Function DeleteOneObjectId

pg_documentdb/src/commands/delete.c:1742–1793

* DeleteOneObjectId handles the case where we are deleting a single document * by _id from a collection that is sharded on some other key. In this case, * we need to look across all shards for a matching _id, then delete only that * one. * * Citus does not support SELECT .. FOR UPDATE, and it is very difficult to * support efficiently without running into frequent deadlocks. Therefore, * we

 * be deleted or updated concurrently. In that case, we try again.
 */
static void
DeleteOneObjectId(MongoCollection *collection, DeleteOneParams *deleteOneParams,
				  bson_value_t *objectId, bool isIdValueCollationAware, bool
				  queryHasNonIdFilters,
				  bool forceInlineWrites, text *transactionId, DeleteOneResult *result)
{
	const int maxTries = 5;

	if (transactionId != NULL)
	{
		RetryableWriteResult writeResult;

		/*
		 * Try to find a retryable write record for the transaction ID in any shard.
		 */
		if (FindRetryRecordInAnyShard(collection->collectionId, transactionId,
									  &writeResult))
		{
			/* found a record, return the previous result */
			result->isRowDeleted = writeResult.rowsAffected > 0;
			return;
		}
	}

	for (int tryNumber = 0; tryNumber < maxTries; tryNumber++)
	{
		int64 shardKeyValue = 0;

		if (!FindShardKeyValueForDocumentId(collection, deleteOneParams->query, objectId,
											isIdValueCollationAware, queryHasNonIdFilters,
											&shardKeyValue,
											deleteOneParams->variableSpec,
											deleteOneParams->collationString))
		{
			/* no document matches both the query and the object ID */
			return;
		}

		CallDeleteOne(collection, deleteOneParams, shardKeyValue, transactionId,
					  forceInlineWrites, result);

		if (result->isRowDeleted)
		{
			/* Document has been successfully removed */
			return;
		}
	}

	ereport(ERROR, (errcode(ERRCODE_INTERNAL_ERROR),
					errmsg("Unable to remove document even after %d attempts",
						   maxTries)));
}


/*