Removing an element from an array in a MongoDB document, and another in a parallel array in the same document, without knowing index ahead of time

I have a document format that consists of two parallel arrays, playerColors and players. Each player object in the players array has an associated color integer in the playerColors array at the same index. How can I construct a query that removes a player by their id and simultaneously removes their associated color integer from the playerColors array?

My initial thought was to use a find query to locate the index of the player, followed by an update query to remove the corresponding entries in both playerColors and players arrays by index. However, would this introduce a race condition if there are other potential updates that modify the arrays?

First of all the data model you are following is not a scalable one. The one suggested in the comments is a better alternative. Having said that, to achieve the update of two arrays in a single query, you can use pipelined form of updates like this:

db.collection.update({},
[
{
$addFields: {
matchingIndex: {
"$indexOfArray": [
"$array2",
"b"
]
}
}
},
{
"$addFields": {
"array1": {
"$cond": {
"if": {
"$lt": [
"$matchingIndex",
0
]
},
"then": "$array1",
"else": {
"$concatArrays": [
{
$slice: [
"$array1",
"$matchingIndex"
]
},
{
$slice: [
"$array1",
{
$add: [
1,
"$matchingIndex"
]
},
{
$size: "$array1"
}
]
}
]
}
}
},
"array2": {
"$cond": {
"if": {
"$lt": [
"$matchingIndex",
0
]
},
"then": "$array2",
"else": {
"$concatArrays": [
{
$slice: [
"$array2",
"$matchingIndex"
]
},
{
$slice: [
"$array2",
{
$add: [
1,
"$matchingIndex"
]
},
{
$size: "$array2"
}
]
}
]
}
}
}
}
},
{
"$unset": "matchingIndex"
}
])

In this query, we first find a matching index, for the element we want to delete from array2. After that, we modify array1 and array2 as follows: if matchingIndex is negative we leave the arrays unchanged, otherwise, we generate a new array by splicing and concatenating them. You can modify the example, as per your use case.

Playground link.