Szymon Miezal created CASSANDRA-19413:
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Summary: Batch size guardrail ignores primary key size
Key: CASSANDRA-19413
URL: https://issues.apache.org/jira/browse/CASSANDRA-19413
Project: Cassandra
Issue Type: Bug
Components: Feature/Guardrails
Reporter: Szymon Miezal
{color:#1f2328}The size of a mutation does not consider the primary key size.
In the context of BATCHed mutations, this means that INSERTs, DELETEs, and
UPDATEs for tables with a simple PRIMARY KEY and no clustering columns would be
equal to zero (or almost zero depending on the version). Consequently, the
batch_size_fail_threshold_in_kb has no effect for such tables, and it cannot
protect the cluster from being overloaded.{color}
{color:#1f2328}A test that reproduces the problem in 3.11 -
[https://github.com/szymon-miezal/cassandra/commit/50b27c1e9030ce5ace6a6486a9876493c4ad41ae#diff-8cb249caec219439da461a4369f20530bb7d6cc0467c7e46f16288e22b574e61R43]
{color}
{color:#1f2328}There are a few ways it could be solved:{color}
* {color:#1f2328}Modifying the existing batch_size_fail_threshold_in_kb to
take into account the primary keys size (it has the disadvantage of changing
the semantic of the guardrail thus introducing a regression).
{color}
* {color:#1f2328}Adding a new guardrail e.g.
{color:#1f2328}batch_size_with_pk_fail_threshold_in_kb that is going to be
calculated taking primary key into account.{color}{color}
* {{{color:#1f2328}{color:#1f2328}Adding a -D switch{color:#1f2328} that by
default would be {color}{{false}}{color:#1f2328} meaning that in case the new
formula (which takes PK into account) yields value over the error threshold it
will gracefully tell us about it in an additional log message. Changing the
flag value to {color}{{true}}{color:#1f2328} would be equivalent to the new
formula and error will be thrown in case we get over the
threshold.{color}{color}{color}}}
{{{color:#1f2328}{color:#1f2328}{color:#1f2328}I have a preference for going
with an option that adds a new guardrail.{color}{color}{color}}}
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