Artifact Content
Not logged in

Artifact db4ec85c3c21529a787eb6c6473f5eb33738a088:

<html dir="LTR" xmlns="" xmlns:xlink="" xmlns:MSHelp="" xmlns:tool="" xmlns:ndoc="urn:ndoc-preprocess">
    <meta http-equiv="Content-Type" content="text/html; charset=Windows-1252" />
    <title>Provider Limitations</title>
    <link rel="stylesheet" type="text/css" href="../Include/ndoc.css" />
    <div id="header">
      <table width="100%" id="topTable">
        <tr id="headerTableRow1">
          <td align="left">
            <span id="runningHeaderText">Provider Limitations</span>
        <tr id="headerTableRow2">
          <td align="left">
            <span id="nsrTitle">SQLite.NET Class Library Documentation</span>
        <tr id="headerTableRow3" style="display:none">
            <a id="seeAlsoSectionLink" href="#seeAlsoToggle" onclick="OpenSection(seeAlsoToggle)">See Also</a>
            <a id="exampleSectionLink" href="#codeExampleToggle" onclick="OpenSection(codeExampleToggle)">Example</a>
      <table width="100%" id="bottomTable" cellspacing="0" cellpadding="0" style="display:none">
            <span onclick="ExpandCollapseAll(toggleAllImage)" style="cursor:default;" onkeypress="ExpandCollapseAll_CheckKey(toggleAllImage)" tabindex="0">
              <img ID="toggleAllImage" class="toggleAll" src="collall.gif" />
              <label id="collapseAllLabel" for="toggleAllImage" style="display: none;">
							Collapse All
              <label id="expandAllLabel" for="toggleAllImage" style="display: none;">
							Expand All
    <div id="mainSection">
    <div id="mainBody">
      <h1 class="heading">Limitations of this ADO.NET SQLite Data Provider</h1>
      <p>As providers go, this one doesn't have many restrictions. SQLite has no
        support for row-level or table-level locks. When a connection locks the database for writing, no other connection or process may read or write to the database until the write operation is complete.  The SQLite.NET provider attempts to retry
        internally if a database is locked, up to the CommandTimeout property of the
        command in question.</p>
      <p>SQLite is inherently type-less, and only understands a few basic datatypes
        natively. They are (in .NET-speak) Int64, Double, String and Blob. The
        SQLite.NET provider will use the database schema information it can glean to
        enforce type-ness, but it is an inexact science.</p>
        Hierarchical DataReaders are not supported. In the
        case of transactions, any SQLiteCommand created on a connection will (when
        executed) automatically join a transaction in progress, regardless of whether
        that transaction was created before or after the command.</p>
      <p>A SQLiteCommand object <b>can</b> be re-assigned a new SQLiteConnection object
        as long as no DataReaders are active on the command.</p>
      <p>Opening a transaction is considered a write operation, so only use them when
        you want to write to the database! If you hold open an &quot;immediate&quot;
        transaction, all readers on other connections will be blocked until the
        transaction is closed!</p>
      <h4 class="subHeading">Thread Safety</h4>
      <p>Multi-threading in SQLite must be done carefully. Here are the restrictions:</p>
          <b>You May</b>
        Clone() a SQLiteConnection object in one thread and pass the cloned object to
        another thread. Once passed, the other thread becomes the new owner of the
        cloned connection, and the original thread must not keep a reference to the
        clone or call any methods on the clone.
          <STRONG>You May</STRONG>
        create multiple threads, and those threads can create their own
        SQLiteConnection and subsequent objects for accessing a database.&nbsp;
        Multiple connections on multiple threads to the same database file are
        perfectly&nbsp;acceptable&nbsp;and will behave predictably.&nbsp;
          <b>You May NOT</b>
        call methods or properties or otherwise reference any SQLite provider classes
        that belong to another thread.
          <b>You May NOT</b> pass a SQLiteCommand, SQLiteDataReader, SQLiteDataAdapter or
          any other SQLite provider class except a cloned SQLiteConnection to another
      <p>Understand again that SQLite has no fine-grained locking mechanisms. It is
        therefore your own responsibility in a multi-threaded environment to handle
        potential timeouts that may occur if a long-running query in one thread
        prevents a query in another thread from executing. These timeouts will only
        occur if one thread is attempting to read while another thread is attempting to
        write. Whichever thread got its lock first will be the one to execute, and the
        other thread will block until the CommandTimeout value elapses or the other
        thread finishes.</p>
      <div id="footer">
          <a href="">
            Send comments on this topic.</a>