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Core API

This module available in Core API

• clickhouse
• prometheus
• postgres
• mysql
• loki

A datasource module allows get data from different sources

Usage:

script.lua

local ds1 = require('datasource.<TYPE>.<NAME>)

• type - datasource type
  • clickhouse
  • prometheus
  • postgres
  • etc...
• name - datasource name from configuration

Examples:

config.yaml

datasources:
  clickhouse:
    - name: dev
      ...
    - name: prod
      ...
  postgres:
    - name: dev
      ...
    - name: prod
      ...
  prometheus:
    - name: prom1

Usage modules in a script:

local chDev = require('datasource.clickhouse.dev')
local chProd = require('datasource.clickhouse.prod')
local pgDev = require('datasource.postgres.dev')
local pgProd = require('datasource.postgres.prod')
local prom1 = require('datasource.prometheus.prom1')

Null fields (Clickhouse, Postgres, MySQL)

If your query returns a data with null values, you not may get these fields by iteration loop.

The behavior is the same as 'nil' value in the Lua table

An example:

The 'token' field may return a string or null. In this example, if returns null, this string will not be printed

script.lua

res = pg.query('SELECT name, token FROM users')


for _, row in pairs(res) do
    for columnName, columnValue in pairs(row) do
        print(columnName .. ' = ' .. columnValue)
    end
end

You can straight check value to nil

script.lua

res = pg.query('SELECT name, token FROM users')

for _, row in pairs(res) do
    print(row.name)
    print(row.token) -- row.token equals to nil
end