Recently, Materialized Views were modified (see issue #4365) so that local
view updates (when both base and view replicas are the same node) are
synchronous. In particular, when the view's partition key is the same as
the base table's, view writes are synchronous: A write now only returns
after CL copies of the view data have been written.
Alternator's LSI have exactly this case (same partition key as the base).
This makes strongly-consistent (CL=LOCAL_QUORUM) reads in Alternator work
correctly, so we update the documentation accordingly to no longer say
that we don't support this DynamoDB feature.
However unlike LSIs, for GSIs strongly-consistent reads are still not
supported, and should not be supported (they are also not supported by
DynamoDB). Such reads should generate an error. So this patch fixes this
too. A GSI test which tested that strongly consistent reads are forbidden,
which used to xfail, now passes so the patch removes the "xfail".
Finally, we can simplify the LSI tests by using consistent reads instead of
eventually-consistent reads with retries. Beyond simplifying the test, it's
also an opportunity to *use* strongly-consistent reads and make sure that
they work (while, as mentioned above, similar reads for GSIs are refused).
Fixes#5007
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20200311170446.28611-1-nyh@scylladb.com>
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