15.00 - Duplicate NUPI Row Read I/O as a Function of Number of Rows Inserted - Teradata Database

Teradata Database Design

prodname
Teradata Database
vrm_release
15.00
category
User Guide
featnum
B035-1094-015K

Duplicate NUPI Row Read I/O as a Function of Number of Rows Inserted

This table illustrates the absolute and cumulative number of read I/Os required as a function of the number of duplicate NUPI rows inserted into a table. These figures are not a function of the number of AMPs in the configuration because duplicate NUPI values all hash to the same AMP. Therefore, the magnitude of the effect is independent of the number of AMPs on the system.

As you can see, the read I/O burden is tractable up to about 100 duplicate NUPI rows inserted. Beyond that point, the read I/O requirements are increasingly intractable.

The performance of any system is noticeably worsened when any additional duplicate NUPI rows are added.

 

     Number of Rows            Inserted

Number of Prior Logical Reads Required to    Process This Number of Inserted Rows

     Cumulative Number of              Logical Reads

                      1

                                    0

                            0

                      2

                                    1

                            1

                      3

                                    2

                            3

                      4

                                    3

                            6

                      5

                                    4

                          10

                      6

                                    5

                          15

                      7

                                    6

                          21

                      8

                                    7

                          28

                      9

                                    8

                          36

                    10

                                    9

                          45

                    20

                                  19

                        190

                    30

                                  29

                        435

                    40

                                  39

                        780

                    50

                                  49

                     1,225

                    60

                                  59

                     1,770

                    70

                                  69

                     2,415

                    80

                                  79

                     3,160

                    90

                                  89

                     4,005

                  100

                                  99

                     4,950

                  200

                                199

                   19,900

                  300

                                299

                   44,850

                  400

                                399

                   79,800

                  500

                                499

                 124,750

                  600

                                599

                 179,700

                  700

                                699

                 244,650

                  800

                                799

                 319,600

                  900

                                899

                 404,550

               1,000

                                999

                 499,500