SELECT id, key, pg_column_size(value::text) FROM test_jsonb_toaster, jsonb_each(jb);

id | key | pg_column_size

----+-------+----------------

1 | key1 | 12

1 | key2 | 16

1 | key3 | 24

1 | key4 | 40

1 | key5 | 72

1 | key6 | 136

1 | key7 | 264

1 | key8 | 520

1 | key9 | 1032

1 | key10 | 2056

2 | key1 | 16

2 | key2 | 24

2 | key3 | 40

2 | key4 | 72

2 | key5 | 136

2 | key6 | 264

2 | key7 | 520

2 | key8 | 1032

2 | key9 | 2056

2 | key10 | 4104

3 | key1 | 24

3 | key2 | 40

3 | key3 | 72

3 | key4 | 136

3 | key5 | 264

3 | key6 | 520

3 | key7 | 1032

3 | key8 | 2056

3 | key9 | 4104

3 | key10 | 8200

4 | key1 | 40

4 | key2 | 72

4 | key3 | 136

4 | key4 | 264

4 | key5 | 520

4 | key6 | 1032

4 | key7 | 2056

4 | key8 | 4104

4 | key9 | 8200

4 | key10 | 16392

5 | key1 | 72

5 | key2 | 136

5 | key3 | 264

5 | key4 | 520

5 | key5 | 1032

5 | key6 | 2056

5 | key7 | 4104

5 | key8 | 8200

5 | key9 | 16392

5 | key10 | 32776

6 | key1 | 136

6 | key2 | 264

6 | key3 | 520

6 | key4 | 1032

6 | key5 | 2056

6 | key6 | 4104

6 | key7 | 8200

6 | key8 | 16392

6 | key9 | 32776

6 | key10 | 65544

7 | key1 | 264

7 | key2 | 520

7 | key3 | 1032

7 | key4 | 2056

7 | key5 | 4104

7 | key6 | 8200

7 | key7 | 16392

7 | key8 | 32776

7 | key9 | 65544

7 | key10 | 131080

8 | key1 | 520

8 | key2 | 1032

8 | key3 | 2056

8 | key4 | 4104

8 | key5 | 8200

8 | key6 | 16392

8 | key7 | 32776

8 | key8 | 65544

8 | key9 | 131080

8 | key10 | 262152

9 | key1 | 1032

9 | key2 | 2056

9 | key3 | 4104

9 | key4 | 8200

9 | key5 | 16392

9 | key6 | 32776

9 | key7 | 65544

9 | key8 | 131080

9 | key9 | 262152

9 | key10 | 524296

10 | key1 | 2056

10 | key2 | 4104

10 | key3 | 8200

10 | key4 | 16392

10 | key5 | 32776

10 | key6 | 65544

10 | key7 | 131080

10 | key8 | 262152

10 | key9 | 524296

10 | key10 | 1048584

(100 rows)