Function UpdateDocumentByTID

pg_documentdb/src/commands/update.c:3705–3762

* UpdateDocumentByTID performs a TID update on a single shard. * * The TID must be obtained via SelectUpdateCandidate in the current transaction. */

 * The TID must be obtained via SelectUpdateCandidate in the current transaction.
 */
static bool
UpdateDocumentByTID(uint64 collectionId, const char *shardTableName,
					int64 shardKeyHash, ItemPointer tid,
					pgbson *updatedDocument)
{
	StringInfoData updateQuery;
	int argCount = 3;
	Oid argTypes[3];
	Datum argValues[3];

	/* whitespace means not null, n means null */
	char argNulls[3] = { ' ', ' ', ' ' };

	SPI_connect();

	initStringInfo(&updateQuery);

	appendStringInfo(&updateQuery, "UPDATE ");

	if (shardTableName != NULL && shardTableName[0] != '\0')
	{
		appendStringInfo(&updateQuery, "%s.%s", ApiDataSchemaName, shardTableName);
	}
	else
	{
		appendStringInfo(&updateQuery, "%s.documents_" UINT64_FORMAT,
						 ApiDataSchemaName, collectionId);
	}

	appendStringInfo(&updateQuery,
					 " SET document = $3::%s"
					 " WHERE ctid = $2 AND shard_key_value = $1",
					 FullBsonTypeName);

	argTypes[0] = INT8OID;
	argValues[0] = Int64GetDatum(shardKeyHash);

	argTypes[1] = TIDOID;
	argValues[1] = ItemPointerGetDatum(tid);

	/* we use bytea because bson may not have the same OID on all nodes */
	argTypes[2] = BYTEAOID;
	argValues[2] = PointerGetDatum(CastPgbsonToBytea(updatedDocument));

	bool readOnly = false;
	long maxTupleCount = 0;

	SPIPlanPtr plan = GetSPIQueryPlanWithLocalShard(collectionId, shardTableName,
													QUERY_ID_UPDATE_BY_TID,
													updateQuery.data, argTypes, argCount);

	SPI_execute_plan(plan, argValues, argNulls, readOnly, maxTupleCount);
	Assert(SPI_processed == 1);

	SPI_finish();

	return true;
}