloat. On high-volume indices, type mistakes multiply cost. Read Mapping Explosion and Storage Bloat and apply these review checks:

    • Analyzed-but-not-searched fields — Fields used only for filter and aggregation (url, HTTP status_code, tags, IDs) must be keyword, not text. text wastes space; aggregations on text require fielddata or a .keyword sub-field that should not exist if the field is not searched.

    • message.keyword without ignore_above — A keyword sub-field on a large full-text body indexes the entire raw string as one term. Flag this anti-pattern; remove the sub-field when only full-text search is needed, or add ignore_above when a bounded exact-match sub-field is truly required.

    • Dynamic free-form objects — object with "dynamic": true on user-supplied key/value data with thousands of distinct keys causes mapping explosion. Recommend flattened (or strict dynamic / allowlist strategy).

    • doc_values: false — On fields retrieved in hits but never sorted, aggregated, or filtered (e.g. display-only session_id), set "doc_values": false on keyword to save disk at scale.

    • scaled_float — For metrics with bounded precision (e.g. response_time_ms), prefer scaled_float with an appropriate scaling_factor over plain float/double when storage dominates.

    Prefer "dynamic": "strict" on the root mapping unless unknown fields are an explicit requirement.

  4. Apply design: create new index and reindex when types change. Elasticsearch cannot change an existing field's type in place. When review finds wrong types (text→keyword, object→flattened, float→scaled_float, doc_values changes on existing fields), state clearly that fixes require a new index and reindex — not a mapping update on the live index.

    Workflow for correcting an existing high-volume index such as events:

    1. Design the corrected mapping on a new index name (e.g. events-v2) incorporating all fixes from steps 2–3.

    2. Create the destination with PUT /events-v2 and the full corrected mappings (and settings where applicable).

    3. Copy documents with POST /_reindex — for large indices use wait_for_completion=false and track the task. Source: { "index": "events" }, destination: { "index": "events-v2" }.

    4. Verify with GET /events-v2/_count (compare to source count) and GET /events-v2/_mapping (confirm types).

    5. Cut over reads and writes (index alias swap or application config) after validation.

    Example corrected excerpt for the events review pattern:

    {
  "mappings": {
    "properties": {
      "@timestamp": { "type": "date" },
      "event_id": { "type": "keyword" },
      "session_id": { "type": "keyword", "doc_values": false },
      "url": { "type": "keyword" },
      "status_code": { "type": "keyword" },
      "response_time_ms": { "type": "scaled_float", "scaling_factor": 100 },
      "tags": { "type": "keyword" },
      "message": { "type": "text" },
      "labels": { "type": "flattened" }
    }
  }
}

    Do not attempt in-place mapping fixes for these type changes — they are rejected or leave data inconsistent. For greenfield indices, a single PUT /{index} before first ingest avoids reindex entirely.

Review checklist

When the user supplies a mapping JSON and usage notes, walk this checklist in order:

  1. Match each field's type to its stated access pattern (see step 2).

  2. Flag text on filter/agg-only fields; flag missing multi-fields where search and sort/agg share one logical field.

  3. Flag message.keyword (or similar) without ignore_above on large analyzed text.

  4. Flag dynamic object on high-cardinality free-form maps; recommend flattened.

  5. Propose retrieve-only and numeric storage optimizations (doc_values: false, scaled_float).

  6. State that type changes require a new index and POST /_reindex, then show the corrected mapping and reindex plan.

Examples

"Users search product names and also sort and aggregate on them" — one logical field, two access patterns, so use a text field with a keyword multi-field:

{
  "mappings": {
    "properties": {
      "product_name": { "type": "text", "fields": { "keyword": { "type": "keyword", "ignore_above": 256 } } }
    }
  }
}

"A status field is only ever filtered and aggregated, never full-text searched" — use keyword, not text:

{ "mappings": { "properties": { "status": { "type": "keyword" } } } }

"Free-form labels object with unbounded keys" — avoid mapping explosion with flattened:

{ "mappings": { "properties": { "labels": { "type": "flattened" } } } }

Guidelines

  • Minimal mapping — Map only what access patterns require; every sub-field and analyzed form adds indexed data.

  • Never guess access patterns — Wrong type choice is expensive to fix at scale.

  • Verify after create — Always confirm with GET /{index}/_mapping; use GET /{index}/_count after reindex.

  • Cross-skill boundary — Copying documents between indices is POST /_reindex (see the reindex skill for slicing, throttling, and task tracking). Loading files into a new index is bulk ingest, not index design.

Reference material

Operations

HTTP API (shorthand)elastic CLI command
GET /elastic es info
GET /{index}/_mappingelastic es indices get-mapping --index '<index>'
PUT /{index}elastic es indices create --index '<index>' --mappings '<json>' --settings '<json>'
POST /_reindexelastic es reindex --source '<json>' --dest '<json>'
POST /_reindex?wait_for_completion=falseelastic es reindex --wait-for-completion false --source '<json>' --dest '<json>'
GET /{index}/_countelastic es count --index '<index>'

Files

LICENSE

                                 Apache License
                           Version 2.0, January 2004
                        http://www.apache.org/licenses/

   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

   1. Definitions.

      "License" shall mean the terms and conditions for use, reproduction,
      and distribution as defined by Sections 1 through 9 of this document.

      "Licensor" shall mean the copyright owner or entity authorized by
      the copyright owner that is granting the License.

      "Legal Entity" shall mean the union of the acting entity and all
      other entities that control, are controlled by, or are under common
      control with that entity. For the purposes of this definition,
      "control" means (i) the power, direct or indirect, to cause the
      direction or management of such entity, whether by contract or
      otherwise, or (ii) ownership of fifty percent (50%) or more of the
      outstanding shares, or (iii) beneficial ownership of such entity.

      "You" (or "Your") shall mean an individual or Legal Entity
      exercising permissions granted by this License.

      "Source" form shall mean the preferred form for making modifications,
      including but not limited to software source code, documentation
      source, and configuration files.

      "Object" form shall mean any form resulting from mechanical
      transformation or translation of a Source form, including but
      not limited to compiled object code, generated documentation,
      and conversions to other media types.

      "Work" shall mean the work of authorship, whether in Source or
      Object form, made available under the License, as indicated by a
      copyright notice that is included in or attached to the work
      (an example is provided in the Appendix below).

      "Derivative Works" shall mean any work, whether in Source or Object
      form, that is based on (or derived from) the Work and for which the
      editorial revisions, annotations, elaborations, or other modifications
      represent, as a whole, an original work of authorship. For the purposes
      of this License, Derivative Works shall not include works that remain
      separable from, or merely link (or bind by name) to the interfaces of,
      the Work and Derivative Works thereof.

      "Contribution" shall mean any work of authorship, including
      the original version of the Work and any modifications or additions
      to that Work or Derivative Works thereof, that is intentionally
      submitted to Licensor for inclusion in the Work by the copyright owner
      or by an individual or Legal Entity authorized to submit on behalf of
      the copyright owner. For the purposes of this definition, "submitted"
      means any form of electronic, verbal, or written communication sent
      to the Licensor or its representatives, including but not limited to
      communication on electronic mailing lists, source code control systems,
      and issue tracking systems that are managed by, or on behalf of, the
      Licensor for the purpose of discussing and improving the Work, but
      excluding communication that is conspicuously marked or otherwise
      designated in writing by the copyright owner as "Not a Contribution."

      "Contributor" shall mean Licensor and any individual or Legal Entity
      on behalf of whom a Contribution has been received by Licensor and
      subsequently incorporated within the Work.

   2. Grant of Copyright License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      copyright license to reproduce, prepare Derivative Works of,
      publicly display, publicly perform, sublicense, and distribute the
      Work and such Derivative Works in Source or Object form.

   3. Grant of Patent License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      (except as stated in this section) patent license to make, have made,
      use, offer to sell, sell, import, and otherwise transfer the Work,
      where such license applies only to those patent claims licensable
      by such Contributor that are necessarily infringed by their
      Contribution(s) alone or by combination of their Contribution(s)
      with the Work to which such Contribution(s) was submitted. If You
      institute patent litigation against any entity (including a
      cross-claim or counterclaim in a lawsuit) alleging that the Work
      or a Contribution incorporated within the Work constitutes direct
      or contributory patent infringement, then any patent licenses
      granted to You under this License for that Work shall terminate
      as of the date such litigation is filed.

   4. Redistribution. You may reproduce and distribute copies of the
      Work or Derivative Works thereof in any medium, with or without
      modifications, and in Source or Object form, provided that You
      meet the following conditions:

      (a) You must give any other recipients of the Work or
          Derivative Works a copy of this License; and

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works
          that You distribute, all copyright, patent, trademark, and
          attribution notices from the Source form of the Work,
          excluding those notices that do not pertain to any part of
          the Derivative Works; and

      (d) If the Work includes a "NOTICE" text file as part of its
          distribution, then any Derivative Works that You distribute must
          include a readable copy of the attribution notices contained
          within such NOTICE file, excluding those notices that do not
          pertain to any part of the Derivative Works, in at least one
          of the following places: within a NOTICE text file distributed
          as part of the Derivative Works; within the Source form or
          documentation, if provided along with the Derivative Works; or,
          within a display generated by the Derivative Works, if and
          wherever such third-party notices normally appear. The contents
          of the NOTICE file are for informational purposes only and
          do not modify the License. You may add Your own attribution
          notices within Derivative Works that You distribute, alongside
          or as an addendum to the NOTICE text from the Work, provided
          that such additional attribution notices cannot be construed
          as modifying the License.

      You may add Your own copyright statement to Your modifications and
      may provide additional or different license terms and conditions
      for use, reproduction, or distribution of Your modifications, or
      for any such Derivative Works as a whole, provided Your use,
      reproduction, and distribution of the Work otherwise complies with
      the conditions stated in this License.

   5. Submission of Contributions. Unless You explicitly state otherwise,
      any Contribution intentionally submitted for inclusion in the Work
      by You to the Licensor shall be under the terms and conditions of
      this License, without any additional terms or conditions.
      Notwithstanding the above, nothing herein shall supersede or modify
      the terms of any separate license agreement you may have executed
      with Licensor regarding such Contributions.

   6. Trademarks. This License does not grant permission to use the trade
      names, trademarks, service marks, or product names of the Licensor,
      except as required for reasonable and customary use in describing the
      origin of the Work and reproducing the content of the NOTICE file.

   7. Disclaimer of Warranty. Unless required by applicable law or
      agreed to in writing, Licensor provides the Work (and each
      Contributor provides its Contributions) on an "AS IS" BASIS,
      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
      implied, including, without limitation, any warranties or conditions
      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
      PARTICULAR PURPOSE. You are solely responsible for determining the
      appropriateness of using or redistributing the Work and assume any
      risks associated with Your exercise of permissions under this License.

   8. Limitation of Liability. In no event and under no legal theory,
      whether in tort (including negligence), contract, or otherwise,
      unless required by applicable law (such as deliberate and grossly
      negligent acts) or agreed to in writing, shall any Contributor be
      liable to You for damages, including any direct, indirect, special,
      incidental, or consequential damages of any character arising as a
      result of this License or out of the use or inability to use the
      Work (including but not limited to damages for loss of goodwill,
      work stoppage, computer failure or malfunction, or any and all
      other commercial damages or losses), even if such Contributor
      has been advised of the possibility of such damages.

   9. Accepting Warranty or Additional Liability. While redistributing
      the Work or Derivative Works thereof, You may choose to offer,
      and charge a fee for, acceptance of support, warranty, indemnity,
      or other liability obligations and/or rights consistent with this
      License. However, in accepting such obligations, You may act only
      on Your own behalf and on Your sole responsibility, not on behalf
      of any other Contributor, and only if You agree to indemnify,
      defend, and hold each Contributor harmless for any liability
      incurred by, or claims asserted against, such Contributor by reason
      of your accepting any such warranty or additional liability.

   END OF TERMS AND CONDITIONS

   APPENDIX: How to apply the Apache License to your work.

      To apply the Apache License to your work, attach the following
      boilerplate notice, with the fields enclosed by brackets "[]"
      replaced with your own identifying information. (Don't include
      the brackets!)  The text should be enclosed in the appropriate
      comment syntax for the file format. We also recommend that a
      file or class name and description of purpose be included on the
      same "printed page" as the copyright notice for easier
      identification within third-party archives.

   Copyright 2026 Elasticsearch BV

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.

Requirements and compatibility

Works with: Claude Code, Claude apps, OpenAI Codex, GitHub Copilot, Cursor, Gemini CLI, Kiro, OpenCode, Goose, Amp, Roo Code, JetBrains Junie, Factory Droid, Devin (ex-Windsurf), Mistral Vibe, OpenHands, Letta

“Works with” means the tool reads the open Agent Skills format; a skill written for one tool may use features others lack.

The author says: Elasticsearch 8.x or 9.x, self-managed, Elastic Cloud Hosted, or Elastic Cloud Serverless; explicit shard and replica settings apply to self-managed and Elastic Cloud Hosted only (managed internally on Serverless). Requires the `elastic` CLI ≥ 0.2 with `stack es` support.

Security

No issues found by our static scan· No issues found

A static scan is not a guarantee. Skills are third-party content: review a skill before you let an agent use it.

Attribution and licence

Created by
elastic
Publisher
Elastic (Official)
Source
elastic/agent-skills · skills/elasticsearch/elasticsearch-index-design · commit 09d879d
Licence
Apache License 2.0 (redistribution allowed)
  • LICENSE (added by AutoGineer from LICENSE)
  • ATTRIBUTION.md (written by AutoGineer)
Synced
Also distributed in
elastic/agent-skills

AutoGineer is not affiliated with or endorsed by elastic.

Download ZIP

The ZIP holds the skill’s files, its licence files and an ATTRIBUTION.md. Download elasticsearch-index-design.zip