More records after sort

Hello,

I'm facing a strange behaviour and I don't understand why. From a wider query plan, https://explain.dalibo.com/plan/7yh ,a table is scanned and filter based on its primary key, returning 98 records. Then, those records are sorted on another field, and the output is 758,247,643 records.

What can make PostgreSQL to generate records while sorting? What can I do to understand why this is occuring?

                           ->  Sort  (cost=228.52..228.76 rows=98 width=16) (actual time=1.502..31540.651 rows=758247643 loops=1)
                                 Sort Key: i.currency_id
                                 Sort Method: quicksort  Memory: 29kB
                                 ->  Index Scan using account_invoice_pkey on account_invoice i  (cost=0.29..225.28 rows=98 width=16) (actual time=0.035..1.481 rows=98 loops=1)
                                       Index Cond: (id = ANY ('{3839,6912,7164,11026,6479,9973,3599,11306,4092,10652,2732,8625,198,10536,5876,7864,5498,13080,4660,8948,597,10762,12573,11613,12905,11483,11227,12876,4470,8954,5628,4386,9321,4398,11595,7125,8116,1231,1610,6828,2105,9658,1616,5735,9066,4631,51,1185,11736,9579,4303,9983,12759,3889,4667,11258,9423,11855,6555,3164,7597,5596,10396,620,10330,4082,926,3252,5375,8118,7141,3500,12065,2794,2367,12088,7454,7998,11439,8893,6304,10814,7723,4393,3901,3383,5770,5857,4746,1858,5320,4574,8314,11914,7930,7308,6228,3627}'::integer[]))

I can of course describe data model or full query.

Thanks again for reading me,

Nicolas.