Function bson_densify_full

pg_documentdb/src/aggregation/bson_densify.c:368–461

bson_densify_full * Fills the documents for a range that is minimum and maximum across * all the partitions. * * document => The document that needs to be densified * densifySpec => $densify spec of this form: * { * 'partitionByFields': [ ], * field: , * range: { * bounds: "full", * steps: , *

 * The documents are processed in an ORDER BY for the `field` value
 */
Datum
bson_densify_full(PG_FUNCTION_ARGS)
{
	WindowObject winObject = PG_WINDOW_OBJECT();

	bool isNull = false;
	pgbson *document = DatumGetPgBson(WinGetFuncArgCurrent(winObject, 0, &isNull));
	pgbson *spec = DatumGetPgBson(WinGetFuncArgCurrent(winObject, 1, &isNull));

	DensifyWindowState *densifyState = NULL;
	int argPosition = 1;
	SetCachedFunctionState(
		densifyState,
		DensifyWindowState,
		argPosition,
		InitializeDensifyWindowState,
		spec,
		DENSIFY_TYPE_FULL);

	if (densifyState == NULL)
	{
		densifyState = palloc0(sizeof(DensifyWindowState));
		InitializeDensifyWindowState(densifyState, spec, DENSIFY_TYPE_FULL);
	}

	PartitionAwareState *partitionState = GetValidPartitionAwareState(densifyState,
																	  document);

	/* Find the group entry in hash, if this a new group create the entry for this group */
	HTAB *partitionGroupTable = partitionState->partitionInfo;
	bool found;
	DensifyFullEntry searchPartitionKey = { 0 };
	bool moveToExecutorContext = false;
	searchPartitionKey.evaluatedPartitionBy = GetPartitionByFieldsPgbson(document,
																		 densifyState,
																		 moveToExecutorContext);
	DensifyFullEntry *foundEntry = hash_search(partitionGroupTable, &searchPartitionKey,
											   HASH_ENTER, &found);
	if (!found)
	{
		/* When a new group is seen, copy the group by value in executor context so that
		 * it doesn't vanish in the hash table, and set the lastMinValueInGroup to the first
		 * row's value so that densification starts from global minimum value
		 */
		if (searchPartitionKey.evaluatedPartitionBy != NULL)
		{
			foundEntry->evaluatedPartitionBy =
				CopyPgbsonIntoMemoryContext(searchPartitionKey.evaluatedPartitionBy,
											densifyState->executorContext);
		}

		/*
		 * Note: arguments.lowerBound is not available in case of `full` but we use it to store
		 * the minimum value which is the first row's value and because there is no default partitioning done
		 * for `full` it is also the minimum across all partitions that we will create inside this function
		 * using hash
		 */
		foundEntry->lastMinValueInGroup = densifyState->arguments.lowerBound;