Difference between OraclePGA and SGA and the use of latch and lock

Difference between OraclePGA and SGA and the use of latch and lock

Differences between Oracle PGA and SGA and the use of latch and lock

1. What is the difference between PGA and SGA?

SGA is the global area of the system, and PGA is the global area of the process.

Oracle is running, and SGA is the memory structure of oracle, such as putting databuf and share pool, allocating at oracle startup, and recycling at oracle shutdown.

When a PGA is used to connect an oracle database, oracle opens a memory zone for this user only. After the user is disconnected, oracle recycles the memory.

2. What are the application scenarios of latch and lock?

Lock table-level locks and row-level locks can also be divided into shared locks and exclusive locks, that is, they are locked during comparison.

Latch is a memory lock. For example, if a data block is loaded into the memory, the lock is used when multiple sessions compete for the block in the memory.