I tried to DELETE about 7 million rows at once, and the query went up to 15% of the RAM (120 GB in total), which pushed some indexes out and the server load went up to 250, so I had to kill the query.
The involved table does not have neither foreign keys referring to other tables, nor other tables refer to it. The size of the table itself is 19 GB (15% of 120 GB). So why the DELETE tried to put the entire table in memory, or what did it do to take so much memory?
I am using 9.4.5.
Regards,
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Kouber Saparev