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YeltsinDB
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Update table file specification

master
Yury Kurlykov 2019-11-07 22:58:30 +10:00
parent 22ab490e3c
commit 33fdb0183a
1 changed files with 9 additions and 1 deletions
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table_file.md
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@ -2,12 +2,15 @@
## Table file version changelog ## Table file version changelog
### v0.2
+ Added table "write incomplete" flag.
### v0.1 ### v0.1
Initial version. Initial version.
## Overall specification ## Overall specification
1. `TBL!` file signature (4 bytes) 1. `TBL!` file signature (4 bytes) **could be `TBL?` if an operation on a table is incompleted**
2. Table file version (2 bytes) 2. Table file version (2 bytes)
3. The offset to the first page in a table. (8 bytes) 3. The offset to the first page in a table. (8 bytes)
4. The offset to the last page in a table. (8 bytes) 4. The offset to the last page in a table. (8 bytes)
@ -56,3 +59,8 @@ If there is a free page, there actions are being done:
3. Put last available free page as the next page ((6.1) = 5) 3. Put last available free page as the next page ((6.1) = 5)
4. Set current page offset as the offset to the last available free page ((5) = current_page_offset) 4. Set current page offset as the offset to the last available free page ((5) = current_page_offset)
## File signature
*Since v0.2* a file signature could be `TBL?`, which signals for incomplete table write operation.
If that signature is detected, the state of a table should be reverted to that it was before failed
transaction.