Introduced in 2a437ab427.
regular_compaction::select_sstable_writer() creates the sstable writer
when the first partition is consumed from the combined mutation
fragment stream. It gets the schema directly from the table
object. That may be a different schema than the one used by the
readers if there was a concurrent schema alter duringthat small time
window. As a result, the writing consumer attached to readers will
interpret fragments using the wrong version of the schema.
One effect of this is storing values of some columns under a different
column.
This patch replaces all column_family::schema() accesses with accesses
to the _schema memeber which is obtained once per compaction and is
the same schema which readers use.
Fixes#4304.
Tests:
- manual tests with hard-coded schema change injection to reproduce the bug
- build/dev/scylla boot
- tests/sstable_mutation_test
Message-Id: <1551698056-23386-1-git-send-email-tgrabiec@scylladb.com>
58e7ad20eb