PlannerAny session (SET)default 1
seq_page_cost
Sets the planner's estimate of the cost of a sequentially fetched disk page.
How you change it
Any session (SET)
Defaults and ranges on this page were read from pg_settings on live PostgreSQL 18.4. Treat older majors as needing their own check before you copy a value.
What this means
The planner's baseline cost for reading one page sequentially; every other cost constant is expressed relative to it. It is rarely changed directly -- most tuning adjusts random_page_cost relative to this 1.0 anchor.
When it matters
Usually leave at 1.0 and tune random_page_cost instead.
| Default | 1 |
|---|---|
| Range | 0 – 1.79769e+308 |
| Type | real |
| Change scope | Any session (SET) |
| Category | Planner |
Check the current value
SHOW seq_page_cost;Tradeoffs
- • Changing it rescales the whole cost model, which is seldom what you want.
- • If data is almost always cached, some shops lower both page costs together to reflect memory speed.
- • Prefer per-tablespace cost settings over global edits when storage tiers differ.