mirror of https://github.com/postgres/postgres
Some suggestions to clarify the current status of PostgreSQL. Patch
attached. Fred Horch
This commit is contained in:
Bruce Momjian
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@ -1,6 +1,18 @@
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<Sect1>
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<Title>A Short History of <ProductName>Postgres</ProductName></Title>
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<Para>
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The Object-Relational Database Management System now known as
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<ProductName>PostgreSQL</ProductName> was originally called
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<ProductName>Postgres</ProductName>, and briefly called
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<ProductName>Postgres95</ProductName>. With over a decade of
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development behind it, <ProductName>PostgreSQL</ProductName>
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is the most advanced open-source database available anywhere,
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offering multi-version concurrency control and supporting almost
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all SQL constructs, including subselects, transactions, and
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user-defined types and functions.
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</Para>
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<Sect2>
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<Title>The Berkeley <ProductName>Postgres</ProductName> Project</Title>
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@ -37,8 +49,8 @@ and Version 2 was
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Version 3 appeared in 1991 and added support for multiple
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storage managers, an improved query executor, and a
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rewritten rewrite rule system. For the most part,
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releases since then have focused on portability and
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reliability.
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releases until <ProductName>Postgres95</ProductName> (see below)
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focused on portability and reliability.
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</Para>
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<Para>
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@ -70,7 +82,7 @@ and Version 2 was
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ended with Version 4.2.
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</Para>
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</Sect2>
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<Sect2>
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<Title><ProductName>Postgres95</ProductName></Title>
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@ -79,77 +91,75 @@ In 1994,
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<ULink url="mailto:ayu@informix.com">Andrew Yu</ULink>
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and
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<ULink url="http://http.cs.berkeley.edu/~jolly/">Jolly Chen</ULink>
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added a SQL language interpreter to <ProductName>Postgres</ProductName>,
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and the code was subsequently released to
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the Web to find its own way in the world.
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<ProductName>Postgres95</ProductName> was a public-domain, open source descendant
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of this original Berkeley code.
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added a SQL language interpreter to <ProductName>Postgres</ProductName>.
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<ProductName>Postgres95</ProductName> was subsequently released to
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the Web to find its own way in the world as a public-domain,
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open source descendant of the original <ProductName>Postgres</ProductName>
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Berkeley code.
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</Para>
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<Para>
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<ProductName>Postgres95</ProductName> is a derivative of the last official release
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of <ProductName>Postgres</ProductName> (version 4.2). The code is now completely
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ANSI C and the code size has been trimmed by 25%. There
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are a lot of internal changes that improve performance
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and code maintainability.
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<ProductName>Postgres95</ProductName> v1.0.x runs about 30-50%
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faster on the Wisconsin Benchmark compared to v4.2.
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Apart from bug fixes, these are the major enhancements:
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<ProductName>Postgres95</ProductName> code was completely
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ANSI C and trimmed in size by 25%. Many
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internal changes improved performance and maintainability.
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<ProductName>Postgres95</ProductName> v1.0.x ran about 30-50%
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faster on the Wisconsin Benchmark compared to
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<ProductName>Postgres</ProductName> v4.2.
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Apart from bug fixes, these were the major enhancements:
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<ItemizedList>
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<ListItem>
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<Para>
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The query language <ProductName>Postquel</ProductName> has been replaced with
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<Acronym>SQL</Acronym> (implemented in the server). We do not yet support
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subqueries (which can be imitated with user defined
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<Acronym>SQL</Acronym> functions). Aggregates have been
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re-implemented. We also added support for ``GROUP BY''.
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The <FileName>libpq</FileName> interface is still available for <Acronym>C</Acronym>
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The query language <ProductName>Postquel</ProductName> was replaced with
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<Acronym>SQL</Acronym> (implemented in the server). Subqueries were not supported until <ProductName>PostgreSQL</ProductName> (see below), but they
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could be imitated in <ProductName>Postgres95</ProductName> with user-defined
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<Acronym>SQL</Acronym> functions. Aggregates were
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re-implemented. Support for ``GROUP BY'' was also added.
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The <FileName>libpq</FileName> interface remained available for <Acronym>C</Acronym>
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programs.
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</Para>
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</ListItem>
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<ListItem>
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<Para>
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In addition to the monitor program, we provide a new
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program (<Application>psql</Application>) which supports <Acronym>GNU</Acronym> <FileName>readline</FileName>.
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In addition to the monitor program, a new program
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(<Application>psql</Application>) was provided for interactive SQL queries
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using <Acronym>GNU</Acronym> <FileName>readline</FileName>.
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</Para>
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</ListItem>
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<ListItem>
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<Para>
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We added a new front-end library, <FileName>libpgtcl</FileName>, that
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supports <Acronym>Tcl</Acronym>-based clients. A sample shell,
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pgtclsh, provides new Tcl commands to interface <Application>tcl</Application>
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A new front-end library, <FileName>libpgtcl</FileName>,
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supported <Acronym>Tcl</Acronym>-based clients. A sample shell,
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pgtclsh, provided new Tcl commands to interface <Application>tcl</Application>
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programs with the <ProductName>Postgres95</ProductName> backend.
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</Para>
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</ListItem>
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<ListItem>
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<Para>
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The large object interface has been overhauled. We
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kept Inversion large objects as the only mechanism
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for storing large objects. (This is not to be
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confused with the Inversion file system which has been
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removed.)
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The large object interface was overhauled. The Inversion large objects were
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the only mechanism for storing large objects.
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(The Inversion file system was removed.)
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</Para>
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</ListItem>
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<ListItem>
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<Para>
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The instance-level rule system has been removed.
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Rules are still available as rewrite rules.
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The instance-level rule system was removed.
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Rules were still available as rewrite rules.
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</Para>
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</ListItem>
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<ListItem>
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<Para>
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A short tutorial introducing regular <Acronym>SQL</Acronym> features as
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well as those of ours is distributed with the source
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code.
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well as those of <ProductName>Postgres95</ProductName> was
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distributed with the source code.
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</Para>
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</ListItem>
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<ListItem>
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<Para>
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<Acronym>GNU</Acronym> make (instead of <Acronym>BSD</Acronym> make) is used for the
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build. Also, <ProductName>Postgres95</ProductName> can be compiled with an
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unpatched <ProductName>gcc</ProductName> (data alignment of doubles has been
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fixed).
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<Acronym>GNU</Acronym> make (instead of <Acronym>BSD</Acronym> make) was used
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for the build. Also, <ProductName>Postgres95</ProductName> could be
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compiled with an unpatched <ProductName>gcc</ProductName>
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(data alignment of doubles was fixed).
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</Para>
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</ListItem>
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</ItemizedList>
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@ -160,36 +170,39 @@ and code maintainability.
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<Title><ProductName>PostgreSQL</ProductName></Title>
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<Para>
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By 1996, it became clear that the name <Quote>Postgres95</Quote> would not stand
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the test of time. A new name, <ProductName>PostgreSQL</ProductName>,
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was chosen to reflect the
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relationship between original <ProductName>Postgres</ProductName>
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and the more recent
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versions with <Acronym>SQL</Acronym> capability.
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At the same time, the version numbering
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was reset to start at 6.0,
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putting the numbers back into the sequence originally begun by
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the <ProductName>Postgres</ProductName> Project.
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By 1996, it became clear that the name <Quote>Postgres95</Quote> would
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not stand the test of time. We chose a new name,
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<ProductName>PostgreSQL</ProductName>, to reflect the relationship
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between the original <ProductName>Postgres</ProductName> and the more
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recent versions with <Acronym>SQL</Acronym> capability. At the same
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time, we set the version numbering to start at 6.0, putting the
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numbers back into the sequence originally begun by the
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<ProductName>Postgres</ProductName> Project.
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</Para>
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<Para>
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The emphasis on development for the v1.0.x releases of
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<ProductName>Postgres95</ProductName>
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was on stabilizing the backend code.
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With the v6.x series of <ProductName>PostgreSQL</ProductName>,
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the emphasis has shifted from
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identifying and understanding existing problems in the backend
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to augmenting features and capabilities, although
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The emphasis during development of <ProductName>Postgres95</ProductName>
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was on identifying and understanding existing problems in the backend code.
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With <ProductName>PostgreSQL</ProductName>,
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the emphasis has shifted to augmenting features and capabilities, although
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work continues in all areas.
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</Para>
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<Para>
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Major enhancements include:
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Major enhancements in <ProductName>PostgreSQL</ProductName> include:
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</Para>
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<ItemizedList>
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<ListItem>
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<Para>
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Table-level locking has been replaced with multi-version concurrency control,
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which allows readers to continue reading consistent data during writer activity
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and enables hot backups from pg_dump while the database stays available for
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queries.
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</Para>
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</ListItem>
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<ListItem>
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<Para>
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Important backend features, including subselects, defaults,
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constraints, and triggers, have been implemented.
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</Para>
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