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Table Level Lock Modes
what are the differences among these table level lock modes - IN SHARE MODE, IN SHARE UPDATE MODE, IN EXCLUSIVE MODE ?


  
Total Answers and Comments: 1 Last Update: July 20, 2008     Asked by: kranthi.kunta 
  
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July 20, 2008 04:58:44   #1  
Pintu_unix Member Since: June 2008   Contribution: 1    

RE: Table Level Lock Modes
SHARE UPDATE EXCLUSIVE
This mode protects a table against concurrent schema changes and VACUUM runs. Acquired by VACUUM (without FULL) ANALYZE and CREATE INDEX CONCURRENTLY

EXCLUSIVE
This mode allows only concurrent ACCESS SHARE locks i.e. only reads from the table can proceed in parallel with a transaction holding this lock mode. This lock mode is not automatically acquired on user tables by any PostgreSQL command. However it is acquired on certain system catalogs in some operations.

SHARE
This mode protects a table against concurrent data changes. Acquired by CREATE INDEX (without CONCURRENTLY).

 
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