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tools / sql-explain

SQL Explain

Explain query plans, indexes, joins, scans, sort steps, and likely SQL performance bottlenecks from pasted EXPLAIN output.

P1DevOps / ObservabilityHigh severity
100
debug signal score
4 signals

4 signals detected. Start with sequential scan.

Detected signals

Sequential scan

The database scans many rows instead of using a selective index.

Check WHERE predicates, cardinality, statistics, and candidate indexes.

Nested loop risk

Nested loops can explode with large row counts.

Compare estimated vs actual rows and consider indexes or join strategy changes.

Disk sort or expensive sort

Sorting spilled to disk or required expensive work.

Add indexes for sort keys or increase memory only after confirming query shape.

Slow execution time

Execution time is high enough to investigate.

Collect plan with buffers/analyze and compare with normal runtime.

Highlighted lines
line 1
Seq Scan on users cost=0.00..431.00 rows=21000
Sequential scan
line 2
Nested Loop
Nested loop risk
line 3
Sort Method: external merge Disk: 2048kB
Disk sort or expensive sort
line 4
Execution Time: 5321.44 ms
Slow execution time
Fix checklist
Check WHERE predicates, cardinality, statistics, and candidate indexes.
Compare estimated vs actual rows and consider indexes or join strategy changes.
Add indexes for sort keys or increase memory only after confirming query shape.
Collect plan with buffers/analyze and compare with normal runtime.
Capture the exact SQL and plan with actual rows.
Compare estimated vs actual rows.
Check indexes, statistics, sort, join order, and locks.

DebugTools product

SQL Explain

SQL Explain is a focused DebugTools mini-product for developers. Explain query plans, indexes, joins, scans, sort steps, and likely SQL performance bottlenecks from pasted EXPLAIN output.

Use cases

  • Inspect CI, Kubernetes, trace, SQL, JVM, and production incident signals.
  • Move from noisy output to the next command or measurement to run.
  • Create an investigation note that is easy for teammates to follow.

How it works

  • Paste or load the snippet you want to inspect in SQL Explain.
  • Run the tool in the browser and review the highlighted output.
  • Copy, export, or turn the result into the next debugging step.

Privacy

  • SQL Explain is local-first. The core workflow runs in your browser and does not require sending pasted content to DebugTools servers.

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