Emi Lu wrote:


Tried to run:

delete from tableA where id <600000;

It is extremely slow.

id is integer and also the primary key. tableA has around 90000 records.

(I do not want to run truncate since I have some foreign key constraint
setup based on tableA. Besides not all data I want to delete; only part
of them).



Since you have some FK constrains on A, so delete each line of A will
confirm that it is not depended, which involves a lookup on the dependent
table. Do you have indexes built on these dependents?


No, I do not have indexes setup for those dependents.

If I setup index for those columns, it will speed up the deletion, right?

Thank you.


http://archives.postgresql.org/pgsql-general/2003-02/msg01615.php

If deletioin is 80% data, will index helps?

Emi



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