Hi Brian! thanks - this is much clearer!
I spotted one typo now: "So "materializing" is out, but what is not out is "materialized tables"." I think you mean "materialized views" i.o. "materialized tables" kind regards, Roland On Thu, Jul 16, 2009 at 12:37 AM, Brian Aker<[email protected]> wrote: > Hi! > > Thanks for the feedback, I've updated the blog to try to clarify my > language. > > Cheers, > -Brian > > On Jul 15, 2009, at 3:31 PM, Roland Bouman wrote: > >> Hi! >> >> On Wed, Jul 15, 2009 at 10:38 PM, Brian Aker<[email protected]> wrote: >>> >>> Here is a blog entry wrote up on the state of Views/Triggers: >>> http://krow.livejournal.com/641510.html >>> >>> Comments either here or there are welcome! >> >> No offense but to me your wording is at times quite confusing. Look at >> this: >> >> " >> There are plans to add "non-materializing views", but that is still a >> couple of milestones off. >> ... >> One of the problems when talking about views is that the word >> 'materialize' has been over used. >> To 'materialize' a view, it means that you take the view definition, >> turn it into a temporary table, and then join it against a query. In >> Drizzle we consider this a 'no no'. >> ... >> Subqueries at this point are only semi-useful. Many of the common >> methods of using them result in a 'derived' table, aka a materialized >> table, which just makes them too slow. >> ... >> So 'materializing' is out, but what is not out is 'materialized joins'. >> This is an SQL feature whereby a table is created and is updated based >> on entries from other tables. This is something I do expect us to >> support at some point. >> .... >> We can also have materialized views via the same method. The 'tires' >> on this project have been kicked around but no one has started it yet. >> ... >> Materialized Views are pretty cool, materializing a view though pretty >> much make you want to cry. >> " >> >> All documentation I have seen so far uses the term "materialized view" >> to denote a special class of database view objects that use a base >> table to cache the result of the SQL query underlying the view. This >> is also what Justin is referring too AFAICS. For that reason, the term >> "non-materializing view" you used in the second paragraph is confusing >> to me - at a glance it looks like you mean "views, not materialized >> views" but I think you meant in fact views that can be evaluated >> without first evaluating the views' underlying query and storing the >> result in a temporary table. >> >> Later on you refer to the term "materialized join". I have never seen >> that term, except as part of "materialized join view", in which case >> it refers to a materialized view that has an underlying query that >> contains a join. In your post, you seem to use the term "materialized >> join" to denote what is usually referred to as "materialized view" - >> ("This is an SQL feature whereby a table is created and is updated >> based on entries from other tables. "). A materialized view need not >> be based on a join query at all (I mean, a query involving a JOIN >> operation), therefore it is confusing to use the term "materialized >> join" if you actually mean "materialized view". >> >> Another point that I found confusing is your use of the term "derived >> table". You seem to use that term to denote any case where a subquery >> is first evaluated and stored in a temptable for later use. So far, >> I've seen the term "derived table" being used exclusively for a >> special class of subqueries, "a subquery in the FROM clause", also >> known as an "inline view". The term derived table is normally used to >> denote this syntax construct, regardless of whether the unerlying >> implementation has to first evealuate the subquery and store it in a >> temporary table. >> >> So I guess I'm saying I'm not really sure what you mean anymore when >> you say "materialized view". >> >> kind regards, >> >> Roland >> >>> >>> Cheers, >>> -Brian >>> >>> _______________________________________________ >>> Mailing list: https://launchpad.net/~drizzle-discuss >>> Post to : [email protected] >>> Unsubscribe : https://launchpad.net/~drizzle-discuss >>> More help : https://help.launchpad.net/ListHelp >>> >> >> >> >> -- >> Roland Bouman >> http://rpbouman.blogspot.com/ >> >> Author of "Pentaho Solutions: Business Intelligence and Data >> Warehousing with Pentaho and MySQL", >> http://www.wiley.com/WileyCDA/WileyTitle/productCd-0470484322.html > > -- Roland Bouman http://rpbouman.blogspot.com/ Author of "Pentaho Solutions: Business Intelligence and Data Warehousing with Pentaho and MySQL", http://www.wiley.com/WileyCDA/WileyTitle/productCd-0470484322.html _______________________________________________ Mailing list: https://launchpad.net/~drizzle-discuss Post to : [email protected] Unsubscribe : https://launchpad.net/~drizzle-discuss More help : https://help.launchpad.net/ListHelp
