postgresql - 从 oracle 迁移后 Postgresql 数据库大小变小

Question

我已经使用 Ora2pg 工具将 Oracle 迁移到 Postgresql。Oracle中迁移前的数据库大小约为2Tb，迁移到Postgresql后的相同数据库大小似乎只有600 gb。注意：记录以相同的行数正确迁移。

我还想知道 Postgresql 在从 Oracle 中的 Blob 迁移后如何处理 Bytea 数据类型。

Answer 1

You might want to check if all migrated objects are present.

However, this is not surprising, and there are several things that can contribute to that:

• You counted the size of the tablespaces in Oracle, but they were partly empty.

• Your table and index blocks were fragmented, while they are not in the newly imported PostgreSQL database.

• Depending on which options you installed in Oracle, the data dictionary can be quite large (though that alone cannot explain the observed difference).