I am trying to create a business hours application using DynamoDB.
I saw lots of examples and schema designs for different databases but just can't find the right table design for DynamoDB.
Here are my requirements:
every business should have default working hours (Monday 08:00 - 14:00, 16:00 - 20:00) and special events (26/11/2020 shop is closed / opened between 10:00 - 14:00 due to Thanksgiving)
every day can have multiple work durations (08:00 - 14:00, 16:00 - 20:00)
Those are the operations I need to allow:
Create / edit working hours for each business (including special events)
Check whether a business (or a list of businesses) are open right now - by providing a list of business ids.
Get business (or list of businesses) working hours between 2 dates (for example 23/04/2020 - 25/04/2020) by providing a list of business ids and date range for each id
What I've tried:
Defined a table where business id is the partition key (HASH) and special dates / day of week is the sort key (RANGE).
The problem with this approach is that I cannot query by multiple business hours unless I use the scan api which is not recommended due to expensive operations.
Please advice what kind of table design I should use for this application.
You probably need to first construct your overarching logic outside of DynamoDB, do decide if a business is working or not, and only use quarries in Dynamo for a subset of that logic.
Lets say though we use DynamoDB for querying in regards to normal working hours, and not include logic like holidays and special cases, you can use that to filter after you access Dynamo. You can't construct one query in Dynamo to answer all your questions that is more like what you can do in SQL.
So lets say we have a Table/Subset of values which relate to the normal working day. So you have something like this:
Partition Key (PK): business, Range Key (RK): dayOfWeek, and attributes, opens & closes.
We can then create 2 GSIs:
PK dayOfWeek RK opens
PK dayOfWeek RK closes
Now we can do two queries if a store is open between 3-4pm on Monday:
PK == MONDAY & opens < 2 pm
PK == MONDAY & closes > 4 pm
And collect only the values which appear in both queries.
Obviously though, having a PK of day, is probably not a great idea, as you will only have 7 partitions. So what do you do? Well you probably have more criteria in your query than simply day, for example, the type of store, the city the store is located it, etc. That would mean then you would have a PK of something like: city-category-dayOfWeek.
Similarly on the sorting side, you might want higher rated stores to be the first option, so you might have something like: {rating}-{open} & {rating}-{closes}.
You will just have to get creative, firstly layout all the queries you have before you design your tables. I really like this video on table design, it's terrific.
Related
The first image below is my database schema for a project that will use psql, ruby and active record.
While writing my schema, things got a bit complex. My "special_days" table ended up becoming a join table for "days_of_week" and "organizations". I'm assuming that this is not best practice and will end up causing me trouble.
In the second schema below, I made a separate join table for "days of week" and "organizations". My special_days table still needs to be associated with a day_of_week and an organization, so I think I have to keep the joining information in the special_days table. Is there a better way to do this? It seems that my second attempt is too repetitive.
These are my relationships:
days of week & organizations | many to many
city & organizations | one to many
organization & special days | one to many
day of week & special days | one to many
Some more information about the requirements might be useful. Are you required to do something like define which days are holidays, which days are paydays, etc. (e.g. many organizations would define Sat and Sun as non-work days and many U.S. organization would define July 4 as a non-work day)? I'm not sure what days_of_the week represents. Is this a table with 7 records in it (M,T,W,Th,F,S,Sun)? If I'm guessing correctly at the requirements it might be better to do something like have a table called special_day that has a date column and a recurrence column (e.g. weekly, monthly, yearly, etc.). You could then have a organization_special_day table that is a many-to-many join table on organization and special_day.
I'm trying to create a schema that will allow me to define times, when a supplier website is non operational (planned not unplanned).
I've gone for non-operational as opposed to operational because many suppliers work 24/7, so non-operting times represent the least number of rows.
For example, a supplier might not work:
On a Sunday
On a recognised holiday date - '1/1/2015'
On a Saturday after 5pm
I'm not overly confident with SQL Server, but have come up with a schema that 'does the job'. However, as we all know, there are good ways, not so good ways, and bad ways, that all work in a fashion, so would appreciate comments and advice on what I have to date.
One of the key features is to use data from WorkingDays and Holidays together to represent a WorkingPeriod entity.
I would appreciate coments no matter how small.
Holiday
Contains all recognised holidays - Easter Monday, Good Friday etc.
HolidayDate
Contains dates of holidays. For instance, this year Easter Monday is 6th Apr 2015.
WorkingDay
Sunday through to Monday, mapped to Asp.Net day of week enums.
WorkingPeriodType
A lookup table containing 2 rows - Holiday, or Day of Week
WorkingPeriod
Merges the Holiday table and the WorkingDay table to represent a single WorkingPeriod entity that can be used in the SupplierNonWorkingTimes table.
SupplierNonWorkingTimes
Contains the ID representing the WorkingDay/Holiday and the times of non- operation.
This is a very subjective question, as you've already observed there's no right and wrong, just different ways. I'm a database guy but I don't know your specific circumstances, so this is just some observations - you'll have to judge for yourself whether any of them are appropriate to you.
I like my naming to be crystal clear, it saves all the
misunderstanding by other people later on. If [WorkingDay] holds the
7 days of the week I would call it [WeekDay]. If you intend
[Holiday] to hold whole-day holidays I would call it [HolidayDay].
The main table [SupplierNonWorkingTime] is about 'non-working' so I
would call the [WorkingPeriod] table [NonWorkingPeriod]. The term
'period' always refers to a whole day, so I would replace 'period'
with 'day' (let's ignore start/stop time for now).
My first impression was that your design is over-normalised. The
[WorkingPeriodType] table has 2 rows that will never change,
[WorkingDay] has 7. For these very low numbers I sometimes prefer a
char(1) with a check constraint. Normalisation is generally good,
but lots of JOINs for trivial queries is not so good. You could
eliminate [WorkingPeriodType] and [WorkingDay] but you've mentioned
.Net enums in your question so if you've got some sort of ORM in
your .Net code this level of normalisation might be right for you.
I'd add a Year field to the [HolidayDate] table, then the PK
becomes a better HolidayID+Year - unless you know somewhere that has
lots of Christmas' :)
I'd add an IsAllDay field to the [SupplierNonWorkingTime] table,
otherwise you have to use 'magic values' to represent 'all day' and
magic values are bad. There should be a check constraint to enforce
start/stop times can only be entered if IsAllDay = false.
Like I said, just my thoughts, hope it's helpful.
I am working on a multiple properties booking system and making me headache about the best practice schema design. Assume the site hosts for example 5000 properties where each of it is maintained by one user. Each property has a booking calendar. My current implementation is a two-table-system with one table for the available dates and the other for the unavailable dates, with a granularity of 1 day each.
property_dates_available (property_id, date);
property_dates_booked (property_id, date);
However, i feel unsure if this is a good solution. In another question i read about a single table solution with both states represented. But i wonder if it is a good idea to mix them up. Also, should the booking calendar be mapped for a full year with all its 365 days per year into the database table or was it better to map only the days a property is available for booking? I think of the dramatically increasing number of rows every year. Also i think of searching the database lately for available properties and am not sure if looking through 5000 * 365 rows might be a bad idea compared to i.e. only 5000 * av. 100 rows.
What would you generally recommend? Is this aspect ignorable? How to best practice implement this?
I don't see why you need a separate table for available dates. If you have a table for booked dates (property_id, date), then you can easily query this table to find out which properties are available for a given date
select properties.property_name
from properties where not exists
(select 1 from property_dates_booked
where properties.property_id = property_dates_booked
and property_dates_booked.date = :date)
:date being a parameter to the query
Only enter actual bookings into the property_dates_booked table (it would be easier to rename the table 'bookings'). If a property is not available for certain dates because of maintenance, then enter a booking for those dates where the customer is 'special' (maybe the 'customer' has a negative id).
I'm writing an application that stores different types of records by user and day. These records are divided in categories.
When designing the database, we create a table User and then for each record type we create a table RecordType and a table Record.
Example:
To store data related to user events we have the following tables:
Event EventType
----- ---------
UserId Id
EventTypeId Name
Value
Day
Our boss pointed out (with some reason) that we're gonna store a lot of rows ( Users * Days ) and suggested an idea that seems a little crazy to me: Create a table with a column for each day of the year, like so:
EventTypeId | UserId | Year | 1 | 2 | 3 | 4 | ... | 365 | 366
This way we only have 1 row per user per year, but we're gonna get pretty big rows.
Since most ORMs (we're going with rails3 for this project) use select * to get the database records, aren't we optimizing something to "deoptimize" another?
What's the community thoughs about this?
This is a violation of First Normal Form. It's an example of repeating groups across columns.
Example of why this is bad: Write a query to find which day a given event occurred. You'll need a WHERE clause with 366 terms, separated by OR. This is tedious to write, and impossible to index.
Relational databases are designed to work well even if you have a lot of rows. Say you have 10000 users, and on average every user generates 10 events every day. After 10 years, you will have 10000*366*10*10 rows, or 366,000,000 rows. That's a fairly large database, but not uncommon.
If you design your indexes carefully to match the queries you run against this data, you should be able to have good performance for a long time. You should also have a strategy for partitioning or archiving old data.
That's breaks the DataBase normal forms principles
http://databases.about.com/od/specificproducts/a/normalization.htm
if it's applicable why don't you replace Day columns with a DateTime column in your event table with a default value (GetDate() we are talking about SQL)
then you could group by Date ...
I wouldn't do it. As long as you take the time to index the table appropriately, the database server should work well with tables that have lots of rows. If it's significantly slowing down your database performance, I'd start by making sure your queries aren't forcing a lot of full table scans.
Some other potential problems I see:
It probably will hurt ORM performance.
It's going to create maintainability problems on down the road. You probably don't want to be working with objects that have 366 fields for every day of the year, so there's probably going to have to be a lot of boilerplate glue code to keep track of.
Any query that wants to search against a range of dates is going to be an unholy mess.
It could be even more wasteful of space. These rows are big, and the number of rows you have to create for each customer is going to be the sum of the maximum number of times each different kind of event happened in a single day. Unless the rate at which all of these events happens is very constant and regular, those rows are likely to be mostly empty.
If anything, I'd suggest sharding the table based on some other column instead if you really do need to get the table size down. Perhaps by UserId or year?
I wasn't sure how I should word the title; I apologize if it is unclear. I’m developing a relational database for a vocational school. I want to provide students with their class schedules online. I would like to make the design as flexible as possible. I want to store exact dates and times including the term and year. I am interested in learning how any of you would approach this. Also I’m searching for a book, training video, tutorial or discussion on this specific topic.
The part I’m unsure of is how to have the amount of days vary from one schedule to another. I understand it is a one-to-many relationship; however, I’m unsure how I should set it up in this scenario. Also what about leap year?
My Approach is to make a Month/Day Table, Year Table and Term Table with foreign keys in a Schedule Table. To Address Leap Year I would just make the Month/Day Table 366 days. I’m unsure if this idea is overkill, I’m looking for the most elegant solution for handling any practical variation in a schedule.
I apologize if I’m way off, I’ve been trying to teach myself Relational Database Development but I’m just getting started.
I would like the schedule to output partly like this:
Example Class A Schedule:
01/02/2011 1:00pm-3:00pm
01/03/2011 2:00pm-4:00pm
01/04/2011 1:00pm-3:00pm
01/05/2011 2:00pm-5:00pm
01/08/2011 1:00pm-4:00pm
Example Class B Schedule:
01/02/2011 1:00pm-3:00pm
01/03/2011 2:00pm-4:00pm
Here are some of the business rules; they are similar to those of a college:
Class schedules must not be
constrained to any pattern
Class schedules must store every date
and time class is held
Class Schedules must include the
start and end time
Classes may or may-not be associated
with a term
Schedules may be created and stored
in the database long before the class
is offered
Students must be able to see the
schedules for classes offered
Students must be able to access
schedules for classes they are
registered for
I may or may not understand your business requirement, so this might be really bad advice. However, what I would say is don't create a table to hold days if the only thing in the table is a calendar, without any other attribution around the individual dates.
If your schedule is based on a rotating schedule of an arbitrary number of days, like "Day 1" to "Day 6" or the like, then this deserves its own table, then the occurences of classes become an intersection between the day of the rotation and the class. Each intersection would have a date and time as well as foreign keys to the class and rotation day.
Depending on your business rules, Terms might plug in either above the class or above the arbitrary day schedule. The Term table should probably include starting and ending dates, in any case.
You don't need to do anything special for leap years or days in a month etc, because SQL is smart enough to be able to work out date-related queries.
Can you tell me more about what your business rules are for setting up a schedule? If so, maybe I can hone my advice.
I came up with a design based on what you mentioned, I included it below.
* Primary Key
~ Foreign Key
Classes_Table
*ClassID
ClassName
ClassNumber
~ScheduleID
Schedules_Table
*ScheduleID
~ClassID
Class_Schedule_Table (There Would Be Many Of These Tables, 1 For Each ScheduleID)
*DayID
Date
StartTime
EndTime
~TermID
~ClassID
~ScheduleID
Terms_Table
*TermID
TermName
Students_Table
*StudentID
StudentName
Student_Schedules_Table
*RegistrationID
~StudentID
~ClassID
~ScheduleID