Raymond Raymond <[EMAIL PROTECTED]> writes: > I have some questions about derby cache page, anyone can help me? > 1. Derby writes out dirty pages through two ways: > - A background thread writes out dirty pages based on some > algorithm such as LRU. > - Checkpointing process writes out all the dirty pages. > I want to know after a dirty page has been written out, the > page will be discarded? or the status of the page will be set > as "clean"?
If a page is written by the checkpoint or background writer, it is set to clean and kept in the page cache. You have one more way to write out dirty pages. When a new page is to be put into the page cache, and the page cache is full, a page has to be thrown out of the cache. If a clean page cannot be found, a dirty page will be written and removed from the cache. > 2. If a cache page has been updated serval times, is there any > information can indicate the log instance for every update? > or just the last update? I think you only have information about the last update. You might have a look at BasePage.updateLastLogInstant() and see if you can make it keep more information. -- Knut Anders
