SGTM. Also I think you do actually need to resolve the full partition for the second one. You have to merge tombstones+columns from all replicas to decide if the partition exists. It’s the same reason we have to read all row data for a given row during regular reads to decide if the row exists. Even if only one column is selected.
> On Jan 3, 2025, at 3:23 PM, David Capwell <dcapw...@apple.com> wrote: > > As part of the Accord work we have been extending the harry models to > support even more of the CQL domain and added more test coverage for > different features; in doing so it found the following query is currently > blocked > > — delete partition if static column is in a given state > — confirmed that this does not lead to a full partition read in CAS, but only > a static row read > — We already support delete static column if static condition, which has the > same read cost as delete partition if static condition > DELETE > FROM tbl > WHERE pk = ? — pk is the only partition key, but there are clustering keys > IF s0 = ? — s0 is static > > > I took a stab at fixing this in > https://issues.apache.org/jira/browse/CASSANDRA-20163 and speaking with > Benedict it was deemed that we should bring this up to the ML for visibility. > > In 2.0.11/2.1.1 https://issues.apache.org/jira/browse/CASSANDRA-6430 was > added which blocked this type of query. The main argument seems to be that > some deletes are confusing so should block instead ((assuming static columns) > delete regular column if the partition exists, delete if regular column > matches condition, etc.), but I argue that the case above isn’t ambiguous as > we are working with static columns, so implicitly we are working at the > partition level; aka partition delete. > > Are people ok with this change? > > Another case that was found in testing was > > — delete partition if exists > DELETE > FROM tbl > WHERE pk = ? — pk is the only partition key, but there are clustering keys > IF EXISTS > > I confirmed that this case does a full partition read (even though it doesn’t > need to, just needs liveness info), my patch keeps this blocked not because > its ambiguous, but because it has an unbounded cost (if you do this to a 1tb > partition, you read 1tb… or try to at least…). We could fix this but felt > was out of scope of the work above. > > Thanks!
