** Oracle内部机制(Internals) **

Warning The following list is just speculation; no guarantee of accuracy.


Oracle internals are important for very large, heavy parallel transaction database design, trouble shooting and so on.

Hidden Init Parameters

Oracle hidden init parameters can allow DBA perform advanced operation, i.e. force oracle omit the consistence rule and recover data or adjust advanced server structure. But the parameters have no guarantee. So DBA should pay more attention to backup. More ...

Low level mechanism

SCN Internal

Kernel Subsystems

Kernel Subsystems are oracle internal layers to implement sophisticated functions.
Oracle database have the following kernel systems

Kernel Subsystems:
OPI Oracle Program Interface
KK Compilation Layer - Parse SQL, compile PL/SQL
KX Execution Layer - Bind and execute SQL and PL/SQL
K2 Distributed Execution Layer - 2PC handling
NPI Network Program Interface
KZ Security Layer - Validate privs
KQ Query Layer
RPI Recursive Program Interface
KA Access Layer
KD Data Layer
KT Transaction Layer
KC Cache Layer
KS Services Layer
KJ Lock Manager Layer
KG Generic Layer
KV Kernel Variables (eg. x$KVIS and X$KVII)
S or ODS Operating System Dependencies

Internal X$ tables and dictionary base ...$ tables

Most V$ views are based on internal X$ tables and dictionary base …$ tables.
X$ table actually are memory structure of oracle shared memory.
dictionary base …$ tables are physical tables stored dictionary.

Memroy Structure

There are more oracle database memory structures.

Oracle Lock Lock (JP)

Oracle has a sophisticated latch and lock system to protected data consistency.

Storage Structure

Oracle database stored in tablespaces, datafiles and data blocks.
Block Row Chaining


Oracle database have many internal algorithm, i.e. LRU, latch spin, and public algorithm, i.e. nest loop, sort merge, hash join.

Undocumented Commands

Oracle database has many undocumented commands.

Oracle Trace and Dump

Oracle Construction Scripts

Oracle database construction scripts reveal lots of details of database internal.

Oracle Database File

Oracle Algorithms

Block Structure