release.sgml

关系型数据库 Postgresql 6.5.2

</authorgroup>
<date>
Sun Mar  1 14:57:30 EST 1998
</date>
</docinfo>
-->

<para>
There are <emphasis>many</emphasis> new features and improvements in this release.
Here is a brief, incomplete summary:

<itemizedlist>
<listitem>
<para>
Many new SQL features, including
full <acronym>SQL92</acronym> subselect capability
(everything is here but target-list subselects).
</para>
</listitem>

<listitem>
<para>
Support for client-side environment variables to specify time zone and date style.
</para>
</listitem>

<listitem>
<para>
Socket interface for client/server connection. This is the default now
so you may need to start <application>postmaster</application> with the
<quote>-i</quote> flag.
</para>
</listitem>

<listitem>
<para>
Better password authorization mechanisms. Default table permissions have changed.
</para>
</listitem>

<listitem>
<para>
Old-style <quote>time travel</quote> has been removed. Performance has been improved.
</para>
</listitem>

</itemizedlist>
</para>

<note>
<para>
Bruce Momjian wrote the following notes to introduce the new release.
</para>
</note>

<para>
There are some general 6.3 issues that I want to mention.  These are
only the big items that can not be described in one sentence.  A review
of the detailed changes list is still needed.
</para>
<para>
First, we now have subselects.  Now that we have them, I would like to
mention that without subselects, SQL is a very limited language.
Subselects are a major feature, and you should review your code for
places where subselects provide a better solution for your queries.  I
think you will find that there are more uses for subselects than you may
think.  Vadim has put us on the big SQL map with subselects, and fully
functional ones too.  The only thing you can't do with subselects is to
use them in the target list.
</para>
<para>
Second, 6.3 uses unix domain sockets rather than TCP/IP by default.  To
enable connections from other machines, you have to use the new
postmaster -i option, and of course edit pg_hba.conf.  Also, for this
reason, the format of pg_hba.conf has changed.
</para>
<para>
Third, char() fields will now allow faster access than varchar() or
text. Specifically, the text and varchar() have a penalty for access to
any columns after the first column of this type.  char() used to also
have this access penalty, but it no longer does.  This may suggest that
you redesign some of your tables, especially if you have short character
columns that you have defined as varchar() or text.  This and other
changes make 6.3 even faster than earlier releases.
</para>
<para>
We now have passwords definable independent of any Unix file.  There are
new SQL USER commands.  See the pg_hba.conf manual page for more
information.  There is a new table, pg_shadow, which is used to store
user information and user passwords, and it by default only SELECT-able
by the postgres super-user.  pg_user is now a view of pg_shadow, and is
SELECT-able by PUBLIC.  You should keep using pg_user in your
application without changes.
</para>
<para>
User-created tables now no longer have SELECT permission to PUBLIC by
default.  This was done because the ANSI standard requires it.  You can
of course GRANT any permissions you want after the table is created. 
System tables continue to be SELECT-able by PUBLIC.
</para>
<para>
We also have real deadlock detection code.  No more sixty-second
timeouts.  And the new locking code implements a FIFO better, so there
should be less resource starvation during heavy use.
</para>
<para>
Many complaints have been made about inadequate documenation in previous
releases.  Thomas has put much effort into many new manuals for this
release.  Check out the doc/ directory.
</para>
<para>
For performance reasons, time travel is gone, but can be implemented
using triggers (see pgsql/contrib/spi/README).  Please check out the new
\d command for types, operators, etc.  Also, views have their own
permissions now, not based on the underlying tables, so permissions on
them have to be set separately.  Check /pgsql/interfaces for some new
ways to talk to <productname>Postgres</productname>.
</para>
<para>
This is the first release that really required an explanation for
existing users.  In many ways, this was necessary because the new
release removes many limitations, and the work-arounds people were using
are no longer needed.
</para>

<sect2>
<title>Migration to v6.3</title>

<para>
A dump/restore using <application>pg_dump</application> 
or <application>pg_dumpall</application>
is required for those wishing to migrate data from any
previous release of <productname>Postgres</productname>.
</para>
</sect2>

<sect2>
<title>Detailed Change List</title>

<para>
<programlisting>
Bug Fixes
---------
Fix binary cursors broken by MOVE implementation(Vadim)
Fix for tcl library crash(Jan)
Fix for array handling, from Gerhard Hintermayer
Fix acl error, and remove duplicate pqtrace(Bruce)
Fix psql \e for empty file(Bruce)
Fix for textcat on varchar() fields(Bruce)
Fix for DBT Sendproc (Zeugswetter Andres)
Fix vacuum analyze syntax problem(Bruce)
Fix for international identifiers(Tatsuo)
Fix aggregates on inherited tables(Bruce)
Fix substr() for out-of-bounds data
Fix for select 1=1 or 2=2, select 1=1 and 2=2, and select sum(2+2)(Bruce)
Fix notty output to show status result.  -q option still turns it off(Bruce)
Fix for count(*), aggs with views and multiple tables and sum(3)(Bruce)
Fix cluster(Bruce)
Fix for PQtrace start/stop several times(Bruce)
Fix a variety of locking problems like newer lock waiters getting
	lock before older waiters, and having readlock people not share
	locks if a writer is waiting for a lock, and waiting writers not
	getting priority over waiting readers(Bruce)
Fix crashes in psql when executing queries from external files(James)
Fix problem with multiple order by columns, with the first one having
	NULL values(Jeroen)
Use correct hash table support functions for float8 and int4(Thomas)
Re-enable JOIN= option in CREATE OPERATOR statement (Thomas)
Change precedence for boolean operators to match expected behavior(Thomas)
Generate elog(ERROR) on over-large integer(Bruce)
Allow multiple-argument functions in constraint clauses(Thomas)
Check boolean input literals for 'true','false','yes','no','1','0'
	and throw elog(ERROR) if unrecognized(Thomas)
Major large objects fix
Fix for GROUP BY showing duplicates(Vadim)
Fix for index scans in MergeJion(Vadim)

Enhancements
------------
Subselects with EXISTS, IN, ALL, ANY keywords (Vadim, Bruce, Thomas)
New User Manual(Thomas, others)
Speedup by inlining some frequently-called functions
Real deadlock detection, no more timeouts(Bruce)
Add SQL92 "constants" CURRENT_DATE, CURRENT_TIME, CURRENT_TIMESTAMP, 
	CURRENT_USER(Thomas)
Modify constraint syntax to be SQL92-compliant(Thomas)
Implement SQL92 PRIMARY KEY and UNIQUE clauses using indices(Thomas)
Recognize SQL92 syntax for FOREIGN KEY. Throw elog notice(Thomas)
Allow NOT NULL UNIQUE constraint clause (each allowed separately before)(Thomas)
Allow Postgres-style casting ("::") of non-constants(Thomas)
Add support for SQL3 TRUE and FALSE boolean constants(Thomas)
Support SQL92 syntax for IS TRUE/IS FALSE/IS NOT TRUE/IS NOT FALSE(Thomas)
Allow shorter strings for boolean literals (e.g. "t", "tr", "tru")(Thomas)
Allow SQL92 delimited identifiers(Thomas)
Implement SQL92 binary and hexadecimal string decoding (b'10' and x'1F')(Thomas)
Support SQL92 syntax for type coercion of literal strings
	(e.g. "DATETIME 'now'")(Thomas)
Add conversions for int2, int4, and OID types to and from text(Thomas)
Use shared lock when building indices(Vadim)
Free memory allocated for an user query inside transaction block after
	this query is done, was turned off in <= 6.2.1(Vadim)
New SQL statement CREATE PROCEDURAL LANGUAGE(Jan)
New <productname>Postgres</productname> Procedural Language (PL) backend interface(Jan)
Rename pg_dump -H option to -h(Bruce)
Add Java support for passwords, European dates(Peter)
Use indices for LIKE and ~, !~ operations(Bruce)
Add hash functions for datetime and timespan(Thomas)
Time Travel removed(Vadim, Bruce)
Add paging for \d and \z, and fix \i(Bruce)
Add Unix domain socket support to backend and to frontend library(Goran)
Implement CREATE DATABASE/WITH LOCATION and initlocation utility(Thomas)
Allow more SQL92 and/or <productname>Postgres</productname> reserved words as column identifiers(Thomas)
Augment support for SQL92 SET TIME ZONE...(Thomas)
SET/SHOW/RESET TIME ZONE uses TZ backend environment variable(Thomas)
Implement SET keyword = DEFAULT and SET TIME ZONE DEFAULT(Thomas)
Enable SET TIME ZONE using TZ environment variable(Thomas)
Add PGDATESTYLE environment variable to frontend and backend initialization(Thomas)
Add PGTZ, PGCOSTHEAP, PGCOSTINDEX, PGRPLANS, PGGEQO
	frontend library initialization environment variables(Thomas)
Regression tests time zone automatically set with "setenv PGTZ PST8PDT"(Thomas)
Add pg_description table for info on tables, columns, operators, types, and
	aggregates(Bruce)
Increase 16 char limit on system table/index names to 32 characters(Bruce)
Rename system indices(Bruce)
Add 'GERMAN' option to SET DATESTYLE(Thomas)
Define an "ISO-style" timespan output format with "hh:mm:ss" fields(Thomas)
Allow fractional values for delta times (e.g. '2.5 days')(Thomas)
Validate numeric input more carefully for delta times(Thomas)
Implement day of year as possible input to date_part()(Thomas)
Define timespan_finite() and text_timespan() functions(Thomas)
Remove archive stuff(Bruce)
Allow for a pg_password authentication database that is separate from
	the system password file(Todd)
Dump ACLs, GRANT, REVOKE permissions(Matt)
Define text, varchar, and bpchar string length functions(Thomas)
Fix Query handling for inheritance, and cost computations(Bruce)
Implement CREATE TABLE/AS SELECT (alternative to SELECT/INTO)(Thomas)
Allow NOT, IS NULL, IS NOT NULL in constraints(Thomas)
Implement UNIONs for SELECT(Bruce)
Add UNION, GROUP, DISTINCT to INSERT(Bruce)
varchar() stores only necessary bytes on disk(Bruce)
Fix for BLOBs(Peter)
Mega-Patch for JDBC...see README_6.3 for list of changes(Peter)
Remove unused "option" from PQconnectdb()
New LOCK command and lock manual page describing deadlocks(Bruce)
Add new psql \da, \dd, \df, \do, \dS, and \dT commands(Bruce)
Enhance psql \z to show sequences(Bruce)
Show NOT NULL and DEFAULT in psql \d table(Bruce)
New psql .psqlrc file startup(Andrew)
Modify sample startup script in contrib/linux to show syslog(Thomas)
New types for IP and MAC addresses in contrib/ip_and_mac(TomH)
Unix system time conversions with date/time types in contrib/unixdate(Thomas)
Update of contrib stuff(Massimo)
Add Unix socket support to DBD::Pg(Goran)
New python interface (PyGreSQL 2.0)(D'Arcy)
New frontend/backend protocol has a version number, network byte order(Phil)
Security features in pg_hba.conf enhanced and documented, many cleanups(Phil)
CHAR() now faster access than VARCHAR() or TEXT
ecpg embedded SQL preprocessor
Reduce system column overhead(Vadmin)
Remove pg_time table(Vadim)
Add pg_type attribute to identify types that need length (bpchar, varchar)
Add report of offending line when COPY command fails
Allow VIEW permissions to be set separately from the underlying tables. 
	For security, use GRANT/REVOKE on views as appropriate(Jan)
Tables now have no default GRANT SELECT TO PUBLIC.  You must
	explicitly grant such permissions.
Clean up tutorial examples(Darren)

Source Tree Changes
-------------------
Add new html development tools, and flow chart in /tools/backend
Fix for SCO compiles
Stratus computer port Robert Gillies
Added support for shlib for BSD44_derived & i386_solaris
Make configure more automated(Brook)
Add script to check regression test results
Break parser functions into smaller files, group together(Bruce)
Rename heap_create to heap_create_and_catalog, rename heap_creatr
	to heap_create()(Bruce)
Sparc/Linux patch for locking(TomS)
Remove PORTNAME and reorganize port-specific stuff(Marc)
Add optimizer README file(Bruce)
Remove some recursion in optimizer and clean up some code there(Bruce)
Fix for NetBSD locking(Henry)
Fix for libptcl make(Tatsuo)
AIX patch(Darren)
Change IS TRUE, IS FALSE, ... to expressions using "=" rather than
	function calls to istrue() or isfalse() to allow optimization(Thomas)
Various fixes NetBSD/Sparc related(TomH)
Alpha linux locking(Travis,Ryan)
Change elog(WARN) to elog(ERROR)(Bruce)
FAQ for FreeBSD(Marc)
Bring in the PostODBC source tree as part of our standard distribution(Marc)
A minor patch for HP/UX 10 vs 9(Stan)
New pg_attribute.atttypmod for type-specific info like varchar length(Bruce)
Unixware patches(Billy)
New i386 'lock' for spin lock asm(Billy)
Support for multiplexed backends is removed
Start an OpenBSD port
Start an AUX port
Start a Cygnus port
Add string functions to regression suite(Thomas)
Expand a few function names formerly truncated to 16 characters(Thomas)
Remove un-needed malloc() calls and replace with palloc()(Bruce)
</programlisting>
</para>
</sect2>
</sect1>

<sect1>
<title>Release 6.2.1</title>
<!--
<docinfo>
<authorgroup>
<author>
<firstname>Bruce</firstname>
<surname>Momjian</surname>
</author>
</authorgroup>
<date>
Fri Oct 17 00:01:27 EDT 1997
</date>
</docinfo>
-->

<para>
v6.2.1 is a bug-fix and usability release on v6.2.
</para>
<para>
Summary:

<itemizedlist>
<listitem>
<para>
Allow strings to span lines, per <acronym>SQL92</acronym>.
</para>
</listitem>

<listitem>
<para>
Include example trigger function for inserting user names on table updates.
</para>
</listitem>

</itemizedlist>
</para>
<para>
This is a minor bug-fix release on v6.2. 
For upgrades from pre-v6.2 systems, a full dump/reload is required. 
Refer to the v6.2 release notes for instructions.
</para>

<sect2>
<title>Migration from v6.2 to v6.2.1</title>

<para>
This is a minor bug-fix release. A dump/reload is not required from v6.2,
but is required from any release prior to v6.2.
</para>
<para>
In upgrading from v6.2, if you choose to dump/reload you will find that
avg(money) is now calculated correctly. All other bug fixes take effect
upon updating the executables.
</para>
<para>
Another way to avoid dump/reload is to use the following SQL command
from psql to update the existing system table:

<programlisting>
  update pg_aggregate set aggfinalfn = 'cash_div_flt8'
   where aggname = 'avg' and aggbasetype = 790;
</programlisting>
</para>
<para>