topic Re: Joining Large Tables in New SAS User

Joining Large Tables

DiegoDiaz — Thu, 20 Dec 2018 13:02:07 GMT

Hi All-

I have been trying to join two large tables by a simple join but it has not been possible since the tables are huge and the joining process is taking forever. I need a table with the number of transactions and the amount by account and month level. I have transaction data since 1998.

I tried to optimize a PROC SQL and also tried hash table but i am expert using hash table so not sure what is the best way to this.

Any help is much appreciated

Thanks in advance.

Table 1: Account level data ( It has around 7 Millions of records)

Account	Date_Open	Product_Type
123	1/1/2017	CC
234	2/8/2016	DC
345	3/9/2018	CC

Table 1:Transaction Level Data (It has millions of records. may have 10 times the account table) .

Account	Transaction_ID	Transaction_Amt	Posted_Date	Tran_Code
123	1	$ 30	3/4/2000	N
123	2	$ 35	5/3/2001	A
123	3	$ 1,244	4/7/2016	C
234	4	$ 344	9/1/2011	N
234	5	$ 678	4/6/2015	A
234	6	$ 856	4/7/2015	A
345	7	$ 332	9/30/2000	C
345	8	$ 123	8/4/2005	A
345	9	$ 765	4/9/2017	C
345	10	$ 324	9/4/2018	N
345	11	$ 2,344	12/12/2018	A

DATA test(drop=rc);
if 0 then set Transaction_Table(where=(PST50_TRAN_CD_EX IN(&TRA_CD.)));
declare Hash Trans (dataset:"Transaction_Table");
rc = Trans.DefineKey ('Account');
rc = Trans.DefineData ('Posted_Date','Transaction_Amt');
rc = Trans.DefineDone ();
do until (eof) ;
set acct end = eof;
call missing(Transaction_Table);
rc = Trans.find ();
if rc=0 then output;;
end;
stop;
run;

PROC SQL;
CREATE TABLE DD_TABLE_M AS SELECT
A.account,
N(B.Posted_Date) AS NUM_TX,
SUM(B.Transaction_Amt) AS AMT_TX,
D.YR_MTH_NBR
FROM acct A, Transaction_Table B, month D
WHERE A.account = B.account and D.TM_ID = B.TM_ID and
B.PST50_TRAN_CD_EX IN (SELECT DISTINCT Tran_Code FROM Tran_Code WHERE CUS IN('A','C'));
QUIT;

Re: Joining Large Tables

Kurt_Bremser — Thu, 20 Dec 2018 13:28:10 GMT

Is the account table unique with regard to Account? If yes, sort both tables and do a data step merge.

Re: Joining Large Tables

DiegoDiaz — Thu, 20 Dec 2018 13:33:38 GMT

Yes, Account is unique id in both table,

Data step merge option was not optimal for this since i had to sort the tables before and i took even more time,

Thanks

Re: Joining Large Tables

Kurt_Bremser — Thu, 20 Dec 2018 14:21:19 GMT

There are at least three occurences of "123" in your transaction dataset, so it surely is not unique there.

By "unique" I mean that a proc sort nodupkey of the account table by account will not delete any observations.

The fastest method of joining that is not done with in-memory techniques is sort and data step merge, in my experience.

If you want to go down the hash path, I suggest to load the smaller table into hash:

data account;
input Account :$3. Date_Open :mmddyy10. Product_Type :$2.;
format Date_Open yymmddd10.;
datalines;
123 1/1/2017 CC
234 2/8/2016 DC
345 3/9/2018 CC
;
run;

data transaction;
input Account :$3. Transaction_ID Transaction_Amt :comma. Posted_Date :mmddyy10. Tran_Code :$1.;
format Posted_Date yymmddd10.;
datalines;
123 1 30 3/4/2000 N
123 2 35 5/3/2001 A
123 3 1,244 4/7/2016 C
234 4 344 9/1/2011 N
234 5 678 4/6/2015 A
234 6 856 4/7/2015 A
345 7 332 9/30/2000 C
345 8 123 8/4/2005 A
345 9 765 4/9/2017 C
345 10 324 9/4/2018 N
345 11 2,344 12/12/2018 A
;
run;

data want;
set transaction;
if _n_ = 0 then set account; /* initializes the structure */
if _n_ = 1
then do;
  declare hash acc (dataset:'account');
  acc.definekey("account");
  acc.definedata("date_open","product_type");
  acc.definedone();
end;
if not acc.find() then output;
run;