Use IDisk to store metadata files in Databases

[tuanpach]

Changelog category (leave one):

• Improvement

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

Allow to use a configurable disk to store metadata files of databases and tables. The disk name can be set via database_disk.disk config parameter

Currently, we use std::filesystem to store metadata files in databases on the local disk. If local files do not persist after the instance restarts (or scale in/out), the metadata files will be lost.

This PR is to replace std::filesystem with IDisk. Although the metadata files are still on the local disk with DiskLocal, we can store them in other remote disks (e.g. DiskObjectStorage) if needed. So that the metadata files can be fetched after the instance restarts.

Documentation entry for user-facing changes

• Documentation is written (mandatory for new features)

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[robot-clickhouse]

This is an automated comment for commit 1544e63 with description of existing statuses. It's updated for the latest CI running

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[tuanpach]

Failed tests:

• Logical error: 'Block structure mismatch in QueryPipeline stream: different columns:: an issue created
• test_replicated_merge_tree_s3_zero_copy/test.py::test_drop_table: an issue is created

[tuanpach]

Hi @kssenii

There was a failed test. It was caused by reading cached mmap data with db_disk->readFile().

I fixed it by setting the read method to LocalFSReadMethod::read, so it will synchronously read files.

[azat]

Why this is required? I guess because now all disks will be initialized anyway?

[tuanpach]

We start the cluster without the storage config first. So that we can start the s3 cluster start_s3_mock(cluster, "broken_s3", "8083"). If we add storage_conf.xml config first, the s3 cluster has not started, and the disk cannot be initialized at the beginning, so the cluster is unable to start.

[azat]

@tuanpach it will be nice to have a test for this

[tuanpach]

@tuanpach it will be nice to have a test for this

We use a default disk, which is a DiskLocal in all tests. I think it is sufficient.