How can I speed up SQL deletes?

How can I speed up SQL deletes?

5 Answers

1. Make sure your log is adequately sized so that growth events don’t slow you down.
2. If you are deleting the whole table, use TRUNCATE or DROP / CREATE .
3. If you are deleting most of the table, use SELECT INTO to put the data you want to keep into another table, then TRUNCATE , then move the small portion back.

Why is my Postgres query so slow?

PostgreSQL attempts to do a lot of its work in memory, and spread out writing to disk to minimize bottlenecks, but on an overloaded system with heavy writing, it’s easily possible to see heavy reads and writes cause the whole system to slow as it catches up on the demands.

How do I Soft delete in PostgreSQL?

Definitions: A “hard” delete is when rows are deleted using DELETE FROM table WHERE A “soft” delete is when rows are deleted using UPDATE table SET deleted_at = now() WHERE …

Do indexes slow down deletes?

If you update a table, the system has to maintain those indexes that are on the columns being updated. So having a lot of indexes can speed up select statements, but slow down inserts, updates, and deletes.

Why soft delete is bad?

One of the major problem for soft delete is those unwanted data will potentially affects the db performance. Several years ago one of my Client requested me to do soft delete on all database items, my solution to that is to move all “deleted” items to a backup table, instead of leaving it to the current running tables.

Should we ever delete data in a database?

Actual database performance may not require deleting data, unless the data sets are huge. Even a table with millions of rows and dozens of columns may not need deleting if you partition it properly and ensure your queries always use the proper partitions.

How long does delete query take in PostgreSQL?

We are running a very simple delete query on it which takes 45 minutes to complete: 1- Added an index on timestamp column, which did not help. 2- Removed the rows in batches of 20 or 50 using a function, which was still awfully slow.

How to speed up delete time in PostgreSQL?

Continue until you’re happy with the single line delete response time (I got one query to go from 25.6 seconds to 15 ms or about 1700x faster simply by adding different indexes). Then you can proceed to complete your full delete without any hacks.

Which is the best way to batch delete in PostgreSQL?

The best option is to run a batch delete so that triggers are not hit. Disable the triggers before deleting, then re-enable them. This saves you a very large amount of time. For example: ALTER TABLE tablename DISABLE TRIGGER ALL; DELETE …; ALTER TABLE tablename ENABLE TRIGGER ALL; A major key here is you want to minimize the depth of subqueries.

How to return deleted rows in PostgreSQL table?

To return the deleted row (s) to the client, you use the RETURNING clause as follows: DELETE FROM table_name WHERE condition RETURNING (select_list | *) Code language: SQL (Structured Query Language) (sql) The asterisk (*) allows you to return all columns of the deleted row from the table_name.