|
- <?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>Appendix D. SQL Conformance</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 V1.79.1" /><link rel="prev" href="sql-keywords-appendix.html" title="Appendix C. SQL Key Words" /><link rel="next" href="features-sql-standard.html" title="D.1. Supported Features" /></head><body><div xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">Appendix D. SQL Conformance</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="sql-keywords-appendix.html" title="Appendix C. SQL Key Words">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="appendixes.html" title="Part VIII. Appendixes">Up</a></td><th width="60%" align="center">Part VIII. Appendixes</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 12.4 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="features-sql-standard.html" title="D.1. Supported Features">Next</a></td></tr></table><hr></hr></div><div class="appendix" id="FEATURES"><div class="titlepage"><div><div><h2 class="title">Appendix D. SQL Conformance</h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="sect1"><a href="features-sql-standard.html">D.1. Supported Features</a></span></dt><dt><span class="sect1"><a href="unsupported-features-sql-standard.html">D.2. Unsupported Features</a></span></dt><dt><span class="sect1"><a href="xml-limits-conformance.html">D.3. XML Limits and Conformance to SQL/XML</a></span></dt><dd><dl><dt><span class="sect2"><a href="xml-limits-conformance.html#FUNCTIONS-XML-LIMITS-XPATH1">D.3.1. Queries Are Restricted to XPath 1.0</a></span></dt><dt><span class="sect2"><a href="xml-limits-conformance.html#FUNCTIONS-XML-LIMITS-POSTGRESQL">D.3.2.
- Incidental Limits of the Implementation
- </a></span></dt></dl></dd></dl></div><p>
- This section attempts to outline to what extent
- <span class="productname">PostgreSQL</span> conforms to the current SQL
- standard. The following information is not a full statement of
- conformance, but it presents the main topics in as much detail as is
- both reasonable and useful for users.
- </p><p>
- The formal name of the SQL standard is ISO/IEC 9075 <span class="quote">“<span class="quote">Database
- Language SQL</span>”</span>. A revised version of the standard is released
- from time to time; the most recent update appearing in 2016.
- The 2016 version is referred to as ISO/IEC 9075:2016, or simply as SQL:2016.
- The versions prior to that were SQL:2011, SQL:2008, SQL:2006, SQL:2003,
- SQL:1999, and SQL-92. Each version
- replaces the previous one, so claims of conformance to earlier
- versions have no official merit.
- <span class="productname">PostgreSQL</span> development aims for
- conformance with the latest official version of the standard where
- such conformance does not contradict traditional features or common
- sense. Many of the features required by the SQL
- standard are supported, though sometimes with slightly differing
- syntax or function. Further moves towards conformance can be
- expected over time.
- </p><p>
- <acronym class="acronym">SQL-92</acronym> defined three feature sets for
- conformance: Entry, Intermediate, and Full. Most database
- management systems claiming <acronym class="acronym">SQL</acronym> standard
- conformance were conforming at only the Entry level, since the
- entire set of features in the Intermediate and Full levels was
- either too voluminous or in conflict with legacy behaviors.
- </p><p>
- Starting with <acronym class="acronym">SQL:1999</acronym>, the SQL standard defines
- a large set of individual features rather than the ineffectively
- broad three levels found in <acronym class="acronym">SQL-92</acronym>. A large
- subset of these features represents the <span class="quote">“<span class="quote">Core</span>”</span>
- features, which every conforming SQL implementation must supply.
- The rest of the features are purely optional. Some optional
- features are grouped together to form <span class="quote">“<span class="quote">packages</span>”</span>, which
- SQL implementations can claim conformance to, thus claiming
- conformance to particular groups of features.
- </p><p>
- The standard versions beginning with <acronym class="acronym">SQL:2003</acronym>
- are also split into a number
- of parts. Each is known by a shorthand name. Note that these parts
- are not consecutively numbered.
-
- </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>ISO/IEC 9075-1 Framework (SQL/Framework)</p><a id="id-1.11.5.6.2.1.2" class="indexterm"></a></li><li class="listitem"><p>ISO/IEC 9075-2 Foundation (SQL/Foundation)</p><a id="id-1.11.5.6.2.2.2" class="indexterm"></a></li><li class="listitem"><p>ISO/IEC 9075-3 Call Level Interface (SQL/CLI)</p><a id="id-1.11.5.6.2.3.2" class="indexterm"></a></li><li class="listitem"><p>ISO/IEC 9075-4 Persistent Stored Modules (SQL/PSM)</p><a id="id-1.11.5.6.2.4.2" class="indexterm"></a></li><li class="listitem"><p>ISO/IEC 9075-9 Management of External Data (SQL/MED)</p><a id="id-1.11.5.6.2.5.2" class="indexterm"></a></li><li class="listitem"><p>ISO/IEC 9075-10 Object Language Bindings (SQL/OLB)</p><a id="id-1.11.5.6.2.6.2" class="indexterm"></a></li><li class="listitem"><p>ISO/IEC 9075-11 Information and Definition Schemas (SQL/Schemata)</p><a id="id-1.11.5.6.2.7.2" class="indexterm"></a></li><li class="listitem"><p>ISO/IEC 9075-13 Routines and Types using the Java Language (SQL/JRT)</p><a id="id-1.11.5.6.2.8.2" class="indexterm"></a></li><li class="listitem"><p>ISO/IEC 9075-14 XML-related specifications (SQL/XML)</p><a id="id-1.11.5.6.2.9.2" class="indexterm"></a></li></ul></div><p>
- </p><p>
- The <span class="productname">PostgreSQL</span> core covers parts 1, 2, 9,
- 11, and 14. Part 3 is covered by the ODBC driver, and part 13 is
- covered by the PL/Java plug-in, but exact conformance is currently
- not being verified for these components. There are currently no
- implementations of parts 4 and 10
- for <span class="productname">PostgreSQL</span>.
- </p><p>
- PostgreSQL supports most of the major features of SQL:2016. Out of
- 179 mandatory features required for full Core conformance,
- PostgreSQL conforms to at least 160. In addition, there is a long
- list of supported optional features. It might be worth noting that at
- the time of writing, no current version of any database management
- system claims full conformance to Core SQL:2016.
- </p><p>
- In the following two sections, we provide a list of those features
- that <span class="productname">PostgreSQL</span> supports, followed by a
- list of the features defined in <acronym class="acronym">SQL:2016</acronym> which
- are not yet supported in <span class="productname">PostgreSQL</span>.
- Both of these lists are approximate: There might be minor details that
- are nonconforming for a feature that is listed as supported, and
- large parts of an unsupported feature might in fact be implemented.
- The main body of the documentation always contains the most accurate
- information about what does and does not work.
- </p><div class="note"><h3 class="title">Note</h3><p>
- Feature codes containing a hyphen are subfeatures. Therefore, if a
- particular subfeature is not supported, the main feature is listed
- as unsupported even if some other subfeatures are supported.
- </p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="sql-keywords-appendix.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="appendixes.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="features-sql-standard.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Appendix C. <acronym class="acronym">SQL</acronym> Key Words </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> D.1. Supported Features</td></tr></table></div></body></html>
|
