[vdr] Request: E parameter in channels.conf for epg scan

Luca Olivetti luca at ventoso.org
Wed Dec 15 21:07:59 CET 2010


Al 15/12/10 20:35, En/na VDR User ha escrit:
> On Wed, Dec 15, 2010 at 9:21 AM, Luca Olivetti<luca at ventoso.org>  wrote:
>>>> Instead of speculating I actually tried.
>>>> I created a test database with the contents of my channels.conf (only
>>>> containing the number, name, frequency, source, symbol rate and the vpid,
>>>> I
>>>> don't think adding all the fields would change the result considerably).
>>>
>>> Why would you do a test and intentionally discard necessary data
>>> fields?  If you're not going to run tests using _all_ the actual data,
>>> don't bother.
>>
>> Because, without indexes, sqlite will do a linear scan, so, e.g., doubling
>> the data per record, will roughly double the time, and the double of
>> "imperceptible" is "too little to notice".
>> But that anyway would be offset by using indexes and optimizing the data
>> types (e.g. in my query I used strings for parameters and source, and those
>> are very inefficient, intentionally so, just to show that sqlite wouldn't be
>> a bottleneck).
>
> Then you create indexes, not discard a big portion of necessary data.

Ok I created an index

create index transp on channels (freq, params, source, sr);

Now the reply to the query is immediate.
Since I don't have time to create a proper table, I added a dummy column 
in order that each row has at least three times the amount of "necessary 
data".
The reply is still immediate.

Bye
-- 
Luca



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