If there are multi segments, the result of IVF_PQ IP is wrong

[shengjun1985]

Please state you issue using the following template and, most importantly, in English.

Describe the bug
If there are multi segments, the result of IVF_PQ IP is wrong.
There is a bug in merging task result.

Steps/Code to reproduce behavior
(0) create collection whose metric_type is IP
(1) inset data and product multi segments
(2) create IVF_PQ
(3) query the topK nearest items
The result is wrong.

Expected behavior
The result is correct.

Environment details

• Milvus version (v0.10.1)

Screenshots
none

Additional context
from source review

[dvzubarev]

What is "multi segments" ? I searched this repository and found nothing except this issue and PRs.

[shengjun1985]

When the total data in a collection is large enough, ie. multiple gigabytes, Milvus will organize the data in multiple slices, or "segments". For instance, 1 GB of vector data per segment. Then, Milvus will build index for each of the data segment.

Thus, if you have a collection containing 10 GB of vector data, and 1GB per segment, we will have 10 segments.
That is where the "multi-segments" come from.

[dvzubarev]

Thank you, for explanation