Obtaining Additional Results
If a search engine cannot return the number of results requested in your project settings at one time, your search application must retrieve additional pages of results from the search engine. For example, if you want to retrieve 200 results from Google, you must retrieve multiple pages of results because Google can only return a maximum of 100 results per page. Most search engines support one of two methods for getting the next page:
- By using a 'Start' parameter to tell the search engine which result to start at
when returning a page of results. For example, a Google search may use the CGI parameter
start=20 to specify a page of results that begins with result number 21. In this
case, the 'Start' parameter is start.
Because some search engines use a 'Start' parameter to define the specific number of the first result displayed on a page rather than the number of the last result displayed on a previous page, the Watson™ Explorer Engine administration tool provides the 'Start' Offset parameter to identify this difference. For example, you do not need to set this value for a Google search, since its default value is 0. If you were querying a search engine that needed to know to start with result number 21, you would specify a 'Start' Offset of 1.
- By using a 'Page' Parameter to identify the page of results that you want to
retrieve. The search engine associated with your source uses this parameter in conjunction
with the 'Per' Parameter in order to determine which result to begin from on any
results page. For example, some search engines use a 'Page' parameter called
currentPage and returns 10 results per page, so you would set the 'Per'
Value to 10 and the 'Page' Parameter to currentPage.
Because some search engines begin numbering pages at 1 instead of 0, the Watson Explorer Engine administration tool provides the 'Page' Offset parameter to identify this number.