Function BuildBsonUpdateMetadata

pg_documentdb/src/update/bson_update.c:594–667

* Builds and sets metadata pertaining to the update based on the updateSpec and querySpec * into the metadata value provided. */

 * into the metadata value provided.
 */
static void
BuildBsonUpdateMetadata(BsonUpdateMetadata *metadata, const bson_value_t *updateSpec,
						const bson_value_t *querySpec, const bson_value_t *arrayFilters,
						const bson_value_t *variableSpec, bool buildSourceDocOnUpsert)
{
	metadata->updateType = DetermineUpdateType(updateSpec);

	/* BuildBsonDocumentFromQuery only gets called for upsert */
	if (buildSourceDocOnUpsert)
	{
		pgbson *emptyDoc = PgbsonInitEmpty();
		metadata->sourceDocOnUpsert = BuildBsonDocumentFromQuery(emptyDoc, querySpec,
																 metadata->updateType);
	}

	/* Build and cache any state pertaining to the update type */
	switch (metadata->updateType)
	{
		case UpdateType_AggregationPipeline:
		{
			if (arrayFilters != NULL)
			{
				if (!IsBsonValueEmptyArray(arrayFilters))
				{
					ereport(ERROR, (errcode(ERRCODE_DOCUMENTDB_BADVALUE),
									errmsg(
										"Specifying arrayFilters is not allowed when performing pipeline-style updates")));
				}
			}

			bool isReplaceStagePresent = false;
			metadata->aggregationState = GetAggregationPipelineUpdateState(updateSpec,
																		   variableSpec,
																		   &
																		   isReplaceStagePresent);

			/*
			 * We materialize the documents after each stage so for update descriptions
			 * consider pipeline updates as replacements.
			 *
			 * TODO: Need to revisit this and see the feasibility of building more granular update descriptions.
			 */
			metadata->commandUpdateType = CommandUpdateType_Replacement;
			break;
		}

		case UpdateType_Operator:
		{
			metadata->operatorState = GetOperatorUpdateState(updateSpec, querySpec,
															 arrayFilters,
															 buildSourceDocOnUpsert);
			metadata->commandUpdateType = CommandUpdateType_Update;
			break;
		}

		case UpdateType_ReplaceDocument:
		{
			/* Simply validate the replace doc */