documentation on database breaking changes
# <img src="https://raw.githubusercontent.com/consensys/tessera/master/tessera-logo.png" width="150" height="36"/>
+> __Important: Breaking change__ <br/>Users running on [21.10.0](https://github.com/ConsenSys/tessera/releases/tag/tessera-21.10.0) and previous versions will need to perform a database upgrade to work with the latest version of Tessera.<li> For non-H2 users, existing database schema will need to be updated. Execute the appropriate provided [alter script](ddls/add-codec).</li> <li> For H2 users, a complete database migration is required before running the [alter script](ddls/add-codec). This is due to the considerable number of changes between version 1.4.200 and version 2.0.202 onwards. See more details from [H2 release](https://github.com/h2database/h2database/releases/tag/version-2.0.202) and their recommended [upgrade process](https://h2database.com/html/tutorial.html#upgrade_backup_restore). Example migration scripts can be found [here](ddls/scripts/h2-upgrade.sh)
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> __Important: If using version 21.4.1 and earlier__ <br/>Tessera is now released as a zipped distribution instead of an uber jar. If using version 21.4.1 and earlier, see the [previous README](https://github.com/ConsenSys/tessera/tree/tessera-21.4.1).
Tessera is a stateless Java system that is used to enable the encryption, decryption, and distribution of private transactions for [Quorum](https://github.com/consensys/quorum/) and/or [Besu](http://github.com/hyperledger/besu)
