send_progress_in_http_headers = 1 is not really needed

[x-yuri]

You only need X-ClickHouse-Summary. And that is returned with send_progress_in_http_headers = 0. I.e. as far as I can see send_progress_in_http_headers can be safely changed to 0. With send_progress_in_http_headers = 1, a relatively slow query (2 sec), and clickhouse being behind nginx, the latter says "upstream sent too big header" because clickhouse produces a lot of "progress" headers:

$ curl -sSv 'http://xx.yyy.xx.yyy:8123/?send_progress_in_http_headers=1' -d 'select ..., count(*) from ... group by ... order by ... limit 1' -X GET -u '...:...'
* Expire in 0 ms for 6 (transfer ...)
*   Trying xx.yyy.xx.yyy...
* TCP_NODELAY set
* Expire in 200 ms for 4 (transfer ...)
* Connected to xx.yyy.xx.yyy (xx.yyy.xx.yyy) port 8123 (#0)
* Server auth using Basic with user '...'
> GET /?send_progress_in_http_headers=1 HTTP/1.1
> Host: xx.yyy.xx.yyy:8123
> Authorization: Basic ...
> User-Agent: curl/7.64.0
> Accept: */*
> Content-Length: 94
> Content-Type: application/x-www-form-urlencoded
> 
} [94 bytes data]
* upload completely sent off: 94 out of 94 bytes
< HTTP/1.1 200 OK
< Date: Thu, 08 Feb 2024 13:22:37 GMT
< Connection: Keep-Alive
< Content-Type: text/tab-separated-values; charset=UTF-8
< X-ClickHouse-Server-Display-Name: ...
< Transfer-Encoding: chunked
< X-ClickHouse-Query-Id: ...
< X-ClickHouse-Format: TabSeparated
< X-ClickHouse-Timezone: UTC
< Keep-Alive: timeout=3
< X-ClickHouse-Progress: {"read_rows":"1111953","read_bytes":"8895624","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< X-ClickHouse-Progress: {"read_rows":"9434898","read_bytes":"75479184","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< X-ClickHouse-Progress: {"read_rows":"18412695","read_bytes":"147301560","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< X-ClickHouse-Progress: {"read_rows":"27260817","read_bytes":"218086536","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< X-ClickHouse-Progress: {"read_rows":"35690512","read_bytes":"285524096","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< X-ClickHouse-Progress: {"read_rows":"44667166","read_bytes":"357337328","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< X-ClickHouse-Progress: {"read_rows":"53121310","read_bytes":"424970480","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< X-ClickHouse-Progress: {"read_rows":"61969813","read_bytes":"495758504","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< X-ClickHouse-Progress: {"read_rows":"70226587","read_bytes":"561812696","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< X-ClickHouse-Progress: {"read_rows":"78697369","read_bytes":"629578952","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< X-ClickHouse-Progress: {"read_rows":"86824087","read_bytes":"694592696","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< X-ClickHouse-Progress: {"read_rows":"94819987","read_bytes":"758559896","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< X-ClickHouse-Progress: {"read_rows":"101288000","read_bytes":"810304000","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< X-ClickHouse-Progress: {"read_rows":"101288000","read_bytes":"810304000","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< X-ClickHouse-Progress: {"read_rows":"101288000","read_bytes":"810304000","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< X-ClickHouse-Progress: {"read_rows":"101288000","read_bytes":"810304000","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< X-ClickHouse-Progress: {"read_rows":"101288000","read_bytes":"810304000","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< X-ClickHouse-Progress: {"read_rows":"101288000","read_bytes":"810304000","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< X-ClickHouse-Progress: {"read_rows":"101288000","read_bytes":"810304000","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< X-ClickHouse-Progress: {"read_rows":"101288000","read_bytes":"810304000","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< X-ClickHouse-Progress: {"read_rows":"101288000","read_bytes":"810304000","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< X-ClickHouse-Progress: {"read_rows":"101288000","read_bytes":"810304000","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< X-ClickHouse-Progress: {"read_rows":"101288000","read_bytes":"810304000","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< X-ClickHouse-Progress: {"read_rows":"101288000","read_bytes":"810304000","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< X-ClickHouse-Progress: {"read_rows":"101288000","read_bytes":"810304000","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< X-ClickHouse-Progress: {"read_rows":"101288000","read_bytes":"810304000","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< X-ClickHouse-Summary: {"read_rows":"101288000","read_bytes":"810304000","written_rows":"0","written_bytes":"0","total_rows_to_read":"101288000","result_rows":"0","result_bytes":"0"}
< 
{ [11 bytes data]
* Connection #0 to host xx.yyy.xx.yyy left intact
165	1