# otp.ShowSnapshotList

### *class* ShowSnapshotList(snapshot_storage='all', \*\*kwargs)

Bases: [`Source`](../source/root.md#onetick.py.Source)

Outputs all snapshots names for global memory storage and/or for memory mapped files.
These snapshots should be written there by the [`onetick.py.Source.save_snapshot()`](../source/save_snapshot.md#onetick.py.Source.save_snapshot).
Output ticks have `SNAPSHOT_NAME`, `STORAGE_TYPE` and `DB_NAME` fields.

* **Parameters:**
  **snapshot_storage** ( *'memory'* *or*  *'memory_mapped_file'*) -- 

  This parameter specifies the place of storage of the snapshot. Possible options are:
  * memory - the snapshot is stored in the dynamic (heap) memory of the process
    that ran (or is still running) the [`onetick.py.Source.save_snapshot()`](../source/save_snapshot.md#onetick.py.Source.save_snapshot) for the snapshot.
  * memory_mapped_file - the snapshot is stored in a memory mapped file.
    For each symbol to get the location of the snapshot in the file system, `ReadSnapshot` looks at
    the **SAVE_SNAPSHOT_DIR** parameter value in the locator section for the database of the symbol.
  * all - shows both, memory, memory_mapped_file snapshots.

  Default: all

### Examples

List snapshots from all snapshot storage types:

```pycon
>>> src = otp.ShowSnapshotList(snapshot_storage='all')  
>>> otp.run(src)  
        Time SNAPSHOT_NAME        STORAGE_TYPE        DB_NAME
0 2003-12-01    snapshot_1              MEMORY        DEMO_L1
1 2003-12-01    snapshot_2              MEMORY        DEMO_L1
2 2003-12-01    snapshot_3  MEMORY_MAPPED_FILE  SNAPSHOT_DEMO
```

List snapshots from memory:

```pycon
>>> src = otp.ShowSnapshotList(snapshot_storage='memory')  
>>> otp.run(src)  
        Time SNAPSHOT_NAME        STORAGE_TYPE        DB_NAME
0 2003-12-01    snapshot_1              MEMORY        DEMO_L1
1 2003-12-01    snapshot_2              MEMORY        DEMO_L1
```

List snapshots from memory mapped files:

```pycon
>>> src = otp.ShowSnapshotList(snapshot_storage='memory_mapped_file')  
>>> otp.run(src)  
        Time SNAPSHOT_NAME        STORAGE_TYPE        DB_NAME
0 2003-12-01    snapshot_3  MEMORY_MAPPED_FILE  SNAPSHOT_DEMO
```

#### SEE ALSO
**SHOW_SNAPSHOT_LIST** OneTick event processor
<br/>
[`onetick.py.ReadSnapshot`](read_snapshot.md#onetick.py.ReadSnapshot)
<br/>
[`onetick.py.FindSnapshotSymbols`](find_snapshot_symbols.md#onetick.py.FindSnapshotSymbols)
<br/>
[`onetick.py.Source.save_snapshot()`](../source/save_snapshot.md#onetick.py.Source.save_snapshot)
<br/>
[`onetick.py.Source.join_with_snapshot()`](../source/join_with_snapshot.md#onetick.py.Source.join_with_snapshot)
<br/>