I would like to populate the children_ids column with all the ids of the children recursively (+ grandchildren etc.)
If I do it top-bottom I will end up doing extra work since there is no need to go all levels down if I can just compute my IMMEDIATE children "children_ids" and just concatenate all their lists.
create table tree(id int primary key, parent int, children_ids text);
insert into tree (id, parent) values
(273, 0),
(274, 273),
(275, 273),
(277, 273),
(278, 277),
(280, 275),
(281, 280),
(282, 281),
(283, 282),
(284, 282),
(285, 282),
(286, 282),
(287, 282),
(288, 282),
(289, 282),
(290, 281),
(291, 290),
(292, 290),
(293, 290),
(294, 290),
(295, 290);
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I'm sorry, what output format are you looking for? Perhaps an array of all descendants for each founder? (founder int, descendants int[]). I recommend a null for no-known-parent rather than zero. Or just founder int, descendant int? With or without sub-trees?
From:
Marcin Barczynski Date: Subject:
Re: Why does VACUUM FULL pg_class sometimes wait for ShareLock on another transaction after getting AccessExclusiveLock on pg_class?
