Skip Headers
Oracle® Database Reference
11g Release 2 (11.2)

E40402-11
Go to Documentation Home
Home
Go to Book List
Book List
Go to Table of Contents
Contents
Go to Index
Index
Go to Master Index
Master Index
Go to Feedback page
Contact Us

Go to previous page
Previous
Go to next page
Next
PDF · Mobi · ePub

V$WAIT_CHAINS

V$WAIT_CHAINS displays information about blocked sessions. A wait chain is comprised of sessions that are blocked by one another. Each row represents a blocked and blocker session pair. If a wait chain is not a cyclical wait chain, then the last row for the chain does not have a blocker.

Column Datatype Description
CHAIN_ID NUMBER A number identifying the wait chain
CHAIN_IS_CYCLE VARCHAR2(5) Indicates whether the final blocked session in the wait chain is blocked by the initial blocked session (TRUE) or not (FALSE)
CHAIN_SIGNATURE VARCHAR2(801) An Oracle-specific text signature of the wait chain. This signature can be used to identify similar wait chains.
CHAIN_SIGNATURE_HASH NUMBER A numeric representation of CHAIN_SIGNATURE
INSTANCE NUMBER Blocked session's instance identifier
OSID VARCHAR2(25) Blocked session's operating system process identifier
PID NUMBER Blocked session's Oracle process identifier
SID NUMBER Blocked session's Oracle session identifier
SESS_SERIAL# NUMBER Blocked session's Oracle session serial number
BLOCKER_IS_VALID VARCHAR2(5) Indicates whether the blocked session has a blocker (TRUE) or not (FALSE)
BLOCKER_INSTANCE NUMBER Blocker session's instance identifier; NULL if BLOCKER_IS_VALID is FALSE
BLOCKER_OSID VARCHAR2(25) Blocker session's operating system process identifier; NULL if BLOCKER_IS_VALID is FALSE
BLOCKER_PID NUMBER Blocker session's Oracle process identifier; NULL if BLOCKER_IS_VALID is FALSE
BLOCKER_SID NUMBER Blocker session's Oracle session identifier; NULL if BLOCKER_IS_VALID is FALSE
BLOCKER_SESS_SERIAL# NUMBER Blocker session's Oracle session serial number; NULL if BLOCKER_IS_VALID is FALSE
BLOCKER_CHAIN_ID NUMBER If not NULL, then the blocker session is a member of another chain specified by this chain identifier. For the remaining wait chain information, see the wait chain with the specified CHAIN_ID.
IN_WAIT VARCHAR2(5) Indicates whether the blocked session is in a wait (TRUE) or not (FALSE)
TIME_SINCE_LAST_WAIT_SECS NUMBER Number of seconds since the last time the blocked session waited; NULL if IN_WAIT is TRUE
WAIT_ID NUMBER A number identifying the wait; NULL if IN_WAIT is FALSE
WAIT_EVENT NUMBER Resource or event number for which the blocked session is waiting; NULL if IN_WAIT is FALSE
WAIT_EVENT_TEXT VARCHAR2(64) Resource or event for which the blocked session is waiting; NULL if IN_WAIT is FALSE
P1 NUMBER First additional wait parameter; NULL if IN_WAIT is FALSE
P1_TEXT VARCHAR2(64) Description of the first additional wait parameter; NULL if IN_WAIT is FALSE
P2 NUMBER Second additional wait parameter; NULL if IN_WAIT is FALSE
P2_TEXT VARCHAR2(64) Description of the second additional wait parameter; NULL if IN_WAIT is FALSE
P3 NUMBER Third additional wait parameter; NULL if IN_WAIT is FALSE
P3_TEXT VARCHAR2(64) Description of the third additional wait parameter; NULL if IN_WAIT is FALSE
IN_WAIT_SECS NUMBER Seconds the blocked session has been in the current wait; NULL if IN_WAIT is FALSE
TIME_REMAINING_SECS NUMBER Seconds remaining until the blocked session ends its wait (-1 if the blocked session can indefinitely wait); NULL if IN_WAIT is FALSE
NUM_WAITERS NUMBER Number of sessions waiting for the blocked session
ROW_WAIT_OBJ# NUMBER Object ID for the table containing the row specified in ROW_WAIT_ROW#; NULL if IN_WAIT is FALSE
ROW_WAIT_FILE# NUMBER Identifier for the datafile containing the row specified in ROW_WAIT_ROW#; NULL if IN_WAIT is FALSE. This column is valid only if the blocked session is currently waiting for another transaction to commit and the value of ROW_WAIT_OBJ# is not -1.
ROW_WAIT_BLOCK# NUMBER Identifier for the block containing the row specified in ROW_WAIT_ROW#; NULL if IN_WAIT is FALSE. This column is valid only if the blocked session is currently waiting for another transaction to commit and the value of ROW_WAIT_OBJ# is not -1.
ROW_WAIT_ROW# NUMBER Current row being locked; NULL if IN_WAIT is FALSE. This column is valid only if the blocked session is currently waiting for another transaction to commit and the value of ROW_WAIT_OBJ# is not -1.