Re: Join on single table

What kind of speed do you need? I had to go to temp tables for a logging application, but not until my table got upwards of a million records or so.. For the numbers your quoting, it should be pretty quick unless your engine needs optimization.. On Friday 11 February 2005 11:56 am, Matthew Weier O'Phinney wrote: > * Micah Stevens <micah@raincross-tech.com>: > > Sounds like a self join should work wonders. > > > > I didn't test this, but the idea should work: > > > > > > select t1.app_id as a1, t2.app_id as a2, t2.word, t2.score > > from tablename as t1 > > left join tablename as t2 > > on t1.resource_id = t2.resource_id and t1.app_id != t2.app_id > > group by word > > order by word > > > > voila, no temp tables. Am I missing something? > > Speed. :-) > > I had tried this as well. The temporary tables really do offer much > better performance. The issues I was having were (1) bad resultsets > (I've now got that fixed) and (2) speed. I still don't have (2) > completely fixed, and it may be something I can't fix. > > > On Thursday 10 February 2005 07:56 pm, Matthew Weier O'Phinney wrote: > >> I have a table which contains the following: > >> id (primary key, auto incrementing) > >> app_id (integer, foreign key) > >> resource_id (integer, foreign key) > >> word > >> score > >> > >> (This is a search index.) I want to find all resource_ids from one > >> app_id that match resource_ids in another app_id by word. > >> > >> I have created a temporary table 'tmp1' that contains all resource_ids > >> from the second app_id (the one whose resources I wish to retrieve). I > >> am then looping through all resource_ids in the main table with the > >> first app_id, and doing the following: > >> > >> * Creating a temporary table tmp2 with a single column 'word' > >> populated by the words associated with resource_id in the main > >> table > >> * Selecting all distinct resource_ids from tmp1 INNER JOIN'd on tmp2 > >> on the word field > >> > >> The issues I'm running into are that (1) each resource_id cycle takes a > >> good amount of time, and (2) I seem to be getting either too many > >> resource_ids or not enough. > >> > >> (1) may be something I just have to deal with. As it is, I'm planning on > >> running the full indexing once, and then doing incremental updates, so > >> it may not be that big of an issue (unless it takes too much time to > >> create the initial index). As for (2), unfortunately, I'm not sur ehow > >> to really trouble shoot the issue. I know, for instance, that in once > >> case, I have a list of 343 words that generates a list of ~12,000 > >> resource_ids (of a possible 18,000) -- but I don't quite know how to > >> spot check 300 values to be certain that this is reasonable. > >> > >> In a previous incarnation of the script, I was looping through each word > >> of each resource_id and then selecting out of tmp1 based on the single > >> word value. The results were very different (very few matches), and, > >> again, the script ran long. > >> > >> Any ideas? > > -- > Matthew Weier O'Phinney | WEBSITES: > Webmaster and IT Specialist | http://www.garden.org > National Gardening Association | > http://www.kidsgardening.com > 802-863-5251 x156 | > http://nationalgardenmonth.org > mailto:matthew@garden.org | > http://vermontbotanical.org