David Capwell created CASSANDRA-15926:
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Summary: When schema does not match sstable serialization header
compaction may fail
Key: CASSANDRA-15926
URL: https://issues.apache.org/jira/browse/CASSANDRA-15926
Project: Cassandra
Issue Type: Improvement
Components: Cluster/Schema, Local/SSTable
Reporter: David Capwell
If the table schema had timeuuid and then an alter is done to change the column
to uuid, then the on-disk serialization header won’t match the table schema;
this is problematic as there isn’t logic to migrate the column from the old
type to the new type.
The ALTER TABLE command does not directly allow this type of schema change
(though possible before 3.0.11, see CASSANDRA-12443), but this is possible if
the following is done
{code}
INSERT INTO system_schema.columns (keyspace_name, table_name, column_name,
clustering_order, column_name_bytes, kind, position, type) VALUES (‘ks',
’table', ‘col', 'none', bytes, 'regular', -1, 'uuid’);
ALTER TABLE ks.table WITH comment = 'something’; — this will trigger the schema
to migrate across the cluster
{code}
The below is a test to show this
{code}
package org.apache.cassandra.distributed.test;
import java.util.UUID;
import org.junit.Test;
import org.apache.cassandra.distributed.Cluster;
import org.apache.cassandra.distributed.impl.IInvokableInstance;
import org.apache.cassandra.utils.UUIDGen;
public class AlterWithOnDiskMismatch extends DistributedTestBase
{
@Test
public void alterTypeMixedSSTablesNoConflict() throws Throwable
{
try (Cluster cluster = init(Cluster.create(1)))
{
IInvokableInstance node = cluster.get(1);
cluster.schemaChange("CREATE TABLE " + KEYSPACE + ".mismatch (key
text primary key, value timeuuid)");
// write valid timeuuid then flush
node.executeInternal("INSERT INTO " + KEYSPACE + ".mismatch (key,
value) VALUES (?, ?)", "k1", UUIDGen.getTimeUUID());
node.flush(KEYSPACE);
// alter schema
Object[] columns = node.executeInternal("SELECT keyspace_name,
table_name, column_name, clustering_order, column_name_bytes, kind, position,
type " +
"FROM system_schema.columns WHERE
keyspace_name=? AND table_name=? AND column_name=?", KEYSPACE, "mismatch",
"value")[0];
columns[columns.length - 1] = "uuid";
node.executeInternal("INSERT INTO system_schema.columns
(keyspace_name, table_name, column_name, clustering_order, column_name_bytes,
kind, position, type) VALUES (?, ?, ?, ?, ?, ?, ?, ?)", columns);
cluster.schemaChange("ALTER TABLE " + KEYSPACE + ".mismatch WITH
comment='upgrade'");
node.executeInternal("INSERT INTO " + KEYSPACE + ".mismatch (key,
value) VALUES (?, ?)", "k2", UUID.randomUUID());
node.flush(KEYSPACE);
node.forceCompact(KEYSPACE, "mismatch");
}
}
@Test
public void alterTypeMixedSSTablesConflict() throws Throwable
{
try (Cluster cluster = init(Cluster.create(1)))
{
IInvokableInstance node = cluster.get(1);
cluster.schemaChange("CREATE TABLE " + KEYSPACE + ".mismatch (key
text primary key, value timeuuid)");
// write valid timeuuid then flush
node.executeInternal("INSERT INTO " + KEYSPACE + ".mismatch (key,
value) VALUES (?, ?)", "k1", UUIDGen.getTimeUUID());
node.flush(KEYSPACE);
// alter schema
Object[] columns = node.executeInternal("SELECT keyspace_name,
table_name, column_name, clustering_order, column_name_bytes, kind, position,
type " +
"FROM system_schema.columns
WHERE keyspace_name=? AND table_name=? AND column_name=?", KEYSPACE,
"mismatch", "value")[0];
columns[columns.length - 1] = "uuid";
node.executeInternal("INSERT INTO system_schema.columns
(keyspace_name, table_name, column_name, clustering_order, column_name_bytes,
kind, position, type) VALUES (?, ?, ?, ?, ?, ?, ?, ?)", columns);
cluster.schemaChange("ALTER TABLE " + KEYSPACE + ".mismatch WITH
comment='upgrade'");
node.executeInternal("INSERT INTO " + KEYSPACE + ".mismatch (key,
value) VALUES (?, ?)", "k1", UUID.randomUUID());
node.flush(KEYSPACE);
node.forceCompact(KEYSPACE, "mismatch");
}
}
}
{code}
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