than zero and cannot exceed 10485760.

<type>character</type> without length specifier is equivalent to

<type>character(1)</type>. If <type>character varying</type> is used

without length specifier, the type accepts strings of any size. The

latter behavior is a <productname>PostgreSQL</productname> extension.

without length specifier, the type accepts strings of any size.

</para>

<para>

<para>

The formal name of the SQL standard is ISO/IEC 9075 <quote>Database

Language SQL</quote>. A revised version of the standard is released

from time to time; the most recent update appearing in2016.

The2016 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,

from time to time; the most recent update appearing in2023.

The2023 version is referred to as ISO/IEC 9075:2023, or simply as SQL:2023.

The versions prior to that were SQL:2016, 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.

<listitem><para>ISO/IEC 9075-13 Routines and Types using the Java Language (SQL/JRT)</para><indexterm><primary>SQL/JRT</primary></indexterm></listitem>

<listitem><para>ISO/IEC 9075-14 XML-related specifications (SQL/XML)</para><indexterm><primary>SQL/XML</primary></indexterm></listitem>

<listitem><para>ISO/IEC 9075-15 Multi-dimensional arrays (SQL/MDA)</para><indexterm><primary>SQL/MDA</primary></indexterm></listitem>

<listitem><para>ISO/IEC 9075-16 Property Graph Queries (SQL/PGQ)</para><indexterm><primary>SQL/PGQ</primary></indexterm></listitem>

</itemizedlist>

Note that some part numbers are not (or no longer) used.

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, 10, and15

implementations of parts 4, 10,15,and16

for <productname>PostgreSQL</productname>.

</para>

<para>

PostgreSQL supports most of the major features of SQL:2016. Out of

PostgreSQL supports most of the major features of SQL:2023. Out of

177 mandatory features required for full Core conformance,

PostgreSQL conforms to at least 170. 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.

system claims full conformance to Core SQL:2023.

</para>

<para>

In the following two sections, we provide a list of those features

that <productname>PostgreSQL</productname> supports, followed by a

list of the features defined in <acronym>SQL:2016</acronym> which

list of the features defined in <acronym>SQL:2023</acronym> which

are not yet supported in <productname>PostgreSQL</productname>.

Both of these lists are approximate: There might be minor details that

are nonconforming for a feature that is listed as supported, and

<title>Unsupported Features</title>

<para>

The following features defined in <acronym>SQL:2016</acronym> are not

The following features defined in <acronym>SQL:2023</acronym> are not

implemented in this release of

<productname>PostgreSQL</productname>. In a few cases, equivalent

functionality is available.