Does VACUUM; with no other arguments run per database or per current schema on amazon redshift?
The reason I am asking this is because when VACUUM completes on one schema and I change the default schema, and run it again, it takes a whole hour to complete.
VACUUM with no arguments runs on the entire database. See the Amazon Redshift VACUUM doc: "Reclaims space and resorts rows in either a specified table or all tables in the current database.".
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We are trying to use redshift serverless. It shows the query history is stored in the table sys_query_history.
But looking at the table, the query_text field has a 4000 characters limit. They'd truncate the query. Is there another way to get the full executed queries in Redshift Serverless?
I have 900+ postgres schemas (which collectively hold 40,000 tables) that I'd like to drop. However, it appears that it wants me to vacuum everything first, because I get this whenever I try to drop a schema.
ERROR: database is not accepting commands to avoid wraparound data loss in database
Is there a way to drop a large number of schemas without having to vacuum first?
IS there any problem is running the vacuum command. It is like a garbage collection for a database. I use postgre database and I use this command before doing any major work like backup or creating a sql scripts of the whole database.
VACUUM reclaims storage occupied by dead tuples. In normal PostgreSQL operation, tuples that are deleted or obsoleted by an update are not physically removed from their table; they remain present until a VACUUM is done. Therefore it's necessary to do VACUUM periodically, especially on frequently-updated tables.
You've got two choices. Do the vacuum, or drop the whole database. xid wrap-around must be avoided.
https://blog.sentry.io/2015/07/23/transaction-id-wraparound-in-postgres
There is not much you can do, except VACUUM oder dropping the database.
In addition, if you don't do the VACUUM, the database will not work for anything, not just for the schemas you want to drop.
Is it possible to view the history of all vacuum and analyze commands executed for a specific table in Amazon Redshift.
You can check the history of VACUUM run using query history tables - SVL_STATEMENTTEXT etc.
Documentation for more details.
Fair warning, these history tables only store data for last 15 days, so in the long run you might wanna take back ups.
You can also check the current sorted-unsorted blocks for a current table in Redshift, that gives a good idea of how the table data is stored.
Documentation for more details.
I have postgres table with jsonb field. Field size is about 2-4kb per row. My application updates 100k rows per day 2000 times (changing 0.1-0.5% of data in field). Autovacuum is off, vacuum full runs every day at night.
Vacuum frees about 100-300gb every day and takes a long time to go causing application downtime.
The question is: can I solve this problem with jsonb field or I must split that field onto other simple tables?
If your concern is long down time then yes VACUUM FULL requires exclusive lock on the table being vacuumed for entire period of run.
I'll suggest you to try pg_repack extension or pg_squeeze extension - depending upon postgres version. Unlike CLUSTER and VACUUM FULL it works online, without holding an exclusive lock on the processed tables during processing. These extensions are really easy to install and use in postgres. These extensions can reduce your downtime significantly and also will help to reduce runs of VACUUM FULL.
I am running an application in a particular server which updates a postgres database table.Is there any way that I can retrieve all the queries executed to that database (may be my table) from a -period of time if I have admin privilege?
You can install the extension pg_stat_statements which will give you a summary of the queries executed.
Note that the number of queries that are stored in the table pg_stat_statements is limited (the limit can be configured). So you probably want to store a snapshot of that table on a regular basis. How often depends on your workload. Increasing pg_stat_statements.max means you can reduce the frequency of taking snapshots from that table.