[ENHANCEMENT] Clickhouse: support label and time access in table view

[fraser-qs]

Description

Extend Clickhouse time series plugin to give feature parity with Prometheus with label mapping and time range search

Screenshots

Checklist

• Pull request has a descriptive title and context useful to a reviewer.
• Pull request title follows the [<catalog_entry>] <commit message> naming convention using one of the
  following catalog_entry values: FEATURE, ENHANCEMENT, BUGFIX, BREAKINGCHANGE, DOC,IGNORE.
• All commits have DCO signoffs.

[shahrokni]

Name convention?
STEP_MS

[shahrokni]

Object.entries(row) creates a new intermediate array of [key, value] pairs for every single row. For a dashboard with 1,000+ points and multiple series, this adds unnecessary memory pressure and garbage collection. Iterate over keys directly to avoid creating extra arrays.

ClickHouse queries often return internal columns (like _part or _sample_factor) or extra metadata that you might not want as labels in your Perses dashboard.

The current code converts everything to a string. While safe, it can be slightly optimized by checking if the value is already a string before calling String(value)

function buildLabels(row: Record<string, unknown>, timestampCol: string, valueCol: string): Labels {
  const labels: Labels = {};
  

  const keys = Object.keys(row);
  
  for (let i = 0; i < keys.length; i++) {
    const key = keys[i];
    

    if (key === timestampCol || key === valueCol || key.startsWith('_')) {
      continue;
    }

    const val = row[key];
    

    if (val === null || val === undefined) {
      labels[key] = '';
    } else {
      labels[key] = typeof val === 'string' ? val : String(val);
    }
  }
  
  return labels;
}

[shahrokni]

Each time this function runs, it creates multiple intermediate arrays (Object.entries, .sort, .map) and several temporary strings before producing the final key. If your ClickHouse query returns thousands of rows, this can lead to significant garbage collection (GC) pressure and slower dashboard rendering.

function labelsToKey(labels: Labels): string {
  const keys = Object.keys(labels).sort();
  let keyString = '';

  for (let i = 0; i < keys.length; i++) {
    const k = keys[i];
    const v = labels[k];
    
   
    if (i > 0) keyString += ',';
    keyString += k + '=' + v;
  }
  
  return keyString;
}

[shahrokni]

The function does not sort the labels. If ClickHouse returns columns in a different order for different rows, your legend items might look inconsistent.

The entries[0]?.[1] is a bit redundant since the code already checked that length === 1