/*
* DynamicScan_MapRelationColumns
* Returns dropped column mapping between two relations. Returns NULL if
* no mapping is necessary.
*/
static AttrNumber*
DynamicScan_MapRelationColumns(ScanState *scanState, Relation oldRelation, Relation newRelation)
{
AttrNumber *attMap = NULL;
if (isDynamicScan((Scan *)scanState->ps.plan) && (oldRelation != newRelation))
{
TupleDesc oldTupDesc = RelationGetDescr(oldRelation);
TupleDesc newTupDesc = RelationGetDescr(newRelation);
attMap = varattnos_map(oldTupDesc, newTupDesc);
}
return attMap;
}
/*
* initNextTableToScan
* Find the next table to scan and initiate the scan if the previous table
* is finished.
*
* If scanning on the current table is not finished, or a new table is found,
* this function returns true.
* If no more table is found, this function returns false.
*/
static bool
initNextTableToScan(DynamicTableScanState *node)
{
ScanState *scanState = (ScanState *)node;
if (scanState->scan_state == SCAN_INIT ||
scanState->scan_state == SCAN_DONE)
{
Oid *pid = hash_seq_search(&node->pidStatus);
if (pid == NULL)
{
node->shouldCallHashSeqTerm = false;
return false;
}
/* Collect number of partitions scanned in EXPLAIN ANALYZE */
if (NULL != scanState->ps.instrument)
{
Instrumentation *instr = scanState->ps.instrument;
instr->numPartScanned ++;
}
/*
* Inside ExecInitScanTupleSlot() we set the tuple table slot's oid
* to range table entry's relid, which for partitioned table always set
* to parent table's oid. In queries where we need to read table oids
* (MPP-20736) we use the tuple table slot's saved oid (refer to slot_getsysattr()).
* This wrongly returns parent oid, instead of partition oid. Therefore,
* to return correct partition oid, we need to update
* our tuple table slot's oid to reflect the partition oid.
*/
scanState->ss_ScanTupleSlot->tts_tableOid = *pid;
scanState->ss_currentRelation = OpenScanRelationByOid(*pid);
Relation lastScannedRel = OpenScanRelationByOid(node->lastRelOid);
TupleDesc lastTupDesc = RelationGetDescr(lastScannedRel);
CloseScanRelation(lastScannedRel);
TupleDesc partTupDesc = RelationGetDescr(scanState->ss_currentRelation);
ExecAssignScanType(scanState, partTupDesc);
AttrNumber *attMap = NULL;
attMap = varattnos_map(lastTupDesc, partTupDesc);
/* If attribute remapping is not necessary, then do not change the varattno */
if (attMap)
{
change_varattnos_of_a_varno((Node*)scanState->ps.plan->qual, attMap, node->scanrelid);
change_varattnos_of_a_varno((Node*)scanState->ps.plan->targetlist, attMap, node->scanrelid);
/*
* Now that the varattno mapping has been changed, change the relation that
* the new varnos correspond to
*/
node->lastRelOid = *pid;
}
/*
* For the very first partition, the targetlist of planstate is set to null. So, we must
* initialize quals and targetlist, regardless of remapping requirements. For later
* partitions, we only initialize quals and targetlist if a column re-mapping is necessary.
*/
if (attMap || node->firstPartition)
{
node->firstPartition = false;
MemoryContextReset(node->partitionMemoryContext);
MemoryContext oldCxt = MemoryContextSwitchTo(node->partitionMemoryContext);
/* Initialize child expressions */
scanState->ps.qual = (List *)ExecInitExpr((Expr *)scanState->ps.plan->qual, (PlanState*)scanState);
scanState->ps.targetlist = (List *)ExecInitExpr((Expr *)scanState->ps.plan->targetlist, (PlanState*)scanState);
MemoryContextSwitchTo(oldCxt);
}
if (attMap)
{
pfree(attMap);
}
ExecAssignScanProjectionInfo(scanState);
scanState->tableType = getTableType(scanState->ss_currentRelation);
BeginTableScanRelation(scanState);
}
return true;
}
