Editing PostgreSQL (section)

== Standards compliance ==
PostgreSQL claims high, but not complete, conformance with the latest [[SQL|SQL standard]] ("as of the version 17 release in September 2024, PostgreSQL conforms to at least 170 of the 177 mandatory features for [[SQL:2023]] Core conformance", and no other databases fully conformed to it<ref>{{Cite web|title=PostgreSQL: About|url=https://www.postgresql.org/about/|access-date=2024-10-14|website=www.postgresql.org}}</ref>). One exception is the handling of unquoted identifiers like table or column names. In PostgreSQL they are folded, internally, to lower case characters<ref name="identifiers"/> whereas the standard says that unquoted identifiers should be folded to upper case. Thus, {{code|Foo}} should be equivalent to {{code|FOO}} not {{code|foo}} according to the standard. Other shortcomings concern the absence of temporal tables allowing automatic logging of row versions during transactions with the possibility of browsing in time (FOR SYSTEM TIME predicate),{{citation needed |date=February 2022}} although relatively SQL compliant third-party extensions are available.<ref name="temporal-extensions" />