Query Execution

DataStoria provides a powerful query execution system that allows you to run ClickHouse queries, view results in various formats. This guide covers everything you need to know about executing queries and managing results.

Overview

The query execution system provides:

• Multiple Execution Methods: Execute full queries or selected portions
• Query Log Inspector: Provides an inspector for query log

Running Queries

Tip: Use the SQL Editor to write queries, and check Query Log Inspector to analyze performance.

Basic Execution

1. Type Your Query: Enter your SQL query in the editor
2. Execute: Press Ctrl + Enter (Windows/Linux) or Command + Enter (Mac)
3. View Results: Results appear in the query results panel below the editor

Executing Selected Text

You can execute only a portion of your query:

1. Select Text: Highlight the portion of the query you want to execute
2. Execute Selection: Press Ctrl + Enter / Command + Enter
3. Results: Only the selected portion is executed

This is useful for:

• Testing individual parts of complex queries
• Debugging specific query sections
• Running queries incrementally

Viewing Results

Result Formats

DataStoria by default uses ClickHouse's PrettyCompactMonoBlock format, but you can use the FORMAT clause in SQL to change the output format as you want.

Table View (Default)

• PrettyCompactMonoBlock: Formatted text table with row numbers
• Best for: Human-readable results, small to medium datasets
• Features:
  • Row numbers
  • Formatted numbers and dates
  • Scrollable table

Vertical Format

Execute queries ending with \G to get vertical format:

SELECT * FROM users WHERE id = 1 \G

• Best for: Wide tables with many columns
• Features: Each row displayed as key-value pairs

JSON Format

• Best for: Programmatic access, API integration
• Features: Structured JSON output

CSV Format

• Best for: Data export, spreadsheet import
• Features: Comma-separated values

Result Display Features

Scrolling and Navigation

• Auto-scroll: Results automatically scroll as new data arrives
• Manual Scroll: Scroll through results manually
• Jump to Top/Bottom: Quick navigation buttons

Query History

Coming soon

Query Management

Cancelling Queries

To cancel a running query:

1. Identify Running Query: Look for queries marked as "Executing"
2. Click Cancel: Use the cancel button on the query
3. Confirmation: Query execution stops immediately

Note: Cancelled queries may still show partial results if data was already received.

Query Timeout

• Default Timeout: Queries have a default timeout period
• Long-running Queries: Very long queries may timeout
• Adjusting Timeout: Configure timeout in connection settings or in the 'App Setting'

Concurrent Queries

• Multiple Queries: You can run multiple queries simultaneously
• Query Queue: Queries are queued and executed in order
• Resource Management: System manages resources efficiently

Performance Metrics

Execution Information

For each query, you can view:

• Execution Time: Total time taken to execute
• Rows Returned: Number of result rows
• Bytes Read: Amount of data read from disk
• Memory Used: Memory consumption during execution
• Query ID: ClickHouse query ID for server-side tracking

Limitations

• Result Size: Very large result sets may impact browser performance
• History Limit: Query history has a maximum size limit
• Concurrent Queries: Too many concurrent queries may slow down the interface
• Export Limits: Very large exports may take significant time

Next Steps

• Query Explain — Understand query execution plans
• Error Diagnostics — Learn how to diagnose and fix errors
• Query Log Inspector — Analyze query performance and history