How can I store a backgammon board in MongoDB? - mongodb

Question

I am new to NoSQL databases, and even though I've looked for it a lot, I cannot find best practices for this sort of thing.
Backgammon, for those of you who don't know, is a game with a board that has twenty four pips (or slots), and a bar which can contain pieces of any color (pieces which get hit are placed on the bar). Plus, each pip (or slot) can contain one or more pieces of the same color.
The structure I'm looking for should be optimized to help me calculate two things quickly:
Is the move valid? For a move to be valid, the target slot must have less than two pieces of the opposing color. For example, if I want to move to slot 4, and I'm black, slot 4 must either have only 1 white piece (that will get hit after this move), or have no pieces, or have one or more black pieces.
What is every player's pip count? The pip count is the number of dice I must have, in total, to win the game. For this, I need to be able to quickly retrieve the location of pieces of one color all throughout the board. The calculation will be done locally, outside of the database. If you are curious about how the pip count will be calculated after I retrieve the query results, check out Beginner's Guide to Counting Pips.
The structure I thought of is something like this:
{
1: {
color: 'black',
pieces: 2
},
2: {
color: 'white',
pieces: 1
},
3: {}
// etc, until 24
24: {}
bar: {
{
color: 'white',
pieces: 1
}
}
}
The only problem with this approach, as you can no doubt see, is the bar. Since the bar can contain pieces of any color, I had to create another object inside the bar key, so that I could later on add pieces whose color is black if needed.
Is there a better structure? Also, I'd appreciate tips and tricks on how well/awful this structure will perform.

Answer 1

Considering the fact that you have only 1 document with a relative constant size, you can safely assume that this 1 document will be kept in memory, thus you shouldn't worry too much about performance issues more so that it's only one document - it's basically asking how good will my HashMap perform...
If it was up to me, I would split bar into 2 bars - bBar and wBar (as in real life by the way, each player has his own bar next to him to keep his own "eaten" pieces).
By the way, any calculations that involve best moves and such should happen in memory. You should not store intermediate calculation results in the DB