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| author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-16 19:46:48 +0000 |
|---|---|---|
| committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-16 19:46:48 +0000 |
| commit | 311bcfc6b3acdd6fd152798c7f287ddf74fa2a98 (patch) | |
| tree | 0ec307299b1dada3701e42f4ca6eda57d708261e /doc/src/sgml/html/catalog-pg-largeobject.html | |
| parent | Initial commit. (diff) | |
| download | postgresql-15-upstream.tar.xz postgresql-15-upstream.zip | |
Adding upstream version 15.4.upstream/15.4upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'doc/src/sgml/html/catalog-pg-largeobject.html')
| -rw-r--r-- | doc/src/sgml/html/catalog-pg-largeobject.html | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/doc/src/sgml/html/catalog-pg-largeobject.html b/doc/src/sgml/html/catalog-pg-largeobject.html new file mode 100644 index 0000000..66466b9 --- /dev/null +++ b/doc/src/sgml/html/catalog-pg-largeobject.html @@ -0,0 +1,48 @@ +<?xml version="1.0" encoding="UTF-8" standalone="no"?> +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>53.30. pg_largeobject</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="catalog-pg-language.html" title="53.29. pg_language" /><link rel="next" href="catalog-pg-largeobject-metadata.html" title="53.31. pg_largeobject_metadata" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">53.30. <code class="structname">pg_largeobject</code></th></tr><tr><td width="10%" align="left"><a accesskey="p" href="catalog-pg-language.html" title="53.29. pg_language">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="catalogs.html" title="Chapter 53. System Catalogs">Up</a></td><th width="60%" align="center">Chapter 53. System Catalogs</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 15.4 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="catalog-pg-largeobject-metadata.html" title="53.31. pg_largeobject_metadata">Next</a></td></tr></table><hr /></div><div class="sect1" id="CATALOG-PG-LARGEOBJECT"><div class="titlepage"><div><div><h2 class="title" style="clear: both">53.30. <code class="structname">pg_largeobject</code></h2></div></div></div><a id="id-1.10.4.32.2" class="indexterm"></a><p> + The catalog <code class="structname">pg_largeobject</code> holds the data making up + <span class="quote">“<span class="quote">large objects</span>”</span>. A large object is identified by an OID + assigned when it is created. Each large object is broken into + segments or <span class="quote">“<span class="quote">pages</span>”</span> small enough to be conveniently stored as rows + in <code class="structname">pg_largeobject</code>. + The amount of data per page is defined to be <code class="symbol">LOBLKSIZE</code> (which is currently + <code class="literal">BLCKSZ/4</code>, or typically 2 kB). + </p><p> + Prior to <span class="productname">PostgreSQL</span> 9.0, there was no permission structure + associated with large objects. As a result, + <code class="structname">pg_largeobject</code> was publicly readable and could be + used to obtain the OIDs (and contents) of all large objects in the system. + This is no longer the case; use + <a class="link" href="catalog-pg-largeobject-metadata.html" title="53.31. pg_largeobject_metadata"><code class="structname">pg_largeobject_metadata</code></a> + to obtain a list of large object OIDs. + </p><div class="table" id="id-1.10.4.32.5"><p class="title"><strong>Table 53.30. <code class="structname">pg_largeobject</code> Columns</strong></p><div class="table-contents"><table class="table" summary="pg_largeobject Columns" border="1"><colgroup><col /></colgroup><thead><tr><th class="catalog_table_entry"><p class="column_definition"> + Column Type + </p> + <p> + Description + </p></th></tr></thead><tbody><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">loid</code> <code class="type">oid</code> + (references <a class="link" href="catalog-pg-largeobject-metadata.html" title="53.31. pg_largeobject_metadata"><code class="structname">pg_largeobject_metadata</code></a>.<code class="structfield">oid</code>) + </p> + <p> + Identifier of the large object that includes this page + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">pageno</code> <code class="type">int4</code> + </p> + <p> + Page number of this page within its large object + (counting from zero) + </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition"> + <code class="structfield">data</code> <code class="type">bytea</code> + </p> + <p> + Actual data stored in the large object. + This will never be more than <code class="symbol">LOBLKSIZE</code> bytes and might be less. + </p></td></tr></tbody></table></div></div><br class="table-break" /><p> + Each row of <code class="structname">pg_largeobject</code> holds data + for one page of a large object, beginning at + byte offset (<code class="literal">pageno * LOBLKSIZE</code>) within the object. The implementation + allows sparse storage: pages might be missing, and might be shorter than + <code class="literal">LOBLKSIZE</code> bytes even if they are not the last page of the object. + Missing regions within a large object read as zeroes. + </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="catalog-pg-language.html" title="53.29. pg_language">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="catalogs.html" title="Chapter 53. System Catalogs">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="catalog-pg-largeobject-metadata.html" title="53.31. pg_largeobject_metadata">Next</a></td></tr><tr><td width="40%" align="left" valign="top">53.29. <code class="structname">pg_language</code> </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 15.4 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 53.31. <code class="structname">pg_largeobject_metadata</code></td></tr></table></div></body></html>
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