Optimized Database Format

The Optimized Database Format was new in Authoring 12.5, and is the version of a database format which forms the platform for the modern, multimodal data collection system. The optimized database format has several benefits compared to the previous format. This format will by default be selected when creating new surveys. The main benefits of the Optimized Database Format are improved scalability and performance, and some new survey functionality that will only be available when using this format.

Scalability:

• Reduced physical storage space is needed for survey databases (on the server). All variables will be stored as more appropriate data types. This will be handled automatically by the system during survey launch. The system will evaluate the actual codes and settings applied to the questions, and choose the most appropriate variable type.
• It is now possible to host several surveys on one single database instance. This is achieved by enabling the storage of response data from several surveys within the same physical database. This functionality will by default not be available, but can be enabled on request (contact [e-mail]) (company setting).

Performance:

• Faster data retrieval for long and complex surveys.
• Faster database generation.
• Reduced memory usage on survey engine (on server).

The Optimized Database Format provides an alternative way of storing responses from single, multi and grid questions. This enables better support for storing responses from multi and grid questions with very long answer lists. In the answer list it will be possible to refer to a loop, in which case the "loop members" (the answer list in the loop) will be used as the answer list, and the responses will be stored in the loop structure in a separate db table with one row per response per respondent. Where loop references are being used, any additional codes added after the loop reference must have an explicit code assigned. Auto-generated codes will not be allocated. This ensures that duplication of codes does not occur.

A further advantage of the loop system may be derived if the loop used in a question refers to the answer list located in the Database Designer. In this case you can add or remove answer options to/from the answer list without the requirement to regenerate (launch) the database. This means that you can for example set up a recurring task to update the answer list so that the respondents will always have an up-to-date list of options to select between.

This database format has allowed a number of new features to be added to Authoring, as listed below:

• The new database format provides a scalable solution.
• Long answer lists are supported, particularly for multi and grid questions.
• Boolean and Date data formats are supported for open text and single questions. These appear as options in the questions' property sheets.

The database format that is to be used for a survey is selected during survey creation on the Survey Name dialog (go to Creating a New Survey for more information), and can be changed on the Survey Overview page. Note that the format must be selected before the Test or Production database is generated (the survey is launched) for the first time. If the Optimized format is selected, then once the database is generated the format is fixed and cannot be changed. If the Legacy format is selected and Survey Layouts are used, then you can later change to Optimized (see the Important note below). Only users with Administrator rights to the survey can select the database type.

Note: When using Reportal with a survey that uses the Optimized format, BitStream files must be used (go to BitStream Files for more information). An error message will be presented if BitStream Files are not used.

Some functionality that is available in the older database format is not available in the Optimized format. The menu commands controlling this functionality will therefore not be accessible when the Optimized format is selected. The functionality that is NOT available in the Optimized format database is as follows:

• Edit Templates - Web Interface templates are not available. These are superceded by Survey Layouts (go to About Survey Layouts for more information).
• Rule-based sendouts - this functionality is superceded by that now available in the Data Processing module. Refer to the Data Processing documentation for more information.
• Online Reporting - this functionality is included in and superceded by Reportal. Refer to the Reportal documentation for further information.
• Individual Reporting - this functionality is included in and superceded by Reportal. Refer to the Reportal documentation for further information.
• Filters - this functionality is included in and superceded by Reportal. Refer to the Reportal documentation for further information.
• Calculate Variables - some of this functionality is included in Reportal. Refer to the Reportal documentation for further information.
• Published Reports - this functionality is included in and superceded by Reportal. Refer to the Reportal documentation for further information.
• Survey Data Exports - this functionality is now available through the Data Processing module. Refer to the Data Processing documentation for more information.
• Survey Data Imports - this functionality is now available through the Data Processing module. Refer to the Data Processing documentation for more information.
• Survey Data Template Editor - this functionality is now available through the Data Processing module. Refer to the Data Processing documentation for more information.
• Online Coding - this functionality will be available in the Optimized format, though with some limitations (go to Online Coding Tool Overview for more information).

Important
For surveys created in the Optimized format, before you launch the survey for the first time and thereby create the database, you can change the type of database that is to be used. However once you have launched the survey and the database exists you can no longer change the type.
For surveys created in Legacy format and using a survey layout, whenever you launch the survey you can select to change the database format to Optimized. Note that once the database is in the Optimized format it cannot be changed back to Legacy again.