Requirements and considerations
Requirements and considerations
- The table must exist.
- For you to import data into a table, the table must already exist in Derby. The table does not have to be empty. If the table is not empty, bulk import performs single inserts which results in slower performance.
- Create indexes and primary key, foreign key, and unique constraints first.
- To avoid a separate create index step, create indexes and primary keys on tables before you import data. However, if your memory and disk spaces resources are limited, you can build the indexes and primary keys after importing data.
- Data types.
- You can import and export only data of the non-binary, built-in data types. Derby implicitly converts the strings to the data type of the receiving column. If any of the implicit conversions fail, the whole import is aborted. For example, "3+7" cannot be converted into an integer. An export that encounters a runtime error stops.
- Note:
- You cannot import or export the binary data types: BLOB, CLOB, CHAR FOR BIT DATA, VARCHAR FOR BIT DATA, LONG VARCHAR FOR BIT DATA, LONG VARBINARY, or LONG BINARY.
- Locking during import.
- Import procedures use the same isolation level as the connection in which they are executed to insert data into tables. During import, the entire table is exclusively locked irrespective of the isolation level.
- Locking during export.
- Export procedures use the same isolation level as the connection in which they are executed to fetch data from tables.
- Import behavior on tables with triggers.
- The import procedure fires INSERT triggers when data is appended to the table. The REPLACE option is not allowed when triggers are enabled on the table.
- Restrictions on the REPLACE option.
- If a table that receives imported data already contains data, you can either replace or append to the existing data. You can use the REPLACE option on tables that have dependent tables, but the replaced data must maintain referential integrity, otherwise the import operation will be rolled back. You cannot use the REPLACE option if the table has enabled triggers.
- Restrictions on tables.
- You cannot use import procedures to import data into a system table or a declared temporary table.
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