Skills Matrix

Junior → staff database engineer competencies for PostgreSQL 18.4 teams - observable skills with evidence examples for leveling and hiring.

Recipe

Rating scale (use in quarterly review)
  0 - No exposure
  1 - Learning (buddy required)
  2 - Independent (routine tasks)
  3 - Mentor others (defines team standards)

When to use:

Performance review calibration
On-call rotation eligibility
Hiring scorecard for database platform roles

Working Example

Core Matrix (excerpt)

Competency	Junior (L3)	Mid (L4)	Senior (L5)	Staff (L6)
psql / SQL	`\d`, joins, LIMIT	CTEs, window functions	pg_catalog debugging	Defines SQL style guide
EXPLAIN	Attach to PR	Review others' plans	Teaches index-only paths	Fleet plan regression policy
Migrations	Author with review	Secondary reviewer	Zero-downtime patterns	Expand-contract ADRs
MVCC / vacuum	Concepts	`n_dead_tup` triage	autovacuum tuning	Fleet bloat governance
Locks	Recognize blockers	`pg_locks` queries	Terminate policy owner	Migration lock SLO
Replication	Know primary/replica	Monitor lag	Slot emergency	Logical vs physical ADR
HA / failover	Read runbook	Drill scribe	Lead staging drill	RTO/RPO accountability
Backup / PITR	Know RPO	`pgbackrest check`	Lead restore drill	DR architecture
Linux CLI	bundle script run	iostat interpretation	Incident commander	Runbook standards
Security / RLS	least privilege	RLS policy review	BYPASSRLS audit	Compliance sign-off

Evidence Examples

Junior EXPLAIN (rating 2 evidence):
  - 5 PRs with EXPLAIN (ANALYZE, BUFFERS) merged without rework in Q2
 
Mid migration review (rating 2 evidence):
  - Secondary reviewer on 8 PRs; caught CONCURRENTLY miss twice
 
Senior failover (rating 3 evidence):
  - Led staging Patroni switchover; RTO 42s documented; trained two mids

Deep Dive

On-Call Eligibility

Level	On-call
Junior	Not primary; shadow only
Mid	Secondary with senior backup
Senior	Primary rotation
Staff	Escalation + cross-region incidents

Hiring Scorecard Mapping

Candidate must demonstrate rating 2+ on:
  - EXPLAIN interpretation live exercise
  - Migration lock risk verbal walkthrough
  - One Linux triage scenario (disk or locks)
Staff candidates add:
  - HA failure scenario design discussion
  - Major upgrade strategy whiteboard

Gap Closure Plans

Gap	30-day action
Weak EXPLAIN	Pair on 4 query PRs using EXPLAIN Review Skill
No Linux CLI	Run two staging simulated incidents with bundle script
No PITR drill	Attend restore drill; restore sandbox table yourself

Gotchas

Self-assessed "expert" without evidence - matrix becomes political. Fix: require links to PRs, drills, post-mortems.
Single dimension leveling - great at queries, unsafe at migrations. Fix: minimum rating across safety rows for on-call.
Ignoring product knowledge - staff engineer without domain context cannot prioritize index work. Fix: embed in squad.
Static matrix years - PG 18 adds features; update yearly. Fix: link to PostgreSQL Roadmap Tracking.

Alternatives

Alternative	Use When	Don't Use When
External certification only	Quick phone screen filter	Internal leveling
Manager gut feel	Tiny team 2-3 people	Growing platform org
Vendor training badges	Supplement evidence	Replace observable work

FAQs

App dev on matrix?

Use same matrix with adjusted on-call row - many app devs target mid on EXPLAIN, junior on HA, per App Dev → DBA Path.

How many staff DBAs needed?

Staff engineer often covers 3-5 senior worth of governance; not a 1:1 headcount formula. Matrix shows depth gaps before hiring.

Matrix for managed RDS only?

Drop Patroni row depth; add RDS snapshot/parameter group fluency. Keep EXPLAIN and migration rows identical.

Onboarding Basics - day one skills
App Dev → DBA Path - progression phases
Team & Onboarding Best Practices - team policy
Query Review Standards - review bar
Career Growth DBA → Staff - staff expectations

Stack versions: This page was written for PostgreSQL 18.4 platform teams on Flyway, Patroni/RDS, and pgBackRest.

Skills Matrix

Junior → staff database engineer competencies for PostgreSQL 18.4 teams - observable skills with evidence examples for leveling and hiring.

Recipe

Rating scale (use in quarterly review)
  0 - No exposure
  1 - Learning (buddy required)
  2 - Independent (routine tasks)
  3 - Mentor others (defines team standards)

When to use:

Performance review calibration
On-call rotation eligibility
Hiring scorecard for database platform roles

Working Example

Core Matrix (excerpt)

Competency	Junior (L3)	Mid (L4)	Senior (L5)	Staff (L6)
psql / SQL	`\d`, joins, LIMIT	CTEs, window functions	pg_catalog debugging	Defines SQL style guide
EXPLAIN	Attach to PR	Review others' plans	Teaches index-only paths	Fleet plan regression policy
Migrations	Author with review	Secondary reviewer	Zero-downtime patterns	Expand-contract ADRs
MVCC / vacuum	Concepts	`n_dead_tup` triage	autovacuum tuning	Fleet bloat governance
Locks	Recognize blockers	`pg_locks` queries	Terminate policy owner	Migration lock SLO
Replication	Know primary/replica	Monitor lag	Slot emergency	Logical vs physical ADR
HA / failover	Read runbook	Drill scribe	Lead staging drill	RTO/RPO accountability
Backup / PITR	Know RPO	`pgbackrest check`	Lead restore drill	DR architecture
Linux CLI	bundle script run	iostat interpretation	Incident commander	Runbook standards
Security / RLS	least privilege	RLS policy review	BYPASSRLS audit	Compliance sign-off

Evidence Examples

Junior EXPLAIN (rating 2 evidence):
  - 5 PRs with EXPLAIN (ANALYZE, BUFFERS) merged without rework in Q2
 
Mid migration review (rating 2 evidence):
  - Secondary reviewer on 8 PRs; caught CONCURRENTLY miss twice
 
Senior failover (rating 3 evidence):
  - Led staging Patroni switchover; RTO 42s documented; trained two mids

Deep Dive

On-Call Eligibility

Level	On-call
Junior	Not primary; shadow only
Mid	Secondary with senior backup
Senior	Primary rotation
Staff	Escalation + cross-region incidents

Hiring Scorecard Mapping

Candidate must demonstrate rating 2+ on:
  - EXPLAIN interpretation live exercise
  - Migration lock risk verbal walkthrough
  - One Linux triage scenario (disk or locks)
Staff candidates add:
  - HA failure scenario design discussion
  - Major upgrade strategy whiteboard

Gap Closure Plans

Gap	30-day action
Weak EXPLAIN	Pair on 4 query PRs using EXPLAIN Review Skill
No Linux CLI	Run two staging simulated incidents with bundle script
No PITR drill	Attend restore drill; restore sandbox table yourself

Gotchas

Self-assessed "expert" without evidence - matrix becomes political. Fix: require links to PRs, drills, post-mortems.
Single dimension leveling - great at queries, unsafe at migrations. Fix: minimum rating across safety rows for on-call.
Ignoring product knowledge - staff engineer without domain context cannot prioritize index work. Fix: embed in squad.
Static matrix years - PG 18 adds features; update yearly. Fix: link to PostgreSQL Roadmap Tracking.

Alternatives

Alternative	Use When	Don't Use When
External certification only	Quick phone screen filter	Internal leveling
Manager gut feel	Tiny team 2-3 people	Growing platform org
Vendor training badges	Supplement evidence	Replace observable work

FAQs

App dev on matrix?

Use same matrix with adjusted on-call row - many app devs target mid on EXPLAIN, junior on HA, per App Dev → DBA Path.

How many staff DBAs needed?

Staff engineer often covers 3-5 senior worth of governance; not a 1:1 headcount formula. Matrix shows depth gaps before hiring.

Matrix for managed RDS only?

Drop Patroni row depth; add RDS snapshot/parameter group fluency. Keep EXPLAIN and migration rows identical.

Onboarding Basics - day one skills
App Dev → DBA Path - progression phases
Team & Onboarding Best Practices - team policy
Query Review Standards - review bar
Career Growth DBA → Staff - staff expectations

Stack versions: This page was written for PostgreSQL 18.4 platform teams on Flyway, Patroni/RDS, and pgBackRest.

Skills Matrix

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Skills Matrix