How to export full-text files with SQL?

Question

There are an easy way to import/export full-text fields as files?

• that solve the problem of \"load as multiple lines\".
  Trying with SQ

Answer 1

You can use plpythonu f.open(), f.write(), f.close() within a postgres function to write to a file.

Language extension would need to be installed.,

https://www.postgresql.org/docs/8.3/static/plpython.html

Working example from the mailing list. https://www.postgresql.org/message-id/flat/20041106125209.55697.qmail%40web51806.mail.yahoo.com#20041106125209.55697.qmail@web51806.mail.yahoo.com

for example plpythonu

CREATE FUNCTION makefile(p_file text, p_content text) RETURNS text AS $$
  o=open(args[0],"w")
  o.write(args[1])
  o.close()
  return "ok"
$$ LANGUAGE PLpythonU;

PS: for safe implementation see this example.

---

Preparing

There are a not-so-obvious procedure to use PLpython extension. Supposing an UBUNTU server:

1. On SQL check SELECT version().
2. On terminal check sudo apt install postgresql-plpython listed versions.
3. Install the correct version, eg. sudo apt install postgresql-plpython-9.6.
4. Back to SQL do CREATE EXTENSION plpythonu.

Testing

The /tmp is default, to create or use other folder, eg. /tmp/sandbox,
use sudo chown postgres.postgres /tmp/sandbox.

Suppose the tables of the question's examples. SQL script, repeating some lines:

  DROP TABLE IF EXISTS ttmp; 
  DROP TABLE IF EXISTS xtmp; 

  CREATE TABLE ttmp (x text);
  COPY ttmp FROM '/tmp/sandbox/original.xml' ( FORMAT text );
  COPY (SELECT x FROM ttmp) TO '/tmp/sandbox/test1-good.xml' (format TEXT);

  CREATE TABLE xtmp (x xml);
  INSERT INTO  xtmp (x) 
     SELECT array_to_string(array_agg(x),E'\n')::xml FROM ttmp
  ;

  COPY (select x::text from xtmp) 
  TO '/tmp/sandbox/test2-bad.xml' ( FORMAT text );

  SELECT makefile('/tmp/sandbox/test3-good.xml',x::text) FROM xtmp;

The sha1sum *.xml output of my XML original file:

4947..  original.xml
4947..  test1-good.xml
949f..  test2-bad.xml
4947..  test3-good.xml