Invalid SQL queries for Apache Druid

[adammruk]

Describe the bug
When using Druid adapter, CubeJS is creating invalid SQL queries, which prevents to use CubeJS with Druid DB.

1. Repetitive error in console:
   When connected to Druid database, in CubeJS backend terminal throws this error every ~30s:

{} 
Error: org.apache.calcite.runtime.CalciteContextException: From line 1, column 34 to line 1, column 38: No match found for function signature NOW()
    at QueryQueue.parseResult (<CubeJS backend path>/node_modules/@cubejs-backend/query-orchestrator/src/orchestrator/QueryQueue.js:100:13)
    at QueryQueue.executeInQueue (<CubeJS backend path>/node_modules/@cubejs-backend/query-orchestrator/src/orchestrator/QueryQueue.js:89:19)
    at runMicrotasks (<anonymous>)
    at processTicksAndRejections (internal/process/task_queues.js:97:5)
    at async Promise.all (index 0)
    at OrchestratorApi.executeQuery (<CubeJS backend path>/node_modules/@cubejs-backend/server-core/src/core/OrchestratorApi.ts:40:20)
    at <CubeJS backend path>/node_modules/@cubejs-backend/server-core/src/core/RefreshScheduler.ts:158:9
    at async Promise.all (index 0)
    at <CubeJS backend path>/node_modules/@cubejs-backend/server-core/src/core/RefreshScheduler.ts:143:7
    at async Promise.all (index 1)

Which actually seems to be correct error, cause in Druid there's no such query like NOW() (for current time, there's CURRENT_TIMESTAMP for example)

2. Another SQL error is with creating some example chart. In playground, after select Measure > Wikipedia Count, following error is visible:

To Reproduce
Steps to reproduce the behavior:

1. Install Apache Druid DB, and load wikipedia example data, as described in https://druid.apache.org/docs/latest/tutorials/index.html
2. Install CubeJS for Druid database: npx cubejs-cli create cubejs -d druid
3. Set .env file:

CUBEJS_DB_URL="http://localhost:8082"
CUBEJS_DB_USER=""
CUBEJS_DB_PASS=""

4. npm install
5. npm run dev
6. Go to the playground (http://localhost:4000/#/schema), and in "Schema" tab generate Schema:
   
7. Go to "Build" tab
8. From "Measures" select "Wikipedia Count"
9. Error with invalid query is visible in Playground, and in terminal every ~30s error with NOW() is visible.

Expected behavior
I should be able to use Druid Database without any errors

Version:
From npm list | grep @cubejs-backend:

├─┬ @cubejs-backend/druid-driver@0.26.16
│ ├─┬ @cubejs-backend/query-orchestrator@0.26.16
│ │ ├── @cubejs-backend/shared@0.26.16 deduped
│ ├─┬ @cubejs-backend/schema-compiler@0.26.16
│ ├─┬ @cubejs-backend/shared@0.26.16
└─┬ @cubejs-backend/server@0.26.16
  ├── @cubejs-backend/dotenv@9.0.2
  ├─┬ @cubejs-backend/server-core@0.26.16
  │ ├─┬ @cubejs-backend/api-gateway@0.26.16
  │ │ ├── @cubejs-backend/shared@0.26.16 deduped
  │ ├── @cubejs-backend/query-orchestrator@0.26.16 deduped
  │ ├── @cubejs-backend/schema-compiler@0.26.16 deduped
  │ ├── @cubejs-backend/shared@0.26.16 deduped
  ├── @cubejs-backend/shared@0.26.16 deduped

Additional context
OS: macOS Big Sur 11.2.1

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[ovr]

Hello @adammruk,

Thank you for submitting an issue. Good catch, I can approve that Apache Druid doesn't support NOW(), I suggest you prepare a PR, it's pretty simple.

You should override nowTimestampSql inside DruidQuery:

https://github.com/cube-js/cube.js/blob/master/packages/cubejs-druid-driver/src/DruidQuery.ts#L14

  public nowTimestampSql(): string {
    return `CURRENT_TIMESTAMP`;
  }

Thanks

[ovr]

Thank you @adammruk , Released in v0.26.19