26

Re: Tjapnichnyj search of the goods in a dial-up of attributes

Akina wrote:

mayton , give we count...
The list on 10 the goods. Each goods have some characteristics (if to look on the same jandeks-market on the average at a category of their goods there 20-30, it is rare more than fifty). Besides extremely rarely the characteristic with very extensive value range comes across, personally I did not see any in which the amount of values would exceed 64 (or at least came nearer to it). But if to take on a maximum... Let 20 the goods on 50 characteristics which coding demands 64 bits, it turns out the order of hundred megabytes. Not great volume. And with the registration of that the table strictly RO - we load a table copy in storage, and here to you already a minus a disk subsystem and a gain of speed.

Some additions. Really at the goods normally no more than fifty unique characteristics.
But your assumption of that that in the whole category of the goods (TV sets, refrigerators) 50 characteristics - is incorrect.
Technologies change each 2-3 years and new characteristics are added to the new goods (SmartTv=true);
And old gradually leave (VGA =true).

27

Re: Tjapnichnyj search of the goods in a dial-up of attributes

[quote =] Further.  you already have statisticans. Us two interest. The first is a frequency of usage of this or that characteristic for a filtration. The second is a selectivity of the characteristic. It I to what? To what to index on all possible sets of characteristics - occupation absolutely hopeless, but here to select the main groups, which indexing gives the considerable effect (frequent applicability and high selectivity) it is necessary. It is very desirable, if the data suffices, to select steams, and even triples, the most demanded groups of characteristics for composite indexes. The index from set more than 3 fields, seems to me, will be , and will work exceptional as a prefix from 2-3 water - and then  to a goat a bayan?

I agree about selectivity. But such characteristic as frequency of usage we cannot in any way
To detect. Actually... It is the marketing information which at us appears already in a maintenance phase
Shop. Therefore now we cannot use it as 100 % of the reliable actor. Though to put in the retrieval
The mechanism popular checkbox we can.
Further. The index from more than 3 fields - is important and necessary. I tell it to you as the regular client of shops of electronics.
And as we cannot at the given stage to define marketing  (or ) one attribute
Over another that I all the same suggest to index all.