|
41 | 41 | for developers to manage concurrent access to data. Internally,
|
42 | 42 | data consistency is maintained by using a multiversion
|
43 | 43 | model (Multiversion Concurrency Control, <acronym>MVCC</acronym>).
|
44 |
| - This means thatwhile querying a databaseeachtransaction sees |
| 44 | + This means that eachSQL statement sees |
45 | 45 | a snapshot of data (a <firstterm>database version</firstterm>)
|
46 | 46 | as it was some
|
47 | 47 | time ago, regardless of the current state of the underlying data.
|
48 |
| - Thisprotects the transactionfrom viewing inconsistent datathat |
49 |
| -could be causedby(other)concurrenttransaction updates on the same |
| 48 | + Thisprevents statementsfrom viewing inconsistent dataproduced |
| 49 | + by concurrenttransactions performing updates on the same |
50 | 50 | data rows, providing <firstterm>transaction isolation</firstterm>
|
51 | 51 | for each database session. <acronym>MVCC</acronym>, by eschewing
|
52 | 52 | the locking methodologies of traditional database systems,
|
|