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git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@329342 c90b9560-bf6c-de11-be94-00142212c4b1
330 lines
9.6 KiB
XML
330 lines
9.6 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
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<!-- $Revision$ -->
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<refentry xml:id="mongocollection.ensureindex" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
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<refnamediv>
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<refname>MongoCollection::ensureIndex</refname>
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<refpurpose>
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Creates an index on the given field(s), or does nothing if the index
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already exists
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</refpurpose>
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</refnamediv>
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<refsect1 role="description">
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&reftitle.description;
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<methodsynopsis>
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<modifier>public</modifier> <type>bool</type><methodname>MongoCollection::ensureIndex</methodname>
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<methodparam><type>string|array</type><parameter>key|keys</parameter></methodparam>
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<methodparam choice="opt"><type>array</type><parameter>options</parameter><initializer>array()</initializer></methodparam>
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</methodsynopsis>
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<para>
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This method creates an index on the collection and the specified fields.
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The key specification can either be just a single field name as string, or an
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array containing one or more field names with their sort direction.
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</para>
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</refsect1>
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<refsect1 role="parameters">
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&reftitle.parameters;
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<para>
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<variablelist>
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<varlistentry>
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<term>
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<parameter>keys</parameter>
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</term>
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<listitem>
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<para>
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An array of fields by which to sort the index on. Each element in the
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array has as key the field name, and as value either
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<literal>1</literal> for ascending sort, or <literal>-1</literal> for
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descending sort.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<parameter>options</parameter>
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</term>
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<listitem>
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<para>
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This parameter is an associative array of the form
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<literal>array("optionname" => <boolean>, ...)</literal>. Currently
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supported options are:
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<itemizedlist>
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&mongo.writes.parameters.writeconcern;
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<listitem>
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<para>
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<literal>"unique"</literal>
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</para>
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<para>
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Create a unique index.
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</para>
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<warning>
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<para>
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A unique index cannot be created on a field if multiple existing
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documents do not contain the field. The field is effectively &null;
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for these documents and thus already non-unique. Sparse indexing may
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be used to overcome this, since it will prevent documents without the
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field from being indexed.
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</para>
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</warning>
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</listitem>
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<listitem>
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<para>
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<literal>"dropDups"</literal>
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</para>
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<para>
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If a unique index is being created and duplicate values exist, drop
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all but one duplicate value.
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</para>
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</listitem>
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<listitem>
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<para>
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<literal>"sparse"</literal>
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</para>
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<para>
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Create a sparse index, which only includes documents containing the
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field. This option is only compatible with single-field indexes.
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</para>
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</listitem>
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<listitem>
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<para>
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<literal>"expireAfterSeconds"</literal>
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</para>
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<para>
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The value of this option should specify the number of seconds after
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which a document should be considered expired and automatically
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removed from the collection. This option is only compatible with
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single-field indexes where the field will contain
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<classname>MongoDate</classname> values.
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</para>
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<para>
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This feature is available in MongoDB 2.2+. See
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<link xlink:href="&url.mongodb.docs.expire_data;">Expire Data from Collections by Setting TTL</link>
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for more information.
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</para>
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</listitem>
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<listitem>
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<para>
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<literal>"background"</literal>
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</para>
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<para>
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By default, index creation is a blocking operation and will stop other
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operations on the database from proceeding until completed. If you
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specify &true; for this option, the index will be created in the
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background while other operations are taking place.
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</para>
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<warning>
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<para>
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Prior to MongoDB 2.1.0, the index build operation is not a background
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build when it replicates to secondaries, irrespective of this option.
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See
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<link xlink:href="&url.mongodb.dochub.indexes.rs;">Building Indexes with Replica Sets</link>
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for more information.
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</para>
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</warning>
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</listitem>
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<listitem>
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<para>
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<literal>"name"</literal>
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</para>
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<para>
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Starting with driver version 1.0.5 you can specify an index name.
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This can be useful if you are indexing many keys and Mongo complains
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about the index name being too long.
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</para>
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</listitem>
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&mongo.writes.parameters.timeout;
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&mongo.writes.parameters.safe;
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</itemizedlist>
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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</refsect1>
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<refsect1 role="returnvalues">
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&reftitle.returnvalues;
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<para>
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Returns an array containing the status of the index creation if the
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<literal>"w"</literal> option is set. Otherwise, returns &true;.
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</para>
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<para>
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Fields in the status array are described in the documentation for
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<function>MongoCollection::insert</function>.
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</para>
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</refsect1>
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<refsect1 role="changelog">
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&reftitle.changelog;
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<para>
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<informaltable>
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<tgroup cols="2">
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<thead>
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<row>
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<entry>&Version;</entry>
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<entry>&Description;</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry>1.3.0</entry>
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<entry>
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The <parameter>options</parameter> parameter no longer accepts a boolean
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to signify a unique index. Instead, this now has to be done with
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<literal>array('unique' => true)</literal>.
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</entry>
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</row>
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<row>
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<entry>1.2.11</entry>
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<entry>
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Emits <constant>E_DEPRECATED</constant> when
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<parameter>options</parameter> is <type>scalar</type>.
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</entry>
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</row>
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<row>
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<entry>1.2.0</entry>
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<entry>Added <literal>"timeout"</literal> option.</entry>
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</row>
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<row>
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<entry>1.0.11</entry>
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<entry>
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<para>
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The <literal>"safe"</literal> option will trigger a primary failover,
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if necessary.
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</para>
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<para>
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<classname>MongoException</classname> will be thrown if the index name
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(either generated or set) is longer than 128 bytes.
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</para>
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</entry>
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</row>
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<row>
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<entry>1.0.2</entry>
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<entry>
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Changed <parameter>options</parameter> parameter from boolean to array.
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Pre-1.0.2, the second parameter was an optional boolean value specifying
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a unique index.
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</entry>
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</row>
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</tbody>
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</tgroup>
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</informaltable>
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</para>
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</refsect1>
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<refsect1 role="errors">
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&reftitle.errors;
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<para>
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Throws <classname>MongoException</classname> if the index name is longer than
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128 bytes. (Version 1.0.11+)
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</para>
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&mongo.errors.exceptions.writeconcern;
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</refsect1>
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<refsect1 role="examples">
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&reftitle.examples;
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<example>
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<title><function>MongoCollection::ensureIndex</function> example</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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$c = new MongoCollection($db, 'foo');
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// create an index on 'x' ascending
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$c->ensureIndex('x');
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// create an index on 'y' ascending
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$c->ensureIndex(array('y' => 1));
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// create an index on 'z' ascending and 'zz' descending
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$c->ensureIndex(array('z' => 1, 'zz' => -1));
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// create a unique index on 'x'
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$c->ensureIndex(array('x' => 1), array("unique" => true));
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?>
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]]>
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</programlisting>
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</example>
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<example>
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<title>Drop duplicates example</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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$collection->insert(array("username" => "joeschmoe"));
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$collection->insert(array("username" => "joeschmoe"));
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/*
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* index creation fails, you can't create a unique index on a key with
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* non-unique values
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*/
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$collection->ensureIndex(array("username" => 1), array("unique" => 1));
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/*
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* index creation succeeds: one of the documents is removed from the collection
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*/
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$collection->ensureIndex(array("username" => 1), array("unique" => 1, "dropDups" => 1));
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/*
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* now we have a unique index, more inserts with the same username (such as the
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* one below) will fail
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*/
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$collection->insert(array("username" => "joeschmoe"));
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?>
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]]>
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</programlisting>
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</example>
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<example>
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<title>Geospatial Indexing</title>
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<para>
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Mongo supports geospatial indexes, which allow you to search for documents
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near a given location or within a shape. For example, to create a
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geospatial index on the "loc" field:
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</para>
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<programlisting role="php">
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<![CDATA[
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<?php
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$collection->ensureIndex(array("loc" => "2d"));
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?>
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]]>
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</programlisting>
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</example>
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</refsect1>
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<refsect1 role="seealso">
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&reftitle.seealso;
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<para>
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MongoDB core docs on
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<link xlink:href="&url.mongodb.dochub.indexes;">vanilla indexes</link> and
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<link xlink:href="&url.mongodb.dochub.geo;">geospatial indexes</link>.
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</para>
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</refsect1>
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</refentry>
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<!-- Keep this comment at the end of the file
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Local variables:
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mode: sgml
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sgml-omittag:t
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sgml-minimize-attributes:nil
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sgml-always-quote-attributes:t
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sgml-indent-step:1
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sgml-indent-data:t
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sgml-parent-document:nil
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sgml-default-dtd-file:"~/.phpdoc/manual.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:nil
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sgml-local-ecat-files:nil
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End:
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vim600: syn=xml fen fdm=syntax fdl=2 si
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vim: et tw=78 syn=sgml
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vi: ts=1 sw=1
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-->
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