Dstore and positioning: tutorial outline about dstore HOT 7 OPEN

on a side note... X- headers are deprecated (http://tools.ietf.org/html/rfc6648) this reminded me to bring this up, i think dstore should stop using them.

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This looks good to me. I agree with Ben, that we should probably eliminate the X- prefix. I tend to think of "natural ordering" as being an order that is deterministic, controlled, and meaningful (when no sort order is defined), but I think that is more conceptual, and I think you basically mean the same thing since you said the server might opt out of that and use an optimization driven order.

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There is the possibility that I have been misusing the term "natural ordering".

To me, "natural ordering" is when you add an item, placing it in a specific "spot" (could be at the end, at the beginning, or in the middle of a collection) and then expect it to find it exactly there when you query the collection without specifying a sorting option.

With "server opting out" I mean this: with "natural ordering", the only meaningful way to do it is by adding a hidden field to the DB table (call it position) and then, every time you add something in a specific spot (or at the end by default), you make sure that sorting by position will result in the order you requested. Again, position is completely hidden to the user who must never worry about its value. (In contrast, the Memory store doesn't need a position field because it will just place the element in the right spot in the array).

There are several ways of keeping natural ordering database-wide, but they are all quite expensive. With MySql, you end up with at least one mass-update per insert/update, to "make space" for example.

So, the server might end up ignoring completely "natural ordering": if so, you can use beforeId, defaultNewToStart, and whatever else you want: if you then ask for a query without specifying any sorting, the collection's order will depend on the database server's mood (basically: very unpredictable).

Makes sense? Should I use a different term rather than "natural ordering"? (Which also means "ordering thing alphabetically so that it makes sense to humans")

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That is exactly what I had in mind with the term, sounds good.

from dstore.

For the tutorial, does it make sense for me to post it here once it's written so that you guys can comment on it etc.? Or shall we close this issue and shall I email it to somebody when I am done? If so, who should I email it to?

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For now, I think you could submit this tutorial in a branch/PR under docs. Thank you for putting this together!

from dstore.

Hi,

OK will do!
The tutorial will be a "beefed up" version of this document, with a nice
introduction etc.

Merc.

On 29 August 2014 04:31, Kris Zyp [email protected] wrote:

For now, I think you could submit this tutorial in a branch/PR under docs.
Thank you for putting this together!

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