On Tuesday 04 September 2007 17:12:26 Arun Kumar PG wrote: > Good work svilan! > > couple questions from what you suggested: > >> skipping creation of objects - only using the data, if time of > >> creation gets critical. > In my query wherein the eagerloading is being done on 8 tables if I > manually run the join query being generated by SA ORM I get a > result set of over 70,000+ records because this is contains > duplicate things. I guess SA ORM traverses the returned result and > creates the right number of objects discarding the duplicate or > unwanted rows. probably, but unless u discard 50% of rows, it makes no much difference.
> How much time is generally spent by SA if let's say we have a > 1,000,000 rows returned and this resultset will form the whole > heirarchy i.e. A (main entity) A.b, A.c [] (a list) , A.c.d [] > (again a list) etc. ? Is that a considerable time ? well u just sum how many constructors has to be executed - per row, multiply by million... IMO anything in python mutiplied by million is considerable time. Maybe in 10 years it will be not. Thats why i want to keep my model separate from the denormalization scheme. > What is the best optimization technique followed (recommended by SA > ORM) when it comes to aggregation of data from multiple tables with > lots of rows in it (and continuously growing) ? SA 0.4 can do query polymorphisms by multiple per-subtype queries, but i have no idea how that works or how much better it is than one huge union/leftouterjoin + the type-switching over it, + u'll miss overall the ordering. Mike, can this mechanism be used somehow for my "vertical" loading, i.e. some load "column" from some related table that is not in the polymorhistic hierarchy? --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~----------~----~----~----~------~----~------~--~---
