I was thinking about this flow definition but I am strugglin Greptime #general

I was thinking about this flow definition, but I a...

Wei

08/20/2025, 3:40 PM

I was thinking about this flow definition, but I am struggling to understand how timewindow works, specifically I need two samples within the last 1 minute.

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CREATE FLOW intf_aggregation
SINK TO interface_sink
AS
SELECT
    router,
    port
    (last_value(rx) - first_value(rx)) * 8/30 as rx_rate,
    (last_value(tx) - first_value(tx)) * 8/30 as tx_rate,
    last_value(discard) - first_value(discard) as discard_delta,
    last_value(crc) - first_value(crc) as crc_delta,
    date_bin('30 s'::INTERVAL, timestamp) as time_window,,
FROM interface
GROUP BY
    time_window;

Ruihang

08/20/2025, 11:57 PM

you can control the sample step using

date_bin

and

group by

. to your case, if

tx

rx

etc are not mono-increase, first/last value might not be a good choose

Wei

08/21/2025, 2:13 PM

I will look into it

Wei

08/21/2025, 2:13 PM

thanks much, Ruihang

Wei

08/21/2025, 6:09 PM

@Ruihang I am looking at this example, https://github.com/GreptimeTeam/greptimedb/blob/main/tests/cases/standalone/common/flow/flow_insert.sql, I include a snippet of the flow here,

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CREATE FLOW find_approx_rate SINK TO approx_rate AS
SELECT
    (max(byte) - min(byte)) / 30.0 as rate,
    date_bin(INTERVAL '30 second', ts) as time_window
from
    bytes_log
GROUP BY
    time_window;

Wei

08/21/2025, 6:11 PM

to be honest, I don't think it is right. the rate can be 'negative'. For instance, ~~car speed is reduced~~, it doesn't sound a good example. Or, in this case, if it is negative, it means a bug some where, that needs attention. or number exceeds i64 bits.

Wei

08/21/2025, 6:48 PM

I tried this, but it errored out,

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CREATE FLOW interface_rate
SINK TO interface_sink
AS
SELECT
  router,
  port,
  (last_value(rx) - first_value(rx)) * 8 / 30 RANGE '30s' as rx,
  (last_value(tx) - first_value(tx)) * 8 / 30 RANGE '30s' as tx,
  last_value(discards) - first_value(discards) RANGE '30s' as discards,
  last_value(crc) - first_value(crc) RANGE '30s' as crc,
  date_bin('30 seconds'::INTERVAL, ts) as time_window
FROM interface
ALIGN '40s'
ORDER BY ts;

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ERROR:  Invalid SQL syntax: sql parser error: Can't use the RANGE keyword in Expr 30 without function

Wei

08/21/2025, 6:48 PM

can you help give me an example, thanks much.

Wei

08/21/2025, 8:56 PM

here is an updated flow,

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CREATE FLOW interface_rate
SINK TO interface_sink
AS
SELECT
  router,
  port,
  (rx2 - rx1) * 8 / 30 as rx,
  (tx2 - tx1) * 8 / 30 as tx,
  discards2 - discards1 as discards,
  crc2 - crc1 as crc,
  time_window
FROM (
select
  router,
  port,
  first_value(rx) range '40s' as rx1,
  last_value(rx) range '40s' as rx2,
  first_value(tx) RANGE '40s' as tx1,
  last_value(tx) RANGE '40s' as tx2,
  first_value(discards) RANGE '40s' as discards1,
  last_value(discards) RANGE '40s' as discards2,
  first_value(crc) RANGE '40s' as crc1,
  last_value(crc) RANGE '40s' as crc2,
  ts as time_window
from interface
align '30s' by (router, port)
order by ts);

it still errored out,

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ERROR:  Failed to encode DataFusion plan

Wei

08/21/2025, 8:57 PM

but I can run the nested select query,

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sdn=> SELECT
  router,
  port,
  (rx2 - rx1) * 8 / 30 as rx,
  (tx2 - tx1) * 8 / 30 as tx,
  discards2 - discards1 as discards,
  crc2 - crc1 as crc,
  time_window
FROM (
select
  router,
  port,
  first_value(rx) range '40s' as rx1,
  last_value(rx) range '40s' as rx2,
  first_value(tx) RANGE '40s' as tx1,
  last_value(tx) RANGE '40s' as tx2,
  first_value(discards) RANGE '40s' as discards1,
  last_value(discards) RANGE '40s' as discards2,
  first_value(crc) RANGE '40s' as crc1,
  last_value(crc) RANGE '40s' as crc2,
  ts as time_window
from interface
align '30s' by (router, port)
order by ts);
 router | port |  rx   |  tx   | discards | crc |        time_window
--------+------+-------+-------+----------+-----+----------------------------
 wdc1   | nic1 |     0 |     0 |        0 |   0 | 2025-08-21 19:20:30.000000
 wdc1   | nic1 |  1156 |    62 |      -60 |   1 | 2025-08-21 19:21:00.000000
 wdc1   | nic1 | -1657 | -1333 |       67 | -38 | 2025-08-21 19:21:30.000000
 wdc1   | nic1 |   321 |  1888 |      -48 |  43 | 2025-08-21 19:22:00.000000
 wdc1   | nic1 |  2188 |   230 |       31 | -68 | 2025-08-21 19:22:30.000000
 wdc1   | nic1 | -2119 | -2401 |      -15 |  60 | 2025-08-21 19:23:00.000000
 wdc1   | nic1 |  -448 |  1922 |      -38 |  17 | 2025-08-21 19:23:30.000000
 wdc1   | nic1 |   727 |  -440 |       26 | -16 | 2025-08-21 19:24:00.000000
 wdc1   | nic1 |   -89 |     0 |       -3 | -43 | 2025-08-21 19:24:30.000000
 wdc1   | nic1 |    86 | -1389 |       11 |   0 | 2025-08-21 19:25:00.000000
 wdc1   | nic1 |  -760 |  2345 |       26 | -23 | 2025-08-21 19:25:30.000000
 wdc1   | nic1 |  2023 |  -687 |        0 |  96 | 2025-08-21 19:26:00.000000
 wdc1   | nic1 | -1800 |   735 |       12 |  -5 | 2025-08-21 19:26:30.000000
 wdc1   | nic1 |  1593 | -1249 |      -34 | -36 | 2025-08-21 19:27:00.000000
 wdc1   | nic1 |   464 |   155 |       19 |  -2 | 2025-08-21 19:27:30.000000
 wdc1   | nic1 | -1987 |   189 |        7 | -10 | 2025-08-21 19:28:00.000000
 wdc1   | nic1 |  -185 | -1687 |      -80 |  17 | 2025-08-21 19:28:30.000000
 wdc1   | nic1 |   528 |  1776 |       95 |  22 | 2025-08-21 19:29:00.000000
 wdc1   | nic1 |   208 | -1635 |      -24 | -14 | 2025-08-21 19:29:30.000000
 wdc1   | nic1 |  1602 |   218 |      -48 | -14 | 2025-08-21 19:30:00.000000
 wdc1   | nic1 |     0 |     0 |        0 |   0 | 2025-08-21 19:30:30.000000
(21 rows)

sdn=>

Wei

08/21/2025, 9:17 PM

this is the err msg from log,

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2025-08-21T21:16:55.581758Z ERROR meta_client::client::procedure: An error occurred in gRPC, status: status: Internal, message: "Failed to encode DataFusion plan", details: [], metadata: MetadataMap { headers: {"content-type": "application/grpc", "x-greptime-err-code": "3001", "date": "Thu, 21 Aug 2025 21:16:55 GMT", "content-length": "0"} }
2025-08-21T21:16:55.581949Z ERROR frontend::instance: Failed to execute query: CREATE FLOW interface_rate
SINK TO interface_sink
AS SELECT
  router,
  port,
  (last_value(rx) range '40s' - first_value(rx) range '40s') * 8 / 30 as rx,
  (last_value(tx) range '40s' - first_value(tx) range '40s') * 8 / 30 as tx,
  (last_value(discards) range '40s' - first_value(discards) range '40s') as discard,
  (last_value(crc) range '40s' - first_value(crc) range '40s') as crc,
  ts as time_window
from interface
align '30s' by (router, port)
order by ts err=0: Table operation error, at src/frontend/src/instance.rs:314:22
1: Failed to execute ddl, at /greptimedb/src/operator/src/statement/ddl.rs:494:14
2: External error, at src/meta-client/src/client.rs:264:14
3: Failed to encode DataFusion plan, at src/meta-client/src/error.rs:163:1
2025-08-21T21:16:55.582051Z ERROR servers::postgres::utils: Failed to handle postgres query, code: EngineExecuteQuery, error: Failed to execute query err=0: Failed to execute query, at /greptimedb/src/servers/src/query_handler/sql.rs:88:49
1: Table operation error, at src/frontend/src/instance.rs:314:22
2: Failed to execute ddl, at /greptimedb/src/operator/src/statement/ddl.rs:494:14
3: External error, at src/meta-client/src/client.rs:264:14
4: Failed to encode DataFusion plan, at src/meta-client/src/error.rs:163:1

Wei

08/21/2025, 9:18 PM

I am running 0.16 ver

Wei

08/21/2025, 9:19 PM

I did another change to get rid of nested sql in flow definition, still got the same error,

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CREATE FLOW interface_rate
SINK TO interface_sink
AS
SELECT
  router,
  port,
  (last_value(rx) range '40s' - first_value(rx) range '40s') * 8 / 30 as rx,
  (last_value(tx) range '40s' - first_value(tx) range '40s') * 8 / 30 as tx,
  (last_value(discards) range '40s' - first_value(discards) range '40s') as discard,
  (last_value(crc) range '40s' - first_value(crc) range '40s') as crc,
  ts as time_window
from interface
align '30s' by (router, port)
order by ts;

Ruihang

08/21/2025, 9:23 PM

we may not use range query in flow. if the data is gauge type, the very first version should match the expectation. what error did you see for that flow

Wei

08/21/2025, 9:27 PM

is there a different way instead of using max() - min()?

Wei

08/21/2025, 9:28 PM

I didn't test it, but I don't think it is right way.

Wei

08/21/2025, 9:42 PM

I tested max() - min() just now, I don't think it is working, I don't know why,

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CREATE FLOW interface_rate
SINK TO interface_sink
AS
SELECT
  router,
  port,
  (max(rx) - min(rx)) * 8 / 30 as rx,
  (max(tx) - min(tx)) * 8 / 30 as tx,
  max(discards) - min(discards) as discards,
  max(crc) - min(crc) as crc,
  date_bin(INTERVAL '30 second', ts) as time_window
FROM  interface
group by time_window, router, port;

when I flushed flow, 0 record,

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sdn=> admin flush_flow('interface_rate');
 ADMIN flush_flow('interface_rate')
------------------------------------
                                  0
(1 row)

sdn=>

Wei

08/21/2025, 9:43 PM

I do see errs in metaserv err log,

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2025-08-21T21:25:31.140613Z ERROR common_meta::ddl::utils: Failed to operate datanode, peer: peer-13(10.240.64.10:6800) err=0: External error, at src/client/src/flow.rs:35:14
1: Failed to request FlowServer 10.240.64.10:6800, code: Client specified an invalid argument, at src/client/src/flow.rs:73:43
2: Failed to encode DataFusion plan, at src/client/src/error.rs:165:1
2025-08-21T21:25:31.140657Z ERROR common_procedure::local::runner: Failed to execute procedure metasrv-procedure::CreateFlow-fdafef8d-3944-4ffa-bf79-4eb3364b08e2, retry: false, clean_poisons: false err=0: Failed to execute procedure due to external error, clean poisons: false
1: Failed to operate on datanode: peer-13(10.240.64.10:6800), at src/common/meta/src/ddl/utils.rs:64:18
2: External error, at src/client/src/flow.rs:35:14
3: Failed to request FlowServer 10.240.64.10:6800, code: Client specified an invalid argument, at src/client/src/flow.rs:73:43
4: Failed to encode DataFusion plan, at src/client/src/error.rs:165:1

Wei

08/21/2025, 9:44 PM

I tested port 6800, it is fine,

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nc -v 10.240.64.10 6800
Connection to 10.240.64.10 6800 port [tcp/*] succeeded!
@@^C

Ruihang

08/21/2025, 9:44 PM

this is not a network issue, still incorrect flow

code: Client specified an invalid argument

Wei

08/21/2025, 9:45 PM

right

Ruihang

08/21/2025, 9:46 PM

is there a different way instead of using max() - min()?

it depends on the semantic data type. if the purpose is to compute instant rate on gauge data, first/last should work. let me check that clause

👍 1

Wei

08/21/2025, 9:47 PM

why still incorrect flow?

Ruihang

08/21/2025, 9:49 PM

let me have a look

Wei

08/21/2025, 9:54 PM

I am able to create a flow with last, first. but still nothing be processed.

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CREATE FLOW interface_rate
SINK TO interface_sink
AS
SELECT
  router,
  port,
  (last_value(rx) - first_value(rx)) * 8 / 30 as rx,
  (last_value(tx) - first_value(tx)) * 8 / 30 as tx,
  last_value(discards) - first_value(discards) as discards,
  last_value(crc) - first_value(crc) as crc,
  date_bin(INTERVAL '30 second', ts) as time_window
FROM  interface
group by time_window, router, port;

Wei

08/21/2025, 9:55 PM

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sdn=> select * from interface_sink;;
 router | port | rx | tx | discards | crc | time_window | update_at
--------+------+----+----+----------+-----+-------------+-----------
(0 rows)

sdn=> admin flush_flow('interface_rate');
 ADMIN flush_flow('interface_rate')
------------------------------------
                                  0
(1 row)

sdn=> select * from interface_sink;;
 router | port | rx | tx | discards | crc | time_window | update_at
--------+------+----+----+----------+-----+-------------+-----------
(0 rows)

sdn=> select * from interface_sink;
 router | port | rx | tx | discards | crc | time_window | update_at
--------+------+----+----+----------+-----+-------------+-----------
(0 rows)

sdn=> admin flush_flow('interface_rate');
ERROR:  Internal error: 1003
sdn=> select * from interface_sink;
 router | port | rx | tx | discards | crc | time_window | update_at
--------+------+----+----+----------+-----+-------------+-----------
(0 rows)

sdn=> admin flush_flow('interface_rate');
 ADMIN flush_flow('interface_rate')
------------------------------------
                                  0
(1 row)

sdn=> select * from interface_sink;
 router | port | rx | tx | discards | crc | time_window | update_at
--------+------+----+----+----------+-----+-------------+-----------
(0 rows)

sdn=>

Wei

08/21/2025, 9:58 PM

this is err from one of flow node,

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2025-08-21T21:52:06.516579Z ERROR client::database: Failed to do Flight get, addr: 10.240.64.6:4001, code: The request does not have valid authentication credentials, source: 0: Not found http or grpc authorization header, at src/client/src/error.rs:165:1
2025-08-21T21:52:11.515503Z ERROR client::database: Failed to do Flight get, addr: 10.240.64.7:4001, code: The request does not have valid authentication credentials, source: 0: Not found http or grpc authorization header, at src/client/src/error.rs:165:1
2025-08-21T21:52:11.516318Z ERROR client::database: Failed to do Flight get, addr: 10.240.64.6:4001, code: The request does not have valid authentication credentials, source: 0: Not found http or grpc authorization header, at src/client/src/error.rs:165:1
2025-08-21T21:52:16.512786Z ERROR flow::batching_mode::task: Failed to execute query for flow=1032 with query: Dml: op=[Insert Into] table=[greptime.sdn.interface_sink]
  Projection: interface.router, interface.port, CAST(last_value(interface.rx) - first_value(interface.rx) AS Int64) * Int64(8) / Int64(30) AS rx, CAST(last_value(interface.tx) - first_value(interface.tx) AS Int64) * Int64(8) / Int64(30) AS tx, last_value(interface.discards) - first_value(interface.discards) AS discards, last_value(interface.crc) - first_value(interface.crc) AS crc, date_bin(IntervalMonthDayNano("IntervalMonthDayNano { months: 0, days: 0, nanoseconds: 30000000000 }"),interface.ts) AS time_window, TimestampNanosecond(1755813121510346049, Some("+00:00")) AS update_at
    Aggregate: groupBy=[[date_bin(IntervalMonthDayNano("IntervalMonthDayNano { months: 0, days: 0, nanoseconds: 30000000000 }"), interface.ts), interface.router, interface.port]], aggr=[[last_value(interface.rx), first_value(interface.rx), last_value(interface.tx), first_value(interface.tx), last_value(interface.discards), first_value(interface.discards), last_value(interface.crc), first_value(interface.crc)]]
      Filter: ts >= TimestampMillisecond(1755813090000, None) AND ts < TimestampMillisecond(1755813120000, None)
        TableScan: interface projection=[router, port, rx, tx, discards, crc, ts] err=0: No available frontend found after timeout: 5s, context: No available frontend found that is able to process query, at src/flow/src/batching_mode/frontend_client.rs:273:10
2025-08-21T21:52:30.606084Z ERROR client::database: Failed to do Flight get, addr: 10.240.64.7:4001, code: The request does not have valid authentication credentials, source: 0: Not found http or grpc authorization header, at src/client/src/error.rs:165:1
2025-08-21T21:52:30.606706Z ERROR client::database: Failed to do Flight get, addr: 10.240.64.6:4001, code: The request does not have valid authentication credentials, source: 0: Not found http or grpc authorization header, at src/client/src/error.rs:165:1
2025-08-21T21:52:35.607133Z ERROR client::database: Failed to do Flight get, addr: 10.240.64.7:4001, code: The request does not have valid authentication credentials, source: 0: Not found http or grpc authorization header, at src/client/src/error.rs:165:1

Ruihang

08/21/2025, 10:02 PM

have you enabled any tls or auth on frontend?

The request does not have valid authentication credentials, source: 0: Not found http or grpc authorization header

Wei

08/21/2025, 10:03 PM

nope

Wei

08/21/2025, 10:03 PM

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[grpc]
## The address to bind the gRPC server.
bind_addr = "10.240.64.6:4001"
## The address advertised to the metasrv, and used for connections from outside the host.
## If left empty or unset, the server will automatically use the IP address of the first network interface
## on the host, with the same port number as the one specified in `grpc.bind_addr`.
server_addr = "10.240.64.6:4001"
## The number of server worker threads.
runtime_size = 8
## Compression mode for frontend side Arrow IPC service. Available options:
## - `none`: disable all compression
## - `transport`: only enable gRPC transport compression (zstd)
## - `arrow_ipc`: only enable Arrow IPC compression (lz4)
## - `all`: enable all compression.
## Default to `none`
flight_compression = "arrow_ipc"

## gRPC server TLS options, see `mysql.tls` section.
[grpc.tls]
## TLS mode.
mode = "disable"

## Certificate file path.
## @toml2docs:none-default
cert_path = ""

## Private key file path.
## @toml2docs:none-default
key_path = ""

## Watch for Certificate and key file change and auto reload.
## For now, gRPC tls config does not support auto reload.
watch = false

## MySQL server options.

Wei

08/21/2025, 10:04 PM

above is the snippet from frontend

👀 1

discord9

08/22/2025, 4:16 AM

https://docs.greptime.com/user-guide/deployments-administration/authentication/static/ might be that frontend had a user provide setting but flownode didn't set that setting, maybe consider add same startup args to flownode as well?

Wei

08/22/2025, 3:00 PM

@discord9 thanks, I do have static user configure. But I thought it was only used for postgresql/mysql query, why grpc picks it up? even though it is disabled in config file.

Wei

08/22/2025, 3:51 PM

I tested it, adding static-user to the flow daemon, that fixed the issue, but it is not making sense to me yet.

Wei

08/22/2025, 3:52 PM

@Ruihang I tested the flow, it does produce the output in sink table, however, the result isn't what I am expecting

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CREATE FLOW interface_rate
SINK TO interface_sink
AS
SELECT
  router,
  port,
  (last_value(rx) - first_value(rx)) * 8 / 30 as rx,
  (last_value(tx) - first_value(tx)) * 8 / 30 as tx,
  last_value(discards) - first_value(discards) as discards,
  last_value(crc) - first_value(crc) as crc,
  date_bin(INTERVAL '60 second', ts) as time_window
FROM  interface
group by time_window, router, port;

Wei

08/22/2025, 3:54 PM

apparently, what it does is, it takes two samples in the time_window, calculate the rate and delta. But, it has a gap between 'time_window'. for instance, this is the data I got,

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sdn=> select * from interface;
 router | port |  rx  |  tx  | discards | crc |             ts
--------+------+------+------+----------+-----+----------------------------
 wdc1   | nic1 | 8616 | 3143 |       44 |  46 | 2025-08-22 15:36:00.000000
 wdc1   | nic1 | 2549 | 2214 |       76 |  73 | 2025-08-22 15:36:30.000000
 wdc1   | nic1 | 2716 |  809 |       68 |  18 | 2025-08-22 15:37:00.000000
 wdc1   | nic1 | 3620 | 4180 |       52 |  91 | 2025-08-22 15:37:30.000000
 wdc1   | nic1 |  633 | 8928 |       84 |  87 | 2025-08-22 15:38:01.000000
 wdc1   | nic1 |  155 |  897 |       48 |  59 | 2025-08-22 15:38:31.000000
 wdc1   | nic1 | 9590 | 8811 |       92 |  81 | 2025-08-22 15:39:01.000000
 wdc1   | nic1 | 4165 | 8380 |       43 |  20 | 2025-08-22 15:39:31.000000
 wdc1   | nic1 | 1363 | 2405 |        2 |  89 | 2025-08-22 15:40:01.000000
 wdc1   | nic1 | 1956 | 9963 |       76 |  80 | 2025-08-22 15:40:31.000000
(10 rows)

sdn=>
sdn=> select * from interface_sink;
 router | port |  rx   |  tx   | discards | crc |        time_window         |         update_at
--------+------+-------+-------+----------+-----+----------------------------+----------------------------
 wdc1   | nic1 | -1617 |  -247 |       32 |  27 | 2025-08-22 15:36:00.000000 | 2025-08-22 15:37:04.185000
 wdc1   | nic1 |   241 |   898 |      -16 |  73 | 2025-08-22 15:37:00.000000 | 2025-08-22 15:38:04.209000
 wdc1   | nic1 |  -127 | -2141 |      -36 | -28 | 2025-08-22 15:38:00.000000 | 2025-08-22 15:39:04.236000
 wdc1   | nic1 | -1446 |  -114 |      -49 | -61 | 2025-08-22 15:39:00.000000 | 2025-08-22 15:40:04.258000
 wdc1   | nic1 |   158 |  2015 |       74 |  -9 | 2025-08-22 15:40:00.000000 | 2025-08-22 15:41:04.281000
(5 rows)

sdn=>

Wei

08/22/2025, 3:54 PM

if I use range, it does give almost right output every 30s.

Wei

08/22/2025, 3:54 PM

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sdn=> SELECT
  router,
  port,
  (last_value(rx) range '40s' - first_value(rx) range '40s') * 8 / 30 as rx,
  (last_value(tx) range '40s' - first_value(tx) range '40s') * 8 / 30 as tx,
  (last_value(discards) range '40s' - first_value(discards) range '40s') as discard,
  (last_value(crc) range '40s' - first_value(crc) range '40s') as crc,
  ts as time_window
from interface
align '30s' by (router, port)
order by ts;
 router | port |  rx   |  tx   | discard | crc |        time_window
--------+------+-------+-------+---------+-----+----------------------------
 wdc1   | nic1 |     0 |     0 |       0 |   0 | 2025-08-22 15:35:30.000000
 wdc1   | nic1 | -1617 |  -247 |      32 |  27 | 2025-08-22 15:36:00.000000
 wdc1   | nic1 |    44 |  -374 |      -8 | -55 | 2025-08-22 15:36:30.000000
 wdc1   | nic1 |   241 |   898 |     -16 |  73 | 2025-08-22 15:37:00.000000
 wdc1   | nic1 |  -796 |  1266 |      32 |  -4 | 2025-08-22 15:37:30.000000
 wdc1   | nic1 |  -127 | -2141 |     -36 | -28 | 2025-08-22 15:38:00.000000
 wdc1   | nic1 |  2516 |  2110 |      44 |  22 | 2025-08-22 15:38:30.000000
 wdc1   | nic1 | -1446 |  -114 |     -49 | -61 | 2025-08-22 15:39:00.000000
 wdc1   | nic1 |  -747 | -1593 |     -41 |  69 | 2025-08-22 15:39:30.000000
 wdc1   | nic1 |   158 |  2015 |      74 |  -9 | 2025-08-22 15:40:00.000000
 wdc1   | nic1 |     0 |     0 |       0 |   0 | 2025-08-22 15:40:30.000000
(11 rows)

sdn=>

Wei

08/22/2025, 3:59 PM

almost, why the first, last line give value 0? I think it should start 30s after the 1st data, not before. the last output should stop at the last record of source, not after.

Ruihang

08/22/2025, 6:30 PM

it does. the first and last record fits into the first and last window, but only one data in that window, so it’s zero

Ruihang

08/22/2025, 6:31 PM

time_window

is the start timestamp of 30s window

Ruihang

08/22/2025, 7:38 PM

https://docs.greptime.com/reference/sql/range/#syntax

Ruihang

08/22/2025, 8:06 PM

Copy code

select ts::bigint from interface;

Ruihang

08/22/2025, 8:09 PM

Copy code

tql eval (1755876960, 1755877231, '30s') rate(interface[40s]);

Ruihang

08/22/2025, 8:10 PM

Copy code

tql eval (1755876960, 1755877231, '30s') rate(interface[40s]) by (router, port)

Ruihang

08/22/2025, 8:11 PM

https://us05web.zoom.us/j/84745389829?pwd=tkjEuipqJhmZo1Z4b1R4wbbruhJDpt.1

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