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@@ -175,6 +175,45 @@ $this->view->paginator = $paginator;
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]]></programlisting>
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</para>
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</sect2>
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+
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+ <sect2 id="zend.paginator.usage.dbselect">
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+ <title>The DbSelect and DbTableSelect adapter</title>
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+ <para>
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+ The usage of most adapters is pretty straight-forward. However, the
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+ database adapters require a more detailed explanation. Contrary to popular
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+ believe, these adapters do NOT fetch all records from the database in order to count them.
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+ Instead, the adapters manipulates the original query to produce the corresponding
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+ COUNT query. Paginator then executes that COUNT query to get the number of rows.
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+ This does require an extra round-trip to the database, but this is many times
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+ faster than fetching an entire result set and using count(). Especially with
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+ large collections of data.
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+ </para>
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+
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+ <para>
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+ The database adapters will try and build the most efficient query that will execute
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+ on pretty much all modern databases. However, depending on your database or even your
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+ own schema setup, there might be more efficient ways to get a rowcount. For this scenario
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+ the database adapters allow you to set a custom COUNT query. For example,
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+ if you keep track of the count of blog posts in a separate table, you could achieve a
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+ faster count query with the following setup:
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+ </para>
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+
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+ <programlisting language="php"><![CDATA[
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+$adapter = new Zend_Paginator_Adapter_DbSelect($db->select()->from('posts'));
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+$adapter->setRowCount(
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+ $db->select()->from('item_counts', array(Zend_Paginator_Adapter_DbSelect::ROW_COUNT_COLUMN => 'post_count'))
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+)
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+
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+$paginator = new Zend_Paginator($adapter);
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+]]></programlisting>
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+
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+ <para>
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+ This approach will probably not give you a huge performance gain on
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+ small collections and/or simple select queries. However, with complex
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+ queries and large collections, a similar approach could give you a
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+ significant performance boost.
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+ </para>
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+ </sect2>
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<sect2 id="zend.paginator.rendering">
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<title>Rendering pages with view scripts</title>
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