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Joining SAS Dataset with Teradata table

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Joining SAS Dataset with Teradata table

I have a SAS Dataset with 5 million records and a teradata table with 400 million records for left join on one key variable in PROC SQL. I need 7 variables to keep from SAS Dataset and 2 two from teradata table. I am trying for more efficient way to joins these tables.

 

Any suggestions! 

 

Environment: SAS EG 7.1, SAS 9.4 Grid on linux. 

Note: No indexes on the teradata table or not permitted to create 

Thanks,
Suryakiran

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‎06-28-2017 09:56 AM
SAS Employee
Posts: 203

Re: Joining SAS Dataset with Teradata table

[ Edited ]

Hi @SuryaKiran

 

Your results closely match what I experienced yesterday. I created a 2M row data set and it took 1:57 (one hour and 57 minutes) to move it into a VOLATILE table. I backed off the size to 50K rows (2 columns - $10 and $3). 

 

The first test I ran was a simple INSERT (no MULTISMT=YES) and it took slightly over 4 minutes to insert the 50k rows. Next, I specified TPT=NO MULTISTMT=YES on the target table. The 50K rows were INSERTed in just under 3 minutes. Which isn't great but it is ~33% faster than doing nothing. We can't use TPT=YES because it opens its own connection and cannot see the VOLATILE table. 

 

I used TPT=YES FASTLOAD=YES and was able to load the 2M row table in under 7 seconds. I think it is clear that you really want to use FASTLOAD. 

 

Given your situation, I would describe the problem to your DBA. They could create an empty table for you and allow you to FASTLOAD into it, and delete the contents. If this approach is taken be sure to check out the link, below, on DELETEing data fast. They may allow you to create a table in a playpen. Either of these approached would be greatly preferred to using a VOLATILE table. 

 

When dealing with your DBA express concern that by not being able to create a table you will be using more Teradata resources than required. Point out that if you aren't able to move the small set of data to the server then SAS may unnecessarily read large amounts of data from Teradata into SAS (SAS will perform the join when it is best performed by Teradata). 

 

When I was in SAS consulting I dealt with this type of thing quite often. If you explain it as "I am trying to make efficient use of database resources" you have a good chance of having them help you. 

 

So, ask for permission to create the table in a playpen and if they say "no" then ask them to create the table for you. Either way it is better than the VOLATILE table strategy. 

 

Once you have permission to create your table you will want to ensure that it is indexed proper and has up-to-date statistics. This will help make the join processing as efficient as possible. It may be fine to load the table, then take statistics one time. This could work because your table will be similar each time it is loaded because the data is deleted prior to each new load. I think I discuss statistics in the Troubleshooting SAS and Teradata Query Performance Problems paper.

 

You may find these helpful:

Effectively Moving SAS Data into Teradata

 

Troubleshooting SAS and Teradata Query Performance Problems

 

Teradata Parallel Transporter: Loading Your SAS Data Just Became Easier

 

The SQL Tuning Checklist: Making Slow Database Queries a Thing of the Past

 

DBIDIRECTEXEC: GOFAST=YES for Database Processing (SAS Communities Article)

 

DELETE Your Teradata Data Fast! (This will help if the DBA creates a table for you)

 

Best wishes,

Jeff

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PROC Star
Posts: 253

Re: Joining SAS Dataset with Teradata table

move the SAS table into Teradata and join the table in Teradata.

Frequent Contributor
Posts: 127

Re: Joining SAS Dataset with Teradata table

I only can read tables from teradata. I don't have write permission.

 

Thanks

Thanks,
Suryakiran
PROC Star
Posts: 253

Re: Joining SAS Dataset with Teradata table

see whether you can create a volatile table, which probably should have access and then do you can join with a volatile table.

PROC Star
Posts: 253

Re: Joining SAS Dataset with Teradata table

Please check this link answered by SAS employee may be helpful.

 

https://communities.sas.com/t5/Base-SAS-Programming/Subseting-Teradata-table-with-SAS-dataset/m-p/22...

 

 

Contributor
Posts: 56

Re: Joining SAS Dataset with Teradata table

you can use hash programming to join tables instead of proc sql.
Super User
Posts: 5,257

Re: Joining SAS Dataset with Teradata table

A hash would not solve this particular issue, which is risking to move a whole TD table into SAS for the join.
So first look in the thread that @kiranv_ links to.
An additional tip is the DBKEY option.
Data never sleeps
SAS Employee
Posts: 21

Re: Joining SAS Dataset with Teradata table

A straight forward approach that should work would be to:

 

1. First Bulk Load the SAS dataset to a Teradata table

https://support.sas.com/documentation/cdl/en/acreldb/63647/HTML/default/viewer.htm#a001405937.htm

 

2. join the two Teradata tables (could use an implicit join with SAS PROC SQL, or an explicit SQL passthrough join).

 

3.  Then, if necessary, pull the resulting join back down to SAS as a SAS dataset.

 

 

 

Frequent Contributor
Posts: 127

Re: Joining SAS Dataset with Teradata table

I tried to insert data into volatile table in teradata as mentioned by @kiranv_ and then by using explicit sql-passthrough to get my data into sas. The issue here is I have 1 million SAS data to be inserted into volatile table, this is taking long time. I belive we cannot use FASTLOAD or MULTILOAD if we are inserting into volatile table. I used TPT and MULTISTMT, but my problem is not solved. Is there a way I can inprove the performance.

Note: I only can create volatile tables in Teradata.

 

 

LIBNAME TD TERADATA SERVER=ABCD   USER=XXXX PASSWORD=XXXXXX CONNECTION=GLOBAL DBMSTEMP=YES;

PROC DELETE DATA=TD.temp1;
RUN;

proc sql;
  connect to teradata(SERVER=ABCD   USER=XXXX PASSWORD=XXXXXX CONNECTION=GLOBAL);
 execute
  (CREATE VOLATILE TABLE temp1(NAME CHAR(10), STATE CHAR(3)) 
		ON COMMIT PRESERVE ROWS) 	by teradata;
  execute ( COMMIT WORK ) by teradata;
 quit;

options sastrace=',,,d' sastraceloc=saslog;
proc append  base=TD.temp1(TPT=YES multistmt=yes DBCOMMIT=10000) data=WORK.HOME FORCE ;
run;

 

Thanks,
Suryakiran
PROC Star
Posts: 253

Re: Joining SAS Dataset with Teradata table

[ Edited ]

this could be due to  primary index. Here name is your primary index. If you do not explicitly mention primary index, then your first column will become primary index. Is your name column unique, if not, it will leading to skewing , which in turn will effect your performance. If I were you, I will do few changes.

1. I will create your volatile table as multiset table with no primary index. (no PI is best for staging tables as data can be inserted fastly because data can be loaded into this tables randomly). Multiset table will not check for  duplicate records further enhancing performance. If you do not mention set or multiset table in ANSI mode, set tables are created, Set tables will check for duplicates )

2. I will name as varchar(10) instead of char(10)

please check the code below.

 

proc sql;
  connect to teradata(SERVER=ABCD   USER=XXXX PASSWORD=XXXXXX CONNECTION=GLOBAL);
 execute
  (CREATE multiset VOLATILE TABLE temp1(NAME VARCHAR(10), STATE CHAR(3))
		 NO PRIMARY INDEX ON COMMIT PRESERVE ROWS)	by teradata;
  execute ( COMMIT WORK ) by teradata;
 quit;

 

Frequent Contributor
Posts: 127

Re: Joining SAS Dataset with Teradata table

I did as you mentioned, but still its taking 2 hours to send 1 million SAS Data to Volatile Table

Thanks,
Suryakiran
PROC Star
Posts: 253

Re: Joining SAS Dataset with Teradata table

I did some bechmarking in our own environment and what I found in our environment was 1 million records records was taking approximately 2 minutes(without fastload).this table has around 150 columns.

I do not know how much spool space is available for you, whether that has any impact on this. If possible, please give us some info like how many columns are there in your table. IS this only process, which takes time.

if possible, Try loading your table when the workload is very less and see whether that does have any impact. I would ask @JBailey , who is an expert and wrote quite few articles on moving data from SAS into teradata.

 

one of best articles of @JBailey on moving data from SAS to teradata is given below, which could be of some help.

https://support.sas.com/resources/papers/EffectivelyMovingSASDataintoTeradata.pdf

 

SAS Employee
Posts: 203

Re: Joining SAS Dataset with Teradata table

Hi @kiranv_

 

You are way too kind!

 

I really need to take some time and update the doc you referenced, but the content is mostly relevant. 

 

Best wishes,

Jeff

Respected Advisor
Posts: 3,896

Re: Joining SAS Dataset with Teradata table

@SuryaKiran

Make sure you also set DBCOMMIT=0

http://support.sas.com/documentation/cdl/en/acreldb/69580/HTML/default/viewer.htm#p0he4t6yjfmkhpn16q...

 

2 hours for 1M records is seriously slow. Is reading data from Teradata also that slow?

 

SAS Employee
Posts: 203

Re: Joining SAS Dataset with Teradata table

Hi @SuryaKiran

 

It has been a while since I have played around with this. I will take some time and see what I can come up with. I will try to get back here by Friday.

 

Does the DDL for temp1 reflect what you are actually loading into the database?

 

In the meantime: One suggestion, discuss this with your DBA and see if they will create a permanent table for you. They can let you load it and delete all the rows but not drop it. This will could allow you to FASTLOAD into it and then work from there.

 

I will let you know what I find.

 

Best wishes,

Jeff

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