On Feb 17, 2017, at 10:31 AM, Magnus Hagander <mag...@hagander.net> wrote: > > On Thu, Feb 16, 2017 at 9:58 PM, David Christensen <da...@endpoint.com> wrote: > Extracted from a larger patch, this patch provides the basic infrastructure > for turning data > checksums off in a cluster. This also sets up the necessary pg_control > fields to support the > necessary multiple states for handling the transitions. > > We do a few things: > > - Change "data_checksums" from a simple boolean to "data_checksum_state", an > enum type for all of > the potentially-required states for this feature (as well as enabling). > > - Add pg_control support for parsing/displaying the new setting. > > - Distinguish between the possible checksum states and be specific about > whether we care about > checksum read failures or write failures at all call sites, turning > DataChecksumsEnabled() into two > functions: DataChecksumsEnabledReads() and DataChecksumsEnabledWrites(). > > - Create a superuser function pg_disable_checksums() to perform the actual > disabling of this in the > cluster. > > I have *not* changed the default in initdb to enable checksums, but this > would be trivial. > > > Per the point made by somebody else (I think Simon?) on the other thread, I > think it also needs WAL support. Otherwise you turn it off on the master, but > it remains on on a replica which will cause failures once datablocks without > checksum starts replicating.
Enclosed is a version which supports WAL logging and proper application of the checksum state change. I have verified it works with a replica as far as applying the updated data_checksum_state, though I had to manually call pg_switch_wal() on the master to get it to show up on the replica. (I don’t know if this is a flaw in my patch or just a natural consequence of testing on a low-volume local cluster.) -- David Christensen End Point Corporation da...@endpoint.com 785-727-1171
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