Package "postgresql-9.5-pg-checksums"

Activate/deactivate/verify PostgreSQL data checksums
Data checksums allow the PostgreSQL database server to identify I/O failures
when reading data from storage. The checksums stored in the page header of
each data page are compared to the computed checksum of the read data.

Data checksums need to be activated at instance creation time, all current
versions of PostgreSQL including v11 do not allow activating (or deactivating)
checksums afterwards.

pg_checksums can activate or deactivate data checksums as long at the database
cluster is shutdown cleanly. Activating checksums requires all database blocks
to be read and all page headers to be updated, so can take a long time on a
large database. Deactivating checksums only requires the cluster control file
to be updated so is quick.

In addition, pg_checksums can verify the checksums in an offline cluster.