Ted, yes, 10K rows one for each customer. But if you write each order as a column, and there are 10 'columns' in an order, you have to somehow serialize the 10 columns that represent the order so you get one column per order_id. Of course you could still write out a column as order_id,order_column and then get your 6000 columns. If you did that, then you have the issue of your column id. Did you go column_id,order_id or did you go order_id, column_id? (One has to ask... :-) )
IMHO I'd elect to put the 10 columns of the order in a single column rather than write the 10 columns as individual columns. But that's just me. :-) -Mike > Date: Wed, 22 Dec 2010 19:00:25 -0800 > Subject: Re: Insert into tall table 50% faster than wide table > From: [email protected] > To: [email protected] > > > Each column is the order so you write one column for each order > As stated earlier, wide table has 6,000 columns instead of 600. :-) > > Bryan: > Can you describe how you form row keys in each case ? > > > On Wed, Dec 22, 2010 at 6:53 PM, Michael Segel > <[email protected]>wrote: > > > > > HBase does version cells. > > > > But I saw something of interest: > > " > > >>> In my test, there are 10,000 customers, each customer has 600 orders > > and each order has 10 columns. The tall table approach results in 6 mil rows > > of 10 columns. The wide table approach results is 10,000 rows of 6,000 > > columns. I'm using hbase 0.89-20100924 and hadoop 0.20.2. I am adding the > > orders using a Put for each order, submitted in batches of 1000 as a list of > > Puts. > > >>> > > >>> Are there techniques to speed up inserts with the wide table approach > > that I am perhaps overlooking? > > >>> > > >> > > > " > > > > Ok, so you have 10K by 600 by 10. So the 'tall' design has a row key of > > customer_id and Order_id with 10 columns in a single column family. > > So you get 6 million rows and 10 column puts. > > > > Now if you do a 'wide' table... > > Your row key is the 'customer_id' only. Each column is the order so you > > write one column for each order and you have to figure out how you represent > > your columns in the order. > > (An example... your order of 10 items is represented by a string with a > > 'special character' used as a column separator in the order.) > > So you're doing one column write for each order and you have a total of 10K > > rows. > > > > Unless I'm missing something part of the 'slowness' could be how your > > writing your orders on your wide table. There are a couple other unknowns. > > Are you hashing your keys? > > I mean are you getting a bit of 'randomness' in your keys? > > > > So what am I missing? > > > > -Mike > > > > > > > Subject: Re: Insert into tall table 50% faster than wide table > > > From: [email protected] > > > Date: Wed, 22 Dec 2010 18:24:05 -0800 > > > To: [email protected] > > > > > > Actually I don't think this is the problem as HBase versions cells, not > > rows, if I understand correctly. > > > > > > On Dec 22, 2010, at 5:03 PM, Bryan Keller wrote: > > > > > > > Perhaps slow wide table insert performance is related to row > > versioning? If I have a customer row and keep adding order columns one by > > one, I'm thinking that there might be a version kept of the row for every > > order I add? If I am simply inserting a new row for every order, there is no > > versioning going on. Could this be causing performance problems? > > > > > > > > On Dec 22, 2010, at 4:16 PM, Bryan Keller wrote: > > > > > > > >> It appears to be the same or better, not to derail my original > > question. The much slower write performance will cause problems for me > > unless I can resolve that. > > > >> > > > >> On Dec 22, 2010, at 3:52 PM, Peter Haidinyak wrote: > > > >> > > > >>> Interesting, do you know what the time difference would be on the > > other side, doing a lookup/scan? > > > >>> > > > >>> Thanks > > > >>> > > > >>> -Pete > > > >>> > > > >>> -----Original Message----- > > > >>> From: Bryan Keller [mailto:[email protected]] > > > >>> Sent: Wednesday, December 22, 2010 3:41 PM > > > >>> To: [email protected] > > > >>> Subject: Insert into tall table 50% faster than wide table > > > >>> > > > >>> I have been testing a couple of different approaches to storing > > customer orders. One is a tall table, where each order is a row. The other > > is a wide table where each customer is a row, and orders are columns in the > > row. I am finding that inserts into the tall table, i.e. adding rows for > > every order, is roughly 50% faster than inserts into the wide table, i.e. > > adding a row for a customer and then adding columns for orders. > > > >>> > > > >>> In my test, there are 10,000 customers, each customer has 600 orders > > and each order has 10 columns. The tall table approach results in 6 mil rows > > of 10 columns. The wide table approach results is 10,000 rows of 6,000 > > columns. I'm using hbase 0.89-20100924 and hadoop 0.20.2. I am adding the > > orders using a Put for each order, submitted in batches of 1000 as a list of > > Puts. > > > >>> > > > >>> Are there techniques to speed up inserts with the wide table approach > > that I am perhaps overlooking? > > > >>> > > > >> > > > > > > > > > > >
