This commit increases the maximum length of names for keyspaces, tables, materialized views, and indexes from 48 to 192 bytes.
The previous 48-bytes limit was inherited from Cassandra 3 for compatibility. However, this validation was removed in Cassandra 4 and 5 (see CASSANDRA-20389)
and some usage scenarios (such as some feature store workflows generating long table names) now depend on this relaxed constraint.
This change brings ScyllaDB's behavior in line with modern Cassandra versions and better supports these use cases.
The new limit of 192 bytes is derived from underlying filesystem limitations to prevent runtime errors when creating directories for table data.
When a new table is created, ScyllaDB generates a directory for its SSTables. The directory name is constructed from the table name, a dash, and a 32-character UUID.
For a CDC-enabled table, an associated log table is also created, which has the suffix `_scylla_cdc_log` appended to its name.
The directory name for this log table becomes the longest possible representation.
Additionally we reserve 15 bytes for future use, allowing for potential future extensions without breaking existing schemas.
To guarantee that directory creation never fails due to exceeding filesystem name limits, the maximum name length is calculated as follows:
255 bytes (common filesystem limit for a path component)
- 32 bytes (for the 32-character UUID string)
- 1 byte (for the '-' separator)
- 15 bytes (for the '_scylla_cdc_log' suffix)
- 15 bytes (reserved for future use)
----------
= 192 bytes (Maximum allowed name length)
This calculation is similar in principle to the one proposed for Cassandra to fix related directory creation failures (see apache/cassandra/pull/4038).
This patch also updates/adds all associated tests to validate the new 192-byte limit.
The documentation has been updated accordingly.
Scylla inherited a 48-character limit on the length of table (and
keyspace) names from Cassandra 3. It turns out that Cassandra 4 and
5 unintentionally dropped this limit (see history lesson in
CASSANDRA-20425), and now Cassandra accepts longer table names.
Some Cassandra users are using such longer names and disappointed
that Scylla doesn't allow them.
This patch includes tests for this feature. One test tries a
48-character table name - it passes on Scylla and all versions
of Cassandra. A second test tries a 100-character table name - this
one passes on Cassandra version 4 and above (but not on 3), and
fails on Scylla so marked "xfail". A third test tries a 500-character
table name. This one fails badly on Cassandra (see CASSANDRA-20389),
but passes on Scylla today. This test is important because we need to
be sure that it continues to pass on Scylla even after the Scylla is
fixed to allow the 100-character test.
Refs #4480 - an issue we already have about supporting longer names
Note on the test implementation:
Ideally, the test for a particular table-name length shouldn't just
create the table - it should also make sure we can write table to it
and flush it, i.e., that sstables can get written correctly. But in
practice, these complications are not needed, because in modern Scylla
it is the directory name which contains the table's name, and the
individual sstable files do not contain the table's name. Just creating
the table already creates the long directory name, so that is the part
that needs to be tested. If we created this directory successfully,
later creating the short-named sstables inside it can't fail.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Closesscylladb/scylladb#23229
