Using QueryIterator with a RANDOM_SAMPLE(...) query causes pages after the first to fail

[gehnaphore]

Version 2.6.6 of the Java SDK.

When QueryIterator is used with RANDOM_SAMPLE (seems like a common use case), all pages after the first get dropped with a message like this:

ERROR io.milvus.v2.utils.RpcUtils -- QueryRequest collectionName:radiology_cases failed, error code: 2, reason: failed to create query plan: cannot parse expression: ( RANDOM_SAMPLE(0.01773489873372823) ) and caseId > "cmg7ztvn32flo0764x2jg7tgo", error: random sample expression can only be the last expression in the logical and expression: invalid parameter

This is caused because QueryIterator.setupNextExpr() constructs a query that will be invalid if the oiriginal query uses RANDOM_SAMPLE, since if it is present it seemingly must be alone or the last component of a top-level conjunction.

It may be enough to change

return " ( "+currentExpr+" ) " + " and " + filteredPKStr;

to

return filteredPKStr + " and ( "+currentExpr+" ) ";

I will give this a try and submit a PR if it works.

[xiaofan-luan]

@SpadeA-Tang @zhengbuqian

could we just reorder the random expression to the last?

Right not it seems we have too many limitations on "this could only be the last expressions"

[yhmo]

Seems is a sdk-side workaround.
#1722

@gehnaphore The pr coudl not pass the DCO check, could you add a Signed-off-by to the commit by the this command:
git commit -sm [commit description]

[yhmo]

The pr is merged and released with v2.6.11