In conf we added the following line:
shared_preload_libraries = 'passwordcheck'
After restart postgres, password check is supposed to take effect, and I can test by creating a simple password for the new role. My question is:
Is there any way to list preloaded (enabled) libraries, or show this lib has been successfully loaded?
You can examine the current setting of shared_preload_libraries to see which libraries were loaded at server start time. You can be certain that these libraries are loaded, because otherwise the server would have refused to start and stopped with an error message.
But there are many other ways to load an extension shared library into PostgreSQL, for example by calling C functions or using the LOAD statement. There is no way in PostgreSQL to determine all libraries that are currently loaded into your database backend process.
Related
I've installed Bareos 20.0.1 on Ubuntu 20.04.3 according to their documentations here.
I'm trying to backup a remote PostgreSQL database and apparently, there are three possible scenarios and the pros of the PostgreSQL Plugin (third solution), makes it the obvious choice.
Following the PostgreSQL Plugin documentations, in the Prerequisites for the PostgreSQL Plugin section, there is a line saying:
The plugin must be installed on the same host where the PostgreSQL database runs.
Now what I'm failing to understand is that, if I'm supposed to install the plugin on my database node, how will the bareos machine and the plugin on the db machine communicate?
Furthermore, I've checked out the source code for this module on their GitHub, and I see that the plugin source code tries to find files locally and that is a proof to the aforementioned statement.
In a desperate act, I tried installing the plugin and its dependencies on the bareos node and I keep getting the error Error: python3-fd-mod: Could not read Label File /var/lib/postgresql/13/main/backup_label which is actually trying to find the backup_label file in the bareos node.
Here is the configuration for my fileset:
FileSet {
Name = "psql"
Include {
Options {
compression=GZIP
signature = MD5
}
Plugin = "python"
":module_path=/usr/lib/bareos/plugins"
":module_name=bareos-fd-postgres"
":postgresDataDir=/var/lib/postgresql/13/main"
":walArchive=/var/lib/postgresql/13/wal_archive/"
":dbHost=DATABASE_DNS"
":dbuser=DATABASE_USER"
}
}
Note that the plugin document specifies the dbHost parameter as:
useful, if socket is not in default location. Specify socket-directory with a leading / here
However, since I'm trying a remote database, I'm using the DNS address of the remote database. I verified the bareos connection to database and made sure the backup_label file gets created while the PostgreSQL backup job runs.
I'll be happy to provide more details if necessary. Appreciate any help or even guesses :-D
I have a Django project connecting to a PostgreSQL database which I develop in PyCharm, and I want to enable PostgreSQL history logging.
There is PSQL_HISTORY env variable set to /home/user/apps/postgres/logs/.pycharm_log, but when I start the project in PyCharm and update some data via the Django Admin (which certainly hits the database) -- nothing gets logged and the file is not created at all.
Is there a way to make PyCharm and PSQL_HISTORY work together as I expected?
'psql' is the name of a specific client tool. Why would a completely different tool use psql's configuration options? If you want to log every statement sent to the server, you could configure that in the server side with log_statement=all.
I am using a Windows Machine to connect to a remote DB2 instance. Ran into this issue
SQL1531N The connection failed because the name specified with the DSN connection string keyword could not be found in either the db2dsdriver.cfg configuration file or the db2.cli.ini configuration file. Data source name specified in the connection string: <DSN>
I have configured ODBC Data source using ODBC Data Source Administrator it has connected successfully.
Upon further investigation, I am unable to locate db2dsdriver.cfg on IBM DATA SERVER DRIVER folder. I am able to find db2dsdriver.lvl and dbs2dsdriver.xds. Just not the .cfg file. I am also unsure where HammerDB looks for the config file.
I have looked at the configuration of DB2 from the website but I am unable to get any useful information from there. https://www.hammerdb.com/docs/ch04s02.html
For the tiny footprint ODBC and CLI driver (known as clidriver) from IBM, you are responsible for creating and editing the db2dsdriver.cfg configuration file. It is a small XML file documented here and in related linked pages. The hammerdb documentation also gives a minimal example and you linked to this page in your question.
You can create and edit this file either by command lines to the db2cli tool, or by directly editing with a text editor (or XML editor). It may be easier to use an editor than to learn the command lines, although command lines have the advantage that they lend themselves to scripting this activity for larger installations.
On Microsoft-Windows you can also use Notepad to create and edit the file db2dsdriver.cfg.
An important step is that following editing of the file you must first validate its contents before trying any database connections. Validation checks that the syntax of the XML in the file is correct. To validate, you use the db2cli validate command described here. It must show a successful result before you try to connect to any database. Once validation completes without errors, you can also use db2cli validate -connect -dsn XXX -user YYY -passwd ZZZ to test the connection independently of your application (in this case hammerdb). Once you get a successful connection with the db2cli validate -connect -dsn ... then your application (hammerdb) will connect correctly.
There are many examples of db2dsdriver.cfg contents online , but your first source should be the Db2 Knowledge Centre online, which details the command line options to the db2cli command, along with giving examples of db2dsdriver.cfg.
If you already have a working Db2 configuration with local and remote databases (but no db2dsdriver.cfg file), you can also use a tool db2dsdcfgfill to populate db2dsdriver.cfg from your existing Db2 configuration. See docs here.
I am using helios Eclipse for debugging my code in postgresql.
My aim is to know how postgresql uses join algorithms during the join query, so I started to debug nodenestloop.c which is in the Executor folder.
I gave break points in that file, But whenever I try to debug that file, the control goes to main.c and never comes back,How do I constraint the control only to that particular file(nodenestloop.c)
Below are the following fields which I gave in Debug configurations of Helios Eclipse.
C/C++ Application - src/backend/postgres and
project - pgsql
I followed the steps given in the following link for running the program.
https://wiki.postgresql.org/wiki/Working_with_Eclipse#
I even uncheked the field "Start on Start up=main" , but When I do that, The step in and Step over buttons are not activated and the following problem has popped up.
Could not save master table to file '/home/ravi/workspace/.metadata/.plugins/org.eclipse.core.resources/.safetable/org.eclipse.core.resources'.
/home/ravi/workspace/.metadata/.plugins/org.eclipse.core.resources/.safetable/org.eclipse.core.resources (Permission denied)
So I started eclipse using sudo, but this time the following error has come in the console of eclipse.
"root" execution of the PostgreSQL server is not permitted.
The server must be started under an unprivileged user ID to prevent
possible system security compromise. See the documentation for
more information on how to properly start the server.
Could any one help me with this.
Thank you
Problem 1: User ID mismatch
Reading between the lines, it sounds like you're trying to debug a PostgreSQL instance that's running as the postgres user, or a different user ID to your own anyway. Hence your attempt to use sudo.
That's painful, especially when using an IDE like Eclipse. With plain gdb you can just sudo the gdb command to the desired uid, e.g. sudo -u postgres -p 12345 to attach to pid 12345 running as user postgres. This will not work with Eclipse. In fact, running it with sudo has probably left your workspace with some messed up file permissions; run:
sudo chown -R ravi /home/ravi/workspace/
to fix file ownership.
If you want to debug processes under other user IDs with Eclipse, you'll need to figure out how to make Eclipse run gdb with sudo. Do not just run all of Eclipse with sudo.
Problem 2: Trying to run PostgreSQL under the control of Eclipse
This:
"root" execution of the PostgreSQL server is not permitted. The server must be started under an unprivileged user ID to prevent possible system security compromise. See the documentation for more information on how to properly start the server.
suggests that you're also attempting to let Eclipse start postgres directly. That's very useful if you're trying to debug the postmaster, but since you're talking about the query planner it's clear you want to debug a particular backend. Launching the postmaster under Eclipse is useless for that, you'll be attached to the wrong process.
I think you probably need to read the documentation on PostgreSQL's internals:
Tour of PostgreSQL Internals
PostgreSQL internals through pictures
Documentation chapter - internals
Doing it right
Here's what you need to do - rough outline, since I've only used Eclipse for Java development and do my C development with vim and gdb:
Compile a debug build of PostgreSQL (compiled with ./configure --enable-debug and preferably also CFLAGS="-ggdb -Og -fno-omit-frame-pointer"). Specify a --prefix within your homedir, like --prefix=$HOME/postgres-debug
Put your debug build's bin directory first on your PATH, e.g. export PATH=$HOME/postgres-debug/bin:$PATH
initdb -U postgres -D $HOME/postgres-debug-data a new instance of PostgreSQL from your debug build
Start the new instance with PGPORT=5599 pg_ctl -D $HOME/postgres-debug-data -l $HOME/postgres-debug-data.log -w start
Connect with PGPORT=5599 psql postgres
Do whatever setup you need to do
Get the backend process ID with SELECT pg_backend_pid() in a psql session. Leave that session open; it's the one you'll be debugging.
Attach Eclipse's debugger to that process ID, using the Eclipse project that contains the PostgreSQL extension source code you're debugging. Make sure Eclipse is configured so it can find the PostgreSQL source code you compiled with too (no idea how to do that, see the manual).
Set any desired breakpoints and resume execution
In the psql session, do whatever you need to do to make your extension run and hit the breakpoint
When execution pauses at the breakpoint in Eclipse, debug as desired.
Basic misunderstandings?
Also, in case you're really confused about how all this works: PostgreSQL is a client/server application. If you are attempting to debug a client program that uses libpq or odbc, and expecting a breakpoint to trigger in some PostgreSQL backend extension code, that is not going to happen. The client application communicates with PostgreSQL over a TCP/IP socket. It's a separate program. gdb cannot set breakpoints in the PostgreSQL server when it's connected to the client, because they are separate programs. If you want to debug the server, you have to attach gdb to the server. PostgreSQL uses one process per connection, so you have to attach gdb to the correct server process. Which is why I said to use SELECT pg_backend_pid() above, and attach to the process ID.
See the internals documentation linked above, and:
PostgreSQL site - coding
PostgreSQL wiki - developer resources
Developer FAQ
Attaching gdb to a backend on linux/bsd/unix
I also faced similar issue and resolved it after some struggle
I misunderstood the following point under Debugging with child processes in the wiki (https://wiki.postgresql.org/wiki/Working_with_Eclipse).
5."Start postmaster & one instant of postgresql client (for creating one new postgres)"
The above step should be performed from terminal by starting postgres server and one client.
Hope this helps
Once this is done then debugger in eclipse needs to be started for C/C++ Attach to Application
When I try to connect to my Postgres.app db using dbext, I get the following error:
dbext:PostgreSQL requires a '$HOME/.pgpass' file in order to authenticate. This file is
missing. The binary 'psql' does not accept commandline passwords.
Other programs connect just fine by using a "local" connection. (Postgres.app runs with my userid.)
In vim :!which psql correctly prints /opt/local/bin/psql (which I have symlinked to the one in the Postgres.app bin directory). And Postgres.app is set up to use "local" authentication and there's no clear sense of where a pg_hba.conf file would go (there is no etc directory in the app bundle). Moreover, Postgres.app doesn't have anything in its documentation about changing access configuration.
I've tried using dbext's :DBPromptForBufferParameters directly, as well as #tpope's vim-rails plugin (which returns without comment from dbext setup via :Rdbext.
So what do I do to get dbext to connect using a "local" connection?
Note - I spent a LOT of time trying to figure this out without trying the obvious, thus the post even when I already have the answer. I'm also curious to see if anyone else has a different approach.
It turns out you can just make an empty ~/.pgpass file (restricting read-write permissions to your userid only to avoid warnings). This was counterintuitive for me (since there is in fact no password), but I suppose in retrospect it's obvious I should have tried it.
I'll point this out on the dbext issue tracker.