It's my first day tinkering with the Play framework, and I'm having a hard time with evolutions. I'm using Play 2.4.
I picked a sample app from the many that come up in activator ui, it uses play-slick and play-slick-evolutions for DB connection and evolutions.
I've perused the docs, but I can't seem to find a way to run the evolutions from the command line. When I run activator on bash I get thrown into a shell, and the help doesn't bring up anything about running evolutions, or slick.
I've been doing PHP for a while, so I'm used to being able to run these up/down from the command line. I can drop the tables from the database client and do activator run which should prompt me to run the evolutions, but I'm looking for the right, manual way to do this. I imagine it's possible since it would need to be done on deploy.
As far as I know, they are not designed to be run manually. In development, Play asks you to run them:
In Production I trigger the evolutions by starting my server with the parameter -DapplyEvolutions.default=true. You can write this (without -D of course) also to the application.conf-file to run them always. You can also use only the down- or up-evolutions with -DapplyUpEvolutions.default=true or -DapplyDownEvolutions.default=true.
And of course there is always the option to just copy the part of the script you need manually and apply it with your favorite database tool. However, you then need to tell Play what you did by manually altering the table play_evolutions. An easier solution then would be to not use the evolutions mechanism provided by the Play Framework at all.
A quick hack that works for me and doesn't involve bringing up a play instance:
export PGPASSWORD=<password>
for SQL_FILE in $(ls <path-to-evolution-files>); do
psql -h localhost -U <username> -c "$(sed '1,/Ups/d' <path-to-evolution-files>/$SQL_FILE | sed -n '/Downs/q;p')";
done
Removes everything up to and include Ups and everything after and including Downs, and runs the commands on the Postgres instance.
Related
My database needs to mirror another, to which I have no access except for a nightly export of the sql file. I could script the import using psql.exe, but would prefer everything to be under the control of the dotnet core application.
I can't use the COPY command, because the file contains ALL the sql to set up the schemas and tables, as well as all the sql commands to insert/alter/copy the data.
I can't use \i because that is a postgresql console command, not something I can run through npgsql.
Is what I'm trying to do possible? Is it inherently a bad idea, and should I run a script to import it outside of the dotnet application? Should the dotnet application run and talk to the psql.exe program directly?
You could theoretically parse the SQL file in .NET and send it to PostgreSQL, but this is a very non-trivial thing to do, since you'd need to understand where statements end (identify semicolons) in order to send chunks.
You could, of course, send the entire file as a single chunk, but if it's huge, that may be a bad idea.
At the end of the day, I don't think there's any particular issue with launching psql.exe as an external process from .NET, and properly inspecting its exit code for error handling. Any reason you think you need to avoid that?
I am using an official postgres v12 docker image that I want to initialise with two SQL dump files that are gathered from a remote legacy v9.2 postgres server during the docker build phase:
RUN ssh $REMOTE_USER#$REMOTE_HOST "pg_dumpall -w -U $REMOTE_DB_USER -h localhost -p $REMOTE_DB_PORT --clean --globals-only -l $REMOTE_DB_NAME" >> dump/a_globals.sql
RUN ssh $REMOTE_USER#$REMOTE_HOST "pg_dump -w -U $REMOTE_DB_USER -h localhost -p $REMOTE_DB_PORT --clean --create $REMOTE_DB_NAME" >> dump/b_db.sql
By placing both a_globals.sql and b_db.sql files into the docker image folder docker-entrypoint-initdb.d, then the database is initialised with the legacy SQL files when the v12 container starts (as described here). Docker is working correctly, the dump files are retrieved successfully. However I am running into problems initialising the container's database and require guidance:
When the container starts to initialise its DB, it stops with ERROR: role $someDBRole does not exist. This is because the psql v9.2 dump SQL files DROP roles before reinstating them; the container DB does not like this. Unfortunately it is not until psql v9.4 that pg_dumpall and pg_dump have the option to --if-exists (see pg_dumpall v9.2 documentation). What would you suggest that I do in order to remedy this? I could manually edit the SQL dump files, but this would be impractical as the snapshots of the legacy DB need to be automated. Is there a way to suppress this error during container startup?
If I want to convert from ASCII to UTF-8, is it adequate to simply set the encoding option for pg_dumpall and pg_dump? Or do I need to take into consideration other issues when upgrading?
Is there a way to supress the removal and adding of the postgres super user which is in the dump SQL?
In general are there any other gotchas when containerising and/or updating a postgres DB.
I'm not familiar with Docker so I don't know how straightforward it'll be do to these things, but in general, pg_dump/dumpall output, when it's in SQL format, will work just fine after having gone through some ugly string manipulation.
Pipe it through sed -e 's/DROP ROLE/DROP ROLE IF EXISTS/', ideally when writing the .sqls, but it's fine to just run sed -i -e <...> to munge the files in-place after they're created if you don't have a full shell available. Make it sed -r -e '/^DROP ROLE/DROP ROLE IF EXISTS/ if you're worried about strings containing DROP ROLE in your data, at the cost of portability (AFAIK -r is a GNU addition to sed).
Yes. It's worth checking the data in pg12 to make sure it got imported correctly, but in the general case, pg_dump has been aware of encoding considerations since time immemorial, and a dump->load is absolutely the best way to change your DB encoding.
Sure. Find the lines that do it in your .sql, copy enough of it to be unique, and pipe it through grep -v <what you copied> :D
I can't speak to the containerizing aspect of things, but - and this is more of a general practice, not even really PG-specific - if you're dealing with a large DB that's getting migrated, prepare a small one, as similar as possible to the real one but omitting any bulky data, to test with to get everything working so that doing the real migration is just a matter of changing some vars (I guess $REMOtE_HOST and $REMOTE_PORT in your case). If it's not large, then just be comfortable blowing away any pg12 containers that failed partway through the import, figure out & do whatever to fix the failure, and start from the top again until it works end-to-end.
I'm attempting to import an SQL dump in PgAdmin 4 using the psql client - However the error message returned is - The system cannnot find the file specified.
Here is a screenshot of my psql client -
The file films.sql is currently stored on my desktop, but I suspect the default location that the psql client accesses is not my desktop? Is there anyway to set the location that the client looks in order to resolve this?
The file SQL is viewable here: https://github.com/datacamp/courses-intro-to-sql/tree/master/datasets
I simply want to get the database on my local machine so that I don't need to store queries in an online learning platform. It would be best if this database is available locally to query and practice on.
I've attempted to execute the whole SQL file as a query on the films database but this does not seem to be working either and returns 'Asynchronous query execution/operation underway.
Query returned successfully in 388 msec.' - However it seems to be the case that the Asynchronous query never completes when I refresh the database.
Please can someone help?
Just give the path to your file:
psql -d my_database -f /path/to/the/file.sql
psql -d my_database -f C:/path/to/the/file.sql
Depending on whether you are on a unix/linux machine or Windows.
Oh, and if you aren't familiar with file paths you may want to take a step back and become more familiar with general computer terminology before diving into a RDBMS. Your learning will be much easier if you have a solid foundation to build upon.
I suspect this question might be moot for the asker at this point, but for anyone else stumbling upon it like I did: the interactive connection info prompts are provided by a batch script (in Windows, I'd guess there's an analogous shell script for Unix) called runpsql.bat, which then just passes your inputs as commandline arguments to the psql.exe executable. I was getting this error because I had migrated my Postgres installation and the batch script was calling a nonexistent path for psql.exe, hence The system cannot find the file specified. I edited runpsql.bat to point to the correct location of psql.exe and that resolved the issue. So for OP, I would look into PgAdmin4 and see where it's (presumably) calling runpsql.bat, then make sure that that calls psql.exe with the correct path.
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
I am working through the Zend framework tutorial at http://framework.zend.com/manual/en/.
Right now I am on the 'Create a Model and Database Table' section, and have followed the tutorial's guidelines for initializing database resources. In my terminal I entered
zf configure db-adapter \
then
adapter=PDO_SQLITE&dbname=APPLICATION_PATH "/../data/db/guestbook.db" \
and then
production
At this point, I am supposed to receive a message saying that a db configuration for production has been written to my config file. Instead, the prompt stays open. I've tried using ":q", ":quit", and "\q" to leave the prompt, but those don't work. The server that I am working on runs of RHEL5. I know I can close the terminal and open a new one, but I want to learn how to actually get out of the zend framework command line prompt. Solutions?
Ctrl+c will exit a prompt.