Adding upstream version 3.40.1.upstream/3.40.1 upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
author: Daniel Baumann <daniel.baumann@progress-linux.org> 2024-05-05 17:28:19 +0000
committer: Daniel Baumann <daniel.baumann@progress-linux.org> 2024-05-05 17:28:19 +0000
commit: 18657a960e125336f704ea058e25c27bd3900dcb (patch)
tree: 17b438b680ed45a996d7b59951e6aa34023783f2 /www/dbpage.html
parent: Initial commit. (diff)
download: sqlite3-18657a960e125336f704ea058e25c27bd3900dcb.tar.xz
sqlite3-18657a960e125336f704ea058e25c27bd3900dcb.zip
1 files changed, 236 insertions, 0 deletions
diff --git a/www/dbpage.html b/www/dbpage.html
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+<!DOCTYPE html>
+<html><head>
+<meta name="viewport" content="width=device-width, initial-scale=1.0">
+<meta http-equiv="content-type" content="text/html; charset=UTF-8">
+<link href="sqlite.css" rel="stylesheet">
+<title>The SQLITE_DBPAGE Virtual Table</title>
+<!-- path= -->
+</head>
+<body>
+<div class=nosearch>
+<a href="index.html">
+<img class="logo" src="images/sqlite370_banner.gif" alt="SQLite" border="0">
+</a>
+<div><!-- IE hack to prevent disappearing logo --></div>
+<div class="tagline desktoponly">
+Small. Fast. Reliable.<br>Choose any three.
+</div>
+<div class="menu mainmenu">
+<ul>
+<li><a href="index.html">Home</a>
+<li class='mobileonly'><a href="javascript:void(0)" onclick='toggle_div("submenu")'>Menu</a>
+<li class='wideonly'><a href='about.html'>About</a>
+<li class='desktoponly'><a href="docs.html">Documentation</a>
+<li class='desktoponly'><a href="download.html">Download</a>
+<li class='wideonly'><a href='copyright.html'>License</a>
+<li class='desktoponly'><a href="support.html">Support</a>
+<li class='desktoponly'><a href="prosupport.html">Purchase</a>
+<li class='search' id='search_menubutton'>
+<a href="javascript:void(0)" onclick='toggle_search()'>Search</a>
+</ul>
+</div>
+<div class="menu submenu" id="submenu">
+<ul>
+<li><a href='about.html'>About</a>
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+<li><a href='prosupport.html'>Purchase</a>
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+<div class="searchmenu" id="searchmenu">
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+</script>
+<div class=fancy>
+<div class=nosearch>
+<div class="fancy_title">
+The SQLITE_DBPAGE Virtual Table
+</div>
+</div>
+
+
+
+
+<h1 id="overview"><span>1. </span>Overview</h1>
+
+<p>
+The SQLITE_DBPAGE extension implements an <a href="vtab.html#epoonlyvtab">eponymous-only virtual table</a> that
+provides direct access to the underlying database file by interacting
+with the pager.  SQLITE_DBPAGE is capable of both reading and writing any
+page of the database.  Because interaction is through the pager layer, all
+changes are transactional.
+</p>
+
+<p>
+<b>Warning:</b> writing to the SQLITE_DBPAGE virtual table can very easily
+cause unrecoverably database corruption.  Do not allow untrusted components
+to access the SQLITE_DBPAGE table.  Use appropriate care while using the
+SQLITE_DBPAGE table.  Back up important data prior to experimenting with the
+SQLITE_DBPAGE table.  Writes to the SQLITE_DBPAGE virtual table are
+disabled when the <a href="c3ref/c_dbconfig_defensive.html#sqlitedbconfigdefensive">SQLITE_DBCONFIG_DEFENSIVE</a> flag is set.
+
+</p><p>
+The SQLITE_DBPAGE extension is included in the <a href="amalgamation.html">amalgamation</a> though 
+it is disabled
+by default.  Use the <a href="compile.html#enable_dbpage_vtab">SQLITE_ENABLE_DBPAGE_VTAB</a> compile-time option to enable
+the SQLITE_DBPAGE extension.  The SQLITE_DBPAGE extension makes use of
+unpublished internal interfaces and is not run-time loadable.  The only way
+to add SQLITE_DBPAGE to an application is to compile it in using the
+<a href="compile.html#enable_dbpage_vtab">SQLITE_ENABLE_DBPAGE_VTAB</a> compile-time option.
+</p>
+
+<p>
+The SQLITE_DBPAGE extension is enabled in default builds
+of the <a href="cli.html">command-line shell</a>.
+
+</p><h1 id="usage"><span>2. </span>Usage</h1>
+
+<p>
+The SQLITE_DBPAGE virtual table read/write table that provides direct
+access to the underlying disk file on a page-by-page basis.  The
+virtual table appears to have a schema like this:
+
+</p><div class="codeblock"><pre>CREATE TABLE sqlite_dbpage(
+  pgno INTEGER PRIMARY KEY,
+  data BLOB
+);
+</pre></div>
+
+<p>
+An SQLite database file is divided into pages.
+The first page is 1, the second page is 2, and so forth.
+There is no page 0.
+Every page is the same size.
+The size of every page is a power of 2 between 512 and 65536.
+See the <a href="fileformat2.html">file format</a> documentation for further details.
+
+</p><p>
+The SQLITE_DBPAGE table allows an application to view or replace the
+raw binary content of each page of the database file.
+No attempt is made to interpret the content of the page.
+Content is returned byte-for-byte as it appears on disk.
+
+</p><p>
+The SQLITE_DBPAGE table has one row for each page in the database file.
+SQLITE_DBPAGE allows pages to be read or to be overwritten.
+However the size of the database file cannot be changed.  It is not
+possible to change the number of rows in the SQLITE_DBPAGE table by
+running DELETE or INSERT operations against that table.
+
+</p><h2 id="using_sqlite_dbpage_on_attach_ed_databases"><span>2.1. </span>Using SQLITE_DBPAGE On ATTACH-ed Databases</h2>
+
+<p>
+The SQLITE_DBPAGE table schema shown above is incomplete.  There is
+a third <a href="vtab.html#hiddencol">hidden column</a> named "schema" that determines which
+<a href="lang_attach.html">ATTACH-ed database</a> should be read or written.  Because
+the "schema" column is hidden, it can be used as a parameter when
+SQLITE_DBPAGE is invoked as a <a href="vtab.html#tabfunc2">table-valued function</a>.
+
+</p><p>
+For example, suppose an additional database is attached to the 
+database connection using a statement like this:
+
+</p><div class="codeblock"><pre>ATTACH 'auxdata1.db' AS aux1;
+</pre></div>
+
+<p>
+Then to read the first page of that database file, one merely runs:
+
+</p><div class="codeblock"><pre>SELECT data FROM sqlite_dbpage('aux1') WHERE pgno=1;
+</pre></div>
+
+<p>
+If the "schema" is omitted, it defaults to the primary database
+(usually called 'main', unless renamed using <a href="c3ref/c_dbconfig_defensive.html#sqlitedbconfigmaindbname">SQLITE_DBCONFIG_MAINDBNAME</a>).
+Hence, the following two queries are normally equivalent:
+
+</p><div class="codeblock"><pre>SELECT data FROM sqlite_dbpage('main') WHERE pgno=1;
+SELECT data FROM sqlite_dbpage WHERE pgno=1;
+</pre></div>
+
+<p>
+The SQLITE_DBPAGE table can participate in a join just like any other
+table.  Hence, to see the content of the first page to all connected
+database files, one might run a statement like this:
+
+</p><div class="codeblock"><pre>SELECT dbpage.data, dblist.name
+  FROM pragma_database_list AS dblist
+  JOIN sqlite_dbpage(dblist.name) AS dbpage
+ WHERE dbpage.pgno=1;
+</pre></div>
+<p align="center"><small><i>This page last modified on  <a href="https://sqlite.org/docsrc/honeypot" id="mtimelink"  data-href="https://sqlite.org/docsrc/finfo/pages/dbpage.in?m=21798cdb09def756b">2018-11-12 15:24:40</a> UTC </small></i></p>
+
author	Daniel Baumann <daniel.baumann@progress-linux.org>	2024-05-05 17:28:19 +0000
committer	Daniel Baumann <daniel.baumann@progress-linux.org>	2024-05-05 17:28:19 +0000
commit	18657a960e125336f704ea058e25c27bd3900dcb (patch)
tree	17b438b680ed45a996d7b59951e6aa34023783f2 /www/dbpage.html
parent	Initial commit. (diff)
download	sqlite3-18657a960e125336f704ea058e25c27bd3900dcb.tar.xz sqlite3-18657a960e125336f704ea058e25c27bd3900dcb.zip