**Describe the bug**

Since we upgraded to 20.10.3.30, one of our clickhouse cluster takes much more time to start. (Up to 50 minutes, and before it took ~3 minutes)
The log file is filled with
>  <Debug> DiskLocal: Reserving 1.00 MiB on disk `default`, having unreserved 16.90 TiB

Additionally, the memory consumption increases, linearly, a lot (up to arround 230 G for us) and then drop back to normal values once clickhouse finished starting up. During that loading phase, a single CPU core is used at 100%.
If that memory is not available for the machine, clickhouse gets OOMed by the kernel.


**How to reproduce**
* Issue appeared after we upgraded to ClickHouse server version 20.10.3.30

* How could I find wich of our tables may be responsible for that ?


**Expected behavior**
A fast startup :)

{
        return DB::extractKeyExpressionList(node);
    }
    /** Create local backup (snapshot) for parts with specified prefix.
      * Backup is created in directory clickhouse_dir/shadow/i/, where i - incremental number,
      *  or if 'with_name' is specified - backup is created in directory with specified name.
      */
    PartitionCommandsResultInfo freezePartition(
        const ASTPtr & partition,
        const StorageMetadataPtr & metadata_snapshot,
        const String & with_name,
        ContextPtr context,
        TableLockHolder & table_lock_holder);
    
    PartitionCommandsResultInfo freezeAll(
        const String & with_name,
        const StorageMetadataPtr & metadata_snapshot,
        ContextPtr context,
        TableLockHolder & table_lock_holder);