V$WAIT_CHAINS
displays information about blocked sessions. A wait chain is composed 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 |
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A number identifying the wait chain |
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Indicates whether the final blocked session in the wait chain is blocked by the initial blocked session ( |
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An Oracle-specific text signature of the wait chain. This signature can be used to identify similar wait chains. |
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A numeric representation of |
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Blocked session's instance identifier |
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Blocked session's operating system process identifier |
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Blocked session's Oracle process identifier |
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Blocked session's Oracle session identifier |
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Blocked session's Oracle session serial number |
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Blocked session's PDB identifier |
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Blocked session's PDB name |
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Indicates whether the blocked session has a blocker ( |
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Blocker session's instance identifier; NULL if |
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Blocker session's operating system process identifier; NULL if |
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Blocker session's Oracle process identifier; NULL if |
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Blocker session's Oracle session identifier; NULL if |
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Blocker session's Oracle session serial number; NULL if |
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Blocker session's PDB identifier |
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Blocker session's PDB name |
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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 |
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Indicates whether the blocked session is in a wait ( |
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Number of seconds since the last time the blocked session waited; NULL if |
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A number identifying the wait; NULL if |
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Resource or event number for which the blocked session is waiting; NULL if |
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Resource or event for which the blocked session is waiting; NULL if |
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First additional wait parameter; NULL if |
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Description of the first additional wait parameter; NULL if |
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Second additional wait parameter; NULL if |
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Description of the second additional wait parameter; NULL if |
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Third additional wait parameter; NULL if |
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Description of the third additional wait parameter; NULL if |
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Seconds the blocked session has been in the current wait; NULL if |
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Seconds remaining until the blocked session ends its wait ( |
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Number of sessions waiting for the blocked session |
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Object ID for the table containing the row specified in |
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Identifier for the data file containing the row specified in |
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Identifier for the block containing the row specified in |
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Current row being locked; NULL if |
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The ID of the container to which the data pertains. Possible values include:
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