topic Re: sashdat vs in memory table in SAS Viya

sashdat vs in memory table

elisehoo1 — Sun, 13 Jun 2021 14:51:49 GMT

Hi there,

would like to check what is the difference of loading the data to sashdat (filepath) and the in-memory global table ?

wondering if i am loading the data to sashdat via proce casutil ,does it taking memory ?

and if best the practice is to load the data to global session in memory table or sashdat for VA reporting purpose?

Thanks

Elise

Re: sashdat vs in memory table

sbxkoenk — Sun, 13 Jun 2021 18:10:28 GMT

Hello @elisehoo1 ,

Quickly answering from the top of my head here, so I hope I'm right (and not making any blunders).

For Visual Analytics you absolutely need an in-memory table (mostly a "promoted" one that is available across sessions).

The .sashdat file is not in-memory. It's on-disk, but it's a special Viya format that allows you to rapidly put data in-memory again. The .sashdat file is a kind of permanent copy of an in-memory table.

The .sashdat file is on-disk, so it's not lost when the server is rebooted. After rebooting all in-memory data are "evaporated" of course.

Cheers,

Koen

Re: sashdat vs in memory table

Patrick — Mon, 14 Jun 2021 02:21:49 GMT

May be this link will help:

https://communities.sas.com/t5/SAS-Communities-Library/4-Rules-to-Understand-CAS-Management-of-In-Memory-Data/ta-p/588652

Re: sashdat vs in memory table

elisehoo1 — Thu, 22 Jul 2021 14:08:09 GMT

there was one observation that i observed about the sashdat and in-memory table

let's say if there are two same table name like below , one is in memory table , one is in sashdat.

In the event the in-memory tables have gone missing due to memory has been flushed due unforeseen behavior (server restarts or etc) or this particular in-memory table be unloaded in purpose . The "Magic" happens when we open the sas va report that using this table, it will bring back the in-memory table as the "same name".sashdat will be automatically be picked up and reloaded to the in-memory table .

This is amazing.. but what is the mechanism behind and if any documentation talking about ?