常见等待事件

---Buffer cache

latch: cache buffers chains

latch: cache buffers lru chain

latch: cache buffer handles

buffer busy waits

buffer exterminate

read by other session

---shared pool

latch: shared pool

latch: library cache

latch: library cache lock

latch: library cache pin

--Dictionary Cache

row cache lock

enq: SQ – contention

--transaction

enq: TM – contention

enq: TX - row lock contention

enq: TX - allocate ITL entry

enq: TX - index contention

enq: TX – contention

enq: UL – contention

--Segment

enq: HW – contention

enq: ST – contention

enq: TT – contention

enq: US – contention

--IO

db file sequential read

db file scattered read

db file parallel write

db file parallel read

control file parallel write

direct path read

direct path read temp

direct path write

direct path write temp

--redo

log file sync

log file switch (checkpoint incomplete)

log file switch (private strand flush incomplete)

log file parallel write

log file switch (archiving needed)

log file switch completion

log file switch (clearing log file)

log buffer space

latch: redo allocation

latch: redo writing

latch: redo copy