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Alex Petrov edited comment on CASSANDRA-13992 at 11/21/17 12:18 PM: -------------------------------------------------------------------- Thank you for the review! Committed to trunk with [7eb915097dc3e34e1bb4ef96e6bd8eb67d574622|https://github.com/apache/cassandra/commit/7eb915097dc3e34e1bb4ef96e6bd8eb67d574622] with added unit test and {{hasConditions}} pulled up to statement. was (Author: ifesdjeen): Thank you for the review! Committed to trunk with [7eb915097dc3e34e1bb4ef96e6bd8eb67d574622|https://github.com/apache/cassandra/commit/7eb915097dc3e34e1bb4ef96e6bd8eb67d574622] > Don't send new_metadata_id for conditional updates > -------------------------------------------------- > > Key: CASSANDRA-13992 > URL: https://issues.apache.org/jira/browse/CASSANDRA-13992 > Project: Cassandra > Issue Type: Bug > Reporter: Olivier Michallat > Assignee: Alex Petrov > Priority: Minor > Fix For: 4.0 > > > This is a follow-up to CASSANDRA-10786. > Given the table > {code} > CREATE TABLE foo (k int PRIMARY KEY) > {code} > And the prepared statement > {code} > INSERT INTO foo (k) VALUES (?) IF NOT EXISTS > {code} > The result set metadata changes depending on the outcome of the update: > * if the row didn't exist, there is only a single column \[applied] = true > * if it did, the result contains \[applied] = false, plus the current value > of column k. > The way this was handled so far is that the PREPARED response contains no > result set metadata, and therefore all EXECUTE messages have SKIP_METADATA = > false, and the responses always include the full (and correct) metadata. > CASSANDRA-10786 still sends the PREPARED response with no metadata, *but the > response to EXECUTE now contains a {{new_metadata_id}}*. The driver thinks it > is because of a schema change, and updates its local copy of the prepared > statement's result metadata. > The next EXECUTE is sent with SKIP_METADATA = true, but the server appears to > ignore that, and still sends the metadata in the response. So each response > includes the correct metadata, the driver uses it, and there is no visible > issue for client code. > The only drawback is that the driver updates its local copy of the metadata > unnecessarily, every time. We can work around that by only updating if we had > metadata before, at the cost of an extra volatile read. But I think the best > thing to do would be to never send a {{new_metadata_id}} in for a conditional > update. -- This message was sent by Atlassian JIRA (v6.4.14#64029) --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@cassandra.apache.org For additional commands, e-mail: commits-h...@cassandra.apache.org