1. Teradata Physical Implementation – Case Study

2. Create Table
- Distribution Check & PI Change
- Fallback
Create Index
- USI
- NUSI
Create Join Index
Create & Collect Statistics

3. Create Table – Copy Data
CREATE SET TABLE TPCH.Customer ,NO FALLBACK ,
NO BEFORE JOURNAL,
NO AFTER JOURNAL (
C_CUSTKEY INTEGER NOT NULL,
C_NAME VARCHAR(25) CHARACTER SET LATIN CASESPECIFIC NOT NULL,
C_ADDRESS VARCHAR(40) CHARACTER SET LATIN CASESPECIFIC NOT NULL,
C_NATIONKEY INTEGER NOT NULL,
C_PHONE CHAR(15) CHARACTER SET LATIN CASESPECIFIC NOT NULL,
C_ACCTBAL DECIMAL(15,2) NOT NULL,
C_MKTSEGMENT CHAR(10) CHARACTER SET LATIN CASESPECIFIC NOT NULL,
C_COMMENT VARCHAR(117) CHARACTER SET LATIN CASESPECIFIC NOT NULL)
UNIQUE PRIMARY INDEX ( C_CUSTKEY );
SELECT databasename, Tablename, sum(CurrentPerm)
FROM DBC.TABLESIZE
where databasename = 'TPCH'
group by databasename, Tablename
DatabaseNameTableNameSum(CurrentPerm)
TPCH ORDERTBL
TPCH LINEITEM
TPCH PARTTBL
TPCH PARTSUPP
TPCH NATION
TPCH REGION
TPCH CUSTOMER
TPCH SUPPLIER
show table TPCH.Customer;
If Privileges missing grant to your user
GRANT SELECT ON DBC TO TRAINER;
GRANT SELECT ON TPCH TO TRAINER;
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4. Data Distribution Check
1) Create Customer Table in your User/Database;
- Keep the same definition (No Fallback & Same PI)
- You can create the table and get the data OR can be achieved as below.
CREATE TABLE TRAINER.CUSTOMER AS TPCH.CUSTOMER WITH DATA;
Show table and check the definition and the data in the table.
show table TRAINER.Customer;
2) Check the Table size by AMP
SELECT *
FROM DBC.TABLESIZE
where databasename = 'TRAINER'
and Tablename= 'CUSTOMER‘
VprocDatabaseNameAccountNameTableNameCurrentPermPeakPerm
0TRAINER DBC CUSTOMER
1TRAINER DBC CUSTOMER
-- Current PI of the Table is C_CUSTKEY, Degree of Uniqueness is 100%
select count(distinct C_CUSTKEY), count(1)
from TRAINER.CUSTOMER
Count(Distinct(C_CUSTKEY))Count(1)

5. Change in PI 1) Consider the different PI for CUSTOMER Table.
CREATE MULTISET TABLE TRAINER.Customer_PI ,NO FALLBACK ,
NO BEFORE JOURNAL,
NO AFTER JOURNAL (
C_CUSTKEY INTEGER NOT NULL,
C_NAME VARCHAR(25) CHARACTER SET LATIN CASESPECIFIC NOT NULL,
C_ADDRESS VARCHAR(40) CHARACTER SET LATIN CASESPECIFIC NOT NULL,
C_NATIONKEY INTEGER NOT NULL,
C_PHONE CHAR(15) CHARACTER SET LATIN CASESPECIFIC NOT NULL,
C_ACCTBAL DECIMAL(15,2) NOT NULL,
C_MKTSEGMENT CHAR(10) CHARACTER SET LATIN CASESPECIFIC NOT NULL,
C_COMMENT VARCHAR(117) CHARACTER SET LATIN CASESPECIFIC NOT NULL)
PRIMARY INDEX ( C_MKTSEGMENT );
1) Consider the different PI for CUSTOMER Table.
select C_MKTSEGMENT, count(1)
from TRAINER.CUSTOMER
group by C_MKTSEGMENT
C_MKTSEGMENTCount(1)
FURNITURE 1169
MACHINERY 1174
BUILDING 1296
HOUSEHOLD 1171
AUTOMOBILE1190
select count(distinct C_MKTSEGMENT), count(1)
Count(Distinct(C_MKTSEGMENT))Count(1)
56000
2) Create the Table CUSTOMER_PI , same definition as Customer but with C_MKTSEGMENT as PI.
3) Check the size by AMP.
VprocDatabaseNameAccountNameTableNameCurrentPermPeakPerm
0TRAINER DBC CUSTOMER_PI
1TRAINER DBC CUSTOMER_PI

6. Fallback Impact
CREATE MULTISET TABLE TRAINER.Customer_FB , FALLBACK ,
NO BEFORE JOURNAL,
NO AFTER JOURNAL (
C_CUSTKEY INTEGER NOT NULL,
C_NAME VARCHAR(25) CHARACTER SET LATIN CASESPECIFIC NOT NULL,
C_ADDRESS VARCHAR(40) CHARACTER SET LATIN CASESPECIFIC NOT NULL,
C_NATIONKEY INTEGER NOT NULL,
C_PHONE CHAR(15) CHARACTER SET LATIN CASESPECIFIC NOT NULL,
C_ACCTBAL DECIMAL(15,2) NOT NULL,
C_MKTSEGMENT CHAR(10) CHARACTER SET LATIN CASESPECIFIC NOT NULL,
C_COMMENT VARCHAR(117) CHARACTER SET LATIN CASESPECIFIC NOT NULL)
PRIMARY INDEX ( C_MKTSEGMENT );
1) Create Table CUSTOMER_FB with the FALLBACK ON and check the Table Size.
2) Check the size by AMP.
- Note the size is doubled in total.
- This is just a two amp system so one AMP is the FALLBACK for the other so shows same size with FALLBACK.
VprocDatabaseNameAccountNameTableNameCurrentPermPeakPerm
0TRAINER DBC CUSTOMER_FB
1TRAINER DBC CUSTOMER_FB

7. Create Table
- Distribution Check & PI Change
- Fallback
Create Index
- USI
- NUSI
Create Join Index
Create & Collect Statistics

8. Creating USI Explain the below Query (PI is C_MKT_SEGMENT) EXPLAIN
SELECT * FROM CUSTOMER_PI
WHERE C_CUSTKEY = 1613
We do an all-AMPs RETRIEVE step from TRAINER.CUSTOMER_PI by way of
an all-rows scan with a condition of (
Note – Its is doing the full Table scan
2) Create a USI on C_CUSTKEY
CREATE UNIQUE INDEX
IDX_CKEY (C_CUSTKEY)
ON CUSTOMER_PI; 3)
Note the change in the Explain for Index scan and the change in the response time
CREATE MULTISET TABLE TRAINER.Customer_PI ,NO FALLBACK ,
NO BEFORE JOURNAL,
NO AFTER JOURNAL (
C_CUSTKEY INTEGER NOT NULL,
C_NAME VARCHAR(25) CHARACTER SET LATIN CASESPECIFIC NOT NULL,
C_ADDRESS VARCHAR(40) CHARACTER SET LATIN CASESPECIFIC NOT NULL,
C_NATIONKEY INTEGER NOT NULL,
C_PHONE CHAR(15) CHARACTER SET LATIN CASESPECIFIC NOT NULL,
C_ACCTBAL DECIMAL(15,2) NOT NULL,
C_MKTSEGMENT CHAR(10) CHARACTER SET LATIN CASESPECIFIC NOT NULL,
C_COMMENT VARCHAR(117) CHARACTER SET LATIN CASESPECIFIC NOT NULL)
PRIMARY INDEX ( C_MKTSEGMENT );
EXPLAIN – WITH USI
1) First, we do a two-AMP RETRIEVE step from TRAINER.CUSTOMER_PI by
way of unique index # 4 "TRAINER.CUSTOMER_PI.C_CUSTKEY = 1613"
with no residual conditions. The estimated time for this step is
0.02 seconds.
-> The row is sent directly back to the user as the result of
statement 1. The total estimated time is 0.02 seconds.
EXPLAIN – WITHOUT USI
1) First, we lock a distinct TRAINER."pseudo table" for read on a
RowHash to prevent global deadlock for TRAINER.CUSTOMER_FB.
2) Next, we lock TRAINER.CUSTOMER_FB for read.
3) We do an all-AMPs RETRIEVE step from TRAINER.CUSTOMER_FB by way of
an all-rows scan with a condition of (
"TRAINER.CUSTOMER_FB.C_CUSTKEY = 1613") into Spool 1 (group_amps),
which is built locally on the AMPs. The size of Spool 1 is
estimated with no confidence to be 707 rows. The estimated time
for this step is 0.14 seconds.
-> The contents of Spool 1 are sent back to the user as the result of
statement 1. The total estimated time is 0.14 seconds.

9. Creating NUSI Explain the below Query EXPLAIN
select * from CUSTOMER_PI
where C_NATIONKEY = 17
Note – Its is doing the full Table scan
2) Create a NUSI on C_NATIONKEY
CREATE INDEX
IDX_NTKEY (C_NATIONKEY)
ON CUSTOMER_PI;
3)Explain the same Query again
Note the change in the Explain for Index scan
and the change in the response time – The Index is not used
- We can only Create the Index but can not enforce the usage. The Usage depends on the Optimizer.
EXPLAIN – WITHOUT NUSI
1) First, we lock a distinct TRAINER."pseudo table" for read on a
RowHash to prevent global deadlock for TRAINER.CUSTOMER_PI.
2) Next, we lock TRAINER.CUSTOMER_PI for read.
3) We do an all-AMPs RETRIEVE step from TRAINER.CUSTOMER_PI by way of
an all-rows scan with a condition of (
"TRAINER.CUSTOMER_PI.C_NATIONKEY = 17") into Spool 1 (group_amps),
which is built locally on the AMPs. The size of Spool 1 is
estimated with no confidence to be 707 rows. The estimated time
for this step is 0.14 seconds.
-> The contents of Spool 1 are sent back to the user as the result of
statement 1. The total estimated time is 0.14 seconds.
EXPLAIN – WITH NUSI
1) First, we do a two-AMP RETRIEVE step 1) First, we lock a distinct TRAINER."pseudo table" for read on a
RowHash to prevent global deadlock for TRAINER.CUSTOMER_PI.
2) Next, we lock TRAINER.CUSTOMER_PI for read.
3) We do an all-AMPs RETRIEVE step from TRAINER.CUSTOMER_PI by way of
an all-rows scan with a condition of (
"TRAINER.CUSTOMER_PI.C_NATIONKEY = 17") into Spool 1 (group_amps),
which is built locally on the AMPs. The size of Spool 1 is
estimated with low confidence to be 283 rows. The estimated time
for this step is 0.13 seconds.
-> The contents of Spool 1 are sent back to the user as the result of
statement 1. The total estimated time is 0.13 seconds.

10. Create Table
- Distribution Check & PI Change
- Fallback
Create Index
- USI
- NUSI
Create Join Index
Create & Collect Statistics

11. Creating JOIN Index EXPLAIN the below query: EXPLAIN
SELECT SUM(C_ACCTBAL)
FROM CUSTOMER
WHERE C_NATIONKEY = 10
2) Create a Single table Join Index and
CREATE JOIN INDEX CUSTOMER_JI
AS SELECT
C_CUSTKEY,
C_NATIONKEY,
C_ACCTBAL,
C_MKTSEGMENT
PRIMARY INDEX (C_NATIONKEY);
3) Run the same explain plan again.
EXPLAIN – WITHOUT JI
1) First, we lock a distinct TRAINER."pseudo table" for read on a RowHash to prevent global deadlock for TRAINER.CUSTOMER.
2) Next, we lock TRAINER.CUSTOMER for read.
3) We do an all-AMPs SUM step to aggregate from TRAINER.CUSTOMER by way of an all-rows scan with a condition of ("TRAINER.CUSTOMER.C_NATIONKEY = 10"). Aggregate Intermediate Results are computed globally, then placed in Spool 3. The size of Spool 3 is estimated with high confidence to be 1 row. The estimated time for this step is 0.13 seconds.
4) We do an all-AMPs RETRIEVE step from Spool 3 (Last Use) by way of an all-rows scan into Spool 1 (group_amps), which is built locally on the AMPs. The size of Spool 1 is estimated with high confidence to be 1 row. The estimated time for this step is seconds.
-> The contents of Spool 1 are sent back to the user as the result of statement 1.
EXPLAIN – WITH JI
1) First, we do a single-AMP SUM step to aggregate from TRAINER.CUSTOMER_JI by way of the primary index
"TRAINER.CUSTOMER_JI.C_NATIONKEY = 10" with no residual conditions, and the grouping identifier in field1. Aggregate Intermediate Results are computed locally, then placed in Spool 3. The size of
Spool 3 is estimated with high confidence to be 1 row. The estimated time for this step is 0.03 seconds.
2) Next, we do a single-AMP RETRIEVE step from Spool 3 (Last Use) by way of the primary index "TRAINER.CUSTOMER_JI.C_NATIONKEY = 10“ into Spool 1 (one-amp), which is built locally on that AMP. The
size of Spool 1 is estimated with high confidence to be 1 row. The estimated time for this step is 0.03 seconds.
-> The contents of Spool 1 are sent back to the user as the result of
statement 1.

12. Create Table
- Distribution Check & PI Change
- Fallback
Create Index
- USI
- NUSI
Create Join Index
Create & Collect Statistics

13. Collect Statistics COLLECT STATISTICS EXPLAIN – WITH STATISTICS
Run the Below Explain
EXPLAIN
SELECT *
FROM CUSTOMER_FB
WHERE C_NATIONKEY = 10;
Note the LOW confidence and the number of rows 707.
- Collect Statistics
COLLECT STATISTICS
ON CUSTOMER_FB
COLUMN(C_NATIONKEY);
Explain Again
Note the HIGH confidence and the number of rows 290.
Actual count in the Table
SELECT COUNT(1)
WHERE C_NATIONKEY = 10
246
EXPLAIN – WITHOUT STATISTICS
1) First, we lock a distinct TRAINER."pseudo table" for read on a
RowHash to prevent global deadlock for TRAINER.CUSTOMER_FB.
2) Next, we lock TRAINER.CUSTOMER_FB for read.
3) We do an all-AMPs RETRIEVE step from TRAINER.CUSTOMER_FB by way of
an all-rows scan with a condition of (
"TRAINER.CUSTOMER_FB.C_NATIONKEY = 10") into Spool 1 (group_amps),
which is built locally on the AMPs. The size of Spool 1 is
estimated with no confidence to be 707 rows. The estimated time
for this step is 0.14 seconds.
-> The contents of Spool 1 are sent back to the user as the result of
statement 1. The total estimated time is 0.14 seconds.
EXPLAIN – WITH STATISTICS
1) First, we lock a distinct TRAINER."pseudo table" for read on a
RowHash to prevent global deadlock for TRAINER.CUSTOMER_FB.
2) Next, we lock TRAINER.CUSTOMER_FB for read.
3) We do an all-AMPs RETRIEVE step from TRAINER.CUSTOMER_FB by way of
an all-rows scan with a condition of (
"TRAINER.CUSTOMER_FB.C_NATIONKEY = 10") into Spool 1 (group_amps),
which is built locally on the AMPs. The size of Spool 1 is
estimated with high confidence to be 290 rows. The estimated time
for this step is 0.13 seconds.
-> The contents of Spool 1 are sent back to the user as the result of
statement 1. The total estimated time is 0.13 seconds.