Purely for academic reasons, I'd like to point out that the computationally efficient way to find exact substrings (ie "cat" in "merecats") is a Suffix Tree: http://en.wikipedia.org/wiki/Suffix_tree
You could probably (with a lot of time and mental strength) create a suffix tree system using the GAE data store. Not that you'd want that, I'm just saying, you could ;-) Ben On Jun 3, 7:53 pm, Rafael Sierra <[email protected]> wrote: > On Thu, Jun 3, 2010 at 2:51 PM, Rafael Sierra <[email protected]> wrote: > > On Thu, Jun 3, 2010 at 2:40 PM, Massimiliano > > <[email protected]> wrote: > >> Dear Ikai, > >> I want to search in the datastore "Pizza" and obtain "Pizza with tomatoes", > >> "Pizza with Mushrooms", I don't care about "abcpizza" or "123pizza". > > > Those you can obtain by the filter told some messages ago, but 'I want > > pizza man!' need a full-text of the poor solution I gave in the last > > message. > > ...OR* the poor solution... (not "of") > > > > > > >> Massimiliano > > >> 2010/6/3 Ikai L (Google) <[email protected]> > > >>> The reason search engines work is because they do stemming on terms. For > >>> instance, when you search for "cats" you may want to match "cat" and > >>> "cats" > >>> for better results, and it's fairly unlikely you want to return "abcatst" > >>> or > >>> "youcats123" (sorry, I couldn't think of any words that had "cats" in the > >>> middle). Lucene, an open source Java project for ships with basic > >>> analyzers > >>> that will do things like this. > >>> Otherwise, there aren't easily scalable ways to index on substrings. The > >>> closest you can come is to try to intelligently determine which substrings > >>> in a string can be searched on, and index those terms. > >>> On Thu, Jun 3, 2010 at 9:49 AM, Rafael Sierra <[email protected]> > >>> wrote: > > >>>> Massimiliano, the point is that there's no way to create an index that > >>>> can be used to avoid a full-scan into the database in that kind of > >>>> query, so, even if you can do "ILIKE '%anything%'" in PgSQL or "LIKE > >>>> '%anotherthing%'" in MySQL, it will result in a full-scan on every > >>>> record at database. > > >>>> But, if you have a small set of record in you database, you can do > >>>> something like this:http://dpaste.com/hold/202782/. You can do this > >>>> in larger sets of databases also, but you may deal with some > >>>> DeadLineErrors at your application. > > >>>> Note: This solution has absolutely no performance at all, you can even > >>>> do some kind of pagination (scanning the database only up to N > >>>> registers and breaking after that) but if the scan happens to iterate > >>>> over thousands of records before reach N records found, you will still > >>>> have DeadLineErrors. > > >>>> On Thu, Jun 3, 2010 at 11:04 AM, Massimiliano > >>>> <[email protected]> wrote: > >>>> > So there isn't a scalable solution! > > >>>> > 2010/6/3 Geoffrey Spear <[email protected]> > > >>>> >> On Jun 3, 4:58 am, Massimiliano <[email protected]> > >>>> >> wrote: > >>>> >> > I need just something like *myvar* so I will accept any carachters > >>>> >> > before > >>>> >> > and after the var... > >>>> >> > Or I have to divide the strings in list (each word an elment of the > >>>> >> > list) > >>>> >> > and use the operator IN. > >>>> >> > Thinking > > >>>> >> Building a keyword index for each entity is fairly trivial. > > >>>> >> Indexing so that you can find "oob" in "foobar" isn't, and I don't > >>>> >> believe there's a scalable solution for this. An RDBMS will do > >>>> >> searches like this for you, but it won't scale well. I believe it's > >>>> >> only possible by doing a table scan, which App Engine won't let you do > >>>> >> (short of manually fetching every entity and checking if it contains > >>>> >> your substring, which obviously isn't going to be pretty.) > > >>>> >> -- > >>>> >> You received this message because you are subscribed to the Google > >>>> >> Groups > >>>> >> "Google App Engine" group. > >>>> >> To post to this group, send email to > >>>> >> [email protected]. > >>>> >> To unsubscribe from this group, send email to > >>>> >> [email protected]. > >>>> >> For more options, visit this group at > >>>> >>http://groups.google.com/group/google-appengine?hl=en. > > >>>> > -- > > >>>> > My email: [email protected] > >>>> > My Google Wave: [email protected] > > >>>> > -- > >>>> > You received this message because you are subscribed to the Google > >>>> > Groups > >>>> > "Google App Engine" group. > >>>> > To post to this group, send email to [email protected]. > >>>> > To unsubscribe from this group, send email to > >>>> > [email protected]. > >>>> > For more options, visit this group at > >>>> >http://groups.google.com/group/google-appengine?hl=en. > > >>>> -- > >>>> You received this message because you are subscribed to the Google Groups > >>>> "Google App Engine" group. > >>>> To post to this group, send email to [email protected]. > >>>> To unsubscribe from this group, send email to > >>>> [email protected]. > >>>> For more options, visit this group at > >>>>http://groups.google.com/group/google-appengine?hl=en. > > >>> -- > >>> Ikai Lan > >>> Developer Programs Engineer, Google App Engine > >>> Blog: http://googleappengine.blogspot.com > >>> Twitter: http://twitter.com/app_engine > >>> Reddit: http://www.reddit.com/r/appengine > > >>> -- > >>> You received this message because you are subscribed to the Google Groups > >>> "Google App Engine" group. > >>> To post to this group, send email to [email protected]. > >>> To unsubscribe from this group, send email to > >>> [email protected]. > >>> For more options, visit this group at > >>>http://groups.google.com/group/google-appengine?hl=en. > > >> -- > > >> My email: [email protected] > >> My Google Wave: [email protected] > > >> -- > >> You received this message because you are subscribed to the Google Groups > >> "Google App Engine" group. > >> To post to this group, send email to [email protected]. > >> To unsubscribe from this group, send email to > >> [email protected]. > >> For more options, visit this group at > >>http://groups.google.com/group/google-appengine?hl=en. -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. 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