英文:
n_dead_tup vs n_tup_del in Postgres
问题
n_dead_tup vs n_tup_del 在 pg_stat_all_tables 中的区别是什么？
我理解的是 n_dead_tup 显示了被删除的元组数量，以及作为更新的一部分被删除的旧元组。
n_tup_del 与 n_dead_tup 有什么不同？我能够在执行 VACUUM 后将 n_dead_tup 清零，但 n_tup_del 中仍然有一些计数。
英文:
What is the difference between n_dead_tup vs n_tup_del in pg_stat_all_tables?
What I understand is n_dead_tup shows the number of tuples that were deleted and the old tuples that were deleted as part of updates.
How does n_tup_del differ from n_dead_tup. I am able to clear the n_dead_tup to zero after doing vacuum and I have some count in n_tup_del
答案1
得分: 1
n_tup_del 是永久累积计数（直到重置或崩溃）。n_dead_tup 是一个当前计数器，会在清理操作时减少。它还会在更新操作以及中止的插入和更新操作中增加。
英文:
n_tup_del is permanent cumulative count (until reset, or a crash). n_dead_tup is a current counter which gets decremented by vacuum. It also gets incremented by updates, and by inserts and updates which abort.
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