[CONF] Apache Labs > Physical pages

[confluence]

Physical pages Page edited by Emmanuel Lécharny Changes (2) The *RecordManager* stores all the Btrees in one single file, which is split in many physical pages, all having the same size. {info:title=The page size} Currently, the choice was to use one single size for all the pages, regardless the data we store into them. The rationnal is to get close to the OS page size (frequently 512 bytes or 4096 bytes). This is not necessarily the best choice though, let's say it's something we might want to change later. {info} If we except a small header at the beginning of the file, everything is stored in *PageIO* in the file. h1. PageIO a *PageIO* contains some raw data. As we have to map some logical data that may be wider than a physical fixed size *PageIO*, we link the *PageIO* so that they contain all the data contained in a logical page. Each *PageIO* has a hight byte pointer at the beginning, plus an extra 4 bytes on the first *PageIO* to define the number of bytes stored. Here is the mapping between a logical page and some *PageIO* : !PageIOLogical.png! Full Content The RecordManager stores all the Btrees in one single file, which is split in many physical pages, all having the same size. The page size Currently, the choice was to use one single size for all the pages, regardless the data we store into them. The rationnal is to get close to the OS page size (frequently 512 bytes or 4096 bytes). This is not necessarily the best choice though, let's say it's something we might want to change later. If we except a small header at the beginning of the file, everything is stored in PageIO in the file. PageIO a PageIO contains some raw data. As we have to map some logical data that may be wider than a physical fixed size PageIO, we link the PageIO so that they contain all the data contained in a logical page. Each PageIO has a hight byte pointer at the beginning, plus an extra 4 bytes on the first PageIO to define the number of bytes stored. Here is the mapping between a logical page and some PageIO : Unable to render embedded object: File (PageIOLogical.png) not found. Change Notification Preferences View Online | View Changes | Add Comment --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@labs.apache.org For additional commands, e-mail: commits-h...@labs.apache.org