Reindexing data in Elasticsearch - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start reindexing from source to destination index.

Elasticsearch

{
  "source": { "index": "[1]" },
  "dest": { "index": "new_index" }
}

Drag options to blanks, or click blank then click option'

Aold_index

Bnew_index

Csource_index

Ddest_index

Attempts:

3 left

💡 Hint

Common Mistakes

Using the destination index name as the source index.

Using a non-existent index name.

The source.index must be the name of the existing index you want to copy from.

2fill in blank

medium

Complete the code to add a query filter to reindex only documents where status is 'active'.

Elasticsearch

{
  "source": {
    "index": "old_index",
    "query": { "term": { "status": "[1]" } }
  },
  "dest": { "index": "new_index" }
}

Drag options to blanks, or click blank then click option'

Apending

Binactive

Cactive

Ddeleted

Attempts:

3 left

💡 Hint

Common Mistakes

Using a status value that does not exist in documents.

Using a query type other than term for exact match.

The query filters documents with status equal to active to be reindexed.

3fill in blank

hard

Fix the error in the reindex request by completing the missing field for the destination index.

Elasticsearch

{
  "source": { "index": "old_index" },
  "dest": { "[1]": "new_index" }
}

Drag options to blanks, or click blank then click option'

Asource

Bindex

Cquery

Dtype

Attempts:

3 left

💡 Hint

Common Mistakes

Using source instead of index in destination.

Omitting the destination index field.

The destination index must be specified with the index field inside dest.

4fill in blank

hard

Fill both blanks to reindex documents from 'old_index' to 'new_index' with a script that sets the field 'status' to 'archived'.

Elasticsearch

{
  "source": { "index": "[1]" },
  "dest": { "index": "[2]" },
  "script": {
    "source": "ctx._source.status = 'archived'"
  }
}

Drag options to blanks, or click blank then click option'

Aold_index

Bnew_index

Carchive_index

Dsource_index

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping source and destination index names.

Using an incorrect index name.

The source index is old_index and the destination index is new_index. The script updates the status field to 'archived' during reindexing.

5fill in blank

hard

Fill all three blanks to reindex documents from 'products' to 'products_new' only if 'price' is greater than 100, and add a script to increase 'price' by 10%.

Elasticsearch

{
  "source": {
    "index": "[1]",
    "query": { "range": { "price": { "[2]": 100 } } }
  },
  "dest": { "index": "[3]" },
  "script": {
    "source": "ctx._source.price *= 1.1"
  }
}

Drag options to blanks, or click blank then click option'

Aproducts

Bgt

Cproducts_new

Dgte

Attempts:

3 left

💡 Hint

Common Mistakes

Using gte instead of gt.

Mixing up source and destination index names.

The source index is products. The query uses gt to filter prices greater than 100. The destination index is products_new. The script increases the price by 10%.

Practice

1.

What is the main purpose of _reindex API in Elasticsearch?

easy

A. To delete an index permanently

B. To copy data from one index to another

C. To update the Elasticsearch cluster settings

D. To create a new index with default settings

Solution

1. Step 1: Understand the function of _reindex

   The _reindex API is designed to copy documents from a source index to a destination index.

2. Step 2: Differentiate from other operations

   Deleting an index, updating cluster settings, or creating new indexes are different APIs and not the purpose of _reindex.

3. Final Answer:

   To copy data from one index to another -> Option B

4. Quick Check:

   _reindex copies data [OK]

Hint: Remember: reindex means copying data between indexes [OK]

Common Mistakes:

• Confusing reindex with deleting indexes
• Thinking reindex updates cluster settings
• Assuming reindex creates new indexes without data

2.

Which of the following is the correct minimal syntax to reindex data from old_index to new_index using Elasticsearch's REST API?

{
  "source": {"index": "old_index"},
  "dest": {"index": "new_index"}
}

easy

A. { "source": { "index": "old_index" }, "dest": { "index": "new_index" } }

B. { "source": { "index": "new_index" }, "dest": { "index": "old_index" } }

C. { "source": { "index": "old_index" }, "destination": { "index": "new_index" } }

D. { "src": { "index": "old_index" }, "dest": { "index": "new_index" } }

Solution

1. Step 1: Check the required keys for reindex

   The correct keys are source and dest with nested index names.

2. Step 2: Validate the index names and key spelling

   { "source": { "index": "old_index" }, "dest": { "index": "new_index" } } uses correct keys and index names. { "source": { "index": "new_index" }, "dest": { "index": "old_index" } } swaps source and destination incorrectly. { "source": { "index": "old_index" }, "destination": { "index": "new_index" } } uses wrong key destination. { "src": { "index": "old_index" }, "dest": { "index": "new_index" } } uses wrong key src.

3. Final Answer:

   { "source": { "index": "old_index" }, "dest": { "index": "new_index" } } -> Option A

4. Quick Check:

   Use source and dest keys exactly [OK]

Hint: Use exact keys: source and dest for reindex JSON [OK]

Common Mistakes:

• Swapping source and destination indexes
• Using wrong keys like 'src' or 'destination'
• Misspelling 'dest' or 'source'

3.

Given the following reindex request, what will be the result?

{
  "source": { "index": "products" },
  "dest": { "index": "products_new" },
  "script": {
    "source": "ctx._source.price = ctx._source.price * 1.1"
  }
}

Assuming products has documents with a price field.

medium

A. Only documents with price > 1.1 are copied

B. Documents copied without any price change

C. Reindex fails due to script syntax error

D. All documents copied with price increased by 10%

Solution

1. Step 1: Understand the script in reindex

   The script modifies each document's price by multiplying it by 1.1 during reindexing.

2. Step 2: Effect on documents

   All documents from products are copied to products_new with updated price values increased by 10%.

3. Final Answer:

   All documents copied with price increased by 10% -> Option D

4. Quick Check:

   Script modifies price during reindex [OK]

Hint: Scripts can modify fields during reindexing [OK]

Common Mistakes:

• Assuming script filters documents instead of modifying
• Thinking script causes syntax error
• Believing price remains unchanged

4.

Identify the error in this reindex request:

{
  "source": { "index": "old_index" },
  "dest": { "index": "new_index" },
  "query": {
    "match": { "status": "active" }
  }
}

medium

A. The query should be inside the "source" object

B. "query" is not allowed inside reindex requests

C. The "match" syntax is incorrect

D. The "dest" index name cannot be "new_index"

Solution

1. Step 1: Check placement of query in reindex

   The query must be inside the source object to filter documents.

2. Step 2: Validate other parts

   The match syntax is correct, and dest index name is valid.

3. Final Answer:

   The query should be inside the "source" object -> Option A

4. Quick Check:

   Put query inside source to filter during reindex [OK]

Hint: Put filters inside source, not at top level [OK]

Common Mistakes:

• Placing query outside source object
• Misunderstanding match query syntax
• Thinking destination index name is invalid

5.

You want to reindex data from logs_2023 to logs_archive but only include documents where level is "error" and add a new field archived set to true. Which reindex request achieves this?

hard

A. { "source": { "index": "logs_2023", "query": { "match": { "level": "error" } } }, "dest": { "index": "logs_archive" }, "script": { "source": "ctx._source.archived = false" } }

B. { "source": { "index": "logs_2023" }, "dest": { "index": "logs_archive" }, "query": { "term": { "level": "error" } }, "script": { "source": "ctx._source.archived = true" } }

C. { "source": { "index": "logs_2023", "query": { "term": { "level": "error" } } }, "dest": { "index": "logs_archive" }, "script": { "source": "ctx._source.archived = true" } }

D. { "source": { "index": "logs_2023", "query": { "term": { "level": "error" } } }, "dest": { "index": "logs_archive" }, "script": { "source": "ctx._source.archived = false" } }

Solution

1. Step 1: Filter documents by level "error" inside source

   The query with term filter must be inside the source object to select only error level logs.

2. Step 2: Add new field "archived" with value true via script

   The script sets ctx._source.archived = true to add the new field during reindex.

3. Step 3: Validate requests

   The request that places query inside source with term filter for level: "error" and script setting ctx._source.archived = true is correct. Placing query at top level is invalid. Using match instead of term or setting archived to false is incorrect.

4. Final Answer:

   { "source": { "index": "logs_2023", "query": { "term": { "level": "error" } } }, "dest": { "index": "logs_archive" }, "script": { "source": "ctx._source.archived = true" } } -> Option C

5. Quick Check:

   Filter in source + script sets field true [OK]

Hint: Filter inside source; script adds fields during reindex [OK]

Common Mistakes:

• Placing query outside source object
• Setting wrong value for new field
• Using match instead of term for exact filter