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How to import CSV file data into a PostgreSQL table

How can I write a stored procedure that imports data from a CSV file and populates the table?

Why a stored procedure? COPY does the trick
I have a user interface that uploads the csv file, to hook up this i need the stored procedure that actually copies the data from the cvs file
could you elaborate on how to use the COPY ?
Bozhidar Batsov already gave you a link to an example, the fine manual could also help: postgresql.org/docs/8.4/interactive/sql-copy.html

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Peter Mortensen

Take a look at this short article.

The solution is paraphrased here:

Create your table:

CREATE TABLE zip_codes
(ZIP char(5), LATITUDE double precision, LONGITUDE double precision,
CITY varchar, STATE char(2), COUNTY varchar, ZIP_CLASS varchar);

Copy data from your CSV file to the table:

COPY zip_codes FROM '/path/to/csv/ZIP_CODES.txt' WITH (FORMAT csv);

actually use \copy would do the same trick if you do not have the super user access; it complaints on my Fedora 16 when using COPY with a non-root account.
TIP: you can indicate what columns you have in the CSV using zip_codes(col1, col2, col3). The columns must be listed in the same order that they appear in the file.
@asksw0rder does \copy have the same syntax? bcoz I'm getting a syntax error with \copy
Should I include the header row?
You can easily include the header row -- just add HEADER in the options: COPY zip_codes FROM '/path/to/csv/ZIP_CODES.txt' DELIMITER ',' CSV HEADER; postgresql.org/docs/9.1/static/sql-copy.html
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Peter Mortensen

If you don't have permission to use COPY (which work on the db server), you can use \copy instead (which works in the db client). Using the same example as Bozhidar Batsov:

Create your table:

CREATE TABLE zip_codes
(ZIP char(5), LATITUDE double precision, LONGITUDE double precision,
CITY varchar, STATE char(2), COUNTY varchar, ZIP_CLASS varchar);

Copy data from your CSV file to the table:

\copy zip_codes FROM '/path/to/csv/ZIP_CODES.txt' DELIMITER ',' CSV

Mind that \copy ... must be written in one line and without a ; at the end!

You can also specify the columns to read:

\copy zip_codes(ZIP,CITY,STATE) FROM '/path/to/csv/ZIP_CODES.txt' DELIMITER ',' CSV

See the documentation for COPY:

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.

And note:

For identity columns, the COPY FROM command will always write the column values provided in the input data, like the INSERT option OVERRIDING SYSTEM VALUE.


\copy voters(ZIP,CITY) FROM '/Users/files/Downloads/WOOD.TXT' DELIMITER ',' CSV HEADER; ERROR: extra data after last expected column CONTEXT: COPY voters, line 2: "OH0012781511,87,26953,HOUSEHOLDER,SHERRY,LEIGH,,11/26/1965,08/19/1988,,211 N GARFIELD ST , ,BLOOMD..."
@JZ. I had a similar error. It was because I had extra blank columns. Check your csv and if you have blank columns, that could be the reason.
This is somewhat misleading: the difference between COPY and \copy is much more than just permissions, and you can't simply add a `` to make it magically work. See the description (in the context of export) here: stackoverflow.com/a/1517692/157957
@IMSoP: you're right, I added a mention of server and client to clarify
@Sebastian: the important difference is that \copy works from the client. so you still have to transmit all the data to the server. with COPY (no slash) you first upload all the data to the server with other means (sftp, scp) and then do the import on the server. but transmitting 1.5 MB does not sound like it should talk 3 hours - no matter which way you do it.
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Peter Mortensen

One quick way of doing this is with the Python Pandas library (version 0.15 or above works best). This will handle creating the columns for you - although obviously the choices it makes for data types might not be what you want. If it doesn't quite do what you want you can always use the 'create table' code generated as a template.

Here's a simple example:

import pandas as pd
df = pd.read_csv('mypath.csv')
df.columns = [c.lower() for c in df.columns] # PostgreSQL doesn't like capitals or spaces

from sqlalchemy import create_engine
engine = create_engine('postgresql://username:password@localhost:5432/dbname')

df.to_sql("my_table_name", engine)

And here's some code that shows you how to set various options:

# Set it so the raw SQL output is logged
import logging
logging.basicConfig()
logging.getLogger('sqlalchemy.engine').setLevel(logging.INFO)

df.to_sql("my_table_name2",
          engine,
          if_exists="append",  # Options are ‘fail’, ‘replace’, ‘append’, default ‘fail’
          index = False, # Do not output the index of the dataframe
          dtype = {'col1': sqlalchemy.types.NUMERIC,
                   'col2': sqlalchemy.types.String}) # Datatypes should be SQLAlchemy types

In addition, the if_exists parameter can be set to replace or append to an existing table, e.g. df.to_sql("fhrs", engine, if_exists='replace')
username and password : need to create Login and assign DB to user. If uses pgAdmin, then create "Login/Group role" using GUI
Pandas is a super slow way of loading to sql (vs csv files). Can be orders of magnitude slower.
This could be a way to write data but it is super slow even with batch and good computing power. Using CSVs is a good way to accomplish this.
df.to_sql() is really slow, you can use d6tstack.utils.pd_to_psql() from d6tstack see performance comparison
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Peter Mortensen

Most other solutions here require that you create the table in advance/manually. This may not be practical in some cases (e.g., if you have a lot of columns in the destination table). So, the approach below may come handy.

Providing the path and column count of your CSV file, you can use the following function to load your table to a temp table that will be named as target_table:

The top row is assumed to have the column names.

create or replace function data.load_csv_file
(
    target_table text,
    csv_path text,
    col_count integer
)

returns void as $$

declare

iter integer; -- dummy integer to iterate columns with
col text; -- variable to keep the column name at each iteration
col_first text; -- first column name, e.g., top left corner on a csv file or spreadsheet

begin
    create table temp_table ();

    -- add just enough number of columns
    for iter in 1..col_count
    loop
        execute format('alter table temp_table add column col_%s text;', iter);
    end loop;

    -- copy the data from csv file
    execute format('copy temp_table from %L with delimiter '','' quote ''"'' csv ', csv_path);

    iter := 1;
    col_first := (select col_1 from temp_table limit 1);

    -- update the column names based on the first row which has the column names
    for col in execute format('select unnest(string_to_array(trim(temp_table::text, ''()''), '','')) from temp_table where col_1 = %L', col_first)
    loop
        execute format('alter table temp_table rename column col_%s to %s', iter, col);
        iter := iter + 1;
    end loop;

    -- delete the columns row
    execute format('delete from temp_table where %s = %L', col_first, col_first);

    -- change the temp table name to the name given as parameter, if not blank
    if length(target_table) > 0 then
        execute format('alter table temp_table rename to %I', target_table);
    end if;

end;

$$ language plpgsql;

Hi Mehmet, thanks for the answer you posted but when I run your code I get the following error message : ERROR: schema "data" does not exist
user2867432 you need to change schema name that you use accordingly (e.g., public)
Hi Mehmet, Thanks for solution, it's perfect but This works only if the postgres DB user is superuser, is ther any way to make it work without superuser?
Geeme: read "security definer" here, but I have not used it myself.
Beautiful answer! I am not going to too generic though in my code for readability for others.
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Peter Mortensen

You could also use pgAdmin, which offers a GUI to do the import. That's shown in this SO thread. The advantage of using pgAdmin is that it also works for remote databases.

Much like the previous solutions though, you would need to have your table on the database already. Each person has his own solution, but I usually open the CSV file in Excel, copy the headers, paste special with transposition on a different worksheet, place the corresponding data type on the next column, and then just copy and paste that to a text editor together with the appropriate SQL table creation query like so:

CREATE TABLE my_table (
    /* Paste data from Excel here for example ... */
    col_1 bigint,
    col_2 bigint,
    /* ... */
    col_n bigint
)

pls show a couple of sample rows of your pasted data
T
Tunaki
COPY table_name FROM 'path/to/data.csv' DELIMITER ',' CSV HEADER;

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Peter Mortensen

As Paul mentioned, import works in pgAdmin:

Right-click on table → Import

Select a local file, format and coding.

Here is a German pgAdmin GUI screenshot:

https://i.stack.imgur.com/z9M5o.jpg

A similar thing you can do with DbVisualizer (I have a license and am not sure about free version).

Right-click on a table → Import Table Data...

https://i.stack.imgur.com/107St.jpg


DBVisualizer took 50 seconds to import 1400 rows with three fields -- and I had to cast everything back from a String to whatever it was supposed to be.
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Peter Mortensen

Create a table first Then use the copy command to copy the table details: copy table_name (C1,C2,C3....) from 'path to your CSV file' delimiter ',' csv header;

NOTE:

columns and order are specified by C1,C2,C3.. in SQL

The header option just skips one line from the input, not according to columns' name.


How is this not the accepted answer? Why would I write a python script when the database already has a command to do this?
P
Peter Mortensen

Use this SQL code:

copy table_name(atribute1,attribute2,attribute3...)
from 'E:\test.csv' delimiter ',' csv header

The header keyword lets the DBMS know that the CSV file have a header with attributes.

For more, visit Import CSV File Into PostgreSQL Table.


P
Peter Mortensen

This is a personal experience with PostgreSQL, and I am still waiting for a faster way.

Create a table skeleton first if the file is stored locally: drop table if exists ur_table; CREATE TABLE ur_table ( id serial NOT NULL, log_id numeric, proc_code numeric, date timestamp, qty int, name varchar, price money ); COPY ur_table(id, log_id, proc_code, date, qty, name, price) FROM '\path\xxx.csv' DELIMITER ',' CSV HEADER; When the \path\xxx.csv file is on the server, PostgreSQL doesn't have the permission to access the server. You will have to import the .csv file through the pgAdmin built in functionality. Right click the table name and choose import.

If you still have the problem, please refer this tutorial: Import CSV File Into PostgreSQL Table


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Peter Mortensen

How to import CSV file data into a PostgreSQL table

Steps:

Need to connect a PostgreSQL database in the terminal psql -U postgres -h localhost Need to create a database create database mydb; Need to create a user create user siva with password 'mypass'; Connect with the database \c mydb; Need to create a schema create schema trip; Need to create a table create table trip.test(VendorID int,passenger_count int,trip_distance decimal,RatecodeID int,store_and_fwd_flag varchar,PULocationID int,DOLocationID int,payment_type decimal,fare_amount decimal,extra decimal,mta_tax decimal,tip_amount decimal,tolls_amount int,improvement_surcharge decimal,total_amount ); Import csv file data to postgresql COPY trip.test(VendorID int,passenger_count int,trip_distance decimal,RatecodeID int,store_and_fwd_flag varchar,PULocationID int,DOLocationID int,payment_type decimal,fare_amount decimal,extra decimal,mta_tax decimal,tip_amount decimal,tolls_amount int,improvement_surcharge decimal,total_amount) FROM '/home/Documents/trip.csv' DELIMITER ',' CSV HEADER; Find the given table data select * from trip.test;


Why do we need datatype on the copy command? I mean on step 7
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Peter Mortensen

IMHO, the most convenient way is to follow "Import CSV data into postgresql, the comfortable way ;-)", using csvsql from csvkit, which is a Python package installable via pip.


Link rot is voracious! The article you linked to no longer works, which makes me uncomfortable :(
you might want to mention that his is py.
For me I get a MemoryError if trying to import a large CSV so it looks like it doesn't stream.
@DavidC Interesting. How big is your file? How much memory do you have? If it doesnt stream as it appears, I suggest chunking the data before insertion
The file was 5GBs in size and I have 2GB memory. I gave up on it and use a script to generate CREATE TABLE and COPY commands in the end.
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Peter Mortensen

You can also use pgfutter, or, even better, pgcsv.

These tools create the table columns from you, based on the CSV header.

pgfutter is quite buggy, and I'd recommend pgcsv.

Here's how to do it with pgcsv:

sudo pip install pgcsv
pgcsv --db 'postgresql://localhost/postgres?user=postgres&password=...' my_table my_file.csv

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Peter Mortensen

In Python, you can use this code for automatic PostgreSQL table creation with column names:

import pandas, csv

from io import StringIO
from sqlalchemy import create_engine

def psql_insert_copy(table, conn, keys, data_iter):
    dbapi_conn = conn.connection
    with dbapi_conn.cursor() as cur:
        s_buf = StringIO()
        writer = csv.writer(s_buf)
        writer.writerows(data_iter)
        s_buf.seek(0)
        columns = ', '.join('"{}"'.format(k) for k in keys)
        if table.schema:
            table_name = '{}.{}'.format(table.schema, table.name)
        else:
            table_name = table.name
        sql = 'COPY {} ({}) FROM STDIN WITH CSV'.format(table_name, columns)
        cur.copy_expert(sql=sql, file=s_buf)

engine = create_engine('postgresql://user:password@localhost:5432/my_db')

df = pandas.read_csv("my.csv")
df.to_sql('my_table', engine, schema='my_schema', method=psql_insert_copy)

It's also relatively fast. I can import more than 3.3 million rows in about 4 minutes.


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Peter Mortensen

You can use the Pandas library if the file is not very large.

Be careful when using iter over Pandas dataframes. I am doing this here to demonstrate the possibility. One could also consider the pd.Dataframe.to_sql() function when copying from a dataframe to an SQL table.

Assuming you have created the table you want, you could:

import psycopg2
import pandas as pd
data=pd.read_csv(r'path\to\file.csv', delimiter=' ')

#prepare your data and keep only relevant columns

data.drop(['col2', 'col4','col5'], axis=1, inplace=True)
data.dropna(inplace=True)
print(data.iloc[:3])


conn=psycopg2.connect("dbname=db user=postgres password=password")
cur=conn.cursor()

for index,row in data.iterrows():
      cur.execute('''insert into table (col1,col3,col6)
    VALUES (%s,%s,%s)''', (row['col1'], row['col3'], row['col6'])

cur.close()
conn.commit()

conn.close()
print('\n db connection closed.')

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Peter Mortensen

DBeaver Community Edition (dbeaver.io) makes it trivial to connect to a database, then import a CSV file for upload to a PostgreSQL database. It also makes it easy to issue queries, retrieve data, and download result sets to CSV, JSON, SQL, or other common data formats.

It is a FOSS multi-platform database tool for SQL programmers, DBAs and analysts that supports all popular databases: MySQL, PostgreSQL, SQLite, Oracle, DB2, SQL Server, Sybase, MS Access, Teradata, Firebird, Hive, Presto, etc. It's a viable FOSS competitor to TOAD for Postgres, TOAD for SQL Server, or Toad for Oracle.

I have no affiliation with DBeaver. I love the price (FREE!) and full functionality, but I wish they would open up this DBeaver/Eclipse application more and make it easy to add analytics widgets to DBeaver / Eclipse, rather than requiring users to pay for the $199 annual subscription just to create graphs and charts directly within the application. My Java coding skills are rusty and I don't feel like taking weeks to relearn how to build Eclipse widgets, (only to find that DBeaver has probably disabled the ability to add third-party widgets to the DBeaver Community Edition.)


It would have been nice to understand how to actually use DBeaver to import a CSV file. Anyway, this might help: dbeaver.com/docs/wiki/Data-transfer
Peter suggested that I move this question to comments: "Can DBeaver power users who are Java developers provide some insight about the steps to create analytics widgets to add into the Community Edition of DBeaver? " I would like to know if the analytics plugins are also open source, and how to create them.
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Peter Mortensen

You can create a Bash file as import.sh (that your CSV format is a tab delimiter):

#!/usr/bin/env bash

USER="test"
DB="postgres"
TBALE_NAME="user"
CSV_DIR="$(pwd)/csv"
FILE_NAME="user.txt"

echo $(psql -d $DB -U $USER  -c "\copy $TBALE_NAME from '$CSV_DIR/$FILE_NAME' DELIMITER E'\t' csv" 2>&1 |tee /dev/tty)

And then run this script.


What do you mean by "your CSV format is a tab delimiter"?
D
Dharman

You have 3 options to import CSV files to PostgreSQL: First, using the COPY command through the command line.

https://i.stack.imgur.com/DONA1.png

Second, using the pgAdmin tool’s import/export.

https://i.stack.imgur.com/zeq8o.png

Third, using a cloud solution like Skyvia which gets the CSV file from an online location like an FTP source or a cloud storage like Google Drive.

https://i.stack.imgur.com/TtmaD.png

You can check out the article that explains all of these from here.


Please review Why not upload images of code/errors when asking a question? (e.g., "Images should only be used to illustrate problems that can't be made clear in any other way, such as to provide screenshots of a user interface.) and take the appropriate action (it covers answers as well). Thanks in advance.
It applies at least to the first image. The last image is unreadable (possibly lost fidelity due to falsely being converted to JPEG (unsuitable for screenshots)).
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Peter Mortensen

Create a table and have the required columns that are used for creating a table in the CSV file.

Open postgres and right click on the target table which you want to load. Select import and Update the following steps in the file options section Now browse your file for the filename Select CSV in format Encoding as ISO_8859_5

Now go to Misc. options. Check header and click on import.


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Peter Mortensen

If you need a simple mechanism to import from text/parse multiline CSV content, you could use:

CREATE TABLE t   -- OR INSERT INTO tab(col_names)
AS
SELECT
   t.f[1] AS col1
  ,t.f[2]::int AS col2
  ,t.f[3]::date AS col3
  ,t.f[4] AS col4
FROM (
  SELECT regexp_split_to_array(l, ',') AS f
  FROM regexp_split_to_table(
$$a,1,2016-01-01,bbb
c,2,2018-01-01,ddd
e,3,2019-01-01,eee$$, '\n') AS l) t;

DBFiddle Demo


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Peter Mortensen

I created a small tool that imports csv file into PostgreSQL super easy. It is just a command and it will create and populate the tables, but unfortunately, at the moment, all fields automatically created uses the type TEXT:

csv2pg users.csv -d ";" -H 192.168.99.100 -U postgres -B mydatabase

The tool can be found on https://github.com/eduardonunesp/csv2pg


You made a separate tool for the equivalent of psql -h 192.168.99.100 -U postgres mydatabase -c "COPY users FROM 'users.csv' DELIMITER ';' CSV"? I guess the part where it creates the table is nice, but since every field is text it's not super useful
Ops, thanks for the heads up. Yes, I did it, well it took just a few hours and I learned cool stuff in Go and pq and database API in Go.
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Peter Mortensen

By using any client—I used DataGrip—I created a new database and then within the default schema (public) of the database, right-click the database and then do Import Data from file.

Choose the CSV file from the location and then choose Import File → Formats as TSV → ensure each column name of the data CSV file contributes to the column name of tables.

https://i.stack.imgur.com/shg9S.png


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Peter Mortensen

My idea is to convert your CSV file into SQL queries:

Open tool Convert CSV to Insert SQL Online Paste or upload your CSV file in the Data Source pane Scroll to the Table Generator panel Click Copy to clipboard or Download

Example:

id,name
1,Roberta
2,Oliver

The output of SQL queries:

CREATE TABLE tableName
(
    id    varchar(300),
    name  varchar(300)
);

INSERT INTO tableName (id,name)
VALUES
    ('1', 'Roberta'),
    ('2', 'Oliver');