Sstables store a basic schema in the statistics component. The scylla-sstable tool uses this to be able to read and dump sstables in a self-contained manner, without requiring an external schema source.
The problem is that the schema stored int he statistics component is incomplete: it doesn't store column names for key columns, so these have placeholder names in dump outputs where column names are visible.
This is not a disaster but it is confusing and it can cause errors in scripts which want to check the content of sstables, while also knowing the schema and expecting the proper names for key columns.
To make sstables truly self-contained w.r.t. the schema, add a complete schema to the scylla component. This schema contains the names and types of all columns, as well as some basic information about the schema: keyspace name, table name, id and version.
When available, scylla-sstable's schema loader will use this new more complete schema and fall-back to the old method of loading the (incomplete) schema from the statistics component otherwise.
New feature, no backport required.
Closesscylladb/scylladb#24187
* github.com:scylladb/scylladb:
test/boost/schema_loader_test: add specific test with interesting types
test/lib/random_schema: add random_schema(schema_ptr) constructor
test/boost/schema_loader_test: test_load_schema_from_sstable: add fall-back test
tools/schema_loader: add support for loading from scylla-metadata
tools/schema_loader: extract code which load schema from statistics
sstables: scylla_metadata: add schema member
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