Allow to drop tables from s3_plain disk (so as from web disk)

Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>

src/Disks/DiskDecorator.h

@@ -75,6 +75,7 @@ public:
     DataSourceDescription getDataSourceDescription() const override { return delegate->getDataSourceDescription(); }
     bool isRemote() const override { return delegate->isRemote(); }
     bool isReadOnly() const override { return delegate->isReadOnly(); }
+    bool isWriteOnce() const override { return delegate->isWriteOnce(); }
     bool supportZeroCopyReplication() const override { return delegate->supportZeroCopyReplication(); }
     bool supportParallelWrite() const override { return delegate->supportParallelWrite(); }
     void onFreeze(const String & path) override;

src/Disks/IDisk.h

@@ -308,6 +308,8 @@ public:
 
     virtual bool isReadOnly() const { return false; }
 
+    virtual bool isWriteOnce() const { return false; }
+
     /// Check if disk is broken. Broken disks will have 0 space and cannot be used.
     virtual bool isBroken() const { return false; }
 

src/Disks/ObjectStorages/Cached/CachedObjectStorage.h

@@ -101,6 +101,8 @@ public:
 
     bool isReadOnly() const override { return object_storage->isReadOnly(); }
 
+    bool isWriteOnce() const override { return object_storage->isWriteOnce(); }
+
     const std::string & getCacheConfigName() const { return cache_config_name; }
 
     ObjectStoragePtr getWrappedObjectStorage() { return object_storage; }

src/Disks/ObjectStorages/DiskObjectStorage.cpp

@@ -499,6 +499,11 @@ bool DiskObjectStorage::isReadOnly() const
     return object_storage->isReadOnly();
 }
 
+bool DiskObjectStorage::isWriteOnce() const
+{
+    return object_storage->isWriteOnce();
+}
+
 DiskObjectStoragePtr DiskObjectStorage::createDiskObjectStorage()
 {
     return std::make_shared<DiskObjectStorage>(

src/Disks/ObjectStorages/DiskObjectStorage.h

@@ -177,6 +177,12 @@ public:
     /// with static files, so only read-only operations are allowed for this storage.
     bool isReadOnly() const override;
 
+    /// Is object write-once?
+    /// For example: S3PlainObjectStorage is write once, this means that it
+    /// does support BACKUP to this disk, but does not support INSERT into
+    /// MergeTree table on this disk.
+    bool isWriteOnce() const override;
+
     /// Add a cache layer.
     /// Example: DiskObjectStorage(S3ObjectStorage) -> DiskObjectStorage(CachedObjectStorage(S3ObjectStorage))
     /// There can be any number of cache layers:

src/Disks/ObjectStorages/IObjectStorage.h

@@ -199,6 +199,7 @@ public:
     virtual bool supportsCache() const { return false; }
 
     virtual bool isReadOnly() const { return false; }
+    virtual bool isWriteOnce() const { return false; }
 
     virtual bool supportParallelWrite() const { return false; }
 

src/Disks/ObjectStorages/S3/S3ObjectStorage.h

@@ -216,6 +216,11 @@ public:
     {
         data_source_description.type = DataSourceType::S3_Plain;
     }
+
+    /// Notes:
+    /// - supports BACKUP to this disk
+    /// - does not support INSERT into MergeTree table on this disk
+    bool isWriteOnce() const override { return true; }
 };
 
 }

src/Storages/IStorage.cpp

@@ -253,7 +253,7 @@ bool IStorage::isStaticStorage() const
     if (storage_policy)
     {
         for (const auto & disk : storage_policy->getDisks())
-            if (!disk->isReadOnly())
+            if (!(disk->isReadOnly() || disk->isWriteOnce()))
                 return false;
         return true;
     }

src/Storages/IStorage.h

@@ -583,7 +583,8 @@ public:
     /// Returns storage policy if storage supports it.
     virtual StoragePolicyPtr getStoragePolicy() const { return {}; }
 
-    /// Returns true if all disks of storage are read-only.
+    /// Returns true if all disks of storage are read-only or write-once.
+    /// NOTE: write-once also does not support INSERTs/merges/... for MergeTree
     virtual bool isStaticStorage() const;
 
     virtual bool supportsSubsetOfColumns() const { return false; }

tests/integration/test_attach_backup_from_s3_plain/test.py

@@ -30,9 +30,7 @@ def start_cluster():
         pytest.param("wide", "backup_wide", "s3_backup_wide", int(0), id="wide"),
     ],
 )
-def test_attach_compact_part(
-    table_name, backup_name, storage_policy, min_bytes_for_wide_part
-):
+def test_attach_part(table_name, backup_name, storage_policy, min_bytes_for_wide_part):
     node.query(
         f"""
     -- Catch any errors (NOTE: warnings are ok)
@@ -61,9 +59,6 @@ def test_attach_compact_part(
 
     node.query(
         f"""
-    -- NOTE: be aware not to DROP the table, but DETACH first to keep it in S3.
-    detach table ordinary_db.{table_name};
-
     -- NOTE: DROP DATABASE cannot be done w/o this due to metadata leftovers
     set force_remove_data_recursively_on_drop=1;
     drop database ordinary_db sync;