1.2.6 Odometer Tab and Distance Traveled Chart Changes.

[hargata]

Introduction

Good day, in 1.2.6 there will be some changes on the odometer tab along with the Distance Traveled chart available on the reports page. Below I will list the reason(s) for these changes as well as what you as the user will need to do going forward.

Reasons

We introduced the distance traveled chart in 1.2.0 and it has since spurred quite a few discussions and questions regarding how the distance traveled per month is calculated such as #318 The biggest issue we have faced was that it is very difficult and expensive to determine the distance traveled per month by users solely based on the singular odometer readings across multiple tabs(Odometer, Service/Repair/Upgrades/Fuel).

At the time, we picked the option of least effort short of redesigning how the app handles odometer readings by calculating the difference between the Max and Min odometer reading given a specific month, but this has only spurred more questions. What we have learned is that users were likely only inserting one odometer reading per month and there is no hard and fast rule that specifies when they have to insert an odometer reading.

The Problem with Interpolating Distance Traveled from Odometer Readings

The world pretty much runs on the Gregorian calendar, which dictates certain months have either 30 or 31 days except February which has 28 or 29 days. This is important, because if a user only inserts an odometer reading once a month on say February 15th and their next odometer reading was inserted on April 10th, the distance traveled chart will show a total distance traveled of 0 for the months February, March, and April, because with only one odometer reading per month, the max and min odometer reading is the the same and subtracting them from one another will result in 0. The obvious answer to that would be to interpolate the distance traveled between February 15th and April 10th; however, the calculations of interpolating data can get very expensive, very quickly, it more or less have to perform the following:

1. Iterate through all the months of the year that has odometer readings.
2. Determine if it's a leap year.
3. Calculate amount of days between February 15th and next record(in this example it's April 10th, but could be in any subsequent months, March, April, May, etc...)
4. Calculate days between February 15th and end of the month(February 28th or 29th depending if leap year)
5. Calculate full months(if no records in March) and how many days those months have.
6. Calculate days from beginning of April to April 10th.
7. Calculate the average distance/day.
8. Apply the distance per day across all the months.

It doesn't seem too bad on the surface, until you realize it(the app) has to do this for every month, every year, and if we're calculating for the month of January, it will have to do this with data of the previous year, e.g.: Interpolating distance for January 2024 will have to look for the last odometer record in the year 2023 and then do all of the steps above.

Initial testing has shown that this can potentially tack on an additional minute or 2 depending on amount of records, with about 1000 records we saw a 10 minute long processing time. It is simply not feasible.

The current workaround is that we encourage the user to create an odometer reading at the beginning and end of each month, as outlined here. Problem with this is that some users don't really see the point in creating an entry on the last day of the previous month(e.g.: February 29th) and the beginning of the current month(e.g.: March 1st), and you know what, we agree. It's not practical. Chances are it will have the same odometer reading unless you decided to drive a ton of miles overnight.

Changes

Odometer Tab

Odometer records will now have an additional, optional field called "Initial Odometer", the current "Odometer" field will still be called "Odometer". There will now be a "Distance" column added to the odometer tab that will display the distance traveled between the Initial Odometer and current Odometer. If left blank, the initial odometer field will be populated with the last reported odometer reading in the odometer tab.

Existing Data

If you have a ton of existing odometer records, the app will automatically update those to have an initial odometer reading which basically uses the odometer reading of the last record.

So if you have two odometer records: February 1st with 12000 miles and February 15th with 15000 miles it will convert it to the following:

Date	Initial Odometer	Odometer	Distance
February 1st	12000	12000	0
February 15th	12000	15000	3000

Note that for the very first record the initial odometer reading will always match the ending odometer reading so that the distance traveled is 0.

Automatic Odometer Insert

When this setting is checked, the auto odometer insert from service/repair/upgrade/fuel records will automatically insert an odometer reading with the initial reading being the last reported odometer reading in the odometer tab.

API

You will be given the option to add an optional "initialOdometer" parameter, if not provided or default to 0, it will auto populate with the last reported odometer reading in the odometer tab.

Distance Traveled Chart

The distance traveled chart in the Reports tab will now solely be based off the "Distance" column in the Odometer tab. It will no longer attempt to calculate the min and max mileage across the different tabs(service/repair/upgrade/fuel)

Action Items(what you have to do)

• Mentally prepare for the changes that are coming to the odometer tab.
• Expect a slightly longer loading time when loading the Odometer tab for the first time after upgrading.
• If you have been following the best practices guide, you might have some significant cleaning up to do with your records especially the ones in the beginning and end of each month. It doesn't really affect the integrity of the data, just more of an aesthetic thing.
• Update any existing APIs / third party integration scripts you might have.

When will these changes be released

1.2.6 is scheduled to be released 03/15/2024 but can potentially be delayed depending on dev circumstances.