# Source: https://getlago.com/docs/guide/migration/migration-to-v1.20.0.md

> ## Documentation Index
> Fetch the complete documentation index at: https://getlago.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Migration to v1.20.0

Dear Lago Community, 👋

We will soon release a new version of Lago, including infrastructure improvements to ensure scalability.

# What changes will be made?

One of the changes concerns zero fees, which have no accounting value but still require compute resources. In the next and subsequent versions, Lago will no longer generate these fees.

We know that some of our users have been relying on the `invoice.fees.from_date` and `invoice.fees.to_date` fields linked to zero fees for certain internal processes.
Therefore, we have introduced a new `invoice.billing_periods` field to provide you with the dates of the billing period for each type of charge (see example below).

```diff  theme={"dark"}
{
  "webhook_type": "invoice.created",
  "object_type": "invoice",
  "invoice": {
    "lago_id": "__INVOICE_ID__",
    // TRUNCATED
+    "billing_periods": [
+      {
+        "lago_subscription_id": "__SUBSCRIPTION_ID__",
+        "external_subscription_id": "__EXT_SUBSCRIPTION_ID__",
+        "lago_plan_id": "__PLAN_ID__",
+        "subscription_from_datetime": "2024-12-21T00:00:00Z",
+        "subscription_to_datetime": "2025-01-20T23:59:59Z",
+        "charges_from_datetime": "2024-12-21T00:00:00Z",
+        "charges_to_datetime": "2025-01-20T23:59:59Z",
+        "invoicing_reason": "subscription_periodic"
+      }
+    ]
    // TRUNCATED
  }
}
```

In addition, if you are running a self-hosted instance of Lago, upgrading it will trigger a migration to delete existing zero fees.
This migration may take some time, so if your database contains a large volume of fees, we recommend that you perform the migration before deploying the new version (see steps below).

<Note>
  Cloud users do not need to follow the instructions below, as the migration will be performed by the Lago Team.
</Note>

# What should self-hosted users do?

## 1. Check the number of fees

You can run the following SQL query to check the number of fee objects that will be removed from the database.
If the result is greater than 1M (one million), you should perform the migration before deploying the new version.

```
SELECT count(fees.id) 
FROM fees
        INNER JOIN invoices ON fees.invoice_id = invoices.id
WHERE
        invoices.status IN (1, 2, 6) -- finalized, voided and closed
        AND fees.fee_type = 0 -- charge
        AND fees.amount_cents = 0
        AND fees.units = 0
        AND fees.pay_in_advance = false
        AND fees.true_up_parent_fee_id IS NULL
        AND fees.id NOT IN (
          SELECT f.true_up_parent_fee_id
          FROM fees f
          WHERE f.true_up_parent_fee_id IS NOT NULL
        )
        AND fees.id NOT IN (
          SELECT fee_id
          FROM adjusted_fees
          WHERE adjusted_fees.fee_id IS NOT NULL
        )
```

## 2. Remove zero fees

To delete existing zero fees, open a Rails console in a production instance using `bundle exec rails c` and run the following script:

```
class FeesTax < ApplicationRecord; end

sql = <<~SQL
  SELECT fees.id FROM fees
  INNER JOIN invoices ON fees.invoice_id = invoices.id
  WHERE
    invoices.status IN (1, 2, 6) -- finalized, voided and closed
    AND fees.fee_type = 0 -- charge
    AND fees.amount_cents = 0
    AND fees.units = 0
    AND fees.pay_in_advance = false
    AND fees.true_up_parent_fee_id IS NULL
    AND fees.id NOT IN (
      SELECT f.true_up_parent_fee_id
      FROM fees f
      WHERE f.true_up_parent_fee_id IS NOT NULL
    )
    AND fees.id NOT IN (
      SELECT fee_id
      FROM adjusted_fees
      WHERE adjusted_fees.fee_id IS NOT NULL
    )
    LIMIT 1000
SQL

while (ids = ActiveRecord::Base.connection.select_all(sql).rows.map(&:first)).any?
  FeesTax.where(fee_id: ids).delete_all
  Fee.where(id: ids).delete_all

  puts "Deleted #{ids.size} fees - #{Time.current.iso8601}"
end

puts "All fees have been removed - #{Time.current.iso8601}"
```

It can take a long time to complete this operation. In case of error, you can retry until the script outputs `All fees have been removed - {time}`.

# What is the timeline?

In order to streamline the billing process, we recommend that you perform the migration as soon as possible, and deploy `v1.20.0` as soon as it's available (we will release it **before the end of January**).

Please let us know if you have any questions, we will be happy to help. Thanks!

The Lago Team