Bug Report: Duplicate key error in lookup table of type lookup_unique is recorded as UNKNOWN error in vtgate metrics

[harshit-gangal]

Overview of the Issue

If the lookup table insert results in a duplicate key exception, it is recorded as UNKNOWN, e.g.

vtgate_api_error_counts{code="UNKNOWN",db_type="primary",keyspace="sharded",operation="Execute"} 28

This confuses and should record the metrics errors in alignment with what was sent back to the client.

Reproduction Steps

Vschema:

{
    "sharded": true,
    "vindexes": {
        "hash": {
            "type": "hash"
        },
        "xxhash": {
            "type": "xxhash"
        },
        "lookup_t1": {
            "type": "lookup_unique",
            "params": {
                "from": "c2",
                "table": "lookup_t1_backing",
                "to": "keyspace_id",
                "write_only": "false"
            },
            "owner": "t1"
        }
    },
    "tables": {
        "t1": {
            "column_vindexes": [
                {
                    "column": "c1",
                    "name": "xxhash"
                },
                {
                    "column": "c2",
                    "name": "lookup_t1"
                }
            ]
        },
        "lookup_t1_backing": {
            "column_vindexes": [
                {
                    "column": "c2",
                    "name": "hash"
                }
            ]
        }
    }
}

schema:

CREATE TABLE lookup_t1_backing (  `c2` bigint unsigned NOT NULL,  `keyspace_id` varbinary(128) DEFAULT NULL,  PRIMARY KEY (`c2`));
create table t1 (c1 bigint not null, c2 bigint not null, c3 bigint, primary key(c1));

Run:

insert into t1 (c1,c2) values (20,21);
insert into t1 (c1,c2) values (20,21);

Observe the error and that it is a duplicate key error (1062), then check the vtgate metrics, e.g.:

curl -s http://localhost:15001/metrics | grep api_error

and see that the error was recorded as UNKNOWN instead of ALREADY_EXISTS

Binary Version

`main`

Operating System and Environment details

NA

Log Fragments

No response