Uploading Data with Index Handlers | Apache Solr Reference Guide 7.3

Index Handlers are Request Handlers designed to add, delete and update documents to the index. In addition to having plugins for importing rich documents using Tika or from structured data sources using the Data Import Handler, Solr natively supports indexing structured documents in XML, CSV and JSON.

The recommended way to configure and use request handlers is with path based names that map to paths in the request url. However, request handlers can also be specified with the qt (query type) parameter if the requestDispatcher is appropriately configured. It is possible to access the same handler using more than one name, which can be useful if you wish to specify different sets of default options.

A single unified update request handler supports XML, CSV, JSON, and javabin update requests, delegating to the appropriate ContentStreamLoader based on the Content-Type of the ContentStream.

UpdateRequestHandler Configuration

The default configuration file has the update request handler configured by default.

<requestHandler name="/update" class="solr.UpdateRequestHandler" />

XML Formatted Index Updates

Index update commands can be sent as XML message to the update handler using Content-type: application/xml or Content-type: text/xml.

Adding Documents

The XML schema recognized by the update handler for adding documents is very straightforward:

The <add> element introduces one more documents to be added.
The <doc> element introduces the fields making up a document.
The <field> element presents the content for a specific field.

For example:

<add>
  <doc>
    <field name="authors">Patrick Eagar</field>
    <field name="subject">Sports</field>
    <field name="dd">796.35</field>
    <field name="numpages">128</field>
    <field name="desc"></field>
    <field name="price">12.40</field>
    <field name="title">Summer of the all-rounder: Test and championship cricket in England 1982</field>
    <field name="isbn">0002166313</field>
    <field name="yearpub">1982</field>
    <field name="publisher">Collins</field>
  </doc>
  <doc>
  ...
  </doc>
</add>

The add command supports some optional attributes which may be specified.

commitWithin: Add the document within the specified number of milliseconds.
overwrite: Default is true. Indicates if the unique key constraints should be checked to overwrite previous versions of the same document (see below).

If the document schema defines a unique key, then by default an /update operation to add a document will overwrite (i.e., replace) any document in the index with the same unique key. If no unique key has been defined, indexing performance is somewhat faster, as no check has to be made for an existing documents to replace.

If you have a unique key field, but you feel confident that you can safely bypass the uniqueness check (e.g., you build your indexes in batch, and your indexing code guarantees it never adds the same document more than once) you can specify the overwrite="false" option when adding your documents.

XML Update Commands

Commit and Optimize During Updates

The <commit> operation writes all documents loaded since the last commit to one or more segment files on the disk. Before a commit has been issued, newly indexed content is not visible to searches. The commit operation opens a new searcher, and triggers any event listeners that have been configured.

Commits may be issued explicitly with a <commit/> message, and can also be triggered from <autocommit> parameters in solrconfig.xml.

The <optimize> operation requests Solr to merge internal data structures. For a large index, optimization will take some time to complete, but by merging many small segment files into a larger one, search performance may improve. If you are using Solr’s replication mechanism to distribute searches across many systems, be aware that after an optimize, a complete index will need to be transferred.

You should only consider using optimize on static indexes, i.e., indexes that can be optimized as part of the regular update process (say once-a-day updates). Applications requiring NRT functionalty are discouraged from using optimize.

The <commit> and <optimize> elements accept these optional attributes:

waitSearcher: Default is true. Blocks until a new searcher is opened and registered as the main query searcher, making the changes visible.
expungeDeletes: (commit only) Default is false. Merges segments that have more than 10% deleted docs, expunging them in the process.

expungeDeletes is "less expensive" than optimize, but the same warnings apply.

maxSegments: (optimize only) Default is 1. Merges the segments down to no more than this number of segments.

Here are examples of <commit> and <optimize> using optional attributes:

<commit waitSearcher="false"/>
<commit waitSearcher="false" expungeDeletes="true"/>
<optimize waitSearcher="false"/>

Delete Operations

Documents can be deleted from the index in two ways. "Delete by ID" deletes the document with the specified ID, and can be used only if a UniqueID field has been defined in the schema. "Delete by Query" deletes all documents matching a specified query, although commitWithin is ignored for a Delete by Query. A single delete message can contain multiple delete operations.

<delete>
  <id>0002166313</id>
  <id>0031745983</id>
  <query>subject:sport</query>
  <query>publisher:penguin</query>
</delete>

When using the Join query parser in a Delete By Query, you should use the score parameter with a value of "none" to avoid a ClassCastException. See the section on the Join Query Parser for more details on the score parameter.

Rollback Operations

The rollback command rolls back all add and deletes made to the index since the last commit. It neither calls any event listeners nor creates a new searcher. Its syntax is simple: <rollback/>.

Grouping Operations

You can post several commands in a single XML file by grouping them with the surrounding <update> element.

<update>
  <add>
    <doc><!-- doc 1 content --></doc>
  </add>
  <add>
    <doc><!-- doc 2 content --></doc>
  </add>
  <delete>
    <id>0002166313</id>
  </delete>
</update>

Using curl to Perform Updates

You can use the curl utility to perform any of the above commands, using its --data-binary option to append the XML message to the curl command, and generating a HTTP POST request. For example:

curl http://localhost:8983/solr/my_collection/update -H "Content-Type: text/xml" --data-binary '
<add>
  <doc>
    <field name="authors">Patrick Eagar</field>
    <field name="subject">Sports</field>
    <field name="dd">796.35</field>
    <field name="isbn">0002166313</field>
    <field name="yearpub">1982</field>
    <field name="publisher">Collins</field>
  </doc>
</add>'

For posting XML messages contained in a file, you can use the alternative form:

curl http://localhost:8983/solr/my_collection/update -H "Content-Type: text/xml" --data-binary @myfile.xml

The approach above works well, but using the --data-binary option causes curl to load the whole myfile.xml into memory before posting it to server. This may be problematic when dealing with multi-gigabyte files. This alternative curl command performs equivalent operations but with minimal curl memory usage:

curl http://localhost:8983/solr/my_collection/update -H "Content-Type: text/xml" -T "myfile.xml" -X POST

Short requests can also be sent using a HTTP GET command, if enabled in RequestDispatcher in SolrConfig element, URL-encoding the request, as in the following. Note the escaping of "<" and ">":

curl http://localhost:8983/solr/my_collection/update?stream.body=%3Ccommit/%3E&wt=xml

Responses from Solr take the form shown here:

<response>
  <lst name="responseHeader">
    <int name="status">0</int>
    <int name="QTime">127</int>
  </lst>
</response>

The status field will be non-zero in case of failure.

Using XSLT to Transform XML Index Updates

The UpdateRequestHandler allows you to index any arbitrary XML using the <tr> parameter to apply an XSL transformation. You must have an XSLT stylesheet in the conf/xslt directory of your config set that can transform the incoming data to the expected <add><doc/></add> format, and use the tr parameter to specify the name of that stylesheet.

Here is an example XSLT stylesheet:

<xsl:stylesheet version='1.0' xmlns:xsl='http://www.w3.org/1999/XSL/Transform'>
  <xsl:output media-type="text/xml" method="xml" indent="yes"/>
  <xsl:template match='/'>
    <add>
      <xsl:apply-templates select="response/result/doc"/>
    </add>
  </xsl:template>
  <!-- Ignore score (makes no sense to index) -->
  <xsl:template match="doc/*[@name='score']" priority="100"></xsl:template>
  <xsl:template match="doc">
    <xsl:variable name="pos" select="position()"/>
    <doc>
      <xsl:apply-templates>
        <xsl:with-param name="pos"><xsl:value-of select="$pos"/></xsl:with-param>
      </xsl:apply-templates>
    </doc>
  </xsl:template>
  <!-- Flatten arrays to duplicate field lines -->
  <xsl:template match="doc/arr" priority="100">
    <xsl:variable name="fn" select="@name"/>
    <xsl:for-each select="*">
      <xsl:element name="field">
        <xsl:attribute name="name"><xsl:value-of select="$fn"/></xsl:attribute>
        <xsl:value-of select="."/>
      </xsl:element>
    </xsl:for-each>
  </xsl:template>
  <xsl:template match="doc/*">
    <xsl:variable name="fn" select="@name"/>
      <xsl:element name="field">
        <xsl:attribute name="name"><xsl:value-of select="$fn"/></xsl:attribute>
      <xsl:value-of select="."/>
    </xsl:element>
  </xsl:template>
  <xsl:template match="*"/>
</xsl:stylesheet>

This stylesheet transforms Solr’s XML search result format into Solr’s Update XML syntax. One example usage would be to copy a Solr 1.3 index (which does not have CSV response writer) into a format which can be indexed into another Solr file (provided that all fields are stored):

http://localhost:8983/solr/my_collection/select?q=*:*&wt=xslt&tr=updateXml.xsl&rows=1000

You can also use the stylesheet in XsltUpdateRequestHandler to transform an index when updating:

curl "http://localhost:8983/solr/my_collection/update?commit=true&tr=updateXml.xsl" -H "Content-Type: text/xml" --data-binary @myexporteddata.xml

JSON Formatted Index Updates

Solr can accept JSON that conforms to a defined structure, or can accept arbitrary JSON-formatted documents. If sending arbitrarily formatted JSON, there are some additional parameters that need to be sent with the update request, described below in the section Transforming and Indexing Custom JSON.

Solr-Style JSON

JSON formatted update requests may be sent to Solr’s /update handler using Content-Type: application/json or Content-Type: text/json.

JSON formatted updates can take 3 basic forms, described in depth below:

A single document to add, expressed as a top level JSON Object. To differentiate this from a set of commands, the json.command=false request parameter is required.
A list of documents to add, expressed as a top level JSON Array containing a JSON Object per document.
A sequence of update commands, expressed as a top level JSON Object (aka: Map).

Adding a Single JSON Document

The simplest way to add Documents via JSON is to send each document individually as a JSON Object, using the /update/json/docs path:

curl -X POST -H 'Content-Type: application/json' 'http://localhost:8983/solr/my_collection/update/json/docs' --data-binary '
{
  "id": "1",
  "title": "Doc 1"
}'

Adding Multiple JSON Documents

Adding multiple documents at one time via JSON can be done via a JSON Array of JSON Objects, where each object represents a document:

curl -X POST -H 'Content-Type: application/json' 'http://localhost:8983/solr/my_collection/update' --data-binary '
[
  {
    "id": "1",
    "title": "Doc 1"
  },
  {
    "id": "2",
    "title": "Doc 2"
  }
]'

A sample JSON file is provided at example/exampledocs/books.json and contains an array of objects that you can add to the Solr techproducts example:

curl 'http://localhost:8983/solr/techproducts/update?commit=true' --data-binary @example/exampledocs/books.json -H 'Content-type:application/json'

Sending JSON Update Commands

In general, the JSON update syntax supports all of the update commands that the XML update handler supports, through a straightforward mapping. Multiple commands, adding and deleting documents, may be contained in one message:

curl -X POST -H 'Content-Type: application/json' 'http://localhost:8983/solr/my_collection/update' --data-binary '
{
  "add": {
    "doc": {
      "id": "DOC1",
      "my_field": 2.3,
      "my_multivalued_field": [ "aaa", "bbb" ]   (1)
    }
  },
  "add": {
    "commitWithin": 5000, (2)
    "overwrite": false,  (3)
    "doc": {
      "f1": "v1", (4)
      "f1": "v2"
    }
  },

  "commit": {},
  "optimize": { "waitSearcher":false },

  "delete": { "id":"ID" },  (5)
  "delete": { "query":"QUERY" } (6)
}'

1	Can use an array for a multi-valued field
2	Commit this document within 5 seconds
3	Don’t check for existing documents with the same uniqueKey
4	Can use repeated keys for a multi-valued field
5	Delete by ID (uniqueKey field)
6	Delete by Query

As with other update handlers, parameters such as commit, commitWithin, optimize, and overwrite may be specified in the URL instead of in the body of the message.

The JSON update format allows for a simple delete-by-id. The value of a delete can be an array which contains a list of zero or more specific document id’s (not a range) to be deleted. For example, a single document:

{ "delete":"myid" }

Or a list of document IDs:

{ "delete":["id1","id2"] }

The value of a "delete" can be an array which contains a list of zero or more id’s to be deleted. It is not a range (start and end).

You can also specify _version_ with each "delete":

{
  "delete":"id":50,
  "_version_":12345
}

You can specify the version of deletes in the body of the update request as well.

JSON Update Convenience Paths

In addition to the /update handler, there are a few additional JSON specific request handler paths available by default in Solr, that implicitly override the behavior of some request parameters:

Path Default Parameters

Path	Default Parameters
`/update/json`	`stream.contentType=application/json`
`/update/json/docs`	`stream.contentType=application/json` `json.command=false`

/update/json

stream.contentType=application/json

/update/json/docs

stream.contentType=application/json

json.command=false

The /update/json path may be useful for clients sending in JSON formatted update commands from applications where setting the Content-Type proves difficult, while the /update/json/docs path can be particularly convenient for clients that always want to send in documents – either individually or as a list – without needing to worry about the full JSON command syntax.

Custom JSON Documents

Solr can support custom JSON. This is covered in the section Transforming and Indexing Custom JSON.

CSV Formatted Index Updates

CSV formatted update requests may be sent to Solr’s /update handler using Content-Type: application/csv or Content-Type: text/csv.

A sample CSV file is provided at example/exampledocs/books.csv that you can use to add some documents to the Solr techproducts example:

curl 'http://localhost:8983/solr/my_collection/update?commit=true' --data-binary @example/exampledocs/books.csv -H 'Content-type:application/csv'

CSV Update Parameters

The CSV handler allows the specification of many parameters in the URL in the form: f.parameter.optional_fieldname=value.

The table below describes the parameters for the update handler.

separator: Character used as field separator; default is ",". This parameter is global; for per-field usage, see the split parameter.

Example: separator=%09
trim: If true, remove leading and trailing whitespace from values. The default is false. This parameter can be either global or per-field.

Examples: f.isbn.trim=true or trim=false
header: Set to true if first line of input contains field names. These will be used if the fieldnames parameter is absent. This parameter is global.
fieldnames: Comma-separated list of field names to use when adding documents. This parameter is global.

Example: fieldnames=isbn,price,title
literal.field_name: A literal value for a specified field name. This parameter is global.

Example: literal.color=red
skip: Comma separated list of field names to skip. This parameter is global.

Example: skip=uninteresting,shoesize
skipLines: Number of lines to discard in the input stream before the CSV data starts, including the header, if present. Default=0. This parameter is global.

Example: skipLines=5
encapsulator: The character optionally used to surround values to preserve characters such as the CSV separator or whitespace. This standard CSV format handles the encapsulator itself appearing in an encapsulated value by doubling the encapsulator.

This parameter is global; for per-field usage, see split.

Example: encapsulator="
escape: The character used for escaping CSV separators or other reserved characters. If an escape is specified, the encapsulator is not used unless also explicitly specified since most formats use either encapsulation or escaping, not both. |g |

Example: escape=\
keepEmpty: Keep and index zero length (empty) fields. The default is false. This parameter can be global or per-field.

Example: f.price.keepEmpty=true
map: Map one value to another. Format is value:replacement (which can be empty). This parameter can be global or per-field.

Example: map=left:right or f.subject.map=history:bunk
split: If true, split a field into multiple values by a separate parser. This parameter is used on a per-field basis.
overwrite: If true (the default), check for and overwrite duplicate documents, based on the uniqueKey field declared in the Solr schema. If you know the documents you are indexing do not contain any duplicates then you may see a considerable speed up setting this to false.

This parameter is global.
commit: Issues a commit after the data has been ingested. This parameter is global.
commitWithin: Add the document within the specified number of milliseconds. This parameter is global.

Example: commitWithin=10000
rowid: Map the rowid (line number) to a field specified by the value of the parameter, for instance if your CSV doesn’t have a unique key and you want to use the row id as such. This parameter is global.

Example: rowid=id
rowidOffset: Add the given offset (as an integer) to the rowid before adding it to the document. Default is 0. This parameter is global.

Example: rowidOffset=10

Indexing Tab-Delimited files

The same feature used to index CSV documents can also be easily used to index tab-delimited files (TSV files) and even handle backslash escaping rather than CSV encapsulation.

For example, one can dump a MySQL table to a tab delimited file with:

SELECT * INTO OUTFILE '/tmp/result.txt' FROM mytable;

This file could then be imported into Solr by setting the separator to tab (%09) and the escape to backslash (%5c).

curl 'http://localhost:8983/solr/my_collection/update/csv?commit=true&separator=%09&escape=%5c' --data-binary @/tmp/result.txt

CSV Update Convenience Paths

In addition to the /update handler, there is an additional CSV specific request handler path available by default in Solr, that implicitly override the behavior of some request parameters:

Path Default Parameters

Path	Default Parameters
`/update/csv`	`stream.contentType=application/csv`

/update/csv

stream.contentType=application/csv

The /update/csv path may be useful for clients sending in CSV formatted update commands from applications where setting the Content-Type proves difficult.

Nested Child Documents

Solr indexes nested documents in blocks as a way to model documents containing other documents, such as a blog post parent document and comments as child documents — or products as parent documents and sizes, colors, or other variations as child documents. At query time, the Block Join Query Parsers can search these relationships. In terms of performance, indexing the relationships between documents may be more efficient than attempting to do joins only at query time, since the relationships are already stored in the index and do not need to be computed.

Nested documents may be indexed via either the XML or JSON data syntax (or using SolrJ) - but regardless of syntax, you must include a field that identifies the parent document as a parent; it can be any field that suits this purpose, and it will be used as input for the block join query parsers.

To support nested documents, the schema must include an indexed/non-stored field _root_. The value of that field is populated automatically and is the same for all documents in the block, regardless of the inheritance depth.

XML Examples

For example, here are two documents and their child documents:

<add>
  <doc>
  <field name="id">1</field>
  <field name="title">Solr adds block join support</field>
  <field name="content_type">parentDocument</field>
    <doc>
      <field name="id">2</field>
      <field name="comments">SolrCloud supports it too!</field>
    </doc>
  </doc>
  <doc>
    <field name="id">3</field>
    <field name="title">New Lucene and Solr release is out</field>
    <field name="content_type">parentDocument</field>
    <doc>
      <field name="id">4</field>
      <field name="comments">Lots of new features</field>
    </doc>
  </doc>
</add>

In this example, we have indexed the parent documents with the field content_type, which has the value "parentDocument". We could have also used a boolean field, such as isParent, with a value of "true", or any other similar approach.

JSON Examples

This example is equivalent to the XML example above, note the special _childDocuments_ key need to indicate the nested documents in JSON.

[
  {
    "id": "1",
    "title": "Solr adds block join support",
    "content_type": "parentDocument",
    "_childDocuments_": [
      {
        "id": "2",
        "comments": "SolrCloud supports it too!"
      }
    ]
  },
  {
    "id": "3",
    "title": "New Lucene and Solr release is out",
    "content_type": "parentDocument",
    "_childDocuments_": [
      {
        "id": "4",
        "comments": "Lots of new features"
      }
    ]
  }
]

Note

One limitation of indexing nested documents is that the whole block of parent-children documents must be updated together whenever any changes are required. In other words, even if a single child document or the parent document is changed, the whole block of parent-child documents must be indexed together.

Post Tool Transforming and Indexing Custom JSON