Yes. Are rows in these tables modified after the import? If not, then the indexes won't get fragmented, and there is no need to run any index or statistics maintenance.

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Also for above statement, do you mean when first time import data to a new table, the index is not fragmented, and the statistics is up to date?

But when I second time insert more data into this table, then the index is fragmented and the statistics is out of date?

( the records we imported each time is about 60000)

we'd better either run build index or update statistics before we query it.

(this query is not a simple one, but is to join this table with other tables in another database)

Thanks