Function ProcessDeletion

pg_documentdb/src/commands/delete.c:707–809

* ProcessDeletion processes a single deletion operation defined in * deletionSpec on the given collection. */

 * deletionSpec on the given collection.
 */
static uint64
ProcessDeletion(MongoCollection *collection, DeletionSpec *deletionSpec,
				bool forceInlineWrites, text *transactionId)
{
	if (deletionSpec->deleteOneParams.returnDeletedDocument)
	{
		ereport(ERROR, (errmsg("cannot return deleted document via "
							   "regular delete")));
	}

	pgbson *query = PgbsonInitFromDocumentBsonValue(deletionSpec->deleteOneParams.query);

	/* determine whether query filters by a single shard key value */
	int64 shardKeyHash = 0;

	/* if the collection is sharded, check whether we can use a single hash value */
	bool isShardKeyValueCollationAware = false;
	bool hasShardKeyValueFilter =
		ComputeShardKeyHashForQuery(collection->shardKey, collection->collectionId, query,
									&shardKeyHash, &isShardKeyValueCollationAware);

	/* determine whether query filters by a single object ID */
	bson_iter_t queryDocIter;
	PgbsonInitIterator(query, &queryDocIter);

	uint64_t result = 0;
	const char *collationString = deletionSpec->deleteOneParams.collationString;
	bool applyCollationToShardKeyValue = IsCollationApplicable(collationString) &&
										 isShardKeyValueCollationAware;
	if (deletionSpec->limit == 0)
	{
		if (applyCollationToShardKeyValue)
		{
			/* if shard key value is collation sensitive, we distribute the query */
			/* by omitting the shard key value filter */
			hasShardKeyValueFilter = false;
		}

		/*
		 * Delete as many document as match the query. This is not a retryable
		 * operation, so we ignore transactionId.
		 */
		result = DeleteAllMatchingDocuments(collection, query,
											deletionSpec->deleteOneParams.variableSpec,
											collationString, hasShardKeyValueFilter,
											shardKeyHash);
		pfree(query);
		return result;
	}

	bson_value_t idFromQueryDocument = { 0 };
	bool errorOnConflict = false;
	bool queryHasNonIdFilters = false;
	bool isIdFilterCollationAware = false;
	bool hasObjectIdFilter =
		TraverseQueryDocumentAndGetId(&queryDocIter, &idFromQueryDocument,
									  errorOnConflict, &queryHasNonIdFilters,
									  &isIdFilterCollationAware);