Question about date sorting

capnm · 11-08-2011, 12:05 PM

If I understand correctly ...

The "Date" (date added) column sorts on the underlying datetime, not on the visible date.

But sometimes I want to use this in a nested sort, say Title within Author within Date -- which doesn't work, because I'll just get everything sorted by Date to the (milli)second.

I created a composite column ("{date}"), and that sorted nicely, but I took a whopping performance hit (see here ).

So I'm wondering if I overlooked an option that doesn't require the use of a composite column ...

chaley · 11-08-2011, 02:30 PM

Regarding your post in the date-changed thread: I have an implementation that sorts dates as displayed. The performance penalty is not huge. For a 20,000 book library, the time to sort by a date column went from approximately 1/2 second to 1 second, or some 500 microseconds per book. This is consistent with my mark 1 eyeball estimate of the cost of trimming the date.

Next step is for Kovid to look at it. I might have done something stupid, he might have some suggestions for improvement, or he might object to the principle for a reason I haven't thought of.

One note: the sort will respect strange display templates and do something. If your display template is, for example yyyy/ss, then the month, day, hour, and minute will be filled in with a constant. The results could easily not be what you expect. Continuing the example, 2011/10/25 19:08:10 and 2011/01/19 10:10:10 will sort as equal because the years (2011) and the seconds (10) match.

Starson17 · 11-08-2011, 02:52 PM

Quote:

Originally Posted by chaley

because the years (2011) and the seconds (10) match.

No they don't

(typo)

chaley · 11-08-2011, 02:53 PM

Quote:

Originally Posted by Starson17

No they don't

(typo)

Yes they do. Neener neener.

Starson17 · 11-08-2011, 02:57 PM

Quote:

Originally Posted by chaley

Yes they do. Neener neener.

Neener neener - WTF???? I just finished watching BBC's 8 part series on the English language. I wonder where that one came from

chaley · 11-08-2011, 02:59 PM

Quote:

Originally Posted by Starson17

Neener neener - WTF????

See http://www.urbandictionary.com/defin...=Neener-neener. No idea what the etymology is.

capnm · 11-08-2011, 03:00 PM

That makes a lot of sense -- and saves me a big perfomance hit since I don't have to use a composite column!

p.s. I'd already quoted it but got distracted while you fast fingered guys chatted

Quote:

Originally Posted by chaley

Continuing the example, 2011/10/25 19:08:10 and 2001/01/19 10:10:10 will sort as equal

Starson17 · 11-08-2011, 03:28 PM

Quote:

Originally Posted by capnm

That makes a lot of sense -- and saves me a big perfomance hit since I don't have to use a composite column!

Thanks for the comments on performance vis-a-vis compostie columns. They'll help me too.

Quote:

p.s. I'd already quoted it but got distracted while you fast fingered guys chatted

Hope it didn't bother you too much

chaley · 11-09-2011, 04:44 AM

The change mentioned in post #2 will be in the next release. Users must change a tweak to enable it.

11-08-2011, 12:05 PM	#1
capnm Groupie Posts: 156 Karma: 10001 Join Date: Feb 2011 Device: sony	Question about date sorting If I understand correctly ... The "Date" (date added) column sorts on the underlying datetime, not on the visible date. But sometimes I want to use this in a nested sort, say Title within Author within Date -- which doesn't work, because I'll just get everything sorted by Date to the (milli)second. I created a composite column ("{date}"), and that sorted nicely, but I took a whopping performance hit (see here ). So I'm wondering if I overlooked an option that doesn't require the use of a composite column ...

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11-08-2011, 02:30 PM	#2
chaley Grand Sorcerer Posts: 11,731 Karma: 6690881 Join Date: Jan 2010 Location: Notts, England Device: Kobo Libra 2	Regarding your post in the date-changed thread: I have an implementation that sorts dates as displayed. The performance penalty is not huge. For a 20,000 book library, the time to sort by a date column went from approximately 1/2 second to 1 second, or some 500 microseconds per book. This is consistent with my mark 1 eyeball estimate of the cost of trimming the date. Next step is for Kovid to look at it. I might have done something stupid, he might have some suggestions for improvement, or he might object to the principle for a reason I haven't thought of. One note: the sort will respect strange display templates and do something. If your display template is, for example yyyy/ss, then the month, day, hour, and minute will be filled in with a constant. The results could easily not be what you expect. Continuing the example, 2011/10/25 19:08:10 and 2011/01/19 10:10:10 will sort as equal because the years (2011) and the seconds (10) match. Last edited by chaley; 11-08-2011 at 02:53 PM. Reason: fix typo pointed out by starson17

11-09-2011, 04:44 AM	#9
chaley Grand Sorcerer Posts: 11,731 Karma: 6690881 Join Date: Jan 2010 Location: Notts, England Device: Kobo Libra 2	The change mentioned in post #2 will be in the next release. Users must change a tweak to enable it.