The advantages of this are as follows:
PubCrawler keeps track of documents that you have seen already by storing their ID number
in so called hash tables. The key to the tables is the alias of the corresponding query. If no
alias is provided the query itself makes up the key. In the latter case a change of your
query has a disastrous effect on your database entry. When PubCrawler looks up its hash
table to check for former hits, it won't find any because the key didn't exist previously.
So all hits will be treated as new and you will probably find a lot of documents that you
have seen before.
In contrary, if you change an aliased query, PubCrawler will be able to compare former hits with new ones and filter out documents that you have seen already.
Index with dummy aliases:
The benefit of using descriptive aliases should be obvious from the above examples:
You can see immediately from the index in which research area you got new hits.
NOTE: Changing your alias will have the same effect as described earlier on: It will lead to a reinitialization of your database entry of former hits for that according query! So please start using an appropriate alias when creating your query.