---
layout: docu
redirect_from:
- /internals/storage
- /internals/storage/
- /docs/internals/storage
title: Storage Versions and Format
---
## Compatibility
### Backward Compatibility
_Backward compatibility_ refers to the ability of a newer DuckDB version to read storage files created by an older DuckDB version. Version 0.10 is the first release of DuckDB that supports backward compatibility in the storage format. DuckDB v0.10 can read and operate on files created by the previous DuckDB version – DuckDB v0.9.
For future DuckDB versions, our goal is to ensure that any DuckDB version released **after** can read files created by previous versions, starting from this release. We want to ensure that the file format is fully backward compatible. This allows you to keep data stored in DuckDB files around and guarantees that you will be able to read the files without having to worry about which version the file was written with or having to convert files between versions.
### Forward Compatibility
_Forward compatibility_ refers to the ability of an older DuckDB version to read storage files produced by a newer DuckDB version. DuckDB v0.9 is [**partially** forward compatible with DuckDB v0.10]({% post_url 2024-02-13-announcing-duckdb-0100 %}#forward-compatibility). Certain files created by DuckDB v0.10 can be read by DuckDB v0.9.
Forward compatibility is provided on a **best effort** basis. While stability of the storage format is important – there are still many improvements and innovations that we want to make to the storage format in the future. As such, forward compatibility may be (partially) broken on occasion.
## How to Move Between Storage Formats
When you update DuckDB and open an old database file, you might encounter an error message about incompatible storage formats, pointing to this page.
To move your database(s) to newer format you only need the older and the newer DuckDB executable.
Open your database file with the older DuckDB and run the SQL statement `EXPORT DATABASE 'tmp'`. This allows you to save the whole state of the current database in use inside folder `tmp`.
The content of the `tmp` folder will be overridden, so choose an empty/non yet existing location. Then, start the newer DuckDB and execute `IMPORT DATABASE 'tmp'` (pointing to the previously populated folder) to load the database, which can be then saved to the file you pointed DuckDB to.
A Bash script to achieve this (to be adapted with the file names and executable locations) is the following
```batch
/older/duckdb mydata.old.db -c "EXPORT DATABASE 'tmp'"
/newer/duckdb mydata.new.db -c "IMPORT DATABASE 'tmp'"
```
After this, `mydata.old.db` will remain in the old format, `mydata.new.db` will contain the same data but in a format accessible by the more recent DuckDB version, and the folder `tmp` will hold the same data in a universal format as different files.
Check [`EXPORT` documentation]({% link docs/stable/sql/statements/export.md %}) for more details on the syntax.
### Explicit Storage Versions
[DuckDB v1.2.0 introduced the `STORAGE_VERSION` option]({% post_url 2025-02-05-announcing-duckdb-120 %}#explicit-storage-versions), which allows explicitly specifying the storage version.
Using this, you can opt-in to newer forwards-incompatible features:
```sql
ATTACH 'file.db' (STORAGE_VERSION 'v1.2.0');
```
This setting specifies the minimum DuckDB version that should be able to read the database file. When database files are written with this option, the resulting files cannot be opened by older DuckDB released versions than the specified version. They can be read by the specified version and all newer versions of DuckDB.
If you attach to DuckDB databases, you can query the storage versions using the following command:
```sql
SELECT database_name, tags FROM duckdb_databases();
```
This shows the storage versions:
```text
┌───────────────┬───────────────────────────────────┐
│ database_name │ tags │
│ varchar │ map(varchar, varchar) │
├───────────────┼───────────────────────────────────┤
│ file1 │ {storage_version=v1.2.0} │
│ file2 │ {storage_version=v1.0.0 - v1.1.3} │
│ ... │ ... │
└───────────────┴───────────────────────────────────┘
```
This means that `file2` can be opened by past DuckDB versions while `file1` is compatible only with `v1.2.0` (or future versions).
### Converting Between Storage Versions
To convert from the new format to the old format for compatibility, use the following sequence in DuckDB v1.2.0+:
```sql
ATTACH 'file1.db';
ATTACH 'converted_file.db' (STORAGE_VERSION 'v1.0.0');
COPY FROM DATABASE file1 TO converted_file;
```
## Storage Header
DuckDB files start with a `uint64_t` which contains a checksum for the main header, followed by four magic bytes (`DUCK`), followed by the storage version number in a `uint64_t`.
```bash
hexdump -n 20 -C mydata.db
```
```text
00000000 01 d0 e2 63 9c 13 39 3e 44 55 43 4b 2b 00 00 00 |...c..9>DUCK+...|
00000010 00 00 00 00 |....|
00000014
```
A simple example of reading the storage version using Python is below.
```python
import struct
pattern = struct.Struct('<8x4sQ')
with open('test/sql/storage_version/storage_version.db', 'rb') as fh:
print(pattern.unpack(fh.read(pattern.size)))
```
## Storage Version Table
For changes in each given release, check out the [change log](https://github.com/duckdb/duckdb/releases) on GitHub.
To see the commits that changed each storage version, see the [commit log](https://github.com/duckdb/duckdb/commits/main/src/storage/storage_info.cpp).
| Storage version | DuckDB version(s) |
|----------------:|---------------------------------|
| 65 | v1.2.0 |
| 64 | v0.9.x, v0.10.x, v1.0.0, v1.1.x |
| 51 | v0.8.x |
| 43 | v0.7.x |
| 39 | v0.6.x |
| 38 | v0.5.x |
| 33 | v0.3.3, v0.3.4, v0.4.0 |
| 31 | v0.3.2 |
| 27 | v0.3.1 |
| 25 | v0.3.0 |
| 21 | v0.2.9 |
| 18 | v0.2.8 |
| 17 | v0.2.7 |
| 15 | v0.2.6 |
| 13 | v0.2.5 |
| 11 | v0.2.4 |
| 6 | v0.2.3 |
| 4 | v0.2.2 |
| 1 | v0.2.1 and prior |
## Compression
DuckDB uses [lightweight compression]({% post_url 2022-10-28-lightweight-compression %}).
Note that compression is only applied to persistent databases and is **not applied to in-memory instances**.
### Compression Algorithms
The compression algorithms supported by DuckDB include the following:
* [Constant Encoding]({% post_url 2022-10-28-lightweight-compression %}#constant-encoding)
* [Run-Length Encoding (RLE)]({% post_url 2022-10-28-lightweight-compression %}#run-length-encoding-rle)
* [Bit Packing]({% post_url 2022-10-28-lightweight-compression %}#bit-packing)
* [Frame of Reference (FOR)]({% post_url 2022-10-28-lightweight-compression %}#frame-of-reference)
* [Dictionary Encoding]({% post_url 2022-10-28-lightweight-compression %}#dictionary-encoding)
* [Fast Static Symbol Table (FSST)]({% post_url 2022-10-28-lightweight-compression %}#fsst) – [VLDB 2020 paper](https://www.vldb.org/pvldb/vol13/p2649-boncz.pdf)
* [Adaptive Lossless Floating-Point Compression (ALP)]({% post_url 2024-02-13-announcing-duckdb-0100 %}#adaptive-lossless-floating-point-compression-alp) – [SIGMOD 2024 paper](https://ir.cwi.nl/pub/33334/33334.pdf)
* [Chimp]({% post_url 2022-10-28-lightweight-compression %}#chimp--patas) – [VLDB 2022 paper](https://www.vldb.org/pvldb/vol15/p3058-liakos.pdf)
* [Patas]({% post_url 2022-11-14-announcing-duckdb-060 %}#compression-improvements)
## Disk Usage
The disk usage of DuckDB's format depends on a number of factors, including the data type and the data distribution, the compression methods used, etc.
As a rough approximation, loading 100 GB of uncompressed CSV files into a DuckDB database file will require 25 GB of disk space, while loading 100 GB of Parquet files will require 120 GB of disk space.
## Row Groups
DuckDB's storage format stores the data in _row groups,_ i.e., horizontal partitions of the data.
This concept is equivalent to [Parquet's row groups](https://parquet.apache.org/docs/concepts/).
Several features in DuckDB, including [parallelism]({% link docs/stable/guides/performance/how_to_tune_workloads.md %}) and [compression]({% post_url 2022-10-28-lightweight-compression %}) are based on row groups.
## Troubleshooting
### Error Message When Opening an Incompatible Database File
When opening a database file that has been written by a different DuckDB version from the one you are using, the following error message may occur:
```console
Error: unable to open database "...": Serialization Error: Failed to deserialize: ...
```
The message implies that the database file was created with a newer DuckDB version and uses features that are backward incompatible with the DuckDB version used to read the file.
There are two potential workarounds:
1. Update your DuckDB version to the latest stable version.
2. Open the database with the latest version of DuckDB, export it to a standard format (e.g., Parquet), then import it using to any version of DuckDB. See the [`EXPORT/IMPORT DATABASE` statements]({% link docs/stable/sql/statements/export.md %}) for details.