external
/
citus
mirror of https://github.com/citusdata/citus.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Do not connection re-use for intermediate results 

/*
 * Colocated intermediate results are just files and not required to use
 * the same connections with their co-located shards. So, we are free to
 * use any connection we can get.
 *
 * Also, the current connection re-use logic does not know how to handle
 * intermediate results as the intermediate results always truncates the
 * existing files. That's why, we use one connection per intermediate
 * result.
 */

(cherry picked from commit 5d5a357487)
pull/5081/head
Onder Kalaci 2021-02-10 13:42:58 +01:00
parent 3065966d13
commit 281460fbaa
1 changed files with 46 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

57
src/backend/distributed/commands/multi_copy.c
View File

@ -253,7 +253,8 @@ static CopyShardState * GetShardState(uint64 shardId, HTAB *shardStateHash,
copyOutState, bool isCopyToIntermediateFile);
static MultiConnection * CopyGetPlacementConnection(HTAB *connectionStateHash,
ShardPlacement *placement,
bool stopOnFailure);
bool stopOnFailure,
bool colocatedIntermediateResult);
static bool HasReachedAdaptiveExecutorPoolSize(List *connectionStateHash);
static MultiConnection * GetLeastUtilisedCopyConnection(List *connectionStateList,
char *nodeName, int nodePort);
@ -2230,7 +2231,10 @@ CitusCopyDestReceiverStartup(DestReceiver *dest, int operation,
/* define the template for the COPY statement that is sent to workers */
CopyStmt *copyStatement = makeNode(CopyStmt);
if (copyDest->intermediateResultIdPrefix != NULL)
bool colocatedIntermediateResults =
copyDest->intermediateResultIdPrefix != NULL;
if (colocatedIntermediateResults)
{
copyStatement->relation = makeRangeVar(NULL, copyDest->intermediateResultIdPrefix,
-1);
@ -3448,7 +3452,8 @@ InitializeCopyShardState(CopyShardState *shardState,
}
MultiConnection *connection =
CopyGetPlacementConnection(connectionStateHash, placement, stopOnFailure);
CopyGetPlacementConnection(connectionStateHash, placement, stopOnFailure,
isCopyToIntermediateFile);
if (connection == NULL)
{
failedPlacementCount++;
@ -3544,11 +3549,40 @@ LogLocalCopyExecution(uint64 shardId)
* then it reuses the connection. Otherwise, it requests a connection for placement.
*/
static MultiConnection *
CopyGetPlacementConnection(HTAB *connectionStateHash, ShardPlacement *placement, bool
stopOnFailure)
CopyGetPlacementConnection(HTAB *connectionStateHash, ShardPlacement *placement,
bool stopOnFailure, bool colocatedIntermediateResult)
{
uint32 connectionFlags = FOR_DML;
char *nodeUser = CurrentUserName();
if (colocatedIntermediateResult)
{
/*
* Colocated intermediate results are just files and not required to use
* the same connections with their co-located shards. So, we are free to
* use any connection we can get.
*
* Also, the current connection re-use logic does not know how to handle
* intermediate results as the intermediate results always truncates the
* existing files. That's why we we use one connection per intermediate
* result.
*
* Also note that we are breaking the guarantees of citus.shared_pool_size
* as we cannot rely on optional connections.
*/
uint32 connectionFlagsForIntermediateResult = 0;
MultiConnection *connection =
GetNodeConnection(connectionFlagsForIntermediateResult, placement->nodeName,
placement->nodePort);
/*
* As noted above, we want each intermediate file to go over
* a separate connection.
*/
ClaimConnectionExclusively(connection);
/* and, we cannot afford to handle failures when anything goes wrong */
MarkRemoteTransactionCritical(connection);
return connection;
}
/*
* Determine whether the task has to be assigned to a particular connection
@ -3556,10 +3590,10 @@ CopyGetPlacementConnection(HTAB *connectionStateHash, ShardPlacement *placement,
*/
ShardPlacementAccess *placementAccess = CreatePlacementAccess(placement,
PLACEMENT_ACCESS_DML);
MultiConnection *connection = GetConnectionIfPlacementAccessedInXact(connectionFlags,
list_make1(
placementAccess),
NULL);
uint32 connectionFlags = FOR_DML;
MultiConnection *connection =
GetConnectionIfPlacementAccessedInXact(connectionFlags,
list_make1(placementAccess), NULL);
if (connection != NULL)
{
return connection;
@ -3605,6 +3639,7 @@ CopyGetPlacementConnection(HTAB *connectionStateHash, ShardPlacement *placement,
connectionFlags |= CONNECTION_PER_PLACEMENT;
}
char *nodeUser = CurrentUserName();
connection = GetPlacementConnection(connectionFlags, placement, nodeUser);
if (PQstatus(connection->pgConn) != CONNECTION_OK)