Save PL/pgSQL output from PostgreSQL to a CSV file
SqlPostgresqlCsvPostgresql CopySql Problem Overview
What is the easiest way to save PL/pgSQL output from a PostgreSQL database to a CSV file?
I'm using PostgreSQL 8.4 with pgAdmin III and PSQL plugin where I run queries from.
Sql Solutions
Solution 1 - Sql
Do you want the resulting file on the server, or on the client?
Server side
If you want something easy to re-use or automate, you can use Postgresql's built in COPY command. e.g.
Copy (Select * From foo) To '/tmp/test.csv' With CSV DELIMITER ',' HEADER;
This approach runs entirely on the remote server - it can't write to your local PC. It also needs to be run as a Postgres "superuser" (normally called "root") because Postgres can't stop it doing nasty things with that machine's local filesystem.
That doesn't actually mean you have to be connected as a superuser (automating that would be a security risk of a different kind), because you can use the SECURITY DEFINER option to CREATE FUNCTION to make a function which runs as though you were a superuser.
The crucial part is that your function is there to perform additional checks, not just by-pass the security - so you could write a function which exports the exact data you need, or you could write something which can accept various options as long as they meet a strict whitelist. You need to check two things:
- Which files should the user be allowed to read/write on disk? This might be a particular directory, for instance, and the filename might have to have a suitable prefix or extension.
- Which tables should the user be able to read/write in the database? This would normally be defined by
GRANTs in the database, but the function is now running as a superuser, so tables which would normally be "out of bounds" will be fully accessible. You probably don’t want to let someone invoke your function and add rows on the end of your “users” table…
I've written a blog post expanding on this approach, including some examples of functions that export (or import) files and tables meeting strict conditions.
Client side
The other approach is to do the file handling on the client side, i.e. in your application or script. The Postgres server doesn't need to know what file you're copying to, it just spits out the data and the client puts it somewhere.
The underlying syntax for this is the COPY TO STDOUT command, and graphical tools like pgAdmin will wrap it for you in a nice dialog.
The psql command-line client has a special "meta-command" called \copy, which takes all the same options as the "real" COPY, but is run inside the client:
\copy (Select * From foo) To '/tmp/test.csv' With CSV DELIMITER ',' HEADER
Note that there is no terminating ;, because meta-commands are terminated by newline, unlike SQL commands.
From the docs:
> Do not confuse COPY with the psql instruction \copy. \copy invokes COPY FROM STDIN or COPY TO STDOUT, and then fetches/stores the data in a file accessible to the psql client. Thus, file accessibility and access rights depend on the client rather than the server when \copy is used.
Your application programming language may also have support for pushing or fetching the data, but you cannot generally use COPY FROM STDIN/TO STDOUT within a standard SQL statement, because there is no way of connecting the input/output stream. PHP's PostgreSQL handler (not PDO) includes very basic pg_copy_from and pg_copy_to functions which copy to/from a PHP array, which may not be efficient for large data sets.
Solution 2 - Sql
There are several solutions:
1 psql command
psql -d dbname -t -A -F"," -c "select * from users" > output.csv
This has the big advantage that you can using it via SSH, like ssh postgres@host command - enabling you to get
2 postgres copy command
COPY (SELECT * from users) To '/tmp/output.csv' With CSV;
3 psql interactive (or not)
>psql dbname
psql>\f ','
psql>\a
psql>\o '/tmp/output.csv'
psql>SELECT * from users;
psql>\q
All of them can be used in scripts, but I prefer #1.
4 pgadmin but that's not scriptable.
Solution 3 - Sql
In terminal (while connected to the db) set output to the cvs file
-
Set field seperator to
',':\f ','
-
Set output format unaligned:
\a
-
Show only tuples:
\t
-
Set output:
\o '/tmp/yourOutputFile.csv'
-
Execute your query:
:select * from YOUR_TABLE
-
Output:
\o
You will then be able to find your csv file in this location:
cd /tmp
Copy it using the scp command or edit using nano:
nano /tmp/yourOutputFile.csv
Solution 4 - Sql
CSV Export Unification
This information isn't really well represented. As this is the second time I've needed to derive this, I'll put this here to remind myself if nothing else.
Really the best way to do this (get CSV out of postgres) is to use the COPY ... TO STDOUT command. Though you don't want to do it the way shown in the answers here. The correct way to use the command is:
COPY (select id, name from groups) TO STDOUT WITH CSV HEADER
Remember just one command!
It's great for use over ssh:
$ ssh psqlserver.example.com 'psql -d mydb "COPY (select id, name from groups) TO STDOUT WITH CSV HEADER"' > groups.csv
It's great for use inside docker over ssh:
$ ssh pgserver.example.com 'docker exec -tu postgres postgres psql -d mydb -c "COPY groups TO STDOUT WITH CSV HEADER"' > groups.csv
It's even great on the local machine:
$ psql -d mydb -c 'COPY groups TO STDOUT WITH CSV HEADER' > groups.csv
Or inside docker on the local machine?:
docker exec -tu postgres postgres psql -d mydb -c 'COPY groups TO STDOUT WITH CSV HEADER' > groups.csv
Or on a kubernetes cluster, in docker, over HTTPS??:
kubectl exec -t postgres-2592991581-ws2td 'psql -d mydb -c "COPY groups TO STDOUT WITH CSV HEADER"' > groups.csv
So versatile, much commas!
Do you even?
Yes I did, here are my notes:
The COPYses
Using /copy effectively executes file operations on whatever system the psql command is running on, as the user who is executing it1. If you connect to a remote server, it's simple to copy data files on the system executing psql to/from the remote server.
COPY executes file operations on the server as the backend process user account (default postgres), file paths and permissions are checked and applied accordingly. If using TO STDOUT then file permissions checks are bypassed.
Both of these options require subsequent file movement if psql is not executing on the system where you want the resultant CSV to ultimately reside. This is the most likely case, in my experience, when you mostly work with remote servers.
It is more complex to configure something like a TCP/IP tunnel over ssh to a remote system for simple CSV output, but for other output formats (binary) it may be better to /copy over a tunneled connection, executing a local psql. In a similar vein, for large imports, moving the source file to the server and using COPY is probably the highest-performance option.
PSQL Parameters
With psql parameters you can format the output like CSV but there are downsides like having to remember to disable the pager and not getting headers:
$ psql -P pager=off -d mydb -t -A -F',' -c 'select * from groups;'
2,Technician,Test 2,,,t,,0,,
3,Truck,1,2017-10-02,,t,,0,,
4,Truck,2,2017-10-02,,t,,0,,
Other Tools
No, I just want to get CSV out of my server without compiling and/or installing a tool.
Solution 5 - Sql
If you're interested in all the columns of a particular table along with headers, you can use
COPY table TO '/some_destdir/mycsv.csv' WITH CSV HEADER;
This is a tiny bit simpler than
COPY (SELECT * FROM table) TO '/some_destdir/mycsv.csv' WITH CSV HEADER;
which, to the best of my knowledge, are equivalent.
Solution 6 - Sql
New version - psql 12 - will support --csv.
>psql - devel > >--csv > > Switches to CSV (Comma-Separated Values) output mode. This is equivalent to \pset format csv. > > ---- > > csv_fieldsep > > Specifies the field separator to be used in CSV output format. If the separator character appears in a field's value, that field is output within double quotes, following standard CSV rules. The default is a comma.
Usage:
psql -c "SELECT * FROM pg_catalog.pg_tables" --csv postgres
psql -c "SELECT * FROM pg_catalog.pg_tables" --csv -P csv_fieldsep='^' postgres
psql -c "SELECT * FROM pg_catalog.pg_tables" --csv postgres > output.csv
Solution 7 - Sql
I had to use the \COPY because I received the error message:
ERROR: could not open file "/filepath/places.csv" for writing: Permission denied
So I used:
\Copy (Select address, zip From manjadata) To '/filepath/places.csv' With CSV;
and it is functioning
Solution 8 - Sql
psql can do this for you:
edd@ron:~$ psql -d beancounter -t -A -F"," \
-c "select date, symbol, day_close " \
"from stockprices where symbol like 'I%' " \
"and date >= '2009-10-02'"
2009-10-02,IBM,119.02
2009-10-02,IEF,92.77
2009-10-02,IEV,37.05
2009-10-02,IJH,66.18
2009-10-02,IJR,50.33
2009-10-02,ILF,42.24
2009-10-02,INTC,18.97
2009-10-02,IP,21.39
edd@ron:~$
See man psql for help on the options used here.
Solution 9 - Sql
I'm working on AWS Redshift, which does not support the COPY TO feature.
My BI tool supports tab-delimited CSVs though, so I used the following:
psql -h dblocation -p port -U user -d dbname -F $'\t' --no-align -c "SELECT * FROM TABLE" > outfile.csv
Solution 10 - Sql
In pgAdmin III there is an option to export to file from the query window. In the main menu it's Query -> Execute to file or there's a button that does the same thing (it's a green triangle with a blue floppy disk as opposed to the plain green triangle which just runs the query). If you're not running the query from the query window then I'd do what IMSoP suggested and use the copy command.
Solution 11 - Sql
I've written a little tool called psql2csv that encapsulates the COPY query TO STDOUT pattern, resulting in proper CSV. It's interface is similar to psql.
psql2csv [OPTIONS] < QUERY
psql2csv [OPTIONS] QUERY
The query is assumed to be the contents of STDIN, if present, or the last argument. All other arguments are forwarded to psql except for these:
-h, --help show help, then exit
--encoding=ENCODING use a different encoding than UTF8 (Excel likes LATIN1)
--no-header do not output a header
Solution 12 - Sql
I tried several things but few of them were able to give me the desired CSV with header details.
Here is what worked for me.
psql -d dbame -U username \
-c "COPY ( SELECT * FROM TABLE ) TO STDOUT WITH CSV HEADER " > \
OUTPUT_CSV_FILE.csv
Solution 13 - Sql
If you have longer query and you like to use psql then put your query to a file and use the following command:
psql -d my_db_name -t -A -F";" -f input-file.sql -o output-file.csv
Solution 14 - Sql
To Download CSV file with column names as HEADER use this command:
Copy (Select * From tableName) To '/tmp/fileName.csv' With CSV HEADER;
Solution 15 - Sql
JackDB, a database client in your web browser, makes this really easy. Especially if you're on Heroku.
It lets you connect to remote databases and run SQL queries on them.
Source
(source: jackdb.com)
Once your DB is connected, you can run a query and export to CSV or TXT (see bottom right).
Note: I'm in no way affiliated with JackDB. I currently use their free services and think it's a great product.
Solution 16 - Sql
import json
cursor = conn.cursor()
qry = """ SELECT details FROM test_csvfile """
cursor.execute(qry)
rows = cursor.fetchall()
value = json.dumps(rows)
with open("/home/asha/Desktop/Income_output.json","w+") as f:
f.write(value)
print 'Saved to File Successfully'
Solution 17 - Sql
Per the request of @skeller88, I am reposting my comment as an answer so that it doesn't get lost by people who don't read every response...
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