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<appendix id="release">

<title>Release Notes</title>

<sect1 id="release-devel">

<sect1 id="release-7-4">

<title>Release 7.4</title>

<sect2><title>Overview</title>

</footnote>

</para>

<para> Improved GROUP BY processing by using hash buckets</para>

<para> Improved GROUP BY processing by using hash buckets

<footnote>

<para>

In previous releases, GROUP BY totals were accumulated by

sequentially scanning the list of groups looking for a match;

the 7.4 code places GROUP BY values in hash buckets so the

proper match can be found much quicker. This is particularly

significant in speeding up queries that have a large

number of distinct GROUP BY values.

</para>

</footnote>

</para>

<para> New multi-key hash join capability</para>

<para> New multi-key hash join capability

<footnote>

<para>

In previous releases, hash joins could only occur on single-column

joins. This release allows multi-column hash joins.

</para>

</footnote>

</para>

<para> ANSI joins are now better optimized</para>

<para> ANSI joins are now better optimized

<footnote>

<para>

Prior releases evaluated ANSI join syntax only in the order

specified by the query; 7.4 allows full optimization of

queries using ANSI join syntax, meaning the optimizer considers

all possible join orderings and chooses the most efficient.

</para>

</footnote>

</para>

<para> Faster and more powerful regular expression code</para>

<para> Faster and more powerful regular expression code

<footnote>

<para>

The entire regular expression module has been replaced with a new

version by Henry Spencer, originally written for TCL. The code

greatly improves performance and supports several flavors

of regular expressions.

</para>

</footnote>

</para>

<para> Function-inlining for simple SQL functions</para></glossdef>

<para> Function-inlining for simple SQL functions

<footnote>

<para>

Simple SQL functions can now be inlined by including their SQL

in the main query. This improves performance by preventing

repeated calls to the SQL function --- this allows simple

SQL functions to behave like macros.

</para>

</footnote>

</para></glossdef>

</glossentry>

<glossentry> <glossterm> IPv6</glossterm>

<glossdef><para> Full support for IPv6 connections and IPv6 address

data types</para></glossdef>

data types

<footnote>

<para>

Prior releases allowed only IPv6 connections and IP data types only

supported IPv4 addresses. This release adds full IPv6 support in

both of these areas.

</para>

</footnote>

</para></glossdef>

</glossentry>

<glossentry><glossterm> SSL</glossterm>

<glossdef><para> Major improvements in SSL performance and

reliability</para></glossdef>

reliability

<footnote>

<para>

Several people very familiar with the SSL API have overhauled our

SSL code to improve SSL key negotiation and error recovery.

</para>

</footnote>

</para></glossdef>

</glossentry>

<glossentry><glossterm> Index Growth Prevention</glossterm>

<glossdef><para> Allow free space map to efficiently reuse empty index

pages, and other free space management improvements.</para></glossdef>

pages, and other free space management improvements.

<footnote>

<para>

In prior releases, index pages that were left empty because of

deleted rows could only be reused by rows with index values similar

to the original rows indexed on that page. In 7.4, VACUUM records

empty index pages and allows them to be used for any future index

rows.

</para>

</footnote>

</para></glossdef>

</glossentry>

<glossentry><glossterm> Standards Compliance</glossterm>

<glossentry><glossterm> Threads</glossterm>

<glossdef><para> libpq and ecpg are now fully thread-safe with

--enable-thread-safety</para></glossdef>

--enable-thread-safety

<footnote>

<para>

While prior libpq releases already supported threads, this release

improves thread safety by fixing some non-thread-safe code that

was used in the database connection routines.

</para>

</footnote>

</para></glossdef>

</glossentry>

<glossentry><glossterm> Contrib</glossterm>

<glossdef><para> New version of full text indexing (tsearch2)</para>

<para> New autovacuum tool</para>

<para> New autovacuum tool

<footnote>

<para>

This new tool monitors the database statistics tables for

INSERT/UPDATE/DELETE activity and automatically vacuums tables when

needed.

</para>

</footnote>

</para>

<para> Array handling has been improved and moved into the main

server</para></glossdef>

server

<footnote>

<para>

Many array limitations have been removed and they behave more like

fully-supported data types.

</para>

</footnote>

</para></glossdef>

</glossentry>

</glosslist></para></sect2>

<para> Observe the following incompatibilities:

<itemizedlist>

<listitem><para> The server-side autocommit setting was removed and reimplemented

in client applications and languages.</para></listitem>

in client applications and languages.

<footnote>

<para>

Server-side autocommit was causing too many problems with

languages and applications that wanted to control their own

autocommit behavior so autocommit was removed from the server

and added to individual client API's as appropriate.

</para>

</footnote>

</para></listitem>

<listitem><para> Error message wording has changed substantially in this release,

and error codes have been added.</para></listitem>

<listitem><para> ANSI inner joins may behave differently because they are now better optimized</para></listitem>

<listitem><para> A number of server variables have been renamed for clarity</para></listitem>

<listitem><para> MOVE/FETCH 0 now does nothing</para></listitem>

<listitem><para> A number of server variables have been renamed for

clarity, primarily those related to logging</para></listitem>

<listitem><para> MOVE/FETCH 0 now does nothing

<footnote>

<para>

In prior releases, FETCH 0 would fetch all remaining rows, and

MOVE 0 would move to the end of the cursor.

</para>

</footnote>

</para></listitem>

<listitem><para> MOVE/FETCH now returns the actual number of rows moved/fetched, or zero

if at the beginning/end of the cursor</para></listitem>

<listitem><para> COPY now can process carriage-return/line-feed and carriage-return

terminated files. Literal carriage-returns and line-feeds are no

if at the beginning/end of the cursor

<footnote>

<para>

Prior releases would return the tuple count passed to the

command, not the actual number of rows FETCHed or MOVEd.

</para>

</footnote>

</para></listitem>

<listitem><para> COPY now can process carriage-return and

carriage-return/line-feed end-of-line terminated files.</para></listitem>

<listitem><para>Literal carriage-returns and line-feeds are no

longer accepted as data values; use \r and \n instead.</para></listitem>

<listitem><para> Trailing spaces are now trimmed when converting

from <type>CHAR(n)</type> to

<type>VARCHAR(n)</type> / <type>TEXT</type></para></listitem>

<listitem><para> <function>FLOAT(p)</function> now measures 'p' in bits, not digits</para></listitem>

<listitem><para> Ambiguous date values now must match the ordering specified by DateStyle</para></listitem>

<listitem><para> Ambiguous date values now must match the ordering specified by DateStyle

<footnote>

<para>

In prior releases, a date of <literal>10/20/03</> was

interpreted as a date in October even if the

<varname>DateStyle</> specified the day should be first. In

7.4, <varname>DateStyle</> is honored when converting such

values and will throw an error if the date is invalid for the

current <varname>DateStyle</>.

</para>

</footnote>

</para></listitem>

<listitem><para> The <function>oidrand()</function>, <function>oidsrand()</function>,

and <function>userfntest()</function> functions have been removed.</para></listitem>

and <function>userfntest()</function> functions have been removed.

<footnote>

<para>

These functions were determined to be no longer useful.

</para>

</footnote>

</para></listitem>

<listitem><para> <literal>'now'</literal> will no longer work as a column default; <function>now()</> or

<function>CURRENT_TIMESTAMP</> should be used instead</para></listitem>

<function>CURRENT_TIMESTAMP</> should be used instead

<footnote>

<para>

In prior releases, there was special code so the string

<literal>'now'</literal> was interpreted at

<command>INSERT</> time and not at table creation time, but

this work around didn't cover all cases. Release 7.4

now requires that defaults be defined properly using the

<function>now()</> or the special value

<function>CURRENT_TIMESTAMP</>. These will work in all

situations.

</para>

</footnote>

</para></listitem>

<listitem><para> <literal>'today'</literal> will no longer work as a column default; <function>CURRENT_DATE</>

should be used instead</para></listitem>

should be used instead

<footnote>

<para>

Same description as above.

</para>

</footnote>

</para></listitem>

<listitem><para> Dollar sign (<literal>$</>) is no longer allowed in operator names</para></listitem>

<listitem><para> Dollar sign (<literal>$</>) can be a non-first character in identifiers</para></listitem>

<listitem><para> Dollar sign (<literal>$</>) can be a non-first character in identifiers

<footnote>

<para>

This was done to improve compatibility with other database

systems.

</para>

</footnote>

</para></listitem>

</itemizedlist></para></sect2>

<sect2> <title> Changes </title>

<itemizedlist>

<listitem><para>Allow IPv6 server connections (Nigel Kukard, Johan Jordaan, Bruce, Tom, Kurt

Roeckx, Andrew Dunstan)</para></listitem>

<listitem><para>Fix SSL to handle errors cleanly (Nathan Mueller)</para></listitem>

<listitem><para>Fix SSL to handle errors cleanly (Nathan Mueller)

<footnote>

<para>

In prior releases,

</para>

</footnote>

</para></listitem>

<listitem><para>SSL protocol security and performance improvements (Sean Chittenden)</para></listitem>

<listitem><para>Print lock information when a deadlock is detected (Tom)</para></listitem>

<listitem><para>Update <filename>/tmp</filename> socket mod. times regularly to avoid their removal (Tom)</para></listitem>