How to search list items by regex with Aerospike Expressions

Question

We are migrating from our old aerospike version 3.15.1.4 to version 6.2.0.7. This involves the migration from aerospike-client-go v4.5.2+incompatible to aerospike-client-go/v6 v6.6.0. Predicate Expressions (PredExp) have been deprecated since Aerospike Database 5.2. They were removed in Aerospike Database 6.0. So we have to move to Aerospike Expressions.

We have a bin with a string-list in it. And we want to do a search with a "begins-with" pattern. In the old world, we do that with following code:

as.NewPredExpStringVar("v"),
as.NewPredExpStringValue("^"+regexp.QuoteMeta("search_term")),
as.NewPredExpStringRegex(QueryRegexOptionExtended|QueryRegexOptionIgnoreCase),
as.NewPredExpListBin("ListField"),
as.NewPredExpListIterateOr("v"),

Following examples will search vor exact value in the "new world":

// As filter inside statement
as.NewContainsFilter("ListField", as.ICT_LIST, "search_term")

// As FilterExpression on query-policy
*as.ExpGreater(
    as.ExpListGetByValue(
        as.ListReturnTypeCount,
        as.ExpStringVal("search_term"),
        as.ExpListBin("ListField")),
    as.ExpIntVal(0),

But how can we achive a "begins-with-search" with the new Aerospike Expressions?

We tried the following, without success:

*as.ExpRegexCompare(
    "^"+regexp.QuoteMeta("search_term"),
    as.ExpRegexFlagICASE,
    as.ExpListBin("ListField"),
)

In the aerospike-logs, the following warning appears:

WARNING (exp): (exp.c:1469) build_cmp_regex - error 4 invalid arg type 4 (list) != 3 (str)
WARNING (query): (query.c:1485) basic query job failed msg field processing

---

For more background-info, this is the db-setup:

We have following model which is getting stored inside aerospike:

type MyModel struct {
    ListField []string
    [some-other-fields]
}

And following secondary index: Index name: idx_MYSET_ListField / namespace: myns / set: MYSET / bin: ListField / bin: string / index: list / State: RW

And if I read a sample record over aql:

aql> select PK,ListField from myns.MYSET where PK = 12345
+--------------------+-------------------------------------------------------------------+
| PK | ListField |
+--------------------+-------------------------------------------------------------------+
| 12345 | LIST('["myid:1234", "testid2", "some-other-value", "more-values"]') |
+--------------------+-------------------------------------------------------------------+

Answer 1

Expressions do not support iteration over lists or maps. The list and map APIs normally provide functionality that would solve the use-cases using the iteration provided by the old predexp. This is the first use-case I've come across that used iteration in a way that cannot be replicated with the list/map APIs.

As of 6.3, the only way to replicate this behavior may be to use a Stream UDF.