Database Tuning Chap 8 : IOT Architecture Chap 9 : Cluster Factor Optimization Center for E-Business Technology Seoul National University Seoul, Korea Nam, Kwang Hyun Intelligent Database Systems Lab School of Computer Science & Engineering Seoul National University, Seoul, Korea

Copyright  2008 by CEBT Chap 8 : IOT Architecture  Contents IOT? IOT Performance Analysis Database Tuning - 2

Copyright  2008 by CEBT IOT?  Definition Acronym of ‘Index Organized Table’ Table which is organized like index structure (B*Tree indexes).  Property Limited fast access – Enable to complete all jobs with only Primary Key Index Scan Storage saving – Because IOT is mixed architecture with Primary Key Index and Table Database Tuning - 3

Copyright  2008 by CEBT IOT Performance Analysis  IOT architecture All column values are saved in Index Leaf Block  IOT creation PCTTHRESHOLD should be set as big number. Database Tuning - 4 Index Leaf Block If the size of row is more than 20% of block except block header, columns except key column are saved in Overflow Tablespace

Copyright  2008 by CEBT IOT Performance Analysis  Comparison between general table and IOT Data access  Case Study  Table access via Primary Key Index Scan, and extract 1 row  General Table IOT Table Database Tuning - 5 Only Index Scan But, Index depth is deeper Index Scan & Table Random Access

Copyright  2008 by CEBT IOT Performance Analysis  Comparison between general table and IOT Storage – IOT doesn’t need to have extra storage for Primary Key Index. – Because it is sorted by Primary Key column and other columns are saved with it. Considered case to convert into IOT table – Most columns are used as Primary Key – DML(Data Manipulation Language) ratio is low in table. – Mass history table – Only Primary Key Index exists in table. Database Tuning - 6

Copyright  2008 by CEBT IOT Performance Analysis  IOT related data dictionary view DBA_TABLES inquiry DBA_INDEXES inquiry Database Tuning - 7 Index name follows Primary Key Name 사원 Table’s type is Index

Copyright  2008 by CEBT IOT Performance Analysis  IOT related data dictionary view DBA_SEGMENTS inquiry Database Tuning - 8 IOT Overflow

Copyright  2008 by CEBT References     1/server.111/b28310/tables012.htm 1/server.111/b28310/tables012.htm Database Tuning - 9

Copyright  2008 by CEBT Chap 9 : Cluster Factor Optimization  Contents Cluster Factor? Cluster Factor Optimization Cluster Factor Optimization Method Application Examples Database Tuning - 10

Copyright  2008 by CEBT Cluster Factor?  Definition Relationship between the number of row accessed by index scan and the number of accessed table block to extract concerned rows. Calculate with only table block access except index block access. Database Tuning - 11

Copyright  2008 by CEBT Cluster Factor Optimization  Definition Cluster factor value comes close to the number of rows accessed by index scan (minimize the number of accessed block) If cluster factor is optimized, the quantity of random access by index scan is decreased. Therefore, performance is improved. Database Tuning - 12

Copyright  2008 by CEBT Cluster Factor Optimization  Methods Table reorganization – If few business are in a day, It is hard to save data in same block. Partition table Database Tuning - 13

Copyright  2008 by CEBT Cluster Factor Optimization Cluster table – No more used due to low performance in DML Index-Organized Table (IOT) – Saving with index order, cluster factor is optimized on first column of concerned primary key. Database Tuning - 14