Database Storage Engine Project M1 Database Design

About the milestone

This milestone includes creating documentation and descriptions of the database schemes explained at Database Storage Engine Project.

Questions : Database Layout

This is the design to store survey, section and question information and their related metadata.

Responses : Flat Database Layout

This is the layout we propose for storing survey responses in a single database table.

Responses : Multitable Database Layout

This is the layout we propose for storing survey responses in multiple tables. Responses for each question get stored in a seperate table.

Responses : Sectionflat Database Layout

This is the layout we propose for storing survey responses in multiple tables. Responses for each section get stored in a seperate table.

Question Type mappings

These are database mappings for the question types presented here. Since the question types are presented as single questions, there is no difference between the 3 proposed database layouts.

Mappings for questions to QuestionType classes

Type of question	Mapping in QuestionType classes
Choice matrix questions	ChoiceMatrixQuestionType (NumberOfRows rows and 1 column) with NumberOfRows child questions of type ChoiceQuestionType
Multi scale array	ChoiceMatrixQuestionType (NumberOfRows rows and NumberOfCols columns) with NumberOfRows * NumberOfCols child questions of type ChoiceQuestionType
Various matrix questions	MatrixQuestionType (NumberOfRows rows and NumberOfCols columns) with NumberOfRows * NumberOfCols child questions of a type by choice
Date question	DateQuestionType
Gender question	ChoiceQuestionType (possible to make a specific GenderQuestionType later)
Numerical input	IntegerQuestionType or DoubleQuestionType
Multiple numerical input	MatrixQuestionType (NumberOfRows rows and 1 column) with NumberOfRows child questions of type IntegerQuestionType or DoubleQuestionType
Ranking question	RankingQuestionType
Boilerplate	BoilerplateQuestionType
Yes/No	Same case as gender questions
Language question	LanguageQuestionType
Multiple options without other	MatrixQuestionType (NumberOfRows rows and 1 column) with NumberOfRows child questions of type CheckboxQuestionType
Multiple options with other	OtherQuestionType with X children of type CheckboxQuestionType and 1 child of type IntegerQuestionType/DoubleQuestionType/StringQuestionType/DateQuestionType/...
List questions	ChoiceQuestionType
List question with other	OtherQuestionType with a ChoiceQuestionType and an IntegerQuestionType/DoubleQuestionType/StringQuestionType/DateQuestionType/...
Text question	StringQuestionType
Long text questions	TextFieldQuestionType

Mappings for QuestionType classes to table columns

QuestionType class	Columns in database table
StringQuestionType	input: longtext
TextFieldQuestionType	input: longtext
ChoiceQuestionType	choice: unsigned integer (reference to model_answers)
DateQuestionType	date: date
TimeQuestionType	time: time
IntegerQuestionType	input: integer
DoubleQuestionType	input: double
CheckboxQuestionType	input: unsigned tinyint(1)
BoilerplateQuestionType	none
LanguageQuestionType	input: char(3) (we suggest using the ISO 639-2 language codes)
RankingQuestionType	1: unsigned integer (reference to model_answers) 2: unsigned integer (reference to model_answers) ... as many keys as options. The key is the rank.
MatrixQuestionType	none (data is stored by children)
ChoiceMatrixQuestionType	none (data is stored by children)
OtherQuestionType	none (data is stored by children)

Todo

• Design flat DB layout (Done)
• Design normalized DB layout (Done)
• Design section-flat DB layout (Done)
• Keep in mind all the Question types supported by LimeSurvey1 : Question types (Done)
• Problem with loops with current response layouts (sectionflat and multitable), flat has no support for loops. (Done)

Discussions

Comments and ideas here please:

Metadata requirements for databases

- time question displayed/made available to participant (added by Jason)

this may be an indication of when the page was served to the participants browser (time can be generated by web server/php) or in the case of conditional questions, it may need to indicate the time that the question became visible on the page (in which case it may need to be generated by javascript, with all those inherent problems.. maybe it should indicate how many seconds since the page was loaded, and that can be added to the page-load time?)

- time question answered by participant (added by Jason)

this may be a recording of the time that the data in the question was posted (time could be generated by web serer/php) or the time that the question lost focus (after having gained it) - which would be a javascript issue

Any other metadata requirements?