SSIS,数据流中的源为ADO.NET,目标为OLE DB目标，从源到目标，没有进行字段的数据类型更改及截断等，但是目标字段的长度是源对应字段长度的1.5倍。这个是为什么？比如源字段长度为255，目标字段为382，请帮我看看是为什么？

我想再问下这个1.5倍是怎么来的？因为我也看到有2倍的预估，所以这个长度是随机的？

Hi Lucy Wong, Thank you for your follow‑up question.

1. Your ADO.NET Source uses DT_WSTR (Unicode string).
2. Your OLE DB Destination expects DT_STR (non-Unicode string) or maps to a database column with a fixed byte size.
3. Unicode characters take 2 bytes per character, while non-Unicode (ANSI) takes 1 byte.
4. SSIS internally multiplies the Unicode string length by 1.5 to estimate the worst-case byte size when converting to non-Unicode.

255 × 1.5 = 382.5 → SSIS rounds up to 382 as the destination length.

Thanks,

Lakshmi.

Hi Lucy Wong,

I'm following up to check if the response provided below was helpful.

Please let us know if your issue has been resolved. If you still have any questions or need further assistance, don't hesitate to get in touch we're happy to continue supporting you.

We appreciate your participation and thank you for being an active member of the community.

Best regards,

Lakshmi

Thanks for your reply,but my question is why 1.5,not other numbers?

Hi Lucy,

Great question the reason SSIS uses 1.5 is because it’s a built‑in safety factor. Unicode strings (DT_WSTR) always take 2 bytes per character, while non‑Unicode (DT_STR) usually takes 1 byte, but some code pages can require more. SSIS doesn’t want to risk truncation, so it multiplies by 1.5 as a compromise: larger than 1, smaller than 2, giving enough buffer without doubling the length.

It’s not a strict encoding rule, just an internal SSIS heuristic to keep conversions safe.

Thanks,

Lakshmi