copy-familylisted

# copy-family — the COPY command internals The COPY family under `src/backend/commands/copy*.c` implements SQL-level bulk import/export. It's one of PostgreSQL's oldest performance-critical utility statements, sits at a peculiar layer (utility statement with executor-like semantics), and is the machinery logical replication reuses for initial table sync. Getting the file split right matters — patches often touch the wrong one. ## The 4-file split | File | Lines | Role | |---|---:|---| | `copy.c` | 1,142 | Option parsing + dispatch — `DoCopy` entry from `ProcessUtility`, `WITH (...)` extraction, permission checks, relation open with the right lock, then hands off. | | `copyto.c` | ~1,300 | COPY TO — the output side. Reads tuples from the source (table or query), serializes to text / CSV / binary, writes to file / program / client. | | `copyfrom.c` | 1,996 | COPY FROM — the input side. Reads parsed rows (from `copyfromparse.c`), routes partitions, fires triggers, inserts through table AM, updates indexes. | | `copyfromparse.c` | 2,000+ | Format-parsing layer for COPY FROM — text / CSV / binary tokenizers, escape handling, encoding conversion. Turns bytes into Datums. | The split is deliberate: `copy.c` is the "which direction and with what options" arbiter; `copyto.c` and `copyfrom.c` are the direction-specific engines; `copyfromparse.c` is FROM-only because the TO side doesn't parse (it serializes). ## Entry points - **`DoCopy` (copy.c:63)** — called by `standard_Process