StoreQueryResult Query::store()
{
executeImpl();
MYSQL_RES * res = mysql_store_result(conn->getDriver());
if (!res)
checkError(conn->getDriver());
return StoreQueryResult(res, conn, this);
}
/*
* ExecuteTaskAndStoreResults executes the task on the remote node, retrieves
* the results and stores them, if SELECT or RETURNING is used, in a tuple
* store.
*
* If the task fails on one of the placements, the function retries it on
* other placements (SELECT), reraises the remote error (constraint violation
* in DML), marks the affected placement as invalid (DML on some placement
* failed), or errors out (DML failed on all placements).
*/
static bool
ExecuteTaskAndStoreResults(QueryDesc *queryDesc, Task *task,
bool isModificationQuery,
bool expectResults)
{
TupleDesc tupleDescriptor = queryDesc->tupDesc;
EState *executorState = queryDesc->estate;
MaterialState *routerState = (MaterialState *) queryDesc->planstate;
bool resultsOK = false;
List *taskPlacementList = task->taskPlacementList;
ListCell *taskPlacementCell = NULL;
List *failedPlacementList = NIL;
ListCell *failedPlacementCell = NULL;
int64 affectedTupleCount = -1;
bool gotResults = false;
/*
* Try to run the query to completion on one placement. If the query fails
* attempt the query on the next placement.
*/
foreach(taskPlacementCell, taskPlacementList)
{
ShardPlacement *taskPlacement = (ShardPlacement *) lfirst(taskPlacementCell);
char *nodeName = taskPlacement->nodeName;
int32 nodePort = taskPlacement->nodePort;
bool queryOK = false;
int64 currentAffectedTupleCount = 0;
PGconn *connection = GetOrEstablishConnection(nodeName, nodePort);
if (connection == NULL)
{
failedPlacementList = lappend(failedPlacementList, taskPlacement);
continue;
}
queryOK = SendQueryInSingleRowMode(connection, task->queryString);
if (!queryOK)
{
PurgeConnection(connection);
failedPlacementList = lappend(failedPlacementList, taskPlacement);
continue;
}
/*
* If caller is interested, store query results the first time
* through. The output of the query's execution on other shards is
* discarded if we run there (because it's a modification query).
*/
if (!gotResults && expectResults)
{
queryOK = StoreQueryResult(routerState, connection, tupleDescriptor,
¤tAffectedTupleCount);
}
else
{
queryOK = ConsumeQueryResult(connection, ¤tAffectedTupleCount);
}
if (queryOK)
{
if ((affectedTupleCount == -1) ||
(affectedTupleCount == currentAffectedTupleCount))
{
affectedTupleCount = currentAffectedTupleCount;
}
else
{
ereport(WARNING,
(errmsg("modified "INT64_FORMAT " tuples, but expected "
"to modify "INT64_FORMAT,
currentAffectedTupleCount, affectedTupleCount),
errdetail("modified placement on %s:%d",
nodeName, nodePort)));
}
#if (PG_VERSION_NUM < 90600)
/* before 9.6, PostgreSQL used a uint32 for this field, so check */
Assert(currentAffectedTupleCount <= 0xFFFFFFFF);
#endif
resultsOK = true;
gotResults = true;
/*
* Modifications have to be executed on all placements, but for
* read queries we can stop here.
*/
if (!isModificationQuery)
{
break;
}
}
else
{
PurgeConnection(connection);
failedPlacementList = lappend(failedPlacementList, taskPlacement);
continue;
}
}
