mirror of
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66 lines
3.2 KiB
Groff
66 lines
3.2 KiB
Groff
This migration requires a complete dump of the 6.2 or 6.2.1 database and a
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restore of the database in 6.3.
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There are some general 6.3 issues that I want to mention. These are
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only the big items that can not be described in one sentence. A review
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of the HISTORY files is still needed.
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First, we now have subselects. Now that we have them, I would like to
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mention that without subselects, SQL is a very limited language.
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Subselects are a major feature, and you should review your code for
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places where subselects provide a better solution for your queries. I
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think you will find that there are more uses for subselects than you may
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think. Vadim has put us on the big SQL map with subselects, and fully
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functional ones too. The only thing you can't do with subselects is to
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use them in the target list.
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Second, 6.3 uses unix domain sockets rather than TCP/IP by default. To
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enable connections from other machines, you have to use the new
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postmaster -i option, and of course edit pg_hba.conf. Also, for this
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reason, the format of pg_hba.conf has changed.
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Third, char() fields will now allow faster access than varchar() or
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text. Specifically, the text and varchar() have a penalty for access to
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any columns after the first column of this type. char() used to also
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have this access penalty, but it no longer does. This may suggest that
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you redesign some of your tables, especially if you have short character
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columns that you have defined as varchar() or text. This and other
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changes make 6.3 even faster than earlier releases.
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We now have passwords definable independent of any Unix file. There are
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new SQL USER commands. See the pg_hba.conf manual page for more
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information. There is a new table, pg_shadow, which is used to store
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user information and user passwords, and it by default only SELECT-able
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by the postgres super-user. pg_user is now a view of pg_shadow, and is
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SELECT-able by PUBLIC. You should keep using pg_user in your
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application without changes.
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User-created tables now no longer have SELECT permission to PUBLIC by
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default. This was done because the ANSI standard requires it. You can
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of course GRANT any permissions you want after the table is created.
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System tables continue to be SELECT-able by PUBLIC.
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We also have real deadlock detection code. No more sixty-second
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timeouts. And the new locking code implements a FIFO better, so there
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should be less resource starvation during heavy use.
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Many complaints have been made about inadequate documenation in previous
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releases. Thomas has put much effort into many new manuals for this
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release. Check out the /doc directory.
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For performance reasons, time travel is gone, but can be implemented
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using triggers (see pgsql/contrib/spi/README). Please check out the new
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\d command for types, operators, etc. Also, views have their own
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permissions now, not based on the underlying tables, so permissions on
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them have to be set separately. Check /pgsql/interfaces for some new
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ways to talk to PostgreSQL.
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This is the first release that really required an explaination for
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existing users. In many ways, this was necessary because the new
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release removes many limitations, and the work-arounds people were using
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are no longer needed.
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Long live PostgreSQL.
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-- Bruce Momjian
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