PostgreSQL's cost model — how the planner estimates query cost to pick among candidate plans. Covers src/backend/optimizer/path/costsize.c (the cost functions: costseqscan, costindex, costbitmapheapscan, costnestloop, costmergejoin, costhashjoin, costsort, costhashagg, costwindowagg, etc.) plus the cost GUCs (seqpagecost, randompagecost, cputuplecost, cpuindextuplecost, cpuoperatorcost, parallelsetupcost, paralleltuplecost, jitcost). Loads when the user asks about cost estimation, why a plan differs from expected, how to tune cost GUCs, what units the numbers are in, or when to touch a specific cost function. Skip when the ask is about selectivity estimation (that's clauselistselectivity and extended-stats territory) or about the actual EXPLAIN output rendering.
Install with
Claude CodeCodexCursorGitHub CopilotGemini CLI
Supported by the Atlas install prompt. Skill-specific requirements vary.
Skill stats
Skills1CategoryEngineeringStars0
About this skill
PostgreSQL's cost model — how the planner estimates query cost to pick among candidate plans. Covers src/backend/optimizer/path/costsize.c (the cost functions: costseqscan, costindex, costbitmapheapscan, costnestloop, costmergejoin, costhashjoin, costsort, costhashagg, costwindowagg, etc.) plus the cost GUCs (seqpagecost, randompagecost, cputuplecost, cpuindextuplecost, cpuoperatorcost, parallelsetupcost, paralleltuplecost, jitcost). Loads when the user asks about cost estimation, why a plan differs from expected, how to tune cost GUCs, what units the numbers are in, or when to touch a specific cost function. Skip when the ask is about selectivity estimation (that's clauselistselectivity and extended-stats territory) or about the actual EXPLAIN output rendering.
Quick start
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PostgreSQL's cost model — how the planner estimates query cost to pick among candidate plans. Covers `src/backend/optimizer/path/costsize.c` (the cost functions: `cost_seqscan`, `cost_index`, `cost_bitmap_heap_scan`, `cost_nestloop`, `cost_mergejoin`, `cost_hashjoin`, `cost_sort`, `cost_hashagg`, `cost_windowagg`, etc.) plus the cost GUCs (`seq_page_cost`, `random_page_cost`, `cpu_tuple_cost`, `cpu_index_tuple_cost`, `cpu_operator_cost`, `parallel_setup_cost`, `parallel_tuple_cost`, `jit_*_cost`). Loads when the user asks about cost estimation, why a plan differs from expected, how to tune cost GUCs, what units the numbers are in, or when to touch a specific `cost_*` function. Skip when the ask is about selectivity estimation (that's `clauselist_selectivity` and extended-stats territory) or about the actual EXPLAIN output rendering.
About this listing
Category
Engineering
Reported license
PostgreSQL
Listing language (estimated)
English
Review status
Not individually reviewed
Agent compatibility
Atlas installation supports Claude Code, Codex, and Cursor. Skill-specific dependencies and features are checked during setup.
Claude Code
Codex
Cursor
GitHub Copilot
Gemini CLI