18th Day Oracle Architecture (1)

Oracle Management:

Instance
Instance

RAC (real application cluster) Oracle working environment, one-to-many
Instance1 Instance2
\ /
Database

SGA buffer shared pool share pools are used to cache execution plans for recently executed SQL statements
Main include: Library cache (Shared SQL zone) and data dictionary cache (database dictionary buffer)
(System global Area) database is accessed in block units
Background process
Server process

PGA (Program global area)
The SGA is dynamic.

Show series Commands:
Sql>show SGA sees total as the upper limit of the SGA.
Sql>show parameter View system initialization parameters show parameter sga_max_size is also the SGA upper limit
Sql>select * from V$sgainfo; View the dynamic performance view similar to Windows Task Manager.
The current SGA size can be viewed with the upper-free SGA size.

1. Confirm the execution plan and put it into shared Pool 2. Read the original value into buffer cache to generate two blocks, copy one (old Inage), and then modify the original value to generate a new version (new image). 3.redo Log buffer logs file to disk after user commits the new image that was modified
Minimize disk reads and writes.

Database
Database

dBW
Every 3 seconds
Dirty Data Block Arrival limit
No free buffer
Checkpoint appears.

Lgwr
Commit
Log buffer 1/3 full
No 1M redo data generated
Every 3 seconds
Before dBW writes dirty data

18th Day Oracle Architecture (1)