executor-and-plannerlisted

Edit the PostgreSQL executor or planner — covers src/backend/executor/ (nodeXxx.c, ExecInitNode/ExecProcNode/ExecEndNode/ExecReScan dispatch, PlanState lifecycle, EXPLAIN wiring) and src/backend/optimizer/ (Path → Plan via createplan.c, RelOptInfo lifecycle, add_path cost-dominance pruning, cost_* units in cost.h). Use whenever a PG patch adds or modifies a plan-node executor, introduces a new Path or Plan type, changes cost-model fields in cost.h, adds EXPLAIN output for a node, plumbs a node into execParallel.c, or tweaks join-path enumeration. Skip for end-user query tuning, EXPLAIN ANALYZE of a production query, work_mem / shared_buffers tuning, MySQL / MongoDB / BigQuery / Snowflake / DuckDB / Spark / Trino query engines, ORM query-builder optimization, and pandas / polars dataframe operations.
matejformanek/postgres-claude · ★ 0 · API & Backend · score 70

Install: claude install-skill matejformanek/postgres-claude

# Executor & Planner — operational Companion docs: `knowledge/architecture/executor.md`, `knowledge/architecture/planner.md`, `knowledge/architecture/query-lifecycle.md`. The executor and planner are coupled by the Path-then-Plan handoff and by the 1:1 correspondence between plan-node types and executor node types. If you add a new way to execute something, you almost always touch both subsystems. --- ## Part A — Adding a new executor node A node type has **four** trees to keep in sync: `Plan` (plannodes.h), `PlanState` (execnodes.h), the Path that builds it (pathnodes.h, optional if your node is only emitted by a special-case planner path), and the dispatch switches in `execProcnode.c`. Skipping any one of these compiles cleanly and fails at run time with `unrecognized node type`. ### A.1 The five-or-six functions to implement For a new node `Foo`, in `src/backend/executor/nodeFoo.c` plus header `src/include/executor/nodeFoo.h` (see `parser-and-nodes` skill for the NodeTag / copy / equal / out / read machinery you'll need before any of this compiles — also recapped in A.6): | Function | Purpose | Pattern | |----------|---------|---------| | `ExecInitFoo(Foo *node, EState *estate, int eflags)` | Build `FooState`, recursively init children, allocate ExprContext, init quals/projection, set `ExecProcNode`. | See `ExecInitSeqScan` (`nodeSeqscan.c:220`). | | `ExecFoo(PlanState *pstate)` | The pull-iterator. Return next `TupleTableSlot *`, or empty slot when exhausted. Stat