Filtering out huge emails database

Bspelnl · Jun 6, 2025

Hello guys. What tool would you recommend when it comes to filtering out unsubscribers list from a huge database?
I have excel file with almost 1 million of lines: emails list and other info. Files size is 176,462 KB or so. So that's huge and filtering out just with excel won't work as the computer will get stuck.
Any recommendations? I'm sending emails in big quantities, that's why I need to deal with such huge email databases.

PrimeCove · Jun 6, 2025

Load your unsub list and master list into Pandas, do a .merge() or .isin() check, then export. Way faster and lighter than Excel.

Gogol · Jun 6, 2025

Bspelnl said:
Hello guys. What tool would you recommend when it comes to filtering out unsubscribers list from a huge database?
I have excel file with almost 1 million of lines: emails list and other info. Files size is 176,462 KB or so. So that's huge and filtering out just with excel won't work as the computer will get stuck.
Any recommendations? I'm sending emails in big quantities, that's why I need to deal with such huge email databases.

Is this something you do quite often or is this just a one time thing? If this is a regular thing, I would recommend using rdbms here. This is exactly why you should use something like postgres or mysql to store this kind of data.

I would put a unique index on the email field and also put an index on the status field. That way I can just run something like:

Code:

select email, first_name, last_name from subscribers where status != ‘unsubscribed’

That should take a few hundred milliseconds to execute (might take time to get indexed though, specially if you are importing all the data to mysql/postgres).

p.s. Thread moved to a more suitable section.

suavestamp · Jun 6, 2025

Bspelnl said:
Hello guys. What tool would you recommend when it comes to filtering out unsubscribers list from a huge database?
I have excel file with almost 1 million of lines: emails list and other info. Files size is 176,462 KB or so. So that's huge and filtering out just with excel won't work as the computer will get stuck.
Any recommendations? I'm sending emails in big quantities, that's why I need to deal with such huge email databases.

Hey! For that size, Excel will definitely struggle. I’d recommend using something like Python with pandas, or uploading it to Google BigQuery or a database like MySQL. Much faster and more stable for handling big lists like that.

Filtering out huge emails database

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