https://www.postgresql.org/docs/current/storage.html
https://www.postgresql.org/docs/current/storage-page-layout.html
https://postgrespro.ru/docs/postgrespro/current/storage-page-layout
hot
https://www.postgresql.org/docs/current/storage-hot.html
    ! pg_stat_all_tables

!!!
https://github.com/dmagda/DevMastersDb/blob/main/postgres/postgres_mvcc_backstage.md
    https://postgrespro.com/blog/pgsql/5967910
    https://habr.com/ru/companies/postgrespro/articles/449704/
    https://habr.com/ru/companies/postgrespro/articles/483768/
https://opensource-db.com/postgresql-mvcc/
    !!! *from -> show hidden columns (ctid, xmin, xmax)
https://cloud.google.com/blog/products/databases/deep-dive-into-postgresql-vacuum-garbage-collector
    !!!
https://dev.to/nilelazarus/series/23873
    https://dev.to/nilelazarus/demystifying-the-internals-of-postgresql-chapter-5-2pe4

2024
Otus - MVCC, vacuum and autovacuum in PG ru 53:00 of 1:22:40
    https://www.youtube.com/watch?v=mrobq6Ggggc
    ! 12:00 - pg_size_pretty, pg_total_relation_size
    ! 25:00 - insert
    !   add new record with xmin=txid_current(), xmax=0
    !   delete - xmax=txid_current()
    !   update - for old record we do delete
    !     xmax=txid_current(), 
    !   for new one - insert
    !     xmin=txid_current(), xmax=0
    ! 26:00 rollback - xmax_aborted
    ! 28:00 select *, xmin, xmax, cmin, cmax, ctid from user_data;
    ! 29:00 select * from pg_stat_user_tables;
    !   n_live_tup, n_dead_tup, ratio%, last_autovacuum, ...
    ! 31:00 - ... from heap_page_items(get_raw_page('user_data', 0)) -- neet to set ext
    !   https://www.postgresql.org/docs/current/pageinspect.html
    ! 44:00 vacuum_cost_delay, vacuum_cost_limit, vacuum_cost_page_miss, vacuum_cost_page_dirty
    ! 55:00 vacuum verbose <rel>;
2022
https://habr.com/ru/companies/quadcode/articles/671254/
    !
2020
https://postgrespro.com/blog/pgsql/5967856
????
Rogov - MVCC
    https://habr.com/ru/companies/postgrespro/articles/452762/
    https://habr.com/ru/companies/postgrespro/articles/452320/
    https://habr.com/ru/companies/postgrespro/articles/446652/
    https://habr.com/ru/companies/postgrespro/articles/445820/
    https://habr.com/ru/companies/postgrespro/articles/444536/
    https://habr.com/ru/companies/postgrespro/articles/455590/    
    https://habr.com/ru/companies/postgrespro/articles/442804/