hadoop - Does hive create separate copy of data -

-

when create table in hive using csv file hdfs hive create separate copy of data?

this cause unnecessary waste memory

no, in hive whatever hdfs location have given @ time of table creation. data reside @ same location. there wont separate copy of data either csv or other file formats.


Comments

Post a Comment

Popular posts from this blog

c# - Class in a list -

-
i understand in c# class passed reference. mean when store said class in list stored reference well, or better said c# style "pointer" of sorts? mean list n elements of class not take memory n times size of class n times size of reference class? or thinking wrong? you're right. if create n elements of class t, , class t uses, say, 10 bytes, takes on order of 10*n memory. if store in list<t> , still have 10*n memory objects, plus n times size of c# reference , list overhead. if store same elements in 2 lists, have 10*n objects, plus 2*n references, , 2 times list overhead. they're pointing @ same underlying objects.
Read more

mysql - Django database model for my website -

-
i building aviation website need store aircraft manufacturer, type , version of particular aircraft....boeing 777 300 example. here boeing manufact., 777 version , 300 model. model use is: class manufa(mod...): name=charfield .... manufact=models.foreignkey(manufact) type=models.foreignkey(type) version=models.foreignkey(version) this allows easy search problem every time have display item in search, have make 3 separate queries full name of aircraft form foreign key id....for search page 100 items...thats unimaginable number of queries.. if store these names if change version name or have edit each of rows...how solve can aircraft name same row...no second query.. you have read more of great django docs ;) https://docs.djangoproject.com/en/dev/ref/models/querysets/#select-related btw. should post full model definition
Read more

ios - How to run a segue on itself OR another viewController -

-
Image
i have main tableviewcontroller. when user tap on cell in tableview, if condition statement true, show main tableviewcontroller again(but show data on screen), , if condition false, show viewcontroller. in prepareforsegue method have this: if segue.identifier == "identifier1" { let destination = segue.destinationviewcontroller as? mainviewcontroller // destination!.x = // x variable in view controller } else if segue.identifier == "identifier2" { let destination = segue.destinationviewcontroller as? viewcontroller2 destination!.y = } also, run segue after tap on cells in tableview added this: override func tableview(tableview: uitableview, didselectrowatindexpath indexpath: nsindexpath) { tableview.deselectrowatindexpath(indexpath, animated: true) if condition true { self.performseguewithidentifier("identifier1", sender: self) } else{ self.performseguewithidentifier("identifier2", sender...
Read more