Help me choose a database

Question

Database

Good afternoon!

Need advice on choosing a storage system. Output data: a potentially unlimited array of numeric data, for example:

ID VALUE
1 10.01
2 11.13
3 9.78
4 10.00
5 9.99
6 12.45
... ...

It is required to select a storage that would allow selecting data according to the conditions of their mutual relations, for example, to select the values ​​of X _i , which are local maxims:
where X _i+1 < X _i > X _i-1 .

Such a condition is the simplest, more complex ones are possible, but they have one thing in common: it is required to compare the current value with any other, in order of increasing index (or decreasing). That is, for example, there is some value X _i , it is required to find the value of Y _j closest by index value , such that Y _j > X _i , and j > i .

Answer 1

SELECT *
FROM myTable t1
JOIN myTable t2
    ON t1.Id < t2.Id
    AND t1.Value > t2.Value
WHERE t2.Id = 100
ORDER BY t1.Id DESC
LIMIT 1;

This is so, by the way :)
If you need to make such a selection for all Ids, then you can make a subquery, or GROUP BY.

Answer 2

It looks like stock quotes :) It's
hard to advise blindly without knowing the type of your requests, but your structure is called "time series" (time series). There is a list of software for working with them, for example, here: ces.stat.ucla.edu/software/time-series-analysis . You, I think, will not only have to search for them, but also transform - scale, apply filters, remove noise, etc.

Answer 3

I think that it doesn’t matter ... competent ability to compose SQL queries drives ...

Answer 4

For such simple tables, you can also take a look at nosql solutions. Perhaps they will show themselves better under such data and conditions.

Answer 5

For such a formalized task, if you need maximum speeds, you can also make your own bicycle using the same C, for example, since the task is very simple.

Answer 6

For such tasks, it would be much more correct to store data in memory and dump them, say, on disk from time to time so as not to lose them. I don’t see any special applications for sql or nosql solutions.

Answer 7

Riak and compute everything with distributed MapReduce