Failed to send record batch from the merge iterator when execute explain statement

[jiacai2050]

Describe this problem

When execute explain on a SQL, the server will output

2022-09-14 10:02:17.321 ERRO [analytic_engine/src/instance/read.rs:352] Failed to send record batch from the merge iterator
2022-09-14 10:02:17.321 INFO [analytic_engine/src/row_iter/merge.rs:844] Merge iterator dropped, table_id:TableId(2199023255553), request_id:7802, metrics:Metrics { num_memtables: 1, num_ssts: 1, sst_ids: [12], times_fetch_rows_from_one: 1, total_rows_fetch_from_one: 500, times_fetch_row_from_multiple: 0, duration_since_create: 2.786981ms, init_duration: 2.451551ms, scan_duration: 2.44739ms, scan_count: 2 }, iter_options:IterOptions { batch_size: 500 },

Steps to reproduce

Execute SQL below

        drop table if exists test;
        create table test(ts timestamp timestamp KEY not null, value double)
        with (
        enable_ttl = 'false'
        );
        insert into test(ts,value) values (123,9);
        explain select value from test;

Expected behavior

No error log

Additional Information

No response