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Does Sybase support Row Level Locking?
With Adaptive Server Enterprise 11.9 Sybase introduced row level locking into its product. In fact it went further than that, it introduced 3 different locking levels:
* All Pages Locking
This is the scheme that is implemented in all servers prior to 11.9. Here locks are taken out at the page level, which may included many rows. The name refers to the fact that all of the pages in any data manipulation statement are locked, both data and index.
* Data Page Locking
The other two locking schemes are bundled together under the title Data Page Locking, refering to the fact that only data pages are ever locked in the conventional sense. Data Page Locking is divided into two categories
* Data Only Locking
This locking scheme still locks a page at a time, including all of the rows contained within that page, but uses a new mechanism, called latches, to lock index pages for the shortest amount of time. One of the consequences of this scheme is that it does not update index pages. In order to support this Sybase has introduced a new concept, forwarded rows. These are rows that have had to move because they have grown beyond space allowed for them on the page they were created. 2002 bytes per page.
* Row Level Locking
Just as it sounds, the lock manager only locks the row involved in the operation.
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