ORA-01408 happened when install with Oracle 21c Linux

[qu.ququ]

Install with a new database, got the following ERROR.

CREATE INDEX idx_project_id ON mantis_project_table (id)
ORA-01408: such column list already indexed

[qu.ququ]

The cause should be -- "not support oracle21c well".

Can avoid the error with setting "null" for "CREATE INDEX idx_project_id" in schema.php
": array( 'CreateIndexSQL', array( 'idx_project_id', db_get_table( 'project' ), 'id' ) );" --> ": null;"

[qu.ququ]

The table name can be 128 bytes in 21c version.

But I got ERROR --
APPLICATION ERROR #404 Database identifier "mantis_custom_field_project_table" is too long.
Try reducing the size of g_db_table_prefix/suffix'

After trying, I found the setting option was in core/database_api.php, can set from 30 to 128.