RDS w/Postgres GB-Mo usage keep growing without reason.

Hello,

As a student, I'm currently training in AWS architecture.

My project is the following:

• Using a python script to scrape data every day, which is stored in an S3 bucket (700kb CSV file)
• Lambda function triggered when the file is added, which runs a script to clean and update an RDS database with Postgres

My financial framework is in the freetier offered by AWS.

My problem is as follows: in the monitoring, I see the GB-Mo usage increasing by one Gb every one or two days (as a reminder of the free tier: 20.0 GB-Mo for free for 12 months as part of AWS Free Usage Tier (Global-RDS:StorageUsage)).

However, the file uploaded each day does not exceed 700 kB. I've deactivated automatic backup, and the log files (one per hour at 4 kB per file) are a maximum of 120 kB/day.

The current database consists of two tables, one of 800 kB and one of 2360 kB.

This means that the size of the database increases by about 1 MB per day, yet every 24 to 48 hours, usage increases by one GB, and I can't figure out why.

I launched my instance in the middle of the month, so I shouldn't exceed the free tier this month, but I'm worried about next month.

Do you know how I can solve this problem? Either a misconfigured element is increasing storage usage, or I've misunderstood the notion of 20 GB-Mo...

Thanks in advance!