autovacuum

sqlite incremental vacuum removing only one free page

由 这一生的挚爱 提交于 2021-01-28 01:58:56
问题 I have changed value of auto_vacuum PRAGMA of my sqlite database to INCREMENTAL. When I run PRAGMA incremental_vacuum; through 'DB Browser for SQlite' application it frees all the pages in the free_list . But when I am running same statement using any SQLite library in C# (e.g. Microsoft.Data.SQLite ), it frees only one page from the free_list I verified this by getting the number in current free_list by running PRAGMA freelist_count before and after running PRAGMA incremental_vacuum

How can I tell if PostgreSQL's Autovacuum is running on UNIX?

由 时光毁灭记忆、已成空白 提交于 2020-01-01 00:59:12
问题 How can one tell if the autovacuum daemon in Postgres 9.x is running and maintaining the database cluster? 回答1: PostgreSQL 9.3 Determine if Autovacuum is Running This is specific to Postgres 9.3 on UNIX. For Windows, see this question. Query Postgres System Table SELECT schemaname, relname, last_vacuum, last_autovacuum, vacuum_count, autovacuum_count -- not available on 9.0 and earlier FROM pg_stat_user_tables; Grep System Process Status $ ps -axww | grep autovacuum 24352 ?? Ss 1:05.33

Postgres pg_toast in autovacuum - which table?

由 感情迁移 提交于 2019-12-21 07:04:14
问题 I have an autovacuum process running on pg_toast: select query, from pg_stat_activity where query like '%autov%'; "autovacuum: VACUUM pg_toast.pg_toast_15404513 " How do I find out what table/index/whatever this pg_toast pertains to? Or is the autovacuum working on something else? 回答1: I think you'll want something like: select n.nspname, c.relname from pg_class c inner join pg_namespace n on c.relnamespace = n.oid where reltoastrelid = ( select oid from pg_class where relname = 'pg_toast

why writes in a table prevent vacuums in another?

由 瘦欲@ 提交于 2019-12-08 03:31:02
问题 Having READ COMMITTED isolation level, idle transactions that have performed a write operation will prevent vacuum to cleanup dead rows for the tables that transaction wrote in. That is clear for tables that were written by transactions that are still in progress. Here you can find a good explanation. But it is not clear to me why this limitation affects also to any other tables. For example: transaction T is started and it updates table B, vacuum is executed for table A while T is in "idle

why writes in a table prevent vacuums in another?

由 百般思念 提交于 2019-12-07 03:52:28
Having READ COMMITTED isolation level, idle transactions that have performed a write operation will prevent vacuum to cleanup dead rows for the tables that transaction wrote in. That is clear for tables that were written by transactions that are still in progress. Here you can find a good explanation. But it is not clear to me why this limitation affects also to any other tables. For example: transaction T is started and it updates table B, vacuum is executed for table A while T is in "idle in transaction" state. In this scenario, why dead rows in A cannot be removed? Here what I did: # show

Postgres pg_toast in autovacuum - which table?

由 吃可爱长大的小学妹 提交于 2019-12-03 23:11:29
I have an autovacuum process running on pg_toast: select query, from pg_stat_activity where query like '%autov%'; "autovacuum: VACUUM pg_toast.pg_toast_15404513 " How do I find out what table/index/whatever this pg_toast pertains to? Or is the autovacuum working on something else? I think you'll want something like: select n.nspname, c.relname from pg_class c inner join pg_namespace n on c.relnamespace = n.oid where reltoastrelid = ( select oid from pg_class where relname = 'pg_toast_15404513' and relnamespace = (SELECT n2.oid FROM pg_namespace n2 WHERE n2.nspname = 'pg_toast') ) It'd be nice
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