There are some issues with the compile flag `-Wno-unused-but-set-variable` for clang.
1. `-Wno-unused-but-set-variable` should be set when building source by clang-15 on Linux. (#13000#13016)
2. On macOS Monterey, Apple Clang 13 may treat it as a unknown warning option and the compilation process may interrupt.
This PR introduces a better way to make this compile flag more portable.
1. Test whether the compiler recognizes this flag.
2. Add this flag if the compiler recognizes it.
When running regression test, we always found that the query return empty result after loading finished,
even if we call "sync" before the query.
This is because for `stream load`, the load task result will be returned immediately after the txn's status changed to VISIBLE,
but before writing the edit log.
So if we do the query right after we got the load task result, it is possible that we can not see the latest loaded data.
Same issue with `insert` operation
Issue Number: close#12574
This pr adds `NewJsonReader` which implements GenericReader interface to support read json format file.
TODO:
1. modify `_scann_eof` later.
2. Rename `NewJsonReader` to `JsonReader` when `JsonReader` is deleted.
The index for external table columns from path is incorrect in new scanner. This is a fix for it.
e.g. In the next query, nation and city columns are from path
```
mysql> select nation, city, count(*) from parquet_two_part group by nation, city;
+--------+------------+----------+
| nation | city | count(*) |
+--------+------------+----------+
| cn | beijing | 1199969 |
| cn | shanghai | 1199771 |
| jp | tokyo | 599715 |
| rus | moscow | 600659 |
| us | chicago | 1199805 |
| us | washington | 1201296 |
+--------+------------+----------+
6 rows in set (0.39 sec)
```
1. add "sync" to avoid some potential meta sync problem when running regression test on multi-node cluster
2. Use /tmp dir as dest dir of outfile test, to avoid "No such file or directory" error.
This PR unified the selection of rollup index and materialized view index into uniform logic, which is called selecting materialized index.
Main steps:
### Find candidate indexes
1. When aggregate is present, it's handled in `SelectMaterializedIndexWithAggregate`. The base index and indexes that could use pre-aggregation should be used. The pre-aggregation status is determined by aggregation function, grouping expression, and pushdown predicates.
2. When aggregate is not on top of scan node, it's handled in `SelectMaterializedIndexWithoutAggregate`. The base index and indexes that have all the key columns could be used.
### Filter and order the candidate indexes
1. filter indexes that contain all the required output scan columns.
2. filter indexes that could match prefix index most.
3. order the result index by row count, column count, and index id.
