* refactor: store per-file column set in catalog
Together with the table-wide schema and the partition-wide sort key, this should
be everything we need to read a parquet file directly into memory
without peeking any file-level metadata.
The querier will use this to directly load parquet files into the read
buffer.
**WARNING: This requires a catalog wipe!**
Ref #4124.
* refactor: use proper `ColumnSet` type
This commit changes the code base to use a new reference-counted
PartitionKey type wrapper, instead of passing a bare String around.
This allows the compiler to type check & verify usage of the partition
key, instead of passing a bare string around. By reference counting the
underlying string, we reduce memory usage for some use cases.
* feat: Change data type of catalog Postgres partition's sort_key from a string to an array of string
* test: add column with comma
* fix: use new protonuf field to avoid incompactible
* fix: ensure sort_key is an empty array rather than NULL
* refactor: address review comments
* refactor: address more comments
* chore: clearer comments
* chore: Update iox_catalog/migrations/20220607102200_change_sort_key_type_to_array.sql
* chore: Update iox_catalog/migrations/20220607102200_change_sort_key_type_to_array.sql
* fix: Rename migration so it will be applied after
Co-authored-by: Marko Mikulicic <mkm@influxdata.com>
Marco Neumann
Andrew Lamb
Dom Dwyer
Nga Tran