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Overview
| Comment: | Correct the rollback journal checksum algorithm description. |
|---|---|
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
b69eaea91403ec48d9559db9c3635d9d |
| User & Date: | drh 2017-02-15 22:43:23 |
Context
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2017-02-15
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| 22:44 | Fix a harmless typo in the rollback journal checksum algorithm description. check-in: ebd7ef38cc user: drh tags: trunk | |
| 22:43 | Correct the rollback journal checksum algorithm description. check-in: b69eaea914 user: drh tags: trunk | |
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2017-02-14
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| 20:18 | Enhanced documentation for the ".separator" and ".mode quote" commands in the CLI. check-in: 95afd54c2e user: drh tags: trunk | |
Changes
Changes to pages/fileformat2.in.
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<p>^(The checksum is an unsigned 32-bit integer computed as follows:</p> <ol> <li>Initialize the checksum to the checksum nonce value found in the journal header at offset 12. <li>Initialize index X to be N-200 (where N is the size of a database page in bytes. <li>Interpret the four bytes at offset X into the page as a 4-byte big-endian unsigned integer. Add the value of that integer to the checksum. <li>Subtrace 200 from X. <li>If X is greater than or equal to zero, go back to step 3. </ol>)^ <p>The checksum value is used to guard against incomplete writes of a journal page record following a power failure. A different random nonce is used each time a transaction is started in order to minimize the risk |
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1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 |
<p>^(The checksum is an unsigned 32-bit integer computed as follows:</p> <ol> <li>Initialize the checksum to the checksum nonce value found in the journal header at offset 12. <li>Initialize index X to be N-200 (where N is the size of a database page in bytes. <li>Interpret the byte at offset X into the page as an 8-bit unsigned integer and add the value of that integer to the checksum. <li>Subtrace 200 from X. <li>If X is greater than or equal to zero, go back to step 3. </ol>)^ <p>The checksum value is used to guard against incomplete writes of a journal page record following a power failure. A different random nonce is used each time a transaction is started in order to minimize the risk |