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Enables full-text searching of CouchDB documents using Lucene

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README.md

News

The indexing API has completely changed, please re-read this document and report any surprises/bugs to the bug tracker;

Issue tracking now available at lighthouseapp.

System Requirements

Sun JDK 5 or higher is necessary. Couchdb-lucene is known to be incompatible with OpenJDK as it includes an earlier, and incompatible, version of the Rhino Javascript library.

Build couchdb-lucene

  1. Install Maven 2.
  2. checkout repository
  3. type 'mvn'
  4. configure couchdb (see below)

Configure CouchDB

[couchdb]
os_process_timeout=60000 ; increase the timeout from 5 seconds.

[external]
fti=/usr/bin/java -jar /path/to/couchdb-lucene*-jar-with-dependencies.jar -search

[update_notification]
indexer=/usr/bin/java -jar /path/to/couchdb-lucene*-jar-with-dependencies.jar -index

[httpd_db_handlers]
_fti = {couch_httpd_external, handle_external_req, >}

Indexing Strategy

Document Indexing

You must supply a transform function in order to enable couchdb-lucene .

Add a design document called _design/lucene in your database with an attribute called "transform". The value of this attribute is a Javascript function.

The transform function can return null, to prevent indexing, and either a single Document or an array of Documents.

The transform function is called for each document in the database. To pass information to Lucene, you must populate Document instances with data from the original CouchDB document.

The Document class

You may construct a new Document instance with;

var doc = new Document();

Several functions are available that populate a Document.

// Indexed, analyzed but not stored.
doc.field("name", "value"); 

// Indexed, analyzed and stored.
doc.field("name", "value", "yes"); 

// Indexed, stored but not analyzed.
doc.field("name", "value", "yes", "not_analyzed");

// Extract text from the named attachment and index it (but not store it).
doc.attachment("name", "attachment name"); 

// Interpret "value" as a date using the default date formats.
doc.date("name", "value"); 

// intrepret "value" as a date using the supplied format string
// (see Java's SimpleDateFormat class for the syntax).
doc.date("name", "value", "format"); 

Example Transforms

Index Everything

function(doc) {
  var ret = new Document();

  function idx(obj) {
    for (var key in obj) {
      switch (typeof obj[key]) {
        case 'object':
          idx(obj[key]);
          break;
        case 'function':
          break;
        default:
          ret.field(key, obj[key]);
      /* Uncomment next line to include
       * all attributes into a single field.
           */
      // ret.field("all", obj[key]);
          break;
      }
    }
  }
  
  // Index all attributes
  idx(doc);

  // Index all attachments
  for(var a in doc._attachments) {
    ret.attachment("attachment", a);
  }

  return ret;
}

Index Nothing

function(doc) {
  return null;
}

Index Select Fields

function(doc) {
  var result = new Document();
  result.field("subject", doc.subject, "yes");
  result.field("content", doc.content);
  result.date("indexed_at", new Date());
  return result;
}

Index Attachments

function(doc) {
  var result = new Document();
  for(var a in doc._attachments) {
    result.attachment("attachment", a);
  }
  return result;
}

A More Complex Example

function(doc) {
    var mk = function(name, value, group) {
        var ret = new Document(name, value, "yes");
        ret.field("group", group, "yes");
        return ret;
    };
    var ret = [];
    if(doc.type != "reference") return null;
    for(var g in doc.groups) {
        ret.push(mk("library", doc.groups[g].library, g));
        ret.push(mk("method", doc.groups[g].method, g));
        ret.push(mk("target", doc.groups[g].target, g));
    }
    return ret;
}

Attachment Indexing

Couchdb-lucene uses Apache Tika to index attachments of the following types, assuming the correct content_type is set in couchdb;

Supported Formats

  • Excel spreadsheets (application/vnd.ms-excel)
  • Word documents (application/msword)
  • Powerpoint presentations (application/vnd.ms-powerpoint)
  • Visio (application/vnd.visio)
  • Outlook (application/vnd.ms-outlook)
  • XML (application/xml)
  • HTML (text/html)
  • Images (image/*)
  • Java class files
  • Java jar archives
  • MP3 (audio/mp3)
  • OpenDocument (application/vnd.oasis.opendocument.*)
  • Plain text (text/plain)
  • PDF (application/pdf)
  • RTF (application/rtf)

Searching with couchdb-lucene

You can perform all types of queries using Lucene's default query syntax. The _body field is searched by default which will include the extracted text from all attachments. The following parameters can be passed for more sophisticated searches;

q
the query to run (e.g, subject:hello)
sort
the comma-separated fields to sort on. Prefix with / for ascending order and \ for descending order (ascending is the default if not specified).
limit
the maximum number of results to return
skip
the number of results to skip
include_docs
whether to include the source docs
stale=ok
If you set the stale option ok, couchdb-lucene may not perform any refreshing on the index. Searches may be faster as Lucene caches important data (especially for sorting). A query without stale=ok will use the latest data committed to the index.
debug
if false, a normal application/json response with results appears. if true, an pretty-printed HTML blob is returned instead.
rewrite
(EXPERT) if true, returns a json response with a rewritten query and term frequencies. This allows correct distributed scoring when combining the results from multiple nodes.

All parameters except 'q' are optional.

Special Fields

_db
The source database of the document.
_id
The _id of the document.

Dublin Core

All Dublin Core attributes are indexed and stored if detected in the attachment. Descriptions of the fields come from the Tika javadocs.

dc.contributor
An entity responsible for making contributions to the content of the resource.
dc.coverage
The extent or scope of the content of the resource.
dc.creator
An entity primarily responsible for making the content of the resource.
dc.date
A date associated with an event in the life cycle of the resource.
dc.description
An account of the content of the resource.
dc.format
Typically, Format may include the media-type or dimensions of the resource.
dc.identifier
Recommended best practice is to identify the resource by means of a string or number conforming to a formal identification system.
dc.language
A language of the intellectual content of the resource.
dc.modified
Date on which the resource was changed.
dc.publisher
An entity responsible for making the resource available.
dc.relation
A reference to a related resource.
dc.rights
Information about rights held in and over the resource.
dc.source
A reference to a resource from which the present resource is derived.
dc.subject
The topic of the content of the resource.
dc.title
A name given to the resource.
dc.type
The nature or genre of the content of the resource.

Examples

http://localhost:5984/dbname/_fti?q=field_name:value
http://localhost:5984/dbname/_fti?q=field_name:value&sort=other_field
http://localhost:5984/dbname/_fti?debug=true&sort=billing_size&q=body:document AND customer:[A TO C]

Search Results Format

Here's an example of a JSON response without sorting;

{
  "q": "+_db:enron +content:enron",
  "skip": 0,
  "limit": 2,
  "total_rows": 176852,
  "search_duration": 518,
  "fetch_duration": 4,
  "rows":   [
        {
      "_id": "hain-m-all_documents-257.",
      "score": 1.601625680923462
    },
        {
      "_id": "hain-m-notes_inbox-257.",
      "score": 1.601625680923462
    }
  ]
}

And the same with sorting;

{
  "q": "+_db:enron +content:enron",
  "skip": 0,
  "limit": 3,
  "total_rows": 176852,
  "search_duration": 660,
  "fetch_duration": 4,
  "sort_order":   [
        {
      "field": "source",
      "reverse": false,
      "type": "string"
    },
        {
      "reverse": false,
      "type": "doc"
    }
  ],
  "rows":   [
        {
      "_id": "shankman-j-inbox-105.",
      "score": 0.6131107211112976,
      "sort_order":       [
        "enron",
        6
      ]
    },
        {
      "_id": "shankman-j-inbox-8.",
      "score": 0.7492915391921997,
      "sort_order":       [
        "enron",
        7
      ]
    },
        {
      "_id": "shankman-j-inbox-30.",
      "score": 0.507369875907898,
      "sort_order":       [
        "enron",
        8
      ]
    }
  ]
}

Fetching information about the index

Calling couchdb-lucene without arguments returns a JSON object with information about the index.

http://127.0.0.1:5984/enron/_fti

returns;

{"doc_count":517350,"doc_del_count":1,"disk_size":318543045}

Working With The Source

To develop "live", type "mvn dependency:unpack-dependencies" and change the external line to something like this;

fti=/usr/bin/java -cp /path/to/couchdb-lucene/target/classes:\
/path/to/couchdb-lucene/target/dependency com.github.rnewson.couchdb.lucene.Main

You will need to restart CouchDB if you change couchdb-lucene source code but this is very fast.

Configuration

couchdb-lucene respects several system properties;

couchdb.url
the url to contact CouchDB with (default is "http://localhost:5984")
couchdb.lucene.dir
specify the path to the lucene indexes (the default is to make a directory called 'lucene' relative to couchdb's current working directory.

You can override these properties like this;

fti=/usr/bin/java -Dcouchdb.lucene.dir=/tmp \
-cp /home/rnewson/Source/couchdb-lucene/target/classes:\
/home/rnewson/Source/couchdb-lucene/target/dependency\
com.github.rnewson.couchdb.lucene.Main

Basic Authentication

If you put couchdb behind an authenticating proxy you can still configure couchdb-lucene to pull from it by specifying additional system properties. Currently only Basic authentication is supported.

couchdb.user
the user to authenticate as.
couchdb.password
the password to authenticate with.
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