/*
* CreateColocatedShards creates shards for the target relation colocated with
* the source relation.
*/
void
CreateColocatedShards(Oid targetRelationId, Oid sourceRelationId, bool
useExclusiveConnections)
{
char targetShardStorageType = 0;
List *existingShardList = NIL;
List *sourceShardIntervalList = NIL;
ListCell *sourceShardCell = NULL;
bool colocatedShard = true;
List *insertedShardPlacements = NIL;
/* make sure that tables are hash partitioned */
CheckHashPartitionedTable(targetRelationId);
CheckHashPartitionedTable(sourceRelationId);
/*
* In contrast to append/range partitioned tables it makes more sense to
* require ownership privileges - shards for hash-partitioned tables are
* only created once, not continually during ingest as for the other
* partitioning types.
*/
EnsureTableOwner(targetRelationId);
/* we plan to add shards: get an exclusive lock on target relation oid */
LockRelationOid(targetRelationId, ExclusiveLock);
/* we don't want source table to get dropped before we colocate with it */
LockRelationOid(sourceRelationId, AccessShareLock);
/* prevent placement changes of the source relation until we colocate with them */
sourceShardIntervalList = LoadShardIntervalList(sourceRelationId);
LockShardListMetadata(sourceShardIntervalList, ShareLock);
/* validate that shards haven't already been created for this table */
existingShardList = LoadShardList(targetRelationId);
if (existingShardList != NIL)
{
char *targetRelationName = get_rel_name(targetRelationId);
ereport(ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("table \"%s\" has already had shards created for it",
targetRelationName)));
}
targetShardStorageType = ShardStorageType(targetRelationId);
foreach(sourceShardCell, sourceShardIntervalList)
{
ShardInterval *sourceShardInterval = (ShardInterval *) lfirst(sourceShardCell);
uint64 sourceShardId = sourceShardInterval->shardId;
uint64 newShardId = GetNextShardId();
ListCell *sourceShardPlacementCell = NULL;
int32 shardMinValue = DatumGetInt32(sourceShardInterval->minValue);
int32 shardMaxValue = DatumGetInt32(sourceShardInterval->maxValue);
text *shardMinValueText = IntegerToText(shardMinValue);
text *shardMaxValueText = IntegerToText(shardMaxValue);
List *sourceShardPlacementList = ShardPlacementList(sourceShardId);
InsertShardRow(targetRelationId, newShardId, targetShardStorageType,
shardMinValueText, shardMaxValueText);
foreach(sourceShardPlacementCell, sourceShardPlacementList)
{
ShardPlacement *sourcePlacement =
(ShardPlacement *) lfirst(sourceShardPlacementCell);
uint32 groupId = sourcePlacement->groupId;
const RelayFileState shardState = FILE_FINALIZED;
const uint64 shardSize = 0;
uint64 shardPlacementId = 0;
ShardPlacement *shardPlacement = NULL;
/*
* Optimistically add shard placement row the pg_dist_shard_placement, in case
* of any error it will be roll-backed.
*/
shardPlacementId = InsertShardPlacementRow(newShardId, INVALID_PLACEMENT_ID,
shardState, shardSize, groupId);
shardPlacement = LoadShardPlacement(newShardId, shardPlacementId);
insertedShardPlacements = lappend(insertedShardPlacements, shardPlacement);
}
/*
* CreateShardsWithRoundRobinPolicy creates empty shards for the given table
* based on the specified number of initial shards. The function first updates
* metadata on the coordinator node to make this shard (and its placements)
* visible. Note that the function assumes the table is hash partitioned and
* calculates the min/max hash token ranges for each shard, giving them an equal
* split of the hash space. Finally, function creates empty shard placements on
* worker nodes.
*/
void
CreateShardsWithRoundRobinPolicy(Oid distributedTableId, int32 shardCount,
int32 replicationFactor, bool useExclusiveConnections)
{
char shardStorageType = 0;
List *workerNodeList = NIL;
int32 workerNodeCount = 0;
uint32 placementAttemptCount = 0;
uint64 hashTokenIncrement = 0;
List *existingShardList = NIL;
int64 shardIndex = 0;
DistTableCacheEntry *cacheEntry = DistributedTableCacheEntry(distributedTableId);
bool colocatedShard = false;
List *insertedShardPlacements = NIL;
/* make sure table is hash partitioned */
CheckHashPartitionedTable(distributedTableId);
/*
* In contrast to append/range partitioned tables it makes more sense to
* require ownership privileges - shards for hash-partitioned tables are
* only created once, not continually during ingest as for the other
* partitioning types.
*/
EnsureTableOwner(distributedTableId);
/* we plan to add shards: get an exclusive lock on relation oid */
LockRelationOid(distributedTableId, ExclusiveLock);
/* validate that shards haven't already been created for this table */
existingShardList = LoadShardList(distributedTableId);
if (existingShardList != NIL)
{
char *tableName = get_rel_name(distributedTableId);
ereport(ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("table \"%s\" has already had shards created for it",
tableName)));
}
/* make sure that at least one shard is specified */
if (shardCount <= 0)
{
ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("shard_count must be positive")));
}
/* make sure that at least one replica is specified */
if (replicationFactor <= 0)
{
ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("replication_factor must be positive")));
}
/* make sure that RF=1 if the table is streaming replicated */
if (cacheEntry->replicationModel == REPLICATION_MODEL_STREAMING &&
replicationFactor > 1)
{
char *relationName = get_rel_name(cacheEntry->relationId);
ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("using replication factor %d with the streaming "
"replication model is not supported",
replicationFactor),
errdetail("The table %s is marked as streaming replicated and "
"the shard replication factor of streaming replicated "
"tables must be 1.", relationName),
errhint("Use replication factor 1.")));
}
/* calculate the split of the hash space */
hashTokenIncrement = HASH_TOKEN_COUNT / shardCount;
/* don't allow concurrent node list changes that require an exclusive lock */
LockRelationOid(DistNodeRelationId(), RowShareLock);
/* load and sort the worker node list for deterministic placement */
workerNodeList = ActivePrimaryNodeList();
workerNodeList = SortList(workerNodeList, CompareWorkerNodes);
/* make sure we don't process cancel signals until all shards are created */
HOLD_INTERRUPTS();
workerNodeCount = list_length(workerNodeList);
if (replicationFactor > workerNodeCount)
{
ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("replication_factor (%d) exceeds number of worker nodes "
"(%d)", replicationFactor, workerNodeCount),
errhint("Add more worker nodes or try again with a lower "
"replication factor.")));
}
/* if we have enough nodes, add an extra placement attempt for backup */
placementAttemptCount = (uint32) replicationFactor;
if (workerNodeCount > replicationFactor)
{
placementAttemptCount++;
}
/* set shard storage type according to relation type */
shardStorageType = ShardStorageType(distributedTableId);
for (shardIndex = 0; shardIndex < shardCount; shardIndex++)
{
uint32 roundRobinNodeIndex = shardIndex % workerNodeCount;
/* initialize the hash token space for this shard */
text *minHashTokenText = NULL;
text *maxHashTokenText = NULL;
int32 shardMinHashToken = INT32_MIN + (shardIndex * hashTokenIncrement);
int32 shardMaxHashToken = shardMinHashToken + (hashTokenIncrement - 1);
uint64 shardId = GetNextShardId();
List *currentInsertedShardPlacements = NIL;
/* if we are at the last shard, make sure the max token value is INT_MAX */
if (shardIndex == (shardCount - 1))
{
shardMaxHashToken = INT32_MAX;
}
/* insert the shard metadata row along with its min/max values */
minHashTokenText = IntegerToText(shardMinHashToken);
maxHashTokenText = IntegerToText(shardMaxHashToken);
/*
* Grabbing the shard metadata lock isn't technically necessary since
* we already hold an exclusive lock on the partition table, but we'll
* acquire it for the sake of completeness. As we're adding new active
* placements, the mode must be exclusive.
*/
LockShardDistributionMetadata(shardId, ExclusiveLock);
InsertShardRow(distributedTableId, shardId, shardStorageType,
minHashTokenText, maxHashTokenText);
currentInsertedShardPlacements = InsertShardPlacementRows(distributedTableId,
shardId,
workerNodeList,
roundRobinNodeIndex,
replicationFactor);
insertedShardPlacements = list_concat(insertedShardPlacements,
currentInsertedShardPlacements);
}
CreateShardsOnWorkers(distributedTableId, insertedShardPlacements,
useExclusiveConnections, colocatedShard);
if (QueryCancelPending)
{
ereport(WARNING, (errmsg("cancel requests are ignored during shard creation")));
QueryCancelPending = false;
}
RESUME_INTERRUPTS();
}
/*
* master_get_table_metadata takes in a relation name, and returns partition
* related metadata for the relation. These metadata are grouped and returned in
* a tuple, and are used by the caller when creating new shards. The function
* errors if given relation does not exist, or is not partitioned.
*/
Datum
master_get_table_metadata(PG_FUNCTION_ARGS)
{
text *relationName = PG_GETARG_TEXT_P(0);
Oid relationId = ResolveRelationId(relationName);
DistTableCacheEntry *partitionEntry = NULL;
char *partitionKeyString = NULL;
TypeFuncClass resultTypeClass = 0;
Datum partitionKeyExpr = 0;
Datum partitionKey = 0;
Datum metadataDatum = 0;
HeapTuple metadataTuple = NULL;
TupleDesc metadataDescriptor = NULL;
uint64 shardMaxSizeInBytes = 0;
char shardStorageType = 0;
Datum values[TABLE_METADATA_FIELDS];
bool isNulls[TABLE_METADATA_FIELDS];
CheckCitusVersion(ERROR);
/* find partition tuple for partitioned relation */
partitionEntry = DistributedTableCacheEntry(relationId);
/* create tuple descriptor for return value */
resultTypeClass = get_call_result_type(fcinfo, NULL, &metadataDescriptor);
if (resultTypeClass != TYPEFUNC_COMPOSITE)
{
ereport(ERROR, (errmsg("return type must be a row type")));
}
/* form heap tuple for table metadata */
memset(values, 0, sizeof(values));
memset(isNulls, false, sizeof(isNulls));
partitionKeyString = partitionEntry->partitionKeyString;
/* reference tables do not have partition key */
if (partitionKeyString == NULL)
{
partitionKey = PointerGetDatum(NULL);
isNulls[3] = true;
}
else
{
/* get decompiled expression tree for partition key */
partitionKeyExpr =
PointerGetDatum(cstring_to_text(partitionEntry->partitionKeyString));
partitionKey = DirectFunctionCall2(pg_get_expr, partitionKeyExpr,
ObjectIdGetDatum(relationId));
}
shardMaxSizeInBytes = (int64) ShardMaxSize * 1024L;
/* get storage type */
shardStorageType = ShardStorageType(relationId);
values[0] = ObjectIdGetDatum(relationId);
values[1] = shardStorageType;
values[2] = partitionEntry->partitionMethod;
values[3] = partitionKey;
values[4] = Int32GetDatum(ShardReplicationFactor);
values[5] = Int64GetDatum(shardMaxSizeInBytes);
values[6] = Int32GetDatum(ShardPlacementPolicy);
metadataTuple = heap_form_tuple(metadataDescriptor, values, isNulls);
metadataDatum = HeapTupleGetDatum(metadataTuple);
PG_RETURN_DATUM(metadataDatum);
}
