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Re: [Xen-devel] [OSSTEST PATCH 00/13] Speed up and restore host history



Sander Eikelenboom writes ("Re: [Xen-devel] [OSSTEST PATCH 00/13] Speed up and 
restore host history"):
> /me is ducking under the table ;)
> Seems to be quite a lot of intracate Perl, I never was a prince of Perl
> and that hasn't got any better by not using it actively the past years.

Heh.  Although it's generally not supposed to be intricate.  I have
tried to keep it fairly straightforward.

> Not really, but especially applying style to alternating rows is now
> quite simple with pseudo classes:
> 
>  tr:nth-child(even){
>    background-color: grey;
>  }
> 
>  tr:nth-child(even){
>    background-color: white;
>  }
> 
> You could stuff this in a <head><style> ... </style></head>,
> so you don't have to repeat this every row for the common case.
> For any special cases you could overrule based on class.
> I happen to find it one of the most useful CSS features.

Interesting.  Mmm.  (Although your vignette above ought to have an
`odd' in it I think...)

> > Maybe, but currently the archaeology algorithm is not expressed
> > entirely in SQL so it couldn't be a materialised view.  And converting
> > it to SQL would be annoying because SQL is a rather poor programming
> > language.
> 
> It is a poor programming language, but it is very good at retrieving and
> modifying data. Sometimes it takes some effort to wrap your head around
> the way you have to specify what data you want and in what for, without
> being to explicit in how it is supposed to be retrieved.

Indeed so.

> If I remember correctly Postgres is being used, perhaps there is stull
> some relatively low hanging fruit when analyzing the performance of the
> queries you run at the actual data.

Yes.  One of the biggest problems is I really want to make an index on
runvar *values*.  But if I do that then routine runvar updates have to
update that index.  So what I want is a partial index but the rows of
runvars which are indexed ought to be controlled by the corresponding
row of the flights table.

I am considering denormalising this by including a `finalised' bit in
the runvars table.  But not now...

> I will take a look at the code somewhere this or next week and see if I
> can get any familiarity with it and perhaps end up with some contributions.

All contributions and suggestions are welcome.

Regards,
Ian.

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