In this post, I am providing a solution to split a string by using a different type of delimiters in PostgreSQL.
Splitting a string is a very common requirement for all PostgreSQL Database Developers.
I used regexp_split_to_array to split the string and store the result into a string array. You can pass any delimiters.

Below are two sample example using regexp_split_to_array():

SELECT 
	a[1] AS DiskInfo
	,a[2] AS DiskNumber
	,a[3] AS MessageKeyword
FROM (
    SELECT regexp_split_to_array('Postgres Disk information : disk 2 : failed', ':')
) AS dt(a)


SELECT 
	a[1] AS DiskInfo
	,a[2] AS DiskNumber
	,a[3] AS MessageKeyword
FROM (
    SELECT regexp_split_to_array('Postgres Disk information , disk 2 , failed', ',')
) AS dt(a)

The result:

PostgreSQL 9.4 introduced WITH ORDINALITY for generating a sequence number for each element which are produced by UNNEST().

When we are talking about the string array, internal element numbering is also important for further operation.

I have prepared a small demonstration of this, you can access here.

Create a table with sample data:

CREATE TABLE tbl_TextArray(key varchar(100), tags text[]);

INSERT INTO tbl_TextArray(key, tags)
VALUES 
('first', '{aa,fe,gr,fh}'::text[]),
('sec', '{tr,we,et,ui,er}'::text[]),
('third', '{we,gh,fv,dc,sx}'::text[]);

UNNEST() WITH ORDINALITY:

SELECT key, ArrayOrder, tag
FROM tbl_TextArray, unnest(tags) 
WITH ORDINALITY As T (tag, ArrayOrder);

The Result:

dbrnd=# SELECT key, ArrayOrder, tag
dbrnd-# FROM tbl_TextArray, unnest(tags)
dbrnd-# WITH ORDINALITY As T (tag, ArrayOrder);
  key  | arrayorder | tag
-------+------------+-----
 first |          1 | aa
 first |          2 | fe
 first |          3 | gr
 first |          4 | fh
 sec   |          1 | tr
 sec   |          2 | we
 sec   |          3 | et
 sec   |          4 | ui
 sec   |          5 | er
 third |          1 | we
 third |          2 | gh
 third |          3 | fv
 third |          4 | dc
 third |          5 | sx
(14 rows)

I have already written a couple of articles about the PostgreSQL JSON Data type and its different type of operations.

PostgreSQL 9.4: The JSON data type is Awesome (Part 1/3)

PostgreSQL: How to convert Table Data into JSON formatted Data?

In this post, I am going to share one more demonstration about PostgreSQL JSON.

In our system, I have stored communication message information in the form of JSON. This JSON column contains lots of different types of elements.
Now one of module required to fetch this JSON array elements into a form of STRING Array only. (Something like comma separated).

We have different type of JSON functions and operator so I have achieved this solution using jsonb_array_elements.

Below is a full demonstration of this:

Create one table with sample data:

CREATE TABLE tbl_TestJsonArray
(
	ID INT
	,JsonData JSONB
);

INSERT INTO tbl_TestJsonArray
VALUES (1,'{"Name": ["Anvesh","Roy","Jenny","Neevan"]}');

SQL Query to convert JSON elements into String Array:

SELECT 
	ID
	,(
		SELECT string_agg(trim(JsonString::text, '"'), ', ')
		FROM jsonb_array_elements(JsonData->'Name') JsonString
	) AS StringArray
FROM   tbl_TestJsonArray;

id  |       StringArray
----------------------------------
   1   | Anvesh, Roy, Jenny, Neevan