---
title: Reindex context
description: Use a Painless script in a reindex operation to add, modify, or delete fields within each document in an original index as its reindexed into a target...
url: https://www.elastic.co/elastic/docs-builder/docs/2341/reference/scripting-languages/painless/painless-reindex-context
products:
  - Painless
---

# Reindex context
Use a Painless script in a [reindex](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-reindex) operation to add, modify, or delete fields within each document in an original index as its reindexed into a target index.
**Variables**
<definitions>
  <definition term="params (Map, read-only)">
    User-defined parameters passed in as part of the query.
  </definition>
  <definition term="ctx['op'] (String)">
    The name of the operation.
  </definition>
  <definition term="ctx['_routing'] (String)">
    The value used to select a shard for document storage.
  </definition>
  <definition term="ctx['_index'] (String)">
    The name of the index.
  </definition>
  <definition term="ctx['_id'] (String)">
    The unique document id.
  </definition>
  <definition term="ctx['_version'] (int)">
    The current version of the document.
  </definition>
  <definition term="ctx['_source'] (Map)">
    Contains extracted JSON in a `Map` and `List` structure for the fields existing in a stored document.
  </definition>
</definitions>

**Side Effects**
<definitions>
  <definition term="ctx['op']">
    Use the default of `index` to update a document. Set to `noop` to specify no operation or `delete` to delete the current document from the index.
  </definition>
  <definition term="ctx['_routing']">
    Modify this to change the routing value for the current document.
  </definition>
  <definition term="ctx['_index']">
    Modify this to change the destination index for the current document.
  </definition>
  <definition term="ctx['_id']">
    Modify this to change the id for the current document.
  </definition>
  <definition term="ctx['_version'] (int)">
    Modify this to modify the version for the current document.
  </definition>
  <definition term="ctx['_source']">
    Modify the values in the `Map/List` structure to add, modify, or delete the fields of a document.
  </definition>
</definitions>

**Return**
<definitions>
  <definition term="void">
    No expected return value.
  </definition>
</definitions>

**API**
The standard [Painless API](https://www.elastic.co/guide/en/elasticsearch/painless/current/painless-api-reference-shared.html) is available.