Any practical examples of share, row share, row excl, share row excl ?

From: Aniruddha Kortikar <kortikar_at_mipos2.intel.com>
Date: 11 Aug 92 15:57:12 GMT
Message-ID: <12884_at_inews.intel.com>


Hi there

would anyone have practical examples of above mentioned locks ? I have created following matrix

	User A			User B			Status
	locks in		Locks in

1.	share mode		select for update	succeeds
				update where ...	fails

2. 	share row excl		select for update	succeeds
				update where ...	fails

3.	row share		select for update	succeeds
				update where		succeeds

4.	row exclusive		select for update	succeeds
				update where		succeeds

5.	update where ..		row share		succeeds
 
6.	update where		row excl		succeeds

7.	update where		share mode		fails

8.	update where		share row excl		fails

could anybody tell how these locks differ from each other. and PRACTICAL examples of usage of these categories. I have read pages of chapter 12. but rather than "RX lock prevents another RX or S lock" type of language I would like itif somebody gave me real world exmamples of using these locking modes. If anybody has used "lock table in share mode" or "lock tables in share row excl" will he /she please respond.

Thanks in advance.

Aniruddha Kortikar (kortikar_at_mipos2.intel.com) Received on Tue Aug 11 1992 - 17:57:12 CEST

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