Re: questions on undo log
Xuekun Hu <[email protected]>
| Newsgroups | gmane.comp.db.mysql.devel |
|---|---|
| Message-ID | <CACLBhCRf9ksFx=nqMvfJLZQrOU5ue67x=M5ZvU1cXfbomo98Zg@mail.gmail.com> |
Hi, Libing Many thanks. From the file page types definition, I found FIL_PAGE_UNDO_LOG which should represent the undo log page in buffer pool. So it also means every change to undo log page in buffer pool also follows the page flushing mechanism of buffer pool (writing to disk in background, writing to doublewrite buffer, writing the changes to transaction log etc). My understanding is right? However I also think it is not very accurate about "Innodb buffer pool is for all things in table spaces" like you said. :-) I think it should exclude the data dictionary which has own memory cache and doublewrite buffer. :-) Thx, Xuekun On Tue, Feb 7, 2012 at 10:43 PM, Song Libing <[email protected]> wrote: > On Tue, Jan 31, 2012 at 5:00 PM, Xuekun Hu <[email protected]> wrote: > Hi Xuekun, > IMO, Innodb buffer pool is for all things in table spaces. > It is the method to cache all pages in table spaces. > So undo log, both (slot and undo log space) are included. > The slot is in undo log segment header page. > >> Hi, Guys >> >> When reading innodb code, I'm little confused about the relationship >> between innodb buffer pool and undo log: >> >> From my understanding, in disk tablespace files, undo log can be >> divided into two parts: rollback segments (1023 slots per segment) and >> the undo space pointered by slot. >> >> So my question is which part is cached in innodb buffer pool? the >> slot? or also the undo space? >> >> BTW. If anyone knows any available doc to describe the internal of >> innodb undo log mechanism, that should be very helpful to me. :-) >> >> Many thanks. - Xuekun >> >> -- >> MySQL Internals Mailing List >> For list archives: http://lists.mysql.com/internals >> To unsubscribe: http://lists.mysql.com/internals >> > > > > -- > Sincerely > > Song Libing > 宋 利兵 > ------------------------------------------------------------------- > Software Engineer > Email: [email protected] > Blog: http://www.mysqlops.com/author/sleebin9 > -------------------------------------------------------------------- -- MySQL Internals Mailing List For list archives: http://lists.mysql.com/internals To unsubscribe: http://lists.mysql.com/internals