/*-------------------------------------------------------------------------
*
* nodeSort.c
* Routines to handle sorting of relations.
*
* Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/executor/nodeSort.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/parallel.h"
#include "executor/execdebug.h"
#include "executor/nodeSort.h"
#include "miscadmin.h"
#include "utils/tuplesort.h"
/* ----------------------------------------------------------------
* ExecSort
*
* Sorts tuples from the outer subtree of the node using tuplesort,
* which saves the results in a temporary file or memory. After the
* initial call, returns a tuple from the file with each call.
*
* There are two distinct ways that this sort can be performed:
*
* 1) When the result is a single column we perform a Datum sort.
*
* 2) When the result contains multiple columns we perform a tuple sort.
*
* We could do this by always performing a tuple sort, however sorting
* Datums only can be significantly faster than sorting tuples,
* especially when the Datums are of a pass-by-value type.
*
* Conditions:
* -- none.
*
* Initial States:
* -- the outer child is prepared to return the first tuple.
* ----------------------------------------------------------------
*/
static TupleTableSlot *
ExecSort(PlanState *pstate)
{
SortState *node = castNode(SortState, pstate);
EState *estate;
ScanDirection dir;
Tuplesortstate *tuplesortstate;
TupleTableSlot *slot;
CHECK_FOR_INTERRUPTS();
/*
* get state info from node
*/
SO1_printf("ExecSort: %s\n",
"entering routine");
estate = node->ss.ps.state;
dir = estate->es_direction;
tuplesortstate = (Tuplesortstate *) node->tuplesortstate;
/*
* If first time through, read all tuples from outer plan and pass them to
* tuplesort.c. Subsequent calls just fetch tuples from tuplesort.
*/
if (!node->sort_Done)
{
Sort *plannode = (Sort *) node->ss.ps.plan;
PlanState *outerNode;
TupleDesc tupDesc;
int tuplesortopts = TUPLESORT_NONE;
SO1_printf("ExecSort: %s\n",
"sorting subplan");
/*
* Want to scan subplan in the forward direction while creating the
* sorted data.
*/
estate->es_direction = ForwardScanDirection;
/*
* Initialize tuplesort module.
*/
SO1_printf("ExecSort: %s\n",
"calling tuplesort_begin");
outerNode = outerPlanState(node);
tupDesc = ExecGetResultType(outerNode);
if (node->randomAccess)
tuplesortopts |= TUPLESORT_RANDOMACCESS;
if (node->bounded)
tuplesortopts |= TUPLESORT_ALLOWBOUNDED;
if (node->datumSort)
tuplesortstate = tuplesort_begin_datum(TupleDescAttr(tupDesc, 0)->atttypid,
plannode->sortOperators[0],
plannode->collations[0],
plannode->nullsFirst[0],
work_mem,
NULL,
tuplesortopts);
else
tuplesortstate = tuplesort_begin_heap(tupDesc,
plannode->numCols,
plannode->sortColIdx,
plannode->sortOperators,
plannode->collations,
plannode->nullsFirst,
work_mem,
NULL,
tuplesortopts);
if (node->bounded)
tuplesort_set_bound(tuplesortstate, node->bound);
node->tuplesortstate = (void *) tuplesortstate;
/*
* Scan the subplan and feed all the tuples to tuplesort using the
* appropriate method based on the type of sort we're doing.
*/
if (node->datumSort)
{
for (;;)
{
slot = ExecProcNode(outerNode);
if (TupIsNull(slot))
break;
slot_getsomeattrs(slot, 1);
tuplesort_putdatum(tuplesortstate,
slot->tts_values[0],
slot->tts_isnull[0]);
}
}
else
{
for (;;)
{
slot = ExecProcNode(outerNode);
if (TupIsNull(slot))
break;
tuplesort_puttupleslot(tuplesortstate, slot);
}
}
/*
* Complete the sort.
*/
tuplesort_performsort(tuplesortstate);
/*
* restore to user specified direction
*/
estate->es_direction = dir;
/*
* finally set the sorted flag to true
*/
node->sort_Done = true;
node->bounded_Done = node->bounded;
node->bound_Done = node->bound;
if (node->shared_info && node->am_worker)
{
TuplesortInstrumentation *si;
Assert(IsParallelWorker());
Assert(ParallelWorkerNumber <= node->shared_info->num_workers);
si = &node->shared_info->sinstrument[ParallelWorkerNumber];
tuplesort_get_stats(tuplesortstate, si);
}
SO1_printf("ExecSort: %s\n", "sorting done");
}
SO1_printf("ExecSort: %s\n",
"retrieving tuple from tuplesort");
slot = node->ss.ps.ps_ResultTupleSlot;
/*
* Fetch the next sorted item from the appropriate tuplesort function. For
* datum sorts we must manage the slot ourselves and leave it clear when
* tuplesort_getdatum returns false to indicate there are no more datums.
* For tuple sorts, tuplesort_gettupleslot manages the slot for us and
* empties the slot when it runs out of tuples.
*/
if (node->datumSort)
{
ExecClearTuple(slot);
if (tuplesort_getdatum(tuplesortstate, ScanDirectionIsForward(dir),
false, &(slot->tts_values[0]),
&(slot->tts_isnull[0]), NULL))
ExecStoreVirtualTuple(slot);
}
else
(void) tuplesort_gettupleslot(tuplesortstate,
ScanDirectionIsForward(dir),
false, slot, NULL);
return slot;
}
/* ----------------------------------------------------------------
* ExecInitSort
*
* Creates the run-time state information for the sort node
* produced by the planner and initializes its outer subtree.
* ----------------------------------------------------------------
*/
SortState *
ExecInitSort(Sort *node, EState *estate, int eflags)
{
SortState *sortstate;
TupleDesc outerTupDesc;
SO1_printf("ExecInitSort: %s\n",
"initializing sort node");
/*
* create state structure
*/
sortstate = makeNode(SortState);
sortstate->ss.ps.plan = (Plan *) node;
sortstate->ss.ps.state = estate;
sortstate->ss.ps.ExecProcNode = ExecSort;
/*
* We must have random access to the sort output to do backward scan or
* mark/restore. We also prefer to materialize the sort output if we
* might be called on to rewind and replay it many times.
*/
sortstate->randomAccess = (eflags & (EXEC_FLAG_REWIND |
EXEC_FLAG_BACKWARD |
EXEC_FLAG_MARK)) != 0;
sortstate->bounded = false;
sortstate->sort_Done = false;
sortstate->tuplesortstate = NULL;
/*
* Miscellaneous initialization
*
* Sort nodes don't initialize their ExprContexts because they never call
* ExecQual or ExecProject.
*/
/*
* initialize child nodes
*
* We shield the child node from the need to support REWIND, BACKWARD, or
* MARK/RESTORE.
*/
eflags &= ~(EXEC_FLAG_REWIND | EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK);
outerPlanState(sortstate) = ExecInitNode(outerPlan(node), estate, eflags);
/*
* Initialize scan slot and type.
*/
ExecCreateScanSlotFromOuterPlan(estate, &sortstate->ss, &TTSOpsVirtual);
/*
* Initialize return slot and type. No need to initialize projection info
* because this node doesn't do projections.
*/
ExecInitResultTupleSlotTL(&sortstate->ss.ps, &TTSOpsMinimalTuple);
sortstate->ss.ps.ps_ProjInfo = NULL;
outerTupDesc = ExecGetResultType(outerPlanState(sortstate));
/*
* We perform a Datum sort when we're sorting just a single column,
* otherwise we perform a tuple sort.
*/
if (outerTupDesc->natts == 1)
sortstate->datumSort = true;
else
sortstate->datumSort = false;
SO1_printf("ExecInitSort: %s\n",
"sort node initialized");
return sortstate;
}
/* ----------------------------------------------------------------
* ExecEndSort(node)
* ----------------------------------------------------------------
*/
void
ExecEndSort(SortState *node)
{
SO1_printf("ExecEndSort: %s\n",
"shutting down sort node");
/*
* Release tuplesort resources
*/
if (node->tuplesortstate != NULL)
tuplesort_end((Tuplesortstate *) node->tuplesortstate);
node->tuplesortstate = NULL;
/*
* shut down the subplan
*/
ExecEndNode(outerPlanState(node));
SO1_printf("ExecEndSort: %s\n",
"sort node shutdown");
}
/* ----------------------------------------------------------------
* ExecSortMarkPos
*
* Calls tuplesort to save the current position in the sorted file.
* ----------------------------------------------------------------
*/
void
ExecSortMarkPos(SortState *node)
{
/*
* if we haven't sorted yet, just return
*/
if (!node->sort_Done)
return;
tuplesort_markpos((Tuplesortstate *) node->tuplesortstate);
}
/* ----------------------------------------------------------------
* ExecSortRestrPos
*
* Calls tuplesort to restore the last saved sort file position.
* ----------------------------------------------------------------
*/
void
ExecSortRestrPos(SortState *node)
{
/*
* if we haven't sorted yet, just return.
*/
if (!node->sort_Done)
return;
/*
* restore the scan to the previously marked position
*/
tuplesort_restorepos((Tuplesortstate *) node->tuplesortstate);
}
void
ExecReScanSort(SortState *node)
{
PlanState *outerPlan = outerPlanState(node);
/*
* If we haven't sorted yet, just return. If outerplan's chgParam is not
* NULL then it will be re-scanned by ExecProcNode, else no reason to
* re-scan it at all.
*/
if (!node->sort_Done)
return;
/* must drop pointer to sort result tuple */
ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
/*
* If subnode is to be rescanned then we forget previous sort results; we
* have to re-read the subplan and re-sort. Also must re-sort if the
* bounded-sort parameters changed or we didn't select randomAccess.
*
* Otherwise we can just rewind and rescan the sorted output.
*/
if (outerPlan->chgParam != NULL ||
node->bounded != node->bounded_Done ||
node->bound != node->bound_Done ||
!node->randomAccess)
{
node->sort_Done = false;
tuplesort_end((Tuplesortstate *) node->tuplesortstate);
node->tuplesortstate = NULL;
/*
* if chgParam of subnode is not null then plan will be re-scanned by
* first ExecProcNode.
*/
if (outerPlan->chgParam == NULL)
ExecReScan(outerPlan);
}
else
tuplesort_rescan((Tuplesortstate *) node->tuplesortstate);
}
/* ----------------------------------------------------------------
* Parallel Query Support
* ----------------------------------------------------------------
*/
/* ----------------------------------------------------------------
* ExecSortEstimate
*
* Estimate space required to propagate sort statistics.
* ----------------------------------------------------------------
*/
void
ExecSortEstimate(SortState *node, ParallelContext *pcxt)
{
Size size;
/* don't need this if not instrumenting or no workers */
if (!node->ss.ps.instrument || pcxt->nworkers == 0)
return;
size = mul_size(pcxt->nworkers, sizeof(TuplesortInstrumentation));
size = add_size(size, offsetof(SharedSortInfo, sinstrument));
shm_toc_estimate_chunk(&pcxt->estimator, size);
shm_toc_estimate_keys(&pcxt->estimator, 1);
}
/* ----------------------------------------------------------------
* ExecSortInitializeDSM
*
* Initialize DSM space for sort statistics.
* ----------------------------------------------------------------
*/
void
ExecSortInitializeDSM(SortState *node, ParallelContext *pcxt)
{
Size size;
/* don't need this if not instrumenting or no workers */
if (!node->ss.ps.instrument || pcxt->nworkers == 0)
return;
size = offsetof(SharedSortInfo, sinstrument)
+ pcxt->nworkers * sizeof(TuplesortInstrumentation);
node->shared_info = shm_toc_allocate(pcxt->toc, size);
/* ensure any unfilled slots will contain zeroes */
memset(node->shared_info, 0, size);
node->shared_info->num_workers = pcxt->nworkers;
shm_toc_insert(pcxt->toc, node->ss.ps.plan->plan_node_id,
node->shared_info);
}
/* ----------------------------------------------------------------
* ExecSortInitializeWorker
*
* Attach worker to DSM space for sort statistics.
* ----------------------------------------------------------------
*/
void
ExecSortInitializeWorker(SortState *node, ParallelWorkerContext *pwcxt)
{
node->shared_info =
shm_toc_lookup(pwcxt->toc, node->ss.ps.plan->plan_node_id, true);
node->am_worker = true;
}
/* ----------------------------------------------------------------
* ExecSortRetrieveInstrumentation
*
* Transfer sort statistics from DSM to private memory.
* ----------------------------------------------------------------
*/
void
ExecSortRetrieveInstrumentation(SortState *node)
{
Size size;
SharedSortInfo *si;
if (node->shared_info == NULL)
return;
size = offsetof(SharedSortInfo, sinstrument)
+ node->shared_info->num_workers * sizeof(TuplesortInstrumentation);
si = palloc(size);
memcpy(si, node->shared_info, size);
node->shared_info = si;
}