/* Distributed planner hook */
PlannedStmt *
multi_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
{
PlannedStmt *result = NULL;
/*
* First call into standard planner. This is required because the Citus
* planner relies on parse tree transformations made by postgres' planner.
*/
result = standard_planner(parse, cursorOptions, boundParams);
if (NeedsDistributedPlanning(parse))
{
MultiPlan *physicalPlan = CreatePhysicalPlan(parse);
/* store required data into the planned statement */
result = MultiQueryContainerNode(result, physicalPlan);
}
return result;
}
/* Distributed planner hook */
PlannedStmt *
multi_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
{
PlannedStmt *result = NULL;
bool needsDistributedPlanning = NeedsDistributedPlanning(parse);
Query *originalQuery = NULL;
RelationRestrictionContext *restrictionContext = NULL;
/*
* standard_planner scribbles on it's input, but for deparsing we need the
* unmodified form. So copy once we're sure it's a distributed query.
*/
if (needsDistributedPlanning)
{
originalQuery = copyObject(parse);
/*
* We implement INSERT INTO .. SELECT by pushing down the SELECT to
* each shard. To compute that we use the router planner, by adding
* an "uninstantiated" constraint that the partition column be equal to a
* certain value. standard_planner() distributes that constraint to
* the baserestrictinfos to all the tables where it knows how to push
* the restriction safely. An example is that the tables that are
* connected via equi joins.
*
* The router planner then iterates over the target table's shards,
* for each we replace the "uninstantiated" restriction, with one that
* PruneShardList() handles, and then generate a query for that
* individual shard. If any of the involved tables don't prune down
* to a single shard, or if the pruned shards aren't colocated,
* we error out.
*/
if (InsertSelectQuery(parse))
{
AddUninstantiatedPartitionRestriction(parse);
}
}
/* create a restriction context and put it at the end if context list */
restrictionContext = CreateAndPushRestrictionContext();
PG_TRY();
{
/*
* First call into standard planner. This is required because the Citus
* planner relies on parse tree transformations made by postgres' planner.
*/
result = standard_planner(parse, cursorOptions, boundParams);
if (needsDistributedPlanning)
{
MultiPlan *physicalPlan = CreatePhysicalPlan(originalQuery, parse,
restrictionContext);
/* store required data into the planned statement */
result = MultiQueryContainerNode(result, physicalPlan);
}
}
PG_CATCH();
{
PopRestrictionContext();
PG_RE_THROW();
}
PG_END_TRY();
/* remove the context from the context list */
PopRestrictionContext();
return result;
}