Tuesday, March 27, 2007

What is inside X$tables in Oracle

The below mentioned list may not be complete or accurate, but represents an attempt to figure out what information they contain. I suggest not write queries against these tables as they are internal to Oracle, and Oracle may change them without any prior notification.

X$K2GTE2
Kernel 2 Phase Commit Global Transaction Entry Fixed Table
X$K2GTE
Kernel 2 Phase Commit Global Transaction Entry Fixed Table
X$BH
Buffer headers contain information describing the current contents of a piece of the buffer cache.
X$KCBCBH
Cache Buffer Current Buffer Header Fixed Table. It can predict the potential oss of decreasing the number of database buffers. The db_block_lru_statistics parameter has to be set to true to gather information in this table.
X$KCVFH
File Header Fixed Table
X$KDNCE
SGA Cache Entry Fixed Table
X$KDNST
Sequence Cache Statistics Fixed Table
X$KDXHS
Histogram structure Fixed Table
X$KDXST
Statistics collection Fixed Table
X$KGHLU
One-row summary of LRU statistics for the shared pool
X$KGLBODY
Derived from X$KGLOB (col kglhdnsp = 2)
X$KGLCLUSTER
Derived from X$KGLOB (col kglhdnsp = 5)
X$KGLINDEX
Derived from X$KGLOB (col kglhdnsp = 4)
X$KGLLC
Latch Clean-up state for library cache objects Fixed Table
X$KGLPN
Library cache pin Fixed Table
X$KGLTABLE
Derived from X$KGLOB (col kglhdnsp = 1)
X$KGLTR
Library Cache Translation Table entry Fixed Table
X$KGLTRIGGER
Derived from X$KGLOB (col kglhdnsp = 3)
X$KGLXS
Library Cache Access Table
X$KKMMD
Fixed table to look at what databases are mounted and their status
X$KKSBV
Cursor Cache Bind Variables
X$KSMSP
Each row represents a piece of memory in the shared pool
X$KSQDN
Global database name
X$KSQST
Enqueue statistics by type
X$KSUCF
Cost function for each Kernel Profile (join to X$KSUPL)
X$KSUPL
Resource Limit for each Kernel Profile
X$KSURU
Resource Usage for each Kernel Profile (join with X$KSUPL)
X$KSQST
Gets and waits for different types of enqueues
X$KTTVS
indicate tablespace that has valid save undo segments
X$KVII
Internal instance parameters set at instance initialization
X$KVIS
Oracle Data Block (size_t type) variables
X$KVIT
Instance internal flags, variables and parameters that can change during the life of an instance
X$KXFPCDS
Client Dequeue Statistics
X$KXFPCMS
Client Messages Statistics
X$KZDOS
Represent an os role as defined by the operating system
X$KZSRO
Security state Role: List of enabled roles
X$LE
Lock Element : each PCM lock that is used by the buffer cache (gc_db_locks)
X$MESSAGES
Displays all the different messages that can be sent to the Background processes
X$NLS_PARAMETERS
NLS database parameters

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