postgresql - get a list of columns difference between 2 tables

Question

We are using Redshift which is using Postgres 8.
I need to compare (2) tables which will almost be identical, but the other table will have extra columns so, I need to find out the column difference.

Example:

CREATE TABLE table1 (
    v_id character varying(255) NOT NULL,
    v_created timestamp without time zone NOT NULL,
    abc_102 boolean,
    abc_103 boolean,
    abc_104 boolean,
    def_56 boolean DEFAULT false NOT NULL,
    def_57 boolean DEFAULT false NOT NULL
)

CREATE TABLE table2 (
    v_id character varying(255) NOT NULL,
    v_created timestamp without time zone NOT NULL,
    abc_102 boolean,
    abc_103 boolean,
    abc_104 boolean,
    abc_105 boolean,
    def_56 boolean DEFAULT false NOT NULL,
    def_57 boolean DEFAULT false NOT NULL,
    def_58 boolean DEFAULT false NOT NULL,
)

What query can I use that will give me a list of the column differences?

score 2 · Accepted Answer · answered Apr 20 '16 at 04:44

You can achieve this by selecting all column names from table2 which do not also appear in table1:

SELECT column_name
FROM information_schema.columns 
WHERE table_schema = 'your_schema' AND table_name = 'table2'
    AND column_name NOT IN
    (
        SELECT column_name
        FROM information_schema.columns 
        WHERE table_schema = 'your_schema' AND table_name = 'table1'
    )

postgresql - get a list of columns difference between 2 tables

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