| Class | Innodb::Page::TrxSys |
| In: |
lib/innodb/page/trx_sys.rb
|
| Parent: | Innodb::Page |
A specialized class for TRX_SYS pages, which contain various information about the transaction system within InnoDB. Only one TRX_SYS page exists in any given InnoDB installation, and it is page 5 of the system tablespace (space 0), most commonly named "ibdata1".
The basic structure of a TRX_SYS page is: FIL header, TRX_SYS header, empty space, master binary log information, empty space, local binary log information, empty space, doublewrite information (repeated twice), empty space, and FIL trailer.
| MYSQL_LOG_MAGIC_N | = | 873422344 | A magic number present in each MySQL binary log information structure, which helps identify whether the structure is populated or not. | |
| N_RSEGS | = | 128 | ||
| DOUBLEWRITE_MAGIC_N | = | 536853855 | A magic number present in each doublewrite buffer information structure, which helps identify whether the structure is populated or not. | |
| DOUBLEWRITE_SPACE_ID_STORED_MAGIC_N | = | 1783657386 | A magic number present in the overall doublewrite buffer structure, which identifies whether the space id is stored. |
Read a single doublewrite buffer information structure from a given cursor.
The doublewrite buffer information is located 200 bytes from the end of the page.