private RelNode preprocessNode(RelNode rel) throws SqlUnsupportedException {
/*
* Traverse the tree to do the following pre-processing tasks: 1. replace the convert_from, convert_to function to
* actual implementations Eg: convert_from(EXPR, 'JSON') be converted to convert_fromjson(EXPR); TODO: Ideally all
* function rewrites would move here instead of DrillOptiq.
*
* 2. see where the tree contains unsupported functions; throw SqlUnsupportedException if there is any.
*/
PreProcessLogicalRel visitor =
PreProcessLogicalRel.createVisitor(
planner.getTypeFactory(), context.getDrillOperatorTable());
try {
rel = rel.accept(visitor);
} catch (UnsupportedOperationException ex) {
visitor.convertException();
throw ex;
}
return rel;
}
protected Prel convertToPrel(RelNode drel)
throws RelConversionException, SqlUnsupportedException {
Preconditions.checkArgument(drel.getConvention() == DrillRel.DRILL_LOGICAL);
RelTraitSet traits =
drel.getTraitSet().plus(Prel.DRILL_PHYSICAL).plus(DrillDistributionTrait.SINGLETON);
Prel phyRelNode;
try {
final RelNode relNode = planner.transform(DrillSqlWorker.PHYSICAL_MEM_RULES, traits, drel);
phyRelNode = (Prel) relNode.accept(new PrelFinalizer());
} catch (RelOptPlanner.CannotPlanException ex) {
logger.error(ex.getMessage());
if (JoinUtils.checkCartesianJoin(drel, new ArrayList<Integer>(), new ArrayList<Integer>())) {
throw new UnsupportedRelOperatorException(
"This query cannot be planned possibly due to either a cartesian join or an inequality join");
} else {
throw ex;
}
}
OptionManager queryOptions = context.getOptions();
if (context.getPlannerSettings().isMemoryEstimationEnabled()
&& !MemoryEstimationVisitor.enoughMemory(
phyRelNode, queryOptions, context.getActiveEndpoints().size())) {
log("Not enough memory for this plan", phyRelNode, logger);
logger.debug("Re-planning without hash operations.");
queryOptions.setOption(
OptionValue.createBoolean(
OptionValue.OptionType.QUERY, PlannerSettings.HASHJOIN.getOptionName(), false));
queryOptions.setOption(
OptionValue.createBoolean(
OptionValue.OptionType.QUERY, PlannerSettings.HASHAGG.getOptionName(), false));
try {
final RelNode relNode = planner.transform(DrillSqlWorker.PHYSICAL_MEM_RULES, traits, drel);
phyRelNode = (Prel) relNode.accept(new PrelFinalizer());
} catch (RelOptPlanner.CannotPlanException ex) {
logger.error(ex.getMessage());
if (JoinUtils.checkCartesianJoin(
drel, new ArrayList<Integer>(), new ArrayList<Integer>())) {
throw new UnsupportedRelOperatorException(
"This query cannot be planned possibly due to either a cartesian join or an inequality join");
} else {
throw ex;
}
}
}
/* The order of the following transformation is important */
/*
* 0.) For select * from join query, we need insert project on top of scan and a top project just
* under screen operator. The project on top of scan will rename from * to T1*, while the top project
* will rename T1* to *, before it output the final result. Only the top project will allow
* duplicate columns, since user could "explicitly" ask for duplicate columns ( select *, col, *).
* The rest of projects will remove the duplicate column when we generate POP in json format.
*/
phyRelNode = StarColumnConverter.insertRenameProject(phyRelNode);
/*
* 1.)
* Join might cause naming conflicts from its left and right child.
* In such case, we have to insert Project to rename the conflicting names.
*/
phyRelNode = JoinPrelRenameVisitor.insertRenameProject(phyRelNode);
/*
* 1.1) Swap left / right for INNER hash join, if left's row count is < (1 + margin) right's row count.
* We want to have smaller dataset on the right side, since hash table builds on right side.
*/
if (context.getPlannerSettings().isHashJoinSwapEnabled()) {
phyRelNode =
SwapHashJoinVisitor.swapHashJoin(
phyRelNode, new Double(context.getPlannerSettings().getHashJoinSwapMarginFactor()));
}
/*
* 1.2) Break up all expressions with complex outputs into their own project operations
*/
phyRelNode =
((Prel) phyRelNode)
.accept(
new SplitUpComplexExpressions(
planner.getTypeFactory(),
context.getDrillOperatorTable(),
context.getPlannerSettings().functionImplementationRegistry),
null);
/*
* 1.3) Projections that contain reference to flatten are rewritten as Flatten operators followed by Project
*/
phyRelNode =
((Prel) phyRelNode)
.accept(
new RewriteProjectToFlatten(
planner.getTypeFactory(), context.getDrillOperatorTable()),
null);
/*
* 2.)
* Since our operators work via names rather than indices, we have to make to reorder any
* output before we return data to the user as we may have accidentally shuffled things.
* This adds a trivial project to reorder columns prior to output.
*/
phyRelNode = FinalColumnReorderer.addFinalColumnOrdering(phyRelNode);
/*
* 3.)
* If two fragments are both estimated to be parallelization one, remove the exchange
* separating them
*/
phyRelNode = ExcessiveExchangeIdentifier.removeExcessiveEchanges(phyRelNode, targetSliceSize);
/* 4.)
* Add ProducerConsumer after each scan if the option is set
* Use the configured queueSize
*/
/* DRILL-1617 Disabling ProducerConsumer as it produces incorrect results
if (context.getOptions().getOption(PlannerSettings.PRODUCER_CONSUMER.getOptionName()).bool_val) {
long queueSize = context.getOptions().getOption(PlannerSettings.PRODUCER_CONSUMER_QUEUE_SIZE.getOptionName()).num_val;
phyRelNode = ProducerConsumerPrelVisitor.addProducerConsumerToScans(phyRelNode, (int) queueSize);
}
*/
/* 5.)
* if the client does not support complex types (Map, Repeated)
* insert a project which which would convert
*/
if (!context.getSession().isSupportComplexTypes()) {
logger.debug("Client does not support complex types, add ComplexToJson operator.");
phyRelNode = ComplexToJsonPrelVisitor.addComplexToJsonPrel(phyRelNode);
}
/* 6.)
* Insert LocalExchange (mux and/or demux) nodes
*/
phyRelNode = InsertLocalExchangeVisitor.insertLocalExchanges(phyRelNode, queryOptions);
/* 7.)
* Next, we add any required selection vector removers given the supported encodings of each
* operator. This will ultimately move to a new trait but we're managing here for now to avoid
* introducing new issues in planning before the next release
*/
phyRelNode = SelectionVectorPrelVisitor.addSelectionRemoversWhereNecessary(phyRelNode);
/* 8.)
* Finally, Make sure that the no rels are repeats.
* This could happen in the case of querying the same table twice as Optiq may canonicalize these.
*/
phyRelNode = RelUniqifier.uniqifyGraph(phyRelNode);
return phyRelNode;
}