Function CopyToDirectoryTable

src/backend/commands/copyto.c:2061–2191

* Copy directory table To QD. */

 * Copy directory table To QD.
 */
static uint64
CopyToDirectoryTable(CopyToState cstate)
{
	uint64		processed = 0;
	TupleTableSlot *slot;
	TableScanDesc scandesc;
	ScanKeyData skey;
	Datum		datum;
	bool		isnull;
	char	   *relative_path;
	char	   *scopedFileUrl;
	DirectoryTable	*dirTable;
	UFile	   *file;
	int64_t		file_size;
	pg_cryptohash_ctx	*hashCtx;
	char		hexMd5Sum[256];
	uint8 md5Sum[MD5_DIGEST_LENGTH];
	char	   *md5;

	Assert(cstate->rel);

	dirTable = GetDirectoryTable(RelationGetRelid(cstate->rel));

	/* We use fe_msgbuf as a per-row buffer regardless of copy_dest */
	cstate->fe_msgbuf = makeStringInfo();

	/*
	 * Create a temporary memory context that we can reset once per row to
	 * recover palloc'd memory.  This avoids any problems with leaks inside
	 * datatype output routines, and should be faster than retail pfree's
	 * anyway.  (We don't need a whole econtext as CopyFrom does.)
	 */
	cstate->rowcontext = AllocSetContextCreate(CurrentMemoryContext,
											   "COPY TO",
											   ALLOCSET_DEFAULT_SIZES);

	ScanKeyInit(&skey,
				(AttrNumber) 1,
				BTEqualStrategyNumber, F_TEXTEQ,
				CStringGetTextDatum(cstate->dirfilename));
	scandesc = table_beginscan(cstate->rel, GetActiveSnapshot(), 1, &skey);
	slot = table_slot_create(cstate->rel, NULL);

	processed = 0;
	if (table_scan_getnextslot(scandesc, ForwardScanDirection, slot))
	{
		char 	buffer[4096];
		char	errorMessage[256];
		int		bytesRead;

		/* Deconstruct the tuple ... */
		slot_getallattrs(slot);

		datum = slot_getattr(slot, 1, &isnull);
		Assert(isnull == false);
		relative_path = TextDatumGetCString(datum);
		scopedFileUrl = psprintf("%s/%s", dirTable->location, relative_path);