Rather than potentially letting this slide past 8.4, I threw together an extremely quick-hack patch at the smgr-layer for block-level checksums.
There are some nasties in that the CRC is the first member of PageHeaderData (in order to guarantee inclusion of the LSN), and that it bumps the size of the page header from 24-32 bytes on MAXALIGN=8. I really think most people should use checksums and so I didn't make it optional storage within the page (which would of course increase the complexity). Second, I didn't bump page version numbers. Third, rather than a zero-filled page (which has been commonplace for as long as I can remember), I used a fixed magic number (0xdeadbeef) for pd_checksum as the default CRC; that way, if someone enables/disables it at runtime, they won't get invalid checksums for blocks which hadn't been checksummed previously. This may as well be zero (which means PageInit/PageHeaderIsValid wouldn't have to be touched), but I used it as a test. I ran the regressions and several concurrent benchmark tests which passed successfully, but I'm sure I'm missing quite a bit due to the the fact that it's late, it's just a quick hack, and I haven't gone through the buffer manager locking code in awhile. I'll be happy to work on this or let Alvaro take it; just as long as it gets done for 8.4. -- Jonah H. Harris, Senior DBA myYearbook.com
blkcrc_v1.patch
Description: Binary data
-- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
