When you encounter a problem in PostgreSQL we want to hear about it. Your bug reports are an important part in making PostgreSQL more reliable because even the utmost care cannot guarantee that every part of PostgreSQL will work on every platform under every circumstance.
The following suggestions are intended to assist you in forming bug reports that can be handled in an effective fashion. No one is required to follow them but it tends to be to everyone's advantage.
We cannot promise to fix every bug right away. If the bug is obvious, critical, or affects a lot of users, chances are good that someone will look into it. It could also happen that we tell you to update to a newer version to see if the bug happens there. Or we might decide that the bug cannot be fixed before some major rewrite we might be planning is done. Or perhaps it's simply too hard and there are more important things on the agenda. If you need help immediately, consider obtaining a commercial support contract.
Before you ask "Is this a bug?", please read and re-read the documentation to verify that you can really do whatever it is you are trying. If it is not clear from the documentation whether you can do something or not, please report that too; it's a bug in the documentation. If it turns out that the program does something different from what the documentation says, that's a bug. That might include, but is not limited to, the following circumstances:
A program terminates with a fatal signal or an operating system error message that would point to a problem in the program (a counterexample might be a "disk full" message, since that must be fixed outside of Postgres).
A program produces the wrong output for any given input.
A program refuses to accept valid input.
A program accepts invalid input without a notice or error message.
PostgreSQL fails to compile, build, or install according to the instructions on supported platforms.
Being slow or resource-hogging is not necessarily a bug. Read the documentation or ask on one of the mailing lists for help in tuning your applications. Failing to comply to SQL is not a bug unless compliance for the specific feature is explicitly claimed.
Before you continue, check on the TODO list and in the FAQ to see if your bug is already known. If you can't decode the information on the TODO list, report your problem. The least we can do is make the TODO list clearer.
The most important thing to remember about bug reporting is to state all the facts and only facts. Do not speculate what you think went wrong, what "it seemed to do", or which part of the program has a fault. If you are not familiar with the implementation you would probably guess wrong and not help us a bit. And even if you are, educated explanations are a great supplement to but no substitute for facts. If we are going to fix the bug we still have to see it happen for ourselves first. Reporting the bare facts is relatively straightforward (you can probably copy and paste them from the screen) but all too often important details are left out because someone thought it doesn't matter or the report would be understood anyway.
The following items should be contained in every bug report:
The exact sequence of steps from program startup necessary to reproduce the problem. This should be self-contained; it is not enough to send in a bare select statement without the preceeding create table and insert statements, if the output should depend on the data in the tables. We do not have the time to decode your database schema, and if we are supposed to make up our own data we would probably miss the problem. The best format for a test case for query-language related problems is a file that can be run through the psql frontend that shows the problem. (Be sure to not have anything in your ~/.psqlrc startup file.) You are encouraged to minimize the size of your example, but this is not absolutely necessary. If the bug is reproduceable, we'll find it either way.
If your application uses some other client interface, such as PHP, then please try to isolate the offending queries. We probably won't set up a web server to reproduce your problem. In any case remember to provide the exact input files, do not guess that the problem happens for "large files" or "mid-size databases", etc. since this information is too inexact to be of use.
The output you got. Please do not say that it "didn't work" or "failed". If there is an error message, show it, even if you don't understand it. If the program terminates with an operating system error, say which. If nothing at all happens, say so. Even if the result of your test case is a program crash or otherwise obvious it might not happen on our platform. The easiest thing is to copy the output from the terminal, if possible.
Note: In case of fatal errors, the error message provided by the client might not contain all the information available. In that case, also look at the output of the database server. If you do not keep your server output, this would be a good time to start doing so.
The output you expected is very important to state. If you just write "This command gives me that output." or "This is not what I expected.", we might run it ourselves, scan the output, and think it looks okay and is exactly what we expected. We shouldn't have to spend the time to decode the exact semantics behind your commands. Especially refrain from merely saying that "This is not what SQL says/Oracle does." Digging out the correct behavior from SQL is not a fun undertaking, nor do we all know how all the other relational databases out there behave. (If your problem is a program crash you can obviously omit this item.)
Any command line options and other startup options, including concerned environment variables or configuration files that you changed from the default. Again, be exact. If you are using a pre-packaged distribution that starts the database server at boot time, you should try to find out how that is done.
Anything you did at all differently from the installation instructions.
The PostgreSQL version. You can run the command SELECT version(); to find out what version you are currently running. If this function does not exist, say so, then we know that your version is old enough. If you can't start up the server or a client, look into the README file in the source directory or at the name of your distribution file or package name. If your version is older than 7.0 we will almost certainly tell you to upgrade. There are tons of bug fixes in each new version, that's why we write them.
If you run a pre-packaged version, such as RPMs, say so, including any subversion the package may have. If you are talking about a CVS snapshot, mention that, including its date and time.
Platform information. This includes the kernel name and version, C library, processor, memory information. In most cases it is sufficient to report the vendor and version, but do not assume everyone knows what exactly "Debian" contains or that everyone runs on Pentiums. If you have installation problems information about compilers, make, etc. is also necessary.
Do not spend all your time to figure out which changes in the input make the problem go away. This will probably not help solving it. If it turns out that the bug can't be fixed right away, you will still have time to find and share your work around. Also, once again, do not waste your time guessing why the bug exists. We'll find that out soon enough.
When writing a bug report, please choose non-confusing terminology. The software package as such is called "PostgreSQL", sometimes "Postgres" for short. (Sometimes the abbreviation "Pgsql" is used but don't do that.) When you are specifically talking about the backend server, mention that, don't just say "Postgres crashes". The interactive frontend is called "psql" and is for all intends and purposes completely separate from the backend.
In general, send bug reports to the bug report mailing list. You are invited to find a descriptive subject for your email message, perhaps parts of the error message.
Do not send bug reports to any of the user mailing lists, such as the SQL language mailing list or the general topics mailing list. These mailing lists are for answering user questions and their subscribers normally do not wish to receive bug reports. More importantly, they are unlikely to fix them.
Also, please do not send reports to the developers' mailing list. This list is for discussing the development of PostgreSQL and it would be nice if we could keep the bug reports separate. We might choose to take up a discussion about your bug report on it, if the bug needs more review.
If you have a problem with the documentation, send email to the documentation mailing list. Mention the document, chapter, and sections in your problem report.
If your bug is a portability problem on a non-supported platform, send mail to the porting issues mail list, so we (and you) can work on porting PostgreSQL to your platform.
Note: Due to the unfortunate amount of spam going around, all of the above email addresses are closed mailing lists. That is, you need to be subscribed to them in order to be allowed to post. If you simply want to send mail but do not want to receive list traffic, you can subscribe to the special pgsql-loophole mailing list, which allows you to post to all PostgreSQL mailing lists without receiving any messages. Send email to pgsql-loophole-request@postgresql.org to subscribe.