|Full-Text Search in the Publication Database|
The publication database offers two complementary full-text search algorithms:
The Google-style search function is faster; it returns lists of publication entries ordered by their relevance with respect to the search string. Particularly in the case of short search strings, its results may occasionally be unexpected. At least in its default operation mode, those publication records are selected that contain at least one of the words in the search string. A greater number of search items therefore increases, in general, the number of records found. Please refer to the following detailed description for the proper application and optimisation of the Google-style search function.
The strict full-text search function is activated by setting the Checkbox "Strict search" in the field "Search for". It is significantly slower than the Google-style search function, particularly if the selection of publications is not or not significantly restricted. It returns a list of publication records grouped by publication types as a result, which contains all records that hold all specified search items. A greater number of search items therefore reduces, in general, the number of records found. You can find more information on the strict search function in the description of this algorithm later on this page.
The Google-style search function finds only words in the publication records that match exactly one of the words in the search string. (With the optional operator "*", words are also found that begin with one of the words in the search string.) In contrast, the strict full-text search function finds also records that contain words that include one of the words in the search string. With the search string "electron", the Google-style search function finds therefore only records that hold the word "electron" (in upper- or lowercase); the strict text search function would also find "microelectronics". (With "electron*", the Google-style search function would find "electronics" but not "microelectronics". A preceding asterisk ("*"), such as in "*electron" or "*electron*", is ignored by the Google-style search function.)
Both algorithms search the publication records determined by the other selection criteria. The search may comprise either the entire records, or only parts of them. No text search is carried ot if the field "Text that should be found" is empty; in this case, all records matching the remaining selection criteria are output. The search is case-insensitive; upper- and lower-case letters in the search string make no difference.
The Google-style full-text search function
The Google-style full-text search uses a function of the database back-end. The program code of the publication database has therefore hardly an influence on its operation. Since it is much faster than the strict text search function, it has been implemented as the standard full-text search function.
This full-text search function returns a list of publication records ordered by the relevance of the records found. For each record, its relevance and its publication type is given. The relevance of a publication record increases with the number of occurrences of any one of the words in the search string within the searched part of the record. In addition, the publication type and quality may influence its relevance.
The following rules apply for the Google-style full-text search:
A number of operators can modify the search behaviour. The relevance of the records found changes if at least one of the following operators is used. Search words that occur in more than half of the records are no more ignored. The following operators are available:
The results of a search may differ from those described here if combinations of operators are used. The Google-style full-text search is a feature of the database back-end, and hence out of reach of the developer of the publication database.
The following examples - taken from the documentation of the database back-end - may serve to illustrate the usage of these operators:
The strict full-text search function
This search mode is activated by setting the Checkbox "Strict search" in the field "Search for".
If the search string contains several words the Publication Database by default returns all otherwise matching records that contain all words of the search string, regardless in which order and in which of the fields to be searched these words occur. The following characters are separators between words:
The search text "This is an example" results in a search for records that contain the four words "This", "is", "an", and "example" in arbitrary order and in arbitrary locations within the text fields that have been specified with the selection list "Text search in:".
Search items that consist of one of the above separators or contain a separator but should not be split at the separator can be put between double quotes ("). Pairs of quotes are removed before the actual search; they prevent, however, the splitting of the text between them. The search text may contain an arbitrary number of search items in double quotes. Hence, the search text ""This is" "an example"" results in the two search items ""This is"" and ""an example"". To search for one of the above separators, place it between double quotes (e.g., ""+"" to search for a plus sign). It is possible to use search items that contain one double quote; they must be specified after all search items in pairs of double quotes.
You can put the entire search text in double quotes, e.g., ""This is an example"".) Use this feature if you are quite sure that there are records with your search phrase but the default settings return too many search hits.