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Batch delete

Options for batch deleting documents:

$ vespa feed -t my-endpoint deletes.json

Find documents using a query, delete, repeat. Pseudocode:

while True; do
   query and read document ids, if empty exit
   delete document ids using /document/v1
   wait a sec # optional, add wait to reduce load while deleting

Use a document selection to expire documents. This deletes all documents not matching the expression. It is possible to use parent documents and imported fields for expiry of a document set. The content node will iterate over the corpus and delete documents (that are later compacted out):

<documents garbage-collection="true">
    <document type="mytype" selection="mytype.version > 4" />
</documents>

Use /document/v1 to delete documents identified by a document selection - example dropping all documents from the my_doctype schema:
```
$ curl -X DELETE \
  "$ENDPOINT/document/v1/my_namespace/my_doctype/docid?selection=true&cluster=my_cluster"
```
It is possible to drop a schema, with all its content, by removing the mapping to the content cluster. To understand what is happening, here is the status before the procedure:
```
# ls $VESPA_HOME/var/db/vespa/search/cluster.music/n0/documents

drwxr-xr-x 6 vespa vespa 4096 Oct 25 16:59 books
drwxr-xr-x 6 vespa vespa 4096 Oct 25 12:47 music
```
Remove the schema from configuration:
```
<documents>
    <document type="music" mode="index" />
    
</documents>
```
It is not required to remove the schema file itself. It is however required to add a schema-removal entry to validation-overrides.xml:
```
<validation-overrides>
    <allow until="2022-10-31">schema-removal</allow>
</validation-overrides>
```
Note: Use validation override name content-type-removal before Vespa 8.73

Deploy the application package. This will reconfigure the content node processes, and the directory with the schema data is removed:
```
# ls $VESPA_HOME/var/db/vespa/search/cluster.music/n0/documents

drwxr-xr-x 6 vespa vespa 4096 Oct 25 12:47 music
```
Add the mapping back and redeploy - the cluster now has a books schema with zero documents.
```
# ls $VESPA_HOME/var/db/vespa/search/cluster.music/n0/documents

drwxr-xr-x 6 vespa vespa 4096 Oct 25 17:06 books
drwxr-xr-x 6 vespa vespa 4096 Oct 25 12:47 music
```
Use the Custom Component State API to inspect document count per schema.

The procedure, deploying with and without the schema, is an efficient way to drop all documents. After the procedure, it is good practice to remove validation-overrides.xml or the schema-removal element inside, to avoid accidental data loss later. The directory listing above is just for illustration.

Example

This is an end-to-end example on how to track number of documents, and delete a subset using a selection string.

Feed sample documents

Feed a batch of documents, e.g. using the vector-search sample application:

$ vespa feed <(python3 feed.py 100000 3)

See number of documents for a node using the content.proton.documentdb.documents.total metric (here 100,000):

$ docker exec vespa curl -s http://localhost:19092/prometheus/v1/values | grep ^content.proton.documentdb.documents.total

  content_proton_documentdb_documents_total_max{metrictype="standard",instance="searchnode",documenttype="vector",clustername="vectors",vespa_service="vespa_searchnode",} 100000.0 1695383025000

  content_proton_documentdb_documents_total_last{metrictype="standard",instance="searchnode",documenttype="vector",clustername="vectors",vespa_service="vespa_searchnode",} 100000.0 1695383025000

Using the metric above is useful while feeding this example. Another alternative is visiting all documents to print the ID:

$ vespa visit --field-set "[id]" | wc -l
  100000

At this point, there are 100,000 document in the index.

Define selection

Define the subset of documents to delete - e.g. by age or other criteria. In this example, select random 1%. Do a test run:

$ vespa visit --field-set "[id]" --selection 'id.hash().abs() % 100 == 0' | wc -l
    1016

Hence, the selection string id.hash().abs() % 100 == 0 hits 1,016 documents.

Delete documents

Delete documents, see the number of documents deleted in the response:

$ curl -X DELETE \
  "http://localhost:8080/document/v1/mynamespace/vector/docid?selection=id.hash%28%29.abs%28%29+%25+100+%3D%3D+0&cluster=vectors"

  {
      "pathId":"/document/v1/mynamespace/vector/docid",
      "documentCount":1016
  }

In case of a large result set, a continuation token might be returned in the response, too:

"continuation": "AAAAEAAAA"

If so, add the token and redo the request:

$ curl -X DELETE \
  "http://localhost:8080/document/v1/mynamespace/vector/docid?selection=id.hash%28%29.abs%28%29+%25+100+%3D%3D+0&cluster=vectors&continuation=AAAAEAAAA"

Repeat as long as there are tokens in the output. The token changes in every response.

Validate

Check that all documents matching the selection criterion are deleted:

$ vespa visit --selection 'id.hash().abs() % 100 == 0' --field-set "[id]" | wc -l
  0

List remaining documents:

$ vespa visit --field-set "[id]" | wc -l
  98984