| 摘要 |
PURPOSE: To simultaneously access the indexes of plural transactions without generating any error state during the change of index information by limiting access to a node only to reading access to the other simultaneous transaction and removing the access limitation after record data are fetched. CONSTITUTION: The node is scanned from a route node to the bottom node while using a key record section, the access to the node under scanning and the already accessed node excepting for reading is limited to the other simultaneous transaction, a key record is identified in the bottom node, and access to the key record excepting for reading is limited. Next, the access limitation to the scanned node is canceled and after the key record data are fetched, all the access limitation to the key record are canceled. Thus, simultaneous access is allowed and the information, for which the transaction is changed during the change of index tree structure, is not retrieved.
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