Douglas wrote:
I've playing with the new mon$tables in 2.1RC1 and they are great. Some questions on them:
- What is the difference between page_read and page_fetch?
- What is page_mark?
- What is record_backout?
- What is record_purge?
- What is record_expunge?
- Is it possible to know the execution plan of a statement?
- Is it possible to know the values of parameters passed to a statement?
Vlad Khorsun answers:
- What is the difference between page_read and page_fetch?
page_read is when page is read from disk, i.e. cache miss. page_fetch is when page is found in cache, i.e. cache hit
- What is page_mark?
someone have intention to change page contents
- What is record_backout?
undoing of not needed primary record version. it can be in case of transaction rollback or undo of savepoint if some statement under this savepoint is failed
- What is record_purge?
remove chain of unneded record versions, leaving primary record version (and may be few backversions) on it place as it was created by transaction with number not less than OAT
- What is record_expunge?
remove whole record versions chain as record was deleted by transaction with number less than OAT
- Is it possible to know the execution plan of a statement?
- Is it possible to know the values of parameters passed to a statement?
No