CODEWITHSUNDEEP
postgresqlpsql
Mike T
Mike T

Reputation: 43652

Use psql's \copy for a multi-line query

This is a follow-up question from this answer for "Save PL/pgSQL output from PostgreSQL to a CSV file".

I need to write a client-side CSV file using psql's \copy command. A one liner works: 

db=> \copy (select 1 AS foo) to 'bar.csv' csv header
COPY 1

However, I have long queries that span several lines. I don't need to show the query, as I can't seem to extend this past one line without a parse error: 

db=> \copy (
\copy: parse error at end of line
db=> \copy ( \\
\copy: parse error at end of line
db=> \copy ("
\copy: parse error at end of line
db=> \copy "(
\copy: parse error at end of line
db=> \copy \\
\copy: parse error at end of line

Is it possible to use \copy with a query that spans multiple lines? I'm using psql on Windows.

Upvotes: 54

Views: 30376

Answers (3)

haki
haki

Reputation: 9759

You can combine the server side COPY command with the \g psql command to produce a multi-line query to local file:

db=# COPY (
    SELECT department, count(*) AS employees
    FROM emp
    WHERE role = 'dba'
    GROUP BY department
    ORDER BY employees
) TO STDOUT WITH CSV HEADER \g department_dbas.csv
COPY 5

I describe this technique in detial here https://hakibenita.com/postgresql-unknown-features#use-copy-with-multi-line-sql

Upvotes: 12

Saim
Saim

Reputation: 2523

We may use HEREDOC to feed multiline SQL to psql and use

# Putting the SQL using a HEREDOC
tr '\n' ' ' << SQL| \psql mydatabase
\COPY (
  SELECT
    provider_id,
    provider_name,
    ...
) TO './out.tsv' WITH( DELIMITER E'\t', NULL '', )
SQL

Source: https://minhajuddin.com/2017/05/18/how-to-pass-a-multi-line-copy-sql-to-psql/

Upvotes: 5

Mike T
Mike T

Reputation: 43652

The working solution I have right now is to create a temporary view, which can be declared over multiple lines, then select from it in the \copy command, which fits comfortably on one line. 

db=> CREATE TEMP VIEW v1 AS
db->   SELECT i
db->   FROM generate_series(1, 2) AS i;
CREATE VIEW
db=> \cd /path/to/a/really/deep/directory/structure/on/client
db=> \copy (SELECT * FROM v1) TO 'out.csv' csv header
COPY 2
db=> DROP VIEW v1;
DROP VIEW

Upvotes: 78

Related Questions