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to_clickhouse

Sends events to a ClickHouse table.

to_clickhouse table=string, [host=string, port=int, user=string, password=string,
                             mode=string, primary=field,
                             tls=bool, cacert=string, certfile=string, keyfile=string,
                             skip_peer_verification=bool, skip_host_verification=bool]

Description​

table = string​

The name of the table you want to write to. When giving a plain table name, it will use the default database, otherwise database.table can be specified.

host = string (optional)​

The hostname for the ClickHouse server.

Defaults to "localhost".

port = int (optional)​

The port for the ClickHouse server.

Defaults to 9000 without TLS and 9440 with TLS.

user = string (optional)​

The user to use for authentication.

Defaults to "default".

password = string (optional)​

The password for the given user.

Defaults to "".

mode = string (optional)​

  • "create" if you want to create a table and fail if it already exists
  • "append" to append to an existing table
  • "create_append" to create a table if it does not exist and append to it otherwise.

Defaults to "create_append".

primary = field (optional)​

The primary key to use when creating a table. Required for mode = "create" as well as for mode = "create_append" if the table does not yet exist.

tls = bool (optional)​

Enables TLS.

Defaults to true.

cacert = string (optional)​

Path to the CA certificate used to verify the server's certificate.

Defaults to the Tenzir configuration value tenzir.cacert, which in turn defaults to a common cacert location for the system.

certfile = string (optional)​

Path to the client certificate.

keyfile = string (optional)​

Path to the key for the client certificate.

skip_peer_verification = bool (optional)​

Toggles TLS certificate verification.

Defaults to false.

Path to the key for the client certificate.

Types​

Tenzir uses ClickHouse's clickhouse-cpp client library to communicate with ClickHouse. The below table explains the translation from Tenzir's types to ClickHouse:

TenzirClickHouseComment
boolUInt8
int64Int64
uint64Unt64
doubleFloat64
ipIPv6
subnetTuple(ip IPv6, length UInt8)
timeDateTime64(9)
durationInt64Converted as nanoseconds(duration)
recordTuple(...)Fields in the tuple will be named with the field name
list<T>Array(T)

Tenzir also supports Nullable versions of the above types (or their nested types).

Table Creation​

When a ClickHouse table is created from Tenzir, all columns except the primary will be created as Nullable.

The table will be created from the first event the operator receives.

Examples​

Send CSV file to a local ClickHouse instance, without TLS​

from "my_file.csv"
to_clickhouse table="my_table", tls=false

Create a new table with multiple fields​

from { i: 42, d: 10.0, b: true, l: [42], r:{ s:"string" } }
to_clickhouse table="example", primary=i

This creates the following table:

   ┌─name─┬─type────────────────────┐
1. │ i    │ Int64                   │
2. │ d    │ Nullable(Float64)       │
3. │ b    │ Nullable(UInt8)         │
4. │ l    │ Array(Nullable(Int64))  │
5. │ r    │ Tuple(                 ↴│
   │      │↳    s Nullable(String)) │
   └──────┴─────────────────────────┘