query planner
Choose an executable access path and join strategy for a query.
Use this when A database picks a surprising scan or join even though an index exists.
without the term
“Why did the database choose this scan and join strategy when an index exists? Check its estimates.”
with the term · How do you ask a model for query planner?
Investigate the query planner’s choice. Compare estimates with actual rows and verify statistics before forcing an index.
What is query planner?
The query planner turns a query into an execution plan using available access paths, statistics, and optimization rules. The query plan is the chosen output; the planner is the component making the choice.
Why does query planner matter when vibe coding?
An agent can force an index before checking estimates, query shape, or parameter behavior.
How do you do query planner?
Compare estimated and actual row counts and inspect scans and joins. Refresh appropriate statistics before forcing a strategy. Use a safe environment for EXPLAIN ANALYZE, which executes the query.
What goes wrong with query planner?
A plan for one parameter or tiny fixture may not represent production. Planner costs are not elapsed milliseconds.
Sources for this entry
- PostgreSQL: Using EXPLAIN
Planner estimates, cost units, actual execution statistics, and the fact that ANALYZE executes the statement.
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