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Postgres FD Implementation
Commit 8baa8fcf authored by Bruce Momjian's avatar Bruce Momjian
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Some suggestions to clarify the current status of PostgreSQL. Patch 

attached.

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