pgexplode 0.2.0

Utility for exploding a PostgreSQL table (and any related data) into separate schemas.

pgexplode

A utility for exploding a PostgreSQL table (and any related data) into separate schemas.

Example

Imagine the following table structure and data in a database named exploder_test:

CREATE TABLE tenant (id serial PRIMARY KEY, slug varchar);
CREATE TABLE related (id serial PRIMARY KEY, tenant_id integer NOT NULL REFERENCES tenant(id), value varchar);
INSERT INTO tenant (id, slug) VALUES (1, 'alpha'), (2, 'beta');
INSERT INTO related (tenant_id, value) VALUES
    (1, 'alpha-value-1'),
    (1, 'alpha-value-2'),
    (1, 'alpha-value-3'),
    (2, 'beta-value-1'),
    (2, 'beta-value-2'),
    (2, 'beta-value-3'),
    (2, 'beta-value-4'),
    (2, 'beta-value-5')
;

Running the following command:

python -m pgexplode -d exploder_test -t tenant -s slug

Would create two schemas, alpha and beta and copy the table data as follows:

+ alpha
  ~ tenant: 1
  ~ related: 3
+ beta
  ~ tenant: 1
  ~ related: 5

Outputting/Debugging SQL

Adding an --sql flag to the command above will output the SQL being run, which can be helpful when tweaking or debugging:

-- alpha
DROP SCHEMA IF EXISTS "alpha" CASCADE;
CREATE SCHEMA "alpha";
CREATE TABLE "alpha".tenant (LIKE public.tenant INCLUDING ALL);
INSERT INTO "alpha".tenant (SELECT * FROM tenant WHERE id = 1);
CREATE TABLE "alpha".related (LIKE public.related INCLUDING ALL);
INSERT INTO "alpha".related (SELECT related.* FROM related JOIN tenant ON related.tenant_id = tenant.id WHERE tenant.id = 1);
CREATE SEQUENCE "alpha".related_id_seq;
ALTER SEQUENCE "alpha".related_id_seq OWNED BY "alpha".related.id;
ALTER TABLE "alpha".related ALTER id SET DEFAULT nextval('alpha.related_id_seq'::regclass);
CREATE SEQUENCE "alpha".tenant_id_seq;
ALTER SEQUENCE "alpha".tenant_id_seq OWNED BY "alpha".tenant.id;
ALTER TABLE "alpha".tenant ALTER id SET DEFAULT nextval('alpha.tenant_id_seq'::regclass);
ALTER TABLE "alpha".related ADD CONSTRAINT related_tenant_id_fkey FOREIGN KEY (tenant_id) REFERENCES "alpha".tenant (id);

-- beta
DROP SCHEMA IF EXISTS "beta" CASCADE;
CREATE SCHEMA "beta";
CREATE TABLE "beta".tenant (LIKE public.tenant INCLUDING ALL);
INSERT INTO "beta".tenant (SELECT * FROM tenant WHERE id = 2);
CREATE TABLE "beta".related (LIKE public.related INCLUDING ALL);
INSERT INTO "beta".related (SELECT related.* FROM related JOIN tenant ON related.tenant_id = tenant.id WHERE tenant.id = 2);
CREATE SEQUENCE "beta".related_id_seq;
ALTER SEQUENCE "beta".related_id_seq OWNED BY "beta".related.id;
ALTER TABLE "beta".related ALTER id SET DEFAULT nextval('beta.related_id_seq'::regclass);
CREATE SEQUENCE "beta".tenant_id_seq;
ALTER SEQUENCE "beta".tenant_id_seq OWNED BY "beta".tenant.id;
ALTER TABLE "beta".tenant ALTER id SET DEFAULT nextval('beta.tenant_id_seq'::regclass);
ALTER TABLE "beta".related ADD CONSTRAINT related_tenant_id_fkey FOREIGN KEY (tenant_id) REFERENCES "beta".tenant (id);

You can see in addition to simply creating copies of each table, pgexplode is also making sure the new tables have their own sequences for serial columns, and tables are properly re-keyed within the new schema.