exp,imp 小参数详解（之二）

 COMMIT
Default: n
Specifies whether Import should commit after each array insert. By default, Import commits only after loading each table, and Import performs a rollback when an error occurs, before continuing with the next object.

If a table has nested table columns or attributes, the contents of the nested tables are imported as separate tables. Therefore, the contents of the nested tables are always committed in a transaction distinct from the transaction used to commit the outer table.

If COMMIT=n and a table is partitioned, each partition and subpartition in the Export file is imported in a separate transaction.

For tables containing LOBs, LONG, BFILE, REF, ROWID, or UROWID columns, array inserts are not done. If COMMIT=y, Import commits these tables after each row.

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1.如果指定commit=Y，imp的时候 每个组(array) insert之后，都会commit.(Specifies whether Import should commit after each array insert.)如果是NO，每个表装后才进行一次commit，如果有错，将回滚这个操作。
2.commit=n的情况下，嵌套表和分区表都是在单独的事务中间提交的。（If a table has nested table columns or attributes, the contents of the nested tables are imported as separate tables. Therefore, the contents of the nested tables are always committed in a transaction distinct from the transaction used to commit the outer table.）
3.对于包含LOBS.LONG.BFILE.REF.ROWID.UROWID列的表，如果选择commit=y,imp的时候会在每行插入之后做commit的操作。