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PostgreSQL 8.0 Released
Christopher Cashell writes "The PostgreSQL project has released version 8.0 of their well known Object-Relational Database. New features include: Win32 Native Server, Savepoints, Point-In-Time Recovery, Tablespaces, and lots more. Downloads are available via bittorrent for Unix/Linux, and the much anticipated Win32 version, or via ftp (use a mirror!)." (Here's the official announcement.)
An adequate replacement for MySQL on Windows. Can anyone say WAPP instead of LAMP?
Great, but why should I use PostgreSQL when I already have a database, you might ask? Here's why.
One of the most exciting features of 8.0 is plperl, their Perl-based server side language, allowing for triggers and persistent storage. On another note, I wish MySQL would catch up to PgSQL. Even if you don't like MySQL, the competition keeps them innovating. If PgSQL is light years ahead, what's pushing them?
Hi Folks,
Please take it easy on 'wwwmaster'.
'www' fell over a couple of hours ago, and a couple of mirrors are coming online to round-robin the address.
Can someone please change the the first link ("PostgreSQL project") in the story to point to 'www'?
Thanks.
Goodbye Oracle, hello PostgreSQL. Now I can have a mostly SQL92 compliant database with ACID, transactions and now PITR and tablespaces that I can use on the server and on a win32 desktop.
For those of you wanting a great frontend, try PGAdmin3. It works on Win32 and Linux.
Not only that. Here's the most important link: What's New in 8.0. (To editors: why there are links to torrents, but no link to features?)
Sincerely,
Pan Tarhei Hosé, PhD.
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PostgreSQL has had an ODBC driver for quite some time. You could use that in conjunction with SQL Servers DTS tools to copy data from a SQL Server DB to Pg. There might be some pain involved, particular with indices and constraints, but it shouldn't be too awful.
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To answer the first part of my question, I just found the Supported Platforms part of the manual, and sure enough Mac OS X is there.
The question remains though - are there plans for a Mac OS X installer package?
PostgreSQL offers substantial additional power by incorporating the following additional concepts in such a way that users can easily extend the system:
Other features provide additional power and flexibility:
These features put PostgreSQL into the category of databases referred to as object-relational. Note that this is distinct from those referred to as object-oriented, which in general are not as well suited to supporting traditional relational database languages. So, although PostgreSQL has some object-oriented features, it is firmly in the relational database world.
The difference is explained in this wonderful Wikipedia article on object-relational databases.
A monkey is doing the real work for me.
This guy usually isn't too far behind in creating .pkg for the stable PostgreSQL releases. I have run it on OS X for a number of years and I have been very happy with it.
It's got a long way to go as far as enterprise features.
There is no clustering support in PostgreSQL (and I mean real clustering, not some Java hack where transactions are shipped off to two separate DB servers, both of which don't know they're part of a cluster). This is pretty much a show stopper as far as using PostgreSQL in the company I work for, as high availability is a large concern, and any downtime would be serious.
In previous versions of PostgreSQL, the pg_dump and pg_restore tools were not very good - dumps that included tables or views often would fail on reimport because PostgreSQL wouldn't know the order in which to import everything. You also had to pass in a number of options on the command line just to get a dump that made sense, and large object support was kind of clunky.
That said, I still use PostgreSQL for many many projects and have used PostgreSQL for many years. It's a great product, but it isn't near Oracle in terms of enterprise level features.
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The standard way of finding MacOS software would have answered this question in a heartbeat: VersionTracker or MacUpdate, both of which list installers.
-Dom
If you want to migrate away from SQL-Server then you have MS DTS (at least for the time being).
DTS can pump your MS-SQL-database into postgresql with little problem i'd expect. Now getting the logic (triggers, functions) transferred is a whole other question.
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Could anyone give an example of where you might want to use postgresql over mysql and vice versa?
Here it is.
Master-Slave replication is available through Slony1. (This is currently used by Afilias on the .info domain) Slony2 is in progress and will provide multi-master replication.
Vacuuming is still necessary, but it no longer locks tables. The distribution includes a utility called pg_autovacuum which can take care of all the vacuuming tasks on an automated basis if you desire. (The gentoo release automatically installs this with a nice init script :) )
Check out the new Slony replication engine:
http://www.slony.info/
It is probably the best master->slave data replication engine for PostgreSQL at the moment. It is free and developed by one of the core developers.
Do you know of any database (free or commercial) that supports such a feature (auto)magically?
yes : this one
see http://slony.info/ as the other poster mentioned
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Most of your first request is already implemented in PostgreSQL 8. You can combine a hot backup of the files on the filesystem with the WAL-archiver to have the backup feature you want. It is not per tablespace (yet) so you have to backup your entire database.
For the second request, keep a close eye on the mailinglists. Affilias has hired a core developer to make it happen.
The first stage, master-slave replication, has been released in the form of Slony-1. Yes, it is an add on. No, it is not integrated. But you can add Slony-1 to a running system and add slaves without ever taking the master down, and it is backwards compatible so you can even use it to upgrade running 7.3.x installations to PostgreSQL 8.
The second stage, Slony-2, will be a full multi-master replication solution. (I read something about a 'kickoff' meeting today hosted by Affilias.) The goal is to be able to take a single, out of the box installation of PostgreSQL, plug Slony-1 into it, replicate the database to another box and when that box has caught up switch to full multi-master mode under Slony-2.
The code won't fall out of the sky tomorrow, but people are working on it.
7.x compiles right out of the box- in fact, Apple's Remote Desktop system actually installs and uses PostgreSQL for all its data storage (client system data and whatnot; ARD can collect a lot of per-system data). Very slick.
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Another garage product also fares badly on COUNT(*) however if you do COUNT() they both do real well. It has to do with the fact that when you do COUNT(*) you have to count every row and that takes a fair bit of time. When you do COUNT(key) you count rows in the index file and that is real quick :-)
If your RDBMS is doing a full table scan just to do a count(*), then it (or your code) is badly broken.
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In MySQL (with MyISAM tables), the reason things like count(*) are fast is that MyISAM pre-computes those values. It can do this because it locks the table on insert and update. PostgreSQL doesn't lock the table on modifications -- it allows concurrent access via Multi-Version Concurrency Control (MVCC). Basically, each row in the DB has additional information (used internally by PostgreSQL), which stores which transaction created and last modified the row. PG uses this to determine if any given row should be "visible" to the current transaction. Because this informaiton is constantly changing (and varies from transaction to transaction), you can't precompute things like count(*) and sum(*). See http://developer.postgresql.org/pdf/internalpics.p df for more info (start around page 56).
Postgresql is ready to take on the smaller, non-critical databases that oracle used to get. This is significant proportion of the databases out there, and will take revenue away from oracle. (Mysql will actually probably take more revenue away, but it has too many quality problems and functionality gaps to really deserve to.)
But there are many other, more demanding databases that postgresql isn't yet ready for. Oracle, DB2, and even SQL Server 2005 all have very mature & solid: optimizers, replication, partitioning solutions, parallelism, failover/clustering support, etc.
Here are two examples:
Using db2 for example, you can create a view which is automatically populated by the database like a table (MQT). Then any queries against the base tables that could be sped up by hitting this view will be rewritten by the engine to hit the view. Now, this might seem like needless fluff if you're just writing a hobby php app. But if you need to implement a commercial app like SAP with its 6,000 tables - and you have performance issues - you can make adjustments in the database layer this way. Also, if you're provoding adhoc reporting for hundreds of users on a terrabyte of data - this technique can provide *dramatic* performance benefits.
Another example is partitioning. Back to db2 (which I work with the most): you can spread a database across a dozen separate servers using a hashkey. Now, every query will have all dozen servers working independently on its own fraction of the data. On each of those servers, you can then partition again, this time using ranges or values (MDC) - so that data that doesn't apply to a query will be skipped in tablescans of that table. Using these techniques you can get sub-second response to *adhoc* queries against a terrabyte of data - without indexes (notoriously unreliable here).
Lots more examples where the above came from. Sure, you will pay real money for licensing, hardware, and labor to implement these. Then again, the two above features actually save you in hardware costs. Additionally, some problems are big enough that they can easily justify the cost of licensing a product like this. I've seen these techniques used to save companies million, even hundreds of millions of dollars.
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Postgres knows how many rows are in the table, but it does not know how many of those you can see. Some of them may be inserted speculatively by another transaction. Postgres needs to go through each row to determine whether or not that row is actually visible to you. It is possible to turn this into an O(1) operation if you're willing to do sufficient work on inserts and deletes. Whether this is a good tradeoff depends on how often you do count(*) compared to how often you do inserts and deletes.
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playing around with the beta and RCs several items impressed me:
1) GIS support. Very important for what I do. This is probably due to how closely they work with GRASS (which I haven't used yet).
2) Ability to define and bind operators. Very flexible.
3) Much more relationally compliant while also supporting OOP.
4) PGAdmin II is very handy. A few rough points but now there is no excuse for those afraid of a command line.
It just gets better every release. I am currently porting a MMSQL database over and so far so good.
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Try Slony for full, production quality replication on PostgreSQL:
http://www.slony.info/
No matter which version you use, if you never VACUUM dead row versions will accumulate and eventually kill your performance.
Actually, for 7.4 and newer that isn't true, since they include the aptly named "autovacuum" daemon. And yes, autovacuum also does "VACUUM ANALYZE", so no need to worry about that either.
I switched a an open-source project from MySQL to PostgreSQL a year or so back. The application of proper transactions, referential integrity, views and stored procedures really cleaned up the code.
However, PostgreSQL is not necessarily the easiest DBMS to get used to. For one, some platforms such as *BSD will require a recompile of the kernel to support a bit more then 32 concurrent connections. While well documented if you know what your looking for, this can prove to difficult to implement if for example your on a shared hosting system.
Documentation can be cryptic, tending to be more like a reference manual then an actual manual to teach you how something works. When it comes to optimizing the database itself this becomes painfully obvious as certain switches and options in the postgresql.conf file do little more then offer a one line description with no real clue on how a change will affect it.
In MySQL for example there are sample configation files which show a 'typical' configuration for small, mid-sized and dedicated setups. I have yet to see something similiar and such discussions on the newsgroups have generally shot it down because of the exotic configurations out there.
Vacuuming is one of those things that can really confuse people. While in MySQL deleting and altering rows has no real lasting effect for the user, this is not the case with Postgres. When a row is deleted, the information remains, but is unlinked, making the system run less IO but forcing you to juggle vacuuming, re-indexing and server operations.
You could make use of the auto-vacuum daemon available. I found however, that performance suffered greatly when it was being used on my live system.
More often then not, documentation will speak of load testing and tweaking the server at different values to see how it works. This is sound advice if you have the hardware and time necessary to get things going properly.
On light loads, Postgres can be great, but once you start pounding at it it will slow down unless you know what your doing. The learning curve is far greater then MySQL, the documentation could stand to be more descriptive to end-users/non-Oracle DBA's and the tools available for Windows less advanced but the feature set will make it worth while if you can devote some time for trail and error.
While I think that PostgreSQL is the best open source database out there, there is one very important gotcha wrt: MVCC which can cause data integrity. This only happens when autovacuum is not running, of course.
If you run enough transactions between vacuum runs (iirc a billion), the transaction counter will wrap around and suddenly your data does not have a consistant point of reference regarding visible transactions. Now, if you wait for a billion transactions to run VACUUM, you either:
1) Have extremely poor performance anyway (not to mention having all your stats off so the planner is doing seq scans when it should use an index)
2) Are doing something with the database which I cannot imagine (I guess a huge number of select statements could cause this, but updates cause old tuples to sit around, so you would have bad performance).
Now, I am not aware of this ever actually having happened, but it is in the documentation, so I figure I should point it out. Of course if you let the database get to this point, then you have bigger problems than your data (chief among them being the IT staff and/or management)..
In general, PostgreSQL focuses on data integrity to a degree not seen elsewhere in the open source database world. Even Firebird does not have such a heavy focus in this area, though to be fair it is a different enough product that their focus works well in their target markets.
My company offers application development, remote administration, and implimentation services for PostgreSQL, MySQL, and Firebird. I am very excited about this release because it will enable us to do more with the database manager which makes us most productive.
As a side note, PostgreSQL-Win32 will not run on Win9x because it requires an NTFS filesystem, iirc. So it is not a perfect solution for Windows development yet (until Win9x fades into the distance or until they decide that they should port it to FAT). Of course you could still use the Cygwin installation, I think. But it is better, IMO, to run it on a arguably stable system anyway.
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Before, to do this, you had to create a temporary table with the changed column type, copy all the data over to it, and then rename the temp table as the old table.
Thank you Postgres team! Now, if we can rename a column, that would be a nice bonus.
You're telling me that MySQL locks the entire table when I insert a row? You must be joking - that would bring a database to it's knees.
I'm an Oracle guy, and this is how they do it:
Oracle has the best technology in the industry, hands down (DB2 didn't even get triggers until v5). Postgres appears to be paying much more attention to Oracle's methods than MySQL.
Guess which database I'd use if I had no money to spend?
http://blog.planetargon.com/archives/36-Installing -PostgreSQL-8.0-alongside-7.4.html
Robby Russell
PLANET ARGON
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Oxford University announced a while back that they will be scrapping most of their proprietary DBs for PostgreSQL over the course of '05:
http://news.zdnet.co.uk/software/applications/0
Postgres can perform a case insensitive query, you use the operator ~~* instead of =, e.g.
SELECT * FROM customers WHERE name ~~* 'bob';
matches bob, Bob, BOB, etc.
I hope you find this useful.
Did you already take a look at slony?s play.php
http://gborg.postgresql.org/project/slony1/projdi
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*That's* the problem I remember from earlier setups. Basically, you have to *install* it as an administrator so that it can *run* as a non-administrator.
That's a problem for users in a corporate environment where they aren't authorized to create users on their workstations.
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