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>SQL Conformance</TITLE
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>PostgreSQL 9.1beta1 Documentation</A
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HREF="sql-keywords-appendix.html"
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HREF="sql-keywords-appendix.html"
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TITLE="Supported Features"
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HREF="features-sql-standard.html"
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>Appendix D. SQL Conformance</H1
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>Table of Contents</B
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HREF="features-sql-standard.html"
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>Supported Features</A
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HREF="unsupported-features-sql-standard.html"
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>Unsupported Features</A
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> This section attempts to outline to what extent
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> conforms to the current SQL
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standard. The following information is not a full statement of
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conformance, but it presents the main topics in as much detail as is
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both reasonable and useful for users.
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> The formal name of the SQL standard is ISO/IEC 9075 <SPAN
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>. A revised version of the standard is released
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from time to time; the most recent update appearing in 2008.
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The 2008 version is referred to as ISO/IEC 9075:2008, or simply as SQL:2008.
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The versions prior to that were SQL:2003, SQL:1999, and SQL-92. Each version
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replaces the previous one, so claims of conformance to earlier
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versions have no official merit.
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> development aims for
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conformance with the latest official version of the standard where
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such conformance does not contradict traditional features or common
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sense. The PostgreSQL project is not represented in the ISO/IEC
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9075 Working Group during the preparation of the SQL standard
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releases, but even so, many of the features required by the SQL
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standard are supported, though sometimes with slightly differing
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syntax or function. Further moves towards conformance can be
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> defined three feature sets for
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conformance: Entry, Intermediate, and Full. Most database
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management systems claiming <ACRONYM
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conformance were conforming at only the Entry level, since the
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entire set of features in the Intermediate and Full levels was
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either too voluminous or in conflict with legacy behaviors.
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> Starting with <ACRONYM
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>, the SQL standard defines
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a large set of individual features rather than the ineffectively
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broad three levels found in <ACRONYM
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subset of these features represents the <SPAN
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features, which every conforming SQL implementation must supply.
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The rest of the features are purely optional. Some optional
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features are grouped together to form <SPAN
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SQL implementations can claim conformance to, thus claiming
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conformance to particular groups of features.
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standard versions are also split into a number
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of parts. Each is known by a shorthand name. Note that these parts
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are not consecutively numbered.
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>ISO/IEC 9075-1 Framework (SQL/Framework)</P
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>ISO/IEC 9075-2 Foundation (SQL/Foundation)</P
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>ISO/IEC 9075-3 Call Level Interface (SQL/CLI)</P
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>ISO/IEC 9075-4 Persistent Stored Modules (SQL/PSM)</P
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>ISO/IEC 9075-9 Management of External Data (SQL/MED)</P
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>ISO/IEC 9075-10 Object Language Bindings (SQL/OLB)</P
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>ISO/IEC 9075-11 Information and Definition Schemas (SQL/Schemata)</P
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>ISO/IEC 9075-13 Routines and Types using the Java Language (SQL/JRT)</P
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>ISO/IEC 9075-14 XML-related specifications (SQL/XML)</P
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> core covers parts 1, 2, 9,
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11, and 14. Part 3 is covered by the ODBC driver, and part 13 is
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covered by the PL/Java plug-in, but exact conformance is currently
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not being verified for these components. There are currently no
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implementations of parts 4 and 10
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> PostgreSQL supports most of the major features of SQL:2008. Out of
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179 mandatory features required for full Core conformance,
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PostgreSQL conforms to at least 160. In addition, there is a long
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list of supported optional features. It might be worth noting that at
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the time of writing, no current version of any database management
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system claims full conformance to Core SQL:2008.
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> In the following two sections, we provide a list of those features
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> supports, followed by a
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list of the features defined in <ACRONYM
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are not yet supported in <SPAN
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Both of these lists are approximate: There might be minor details that
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are nonconforming for a feature that is listed as supported, and
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large parts of an unsupported feature might in fact be implemented.
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The main body of the documentation always contains the most accurate
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information about what does and does not work.
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> Feature codes containing a hyphen are subfeatures. Therefore, if a
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particular subfeature is not supported, the main feature is listed
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as unsupported even if some other subfeatures are supported.
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>Supported Features</TD
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