Say granularity is an ordered list of nodes where every node in list is parent of its next node.
For a System X: all granularity could be (Year => Month => Day). For System Y: all granularity could be (Year => Month => Day => Hour => Minutes => Seconds => Milliseconds => Microseconds => Picosecond => Femtosecond => Attosecond) As long as every node has a logic defined to compute the lower limit and upper limit value, implementation should be able to fetch all the data under its parent node. E.G: To get all the data for 2015-10-31, implementation needs to convert this into 2015-10-31-LowerLimitHourNode to 2015-10-31-UpperLimitHourNode to fetch data from hourly partitions, where lower limit hour = 00 and upper limit hour = 23. Similarly any granularity can be handled at implementation level. I guess a banking system in real world would be worried about very fine granularities of time. Even if we assume banking system has day as the finest granularity. A user can still ask for statement from the month of April, 2015 to October, 2015 without specifying the specific date fields. In this case bank will have to execute the logic to fetch all transactions from April to October with both inclusive and also handling its finest granularity which is assumed as day. In this case a banking system would convert 2015-04 to 2015-10 into 2015-04-01 to 2015-10-31 to fetch all data from daily partitions, where 01 is the lower limit for day node in month of April and 31 is the higher limit for day node in month of October. If data is not available in daily partitions and bank's underlying system supports further fine time granularities, it will convert 2015-04 to 2015-10 into 2015-04-01-00 to 2015-10-31-23 to fetch data from hourly partitions. Similarly if data is not available at hourly partitions, it will go to the next level. As long as an upper limit and lower limit is defined for each node, implementation can handle any time granularity. Meta point is that in real world, when a user will communicate to get statement of April to October. His intentions will never be to exclude October. Exclusion of October will be a surprise for him. Regards, Himanshu On Wed, Aug 5, 2015 at 4:56 PM, amareshwarisr . <[email protected]> wrote: > When a system has to understand time at all granularities, and user can > give time at all granularities, shouldn't we chose a specification which is > easy and error prone. > > The example of banking system is not worried about finer granularities of > time. > > On Wed, Aug 5, 2015 at 4:33 PM, Himanshu Gahlaut < > [email protected]> wrote: > > > This has two parts: > > > > (1) Interfacing with user shall be cognitive. Something which user can > > relate to his natural thought process. > > > > E.g.: In a banking system, if a user goes to a banker to get his bank > > statement. He will say "give me statement from 11th October 2015 to 23rd > > October 2015". This clearly communicates in simplified language that user > > is interested in bank statement from 11th October to 23rd October. If > > banker now does not return data of 23rd October, it will be a surprise > for > > user. > > > > Banker can inform every user that To date is exclusive, so if you need > > statement till 23rd October you should come and tell me "give me > statement > > from 11th October to 24th October". I believe a user will immediately > reply > > => If I need statement only till 23rd October, why shall I communicate > 11th > > October to 24th October. If you still insist, next time the user will > come > > and say "give me statement from 11th October to 24th October with 24th > > exclusive". System just made it harder for user to communicate with > banker. > > > > (2) Implementation to achieve cognitive behaviour > > > > With To date inclusive, banker needs to make sure that it gives all > > transaction records for 23rd October 2015 (To date) at the finest > > granularity available with the bank. This will satisfy users requirement > > without any element of surprise. > > > > If the finest granularity is millisecond. It will have a higher limit to > it > > which is 999 in most of the systems. Banker will fetch all partitions > until > > higher limit of finest granularity for 23rd October and return the > > statement to user. > > > > If there was a leap second/millisecond, it is upto the banker to handle > and > > give data for it. When a user wants statement from 11th October to 23rd > > October, user should not worry about the leap second/millisecond which > > happened on any of the days from 11th October to 23rd October > (inclusive). > > > > Regards, > > Himanshu > > > > On Wed, Aug 5, 2015 at 3:16 PM, amareshwarisr . <[email protected]> > > wrote: > > > > > I prefer time-range end date to be exclusive of the end date, because > of > > > the following reasons: > > > > > > 1. Giving a month range end as start of next month is easy, as you need > > not > > > remember and get confused with number of days in month : 30, 31, 28/29 > > (in > > > february leap year) - wont miss ending days because of mistakes. > > > > > > 2. When you are giving a any range, you need not worry about what > > > granularity should the time be specified. > > > For ex, for including time upto 2015-08-01 05th. > > > > > > Should user specify the following with inclusive ranges? > > > > 2015-08-01-04 (would be correct, assuming whole of 4 th hour will be > > > included) > > > > 2015-08-01-04-59 (would be correct, but what if there is leap second > > :p ) > > > > 2015-08-01-04-59-000 (wrong, would include only 000th milli second > and > > > not others) > > > > 2015-08-01-04-59-999 (not sure if we will have leap milli seconds) > > > > > > Looking forward to see other arguments on making timerange end date > > > inclusive. > > > > > > Thanks > > > Amareshwari > > > > > > On Wed, Aug 5, 2015 at 2:50 PM, Rajat Khandelwal <[email protected]> > > > wrote: > > > > > > > Currently the time_range_in clause is inclusive of the start date and > > > > exclusive of the end date. i.e. time_range_in(time_dimension, date1, > > > date2) > > > > translates to date1<=time_dimension<date2 > > > > > > > > Recently there have been multiple discussions regarding this approach > > in > > > > our internal forums at InMobi. There have been arguments that as an > > > > analytics system, it should accept end date inclusive. Starting this > > > thread > > > > to know opinions of other people regarding both approaches. I'm > > defining > > > > and briefly discussing both approaches below: > > > > > > > > Approach 1: End date exclusive. > > > > Disclaimer: I personally prefer this approach and would shamelessly > > argue > > > > in its favor. I'll give links to some of the articles that I very > much > > > > agree with (no need to reinvent the wheel of argument) > > > > > > > > 1. Views of Anders Kaseorg, MIT PhD student in CS; Cofounder of > > > Ksplice, > > > > Inc > > > > < > > > > > > > > > > https://www.quora.com/Why-are-Python-ranges-half-open-exclusive-instead-of-closed-inclusive/answer/Anders-Kaseorg > > > > > > > > > 2. Views of Edgar Dijkstra, Creator of Dijkstra's algorithm > > > > <http://www.cs.utexas.edu/users/EWD/ewd08xx/EWD831.PDF> > > > > 3. Both arguments are for generic ranges. I believe time range is > > > also a > > > > range and don't see why we need to handle that as a special case. > > > > > > > > > > > > Approach 2: End date inclusive. > > > > > > > > 1. Lens query language is a bit like sql and the BETWEEN clause in > > sql > > > > is inclusive of both start and end date. > > > > 2. Most analytic systems --- including google analytics --- follow > > > this > > > > convention > > > > > > > > > > > > I'm posting the question on a bigger forum > > > > < > > > > > > > > > > https://www.quora.com/Should-Time-ranges-in-an-analytical-system-be-half-open-or-closed > > > > > > > > > as well in hopes of getting more opinions. I request everyone to post > > > their > > > > views here regarding both approaches. > > > > > > > > Regards > > > > > > > > > > > -- > > _____________________________________________________________ > > The information contained in this communication is intended solely for > the > > use of the individual or entity to whom it is addressed and others > > authorized to receive it. It may contain confidential or legally > privileged > > information. If you are not the intended recipient you are hereby > notified > > that any disclosure, copying, distribution or taking any action in > reliance > > on the contents of this information is strictly prohibited and may be > > unlawful. If you have received this communication in error, please notify > > us immediately by responding to this email and then delete it from your > > system. 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