Give knowledge about indexes of database system for company education. And introduct concurrency locking (Pesimistic locking and Optimistic locking) to my colleagues.
7. Index
Index entries
B+ tree, non-leaf node, search key
Data entries
B+ tree, leaf node
Data records
record id (rid)
8. Index
Fan-out
non-leaf node, # of children (denoted as F)
Search, (logFN + 1) I/O -> page data
In practice, F is at least 100
log100106 = 3,
3, or 4 I/O <=> 106 records
9. Index
Data entries
K*: Search key, and other fields.
Clustered index
<K, rid>: Search key, and record id
<K, rid-list>: Search key, and record id list.
10. Index
Cluster index vs non-cluster index
Clustered index ( Primary key)
K*
Non-clustered index
<K, rid>
<K, rid-list>