All technological notes.
shared pool

library cache
In a shared server architecture, the library cache also contains private SQL areas.
When a SQL statement is executed, the database attempts to reuse previously executed code.
soft parse / library cache hit
hard parse / library cache miss
shared SQL area
statement parse tree and execution plan.SQL Statement vs area
shared SQL area exists for a unique statement.private SQL area in its PGA.private sql area vs shared sql area
private SQL area pointing to the same shared SQL area.private SQL areas in separate PGAs can be associated with the same shared SQL area.多对一execution steps:
shared pool to see if a shared SQL area exists for a syntactically and semantically identical statement:
shared SQL area in the shared pool. A statement with the same syntax but different semantics uses a child cursor.private SQL area for the user points to the shared SQL area that contains the statement and execution plan.private SQL area on behalf of the session
private SQL area depends on the connection established for the session.与连接类型有关
private SQL area is kept in the SGA.
a dedicated server architecture in which two sessions keep a copy of the same SQL statement in their own PGAs. In a shared server, this copy is in the UGA, which is in the large pool or in the shared pool when no large pool exists.
data dictionary
Special memory locations are designated to hold dictionary data:
Data dictionary cache / row cache
Library cache
All server processes share these caches for access to data dictionary information.
server result cache
SQL query result cache and PL/SQL function result cache, which share the same infrastructure.reserved pool
Chunking分块