Forum

How does Table.Buff...
 
Notifications
Clear all

How does Table.Buffer work?

2 Posts
2 Users
0 Reactions
435 Views
(@kutra100)
Posts: 1
New Member
Topic starter
 

Hi Catalin Bombea

I notice in a lot of your posts you tend to use Table.Buffer to speed up the calculation time of a query. But could you explain how exactly does this work?
I have read a few posts about it but still don't understand the fundamentals. Basically:
1) How does Table.Buffer work?
2) When should one use Table.Buffer?
3) At what step is it best to add Table.Buffer? (I noticed in a few of your posts, you have added it at the point when you add an index. Is there a reason for choosing that particular step?)
4) Also is it true when you create a new step in a query, all the steps get calculated and refreshed starting from the first step which increases the calculation time?

Any help would be great!


-Sam

 
Posted : 21/05/2019 11:04 pm
(@catalinb)
Posts: 1937
Member Admin
 

Hi Sam,

You can take a look at these posts, they are useful: https://www.thebiccountant.com/speedperformance-aspects/

And: https://social.technet.microsoft.com/Forums/en-US/2cc1b370-9976-4a6b-add1-91efc1d522d7/when-to-use-tablebuffer?forum=powerquery

Without buffering, all of the rows would stream through to Excel and only use a small amount of memory. With buffering, it’s going to read all of the rows into memory.

PQ limits the amount of stuff stored in RAM. Anything over that limit gets temporarily stored on your hard drive, which is much slower to access than RAM. 

Depends on your data size, RAM, so it's hard to say for sure that using Buffer will speed things up, it might slow down your query, you'll have to try and see if it works in your situation.

 
Posted : 23/05/2019 3:59 am
Share: