Stefan Miklosovic created CASSANDRA-20209:
---------------------------------------------
Summary: Two snapshot manifests on same table against same
SSTables do not have always same size
Key: CASSANDRA-20209
URL: https://issues.apache.org/jira/browse/CASSANDRA-20209
Project: Apache Cassandra
Issue Type: Bug
Components: Local/Snapshots
Reporter: Stefan Miklosovic
I noticed that two manifests can have different sizes when snapshot is created
on same SSTables. This might be hit in practice in tests when I measure that
two snapshots have same sizes on disk.
The difference is caused by manifest.json, check these two:
{code}
{
"files" : [ "oa-1-big-Data.db" ],
"created_at" : "2025-01-15T13:26:45.04Z",
"expires_at" : null,
"ephemeral" : false
}
{code}
{code}
{
"files" : [ "oa-1-big-Data.db" ],
"created_at" : "2025-01-15T13:27:45.012Z",
"expires_at" : null,
"ephemeral" : false
}
{code}
The difference is in "created_at". One manifest has two decimals for
milliseconds (04) and another one three (012).
The difference is one digit, which will make the whole file bigger, hence their
sizes do not match, hence the sizes of the snapshots as such do not match.
This causes errors when e.g. running multiplex tests in CI. If test happens to
generate two manifests with three places for milliseconds (or two) in both
cases, then it will just pass but every now and then, it doesn't.
The solution is to modify JsonUtils and persuade JSON_OBJECT_MAPPER to
serialize Instant's always with 3 decimal places.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
