Thomas Steinmaurer created CASSANDRA-16442:
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Summary: Improve handling of failed prepared statement loading
Key: CASSANDRA-16442
URL: https://issues.apache.org/jira/browse/CASSANDRA-16442
Project: Cassandra
Issue Type: Improvement
Reporter: Thomas Steinmaurer
In an internal DEV cluster, when going from 3.0 to 3.11 we have seen the
following WARN logs constantly upon Cassandra startup.
{noformat}
...
WARN [main] 2021-02-05 09:25:06,892 QueryProcessor.java:160 - prepared
statement recreation error: SELECT n,v FROM "Ts2Volatile60Min" WHERE k=? LIMIT
?;
WARN [main] 2021-02-05 09:25:06,895 QueryProcessor.java:160 - prepared
statement recreation error: INSERT INTO "Ts2Final01Min" (k,n,v) VALUES (?,?,?)
USING TIMESTAMP ?;
...
{noformat}
I guess 3.11 tries to pre-load prepared statements for tables which don't exist
anymore. On how we got into this situation was our fault I think (Cas 3.0 =>
Upgrade 3.11 => Downgrade 3.0 => with 3.0 some tables got dropped => Upgrade
3.11.10).
Still, perhaps there is room for improvement when it comes to loading persisted
prepared statements, which might fail.
I thought about:
* An additional {{nodetool}} option to wipe the persisted prepared statement
cache
* Perhaps even make the startup code smarter in a way, when loading of a
prepared statement fails, due to a table not being available anymore, then
auto-wipe such entries from the {{prepared_statements}} system table
To get rid of the WARN log, I currently need to work directly on the
"prepared_statements" system table, but I don't know if it is safe to run e.g.
a TRUNCATE statement, thus currently, it seems we need to take each node
offline, execute a Linux {{rm}} command on SSTables for the system table.
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