Concurrency Control Techniques
{"Image DocumentName": "Concurrency Control Techniques", "Image ImageDescription": "If a transaction has a shared lock on a data item, it can read the item but not update it. If a transaction has an exclusive lock on a data item, it can both read and update the item. Since read operations cannot con\ufb02ict, it is permissible for more than one transaction to hold shared locks simultaneously on the same item. On the other hand, an exclusive lock gives a transaction exclusive access to that item. Some systems allow transaction to upgrade read lock to an exclusive lock, or downgrade exclusive lock to a shared lock.", "Image XResolution": "37", "Image YResolution": "37", "Image ResolutionUnit": "Pixels/Centimeter", "Image Software": "SlidePlayer", "Image YCbCrPositioning": "Centered"}