SELECT ts FROM event WHERE ((appkey='n') AND (ecode = 'n')) ORDER BY ts ASC limit 1;

Received exception from server (version 22.3.3):
Code: 10. DB::Exception: Received from localhost:9000. DB::Exception: Not found column ecode in block. There are only columns: appkey, ts, equals(ecode, 'n'). (NOT_FOUND_COLUMN_IN_BLOCK)

SELECT ts FROM event WHERE ((appkey='a') AND (ecode = 'a')) ORDER BY ts ASC limit 1;

0 rows in set. Elapsed: 0.047 sec.

CREATE TABLE event
(
    `appkey` String,
    `ecode` String,
    `userid` String,
    `iid` String,
    `exid` String,
    `did` String,
    `sid` String,
    `pid` Int32,
    `fid` String,
    `appVersion` String,
    `platform` UInt8,
    `revenue` Float64,
    `ts` DateTime,
    `ea` String,
    `eb` String,
    `ec` Int32,
    `ed` Int32,
    `ee` String,
    `ef` String,
    `eg` String,
    `eh` String,
    `ei` String,
    `ej` String,
    `ek` String,
    `el` Float64,
    `em` String,
    `en` String,
    `eo` Int32,
    `ep` Float64,
    `eq` Float64,
    `er` Float64,
    `es` Float64,
    `et` String,
    `eu` String,
    `ev` String,
    `fc` Float64,
    `fd` Float64,
    `fe` Int32,
    `ff` Int32,
    `fg` UInt8,
    `fh` UInt8,
    `fi` DateTime,
    `fj` DateTime,
    `fk` String,
    `fl` String,
    `fm` Int32,
    `fn` Int32,
    `fo` String,
    `fp` String,
    `fq` Int64,
    `fr` Int64,
    `fs` String,
    `ft` Float64,
    `fu` Int64,
    `fv` String,
    `fw` Float64,
    `fx` String,
    `fy` Int32,
    `fz` Int32,
    `ga` String,
    `gb` Int64,
    `gc` Int64,
    `data` String,
    `txt` String,
    `cmp` String,
    `piid` String,
    `uid` String,
    `gd` String,
    `ge` String,
    `rv` Float64
)
ENGINE = MergeTree
PARTITION BY toYYYYMMDD(ts)
ORDER BY (appkey, ecode, ts)
SETTINGS index_granularity = 8192