/*-------------------------------------------------------------------------
*
* nodeWindowAgg.c
* routines to handle WindowAgg nodes.
*
* A WindowAgg node evaluates "window functions" across suitable partitions
* of the input tuple set. Any one WindowAgg works for just a single window
* specification, though it can evaluate multiple window functions sharing
* identical window specifications. The input tuples are required to be
* delivered in sorted order, with the PARTITION BY columns (if any) as
* major sort keys and the ORDER BY columns (if any) as minor sort keys.
* (The planner generates a stack of WindowAggs with intervening Sort nodes
* as needed, if a query involves more than one window specification.)
*
* Since window functions can require access to any or all of the rows in
* the current partition, we accumulate rows of the partition into a
* tuplestore. The window functions are called using the WindowObject API
* so that they can access those rows as needed.
*
* We also support using plain aggregate functions as window functions.
* For these, the regular Agg-node environment is emulated for each partition.
* As required by the SQL spec, the output represents the value of the
* aggregate function over all rows in the current row's window frame.
*
*
* Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* src/backend/executor/nodeWindowAgg.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "catalog/pg_aggregate.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "executor/executor.h"
#include "executor/nodeWindowAgg.h"
#include "miscadmin.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/clauses.h"
#include "parser/parse_agg.h"
#include "parser/parse_coerce.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/datum.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/syscache.h"
#include "windowapi.h"
/*
* All the window function APIs are called with this object, which is passed
* to window functions as fcinfo->context.
*/
typedef struct WindowObjectData
{
NodeTag type;
WindowAggState *winstate; /* parent WindowAggState */
List *argstates; /* ExprState trees for fn's arguments */
void *localmem; /* WinGetPartitionLocalMemory's chunk */
int markptr; /* tuplestore mark pointer for this fn */
int readptr; /* tuplestore read pointer for this fn */
int64 markpos; /* row that markptr is positioned on */
int64 seekpos; /* row that readptr is positioned on */
} WindowObjectData;
/*
* We have one WindowStatePerFunc struct for each window function and
* window aggregate handled by this node.
*/
typedef struct WindowStatePerFuncData
{
/* Links to WindowFunc expr and state nodes this working state is for */
WindowFuncExprState *wfuncstate;
WindowFunc *wfunc;
int numArguments; /* number of arguments */
FmgrInfo flinfo; /* fmgr lookup data for window function */
/*
* We need the len and byval info for the result of each function in order
* to know how to copy/delete values.
*/
int16 resulttypeLen;
bool resulttypeByVal;
bool plain_agg; /* is it just a plain aggregate function? */
int aggno; /* if so, index of its PerAggData */
WindowObject winobj; /* object used in window function API */
} WindowStatePerFuncData;
/*
* For plain aggregate window functions, we also have one of these.
*/
typedef struct WindowStatePerAggData
{
/* Oids of transfer functions */
Oid transfn_oid;
Oid finalfn_oid; /* may be InvalidOid */
/*
* fmgr lookup data for transfer functions --- only valid when
* corresponding oid is not InvalidOid. Note in particular that fn_strict
* flags are kept here.
*/
FmgrInfo transfn;
FmgrInfo finalfn;
/*
* initial value from pg_aggregate entry
*/
Datum initValue;
bool initValueIsNull;
/*
* cached value for current frame boundaries
*/
Datum resultValue;
bool resultValueIsNull;
/*
* We need the len and byval info for the agg's input, result, and
* transition data types in order to know how to copy/delete values.
*/
int16 inputtypeLen,
resulttypeLen,
transtypeLen;
bool inputtypeByVal,
resulttypeByVal,
transtypeByVal;
int wfuncno; /* index of associated PerFuncData */
/* Current transition value */
Datum transValue; /* current transition value */
bool transValueIsNull;
bool noTransValue; /* true if transValue not set yet */
} WindowStatePerAggData;
static void initialize_windowaggregate(WindowAggState *winstate,
WindowStatePerFunc perfuncstate,
WindowStatePerAgg peraggstate);
static void advance_windowaggregate(WindowAggState *winstate,
WindowStatePerFunc perfuncstate,
WindowStatePerAgg peraggstate);
static void finalize_windowaggregate(WindowAggState *winstate,
WindowStatePerFunc perfuncstate,
WindowStatePerAgg peraggstate,
Datum *result, bool *isnull);
static void eval_windowaggregates(WindowAggState *winstate);
static void eval_windowfunction(WindowAggState *winstate,
WindowStatePerFunc perfuncstate,
Datum *result, bool *isnull);
static void begin_partition(WindowAggState *winstate);
static void spool_tuples(WindowAggState *winstate, int64 pos);
static void release_partition(WindowAggState *winstate);
static bool row_is_in_frame(WindowAggState *winstate, int64 pos,
TupleTableSlot *slot);
static void update_frameheadpos(WindowObject winobj, TupleTableSlot *slot);
static void update_frametailpos(WindowObject winobj, TupleTableSlot *slot);
static WindowStatePerAggData *initialize_peragg(WindowAggState *winstate,
WindowFunc *wfunc,
WindowStatePerAgg peraggstate);
static Datum GetAggInitVal(Datum textInitVal, Oid transtype);
static bool are_peers(WindowAggState *winstate, TupleTableSlot *slot1,
TupleTableSlot *slot2);
static bool window_gettupleslot(WindowObject winobj, int64 pos,
TupleTableSlot *slot);
/*
* initialize_windowaggregate
* parallel to initialize_aggregates in nodeAgg.c
*/
static void
initialize_windowaggregate(WindowAggState *winstate,
WindowStatePerFunc perfuncstate,
WindowStatePerAgg peraggstate)
{
MemoryContext oldContext;
if (peraggstate->initValueIsNull)
peraggstate->transValue = peraggstate->initValue;
else
{
oldContext = MemoryContextSwitchTo(winstate->aggcontext);
peraggstate->transValue = datumCopy(peraggstate->initValue,
peraggstate->transtypeByVal,
peraggstate->transtypeLen);
MemoryContextSwitchTo(oldContext);
}
peraggstate->transValueIsNull = peraggstate->initValueIsNull;
peraggstate->noTransValue = peraggstate->initValueIsNull;
peraggstate->resultValueIsNull = true;
}
/*
* advance_windowaggregate
* parallel to advance_aggregates in nodeAgg.c
*/
static void
advance_windowaggregate(WindowAggState *winstate,
WindowStatePerFunc perfuncstate,
WindowStatePerAgg peraggstate)
{
WindowFuncExprState *wfuncstate = perfuncstate->wfuncstate;
int numArguments = perfuncstate->numArguments;
FunctionCallInfoData fcinfodata;
FunctionCallInfo fcinfo = &fcinfodata;
Datum newVal;
ListCell *arg;
int i;
MemoryContext oldContext;
ExprContext *econtext = winstate->tmpcontext;
oldContext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
/* We start from 1, since the 0th arg will be the transition value */
i = 1;
foreach(arg, wfuncstate->args)
{
ExprState *argstate = (ExprState *) lfirst(arg);
fcinfo->arg[i] = ExecEvalExpr(argstate, econtext,
&fcinfo->argnull[i], NULL);
i++;
}
if (peraggstate->transfn.fn_strict)
{
/*
* For a strict transfn, nothing happens when there's a NULL input; we
* just keep the prior transValue.
*/
for (i = 1; i <= numArguments; i++)
{
if (fcinfo->argnull[i])
{
MemoryContextSwitchTo(oldContext);
return;
}
}
if (peraggstate->noTransValue)
{
/*
* transValue has not been initialized. This is the first non-NULL
* input value. We use it as the initial value for transValue. (We
* already checked that the agg's input type is binary-compatible
* with its transtype, so straight copy here is OK.)
*
* We must copy the datum into aggcontext if it is pass-by-ref. We
* do not need to pfree the old transValue, since it's NULL.
*/
MemoryContextSwitchTo(winstate->aggcontext);
peraggstate->transValue = datumCopy(fcinfo->arg[1],
peraggstate->transtypeByVal,
peraggstate->transtypeLen);
peraggstate->transValueIsNull = false;
peraggstate->noTransValue = false;
MemoryContextSwitchTo(oldContext);
return;
}
if (peraggstate->transValueIsNull)
{
/*
* Don't call a strict function with NULL inputs. Note it is
* possible to get here despite the above tests, if the transfn is
* strict *and* returned a NULL on a prior cycle. If that happens
* we will propagate the NULL all the way to the end.
*/
MemoryContextSwitchTo(oldContext);
return;
}
}
/*
* OK to call the transition function
*/
InitFunctionCallInfoData(*fcinfo, &(peraggstate->transfn),
numArguments + 1,
(void *) winstate, NULL);
fcinfo->arg[0] = peraggstate->transValue;
fcinfo->argnull[0] = peraggstate->transValueIsNull;
newVal = FunctionCallInvoke(fcinfo);
/*
* If pass-by-ref datatype, must copy the new value into aggcontext and
* pfree the prior transValue. But if transfn returned a pointer to its
* first input, we don't need to do anything.
*/
if (!peraggstate->transtypeByVal &&
DatumGetPointer(newVal) != DatumGetPointer(peraggstate->transValue))
{
if (!fcinfo->isnull)
{
MemoryContextSwitchTo(winstate->aggcontext);
newVal = datumCopy(newVal,
peraggstate->transtypeByVal,
peraggstate->transtypeLen);
}
if (!peraggstate->transValueIsNull)
pfree(DatumGetPointer(peraggstate->transValue));
}
MemoryContextSwitchTo(oldContext);
peraggstate->transValue = newVal;
peraggstate->transValueIsNull = fcinfo->isnull;
}
/*
* finalize_windowaggregate
* parallel to finalize_aggregate in nodeAgg.c
*/
static void
finalize_windowaggregate(WindowAggState *winstate,
WindowStatePerFunc perfuncstate,
WindowStatePerAgg peraggstate,
Datum *result, bool *isnull)
{
MemoryContext oldContext;
oldContext = MemoryContextSwitchTo(winstate->ss.ps.ps_ExprContext->ecxt_per_tuple_memory);
/*
* Apply the agg's finalfn if one is provided, else return transValue.
*/
if (OidIsValid(peraggstate->finalfn_oid))
{
FunctionCallInfoData fcinfo;
InitFunctionCallInfoData(fcinfo, &(peraggstate->finalfn), 1,
(void *) winstate, NULL);
fcinfo.arg[0] = peraggstate->transValue;
fcinfo.argnull[0] = peraggstate->transValueIsNull;
if (fcinfo.flinfo->fn_strict && peraggstate->transValueIsNull)
{
/* don't call a strict function with NULL inputs */
*result = (Datum) 0;
*isnull = true;
}
else
{
*result = FunctionCallInvoke(&fcinfo);
*isnull = fcinfo.isnull;
}
}
else
{
*result = peraggstate->transValue;
*isnull = peraggstate->transValueIsNull;
}
/*
* If result is pass-by-ref, make sure it is in the right context.
*/
if (!peraggstate->resulttypeByVal && !*isnull &&
!MemoryContextContains(CurrentMemoryContext,
DatumGetPointer(*result)))
*result = datumCopy(*result,
peraggstate->resulttypeByVal,
peraggstate->resulttypeLen);
MemoryContextSwitchTo(oldContext);
}
/*
* eval_windowaggregates
* evaluate plain aggregates being used as window functions
*
* Much of this is duplicated from nodeAgg.c. But NOTE that we expect to be
* able to call aggregate final functions repeatedly after aggregating more
* data onto the same transition value. This is not a behavior required by
* nodeAgg.c.
*/
static void
eval_windowaggregates(WindowAggState *winstate)
{
WindowStatePerAgg peraggstate;
int wfuncno,
numaggs;
int i;
MemoryContext oldContext;
ExprContext *econtext;
WindowObject agg_winobj;
TupleTableSlot *agg_row_slot;
numaggs = winstate->numaggs;
if (numaggs == 0)
return; /* nothing to do */
/* final output execution is in ps_ExprContext */
econtext = winstate->ss.ps.ps_ExprContext;
agg_winobj = winstate->agg_winobj;
agg_row_slot = winstate->agg_row_slot;
/*
* Currently, we support only a subset of the SQL-standard window framing
* rules.
*
* If the frame start is UNBOUNDED_PRECEDING, the window frame consists of
* a contiguous group of rows extending forward from the start of the
* partition, and rows only enter the frame, never exit it, as the current
* row advances forward. This makes it possible to use an incremental
* strategy for evaluating aggregates: we run the transition function for
* each row added to the frame, and run the final function whenever we
* need the current aggregate value. This is considerably more efficient
* than the naive approach of re-running the entire aggregate calculation
* for each current row. It does assume that the final function doesn't
* damage the running transition value, but we have the same assumption in
* nodeAgg.c too (when it rescans an existing hash table).
*
* For other frame start rules, we discard the aggregate state and re-run
* the aggregates whenever the frame head row moves. We can still
* optimize as above whenever successive rows share the same frame head.
*
* In many common cases, multiple rows share the same frame and hence the
* same aggregate value. (In particular, if there's no ORDER BY in a RANGE
* window, then all rows are peers and so they all have window frame equal
* to the whole partition.) We optimize such cases by calculating the
* aggregate value once when we reach the first row of a peer group, and
* then returning the saved value for all subsequent rows.
*
* 'aggregatedupto' keeps track of the first row that has not yet been
* accumulated into the aggregate transition values. Whenever we start a
* new peer group, we accumulate forward to the end of the peer group.
*
* TODO: Rerunning aggregates from the frame start can be pretty slow. For
* some aggregates like SUM and COUNT we could avoid that by implementing
* a "negative transition function" that would be called for each row as
* it exits the frame. We'd have to think about avoiding recalculation of
* volatile arguments of aggregate functions, too.
*/
/*
* First, update the frame head position.
*/
update_frameheadpos(agg_winobj, winstate->temp_slot_1);
/*
* Initialize aggregates on first call for partition, or if the frame head
* position moved since last time.
*/
if (winstate->currentpos == 0 ||
winstate->frameheadpos != winstate->aggregatedbase)
{
/*
* Discard transient aggregate values
*/
MemoryContextResetAndDeleteChildren(winstate->aggcontext);
for (i = 0; i < numaggs; i++)
{
peraggstate = &winstate->peragg[i];
wfuncno = peraggstate->wfuncno;
initialize_windowaggregate(winstate,
&winstate->perfunc[wfuncno],
peraggstate);
}
/*
* If we created a mark pointer for aggregates, keep it pushed up to
* frame head, so that tuplestore can discard unnecessary rows.
*/
if (agg_winobj->markptr >= 0)
WinSetMarkPosition(agg_winobj, winstate->frameheadpos);
/*
* Initialize for loop below
*/
ExecClearTuple(agg_row_slot);
winstate->aggregatedbase = winstate->frameheadpos;
winstate->aggregatedupto = winstate->frameheadpos;
}
/*
* In UNBOUNDED_FOLLOWING mode, we don't have to recalculate aggregates
* except when the frame head moves. In END_CURRENT_ROW mode, we only
* have to recalculate when the frame head moves or currentpos has
* advanced past the place we'd aggregated up to. Check for these cases
* and if so, reuse the saved result values.
*/
if ((winstate->frameOptions & (FRAMEOPTION_END_UNBOUNDED_FOLLOWING |
FRAMEOPTION_END_CURRENT_ROW)) &&
winstate->aggregatedbase <= winstate->currentpos &&
winstate->aggregatedupto > winstate->currentpos)
{
for (i = 0; i < numaggs; i++)
{
peraggstate = &winstate->peragg[i];
wfuncno = peraggstate->wfuncno;
econtext->ecxt_aggvalues[wfuncno] = peraggstate->resultValue;
econtext->ecxt_aggnulls[wfuncno] = peraggstate->resultValueIsNull;
}
return;
}
/*
* Advance until we reach a row not in frame (or end of partition).
*
* Note the loop invariant: agg_row_slot is either empty or holds the row
* at position aggregatedupto. We advance aggregatedupto after processing
* a row.
*/
for (;;)
{
/* Fetch next row if we didn't already */
if (TupIsNull(agg_row_slot))
{
if (!window_gettupleslot(agg_winobj, winstate->aggregatedupto,
agg_row_slot))
break; /* must be end of partition */
}
/* Exit loop (for now) if not in frame */
if (!row_is_in_frame(winstate, winstate->aggregatedupto, agg_row_slot))
break;
/* Set tuple context for evaluation of aggregate arguments */
winstate->tmpcontext->ecxt_outertuple = agg_row_slot;
/* Accumulate row into the aggregates */
for (i = 0; i < numaggs; i++)
{
peraggstate = &winstate->peragg[i];
wfuncno = peraggstate->wfuncno;
advance_windowaggregate(winstate,
&winstate->perfunc[wfuncno],
peraggstate);
}
/* Reset per-input-tuple context after each tuple */
ResetExprContext(winstate->tmpcontext);
/* And advance the aggregated-row state */
winstate->aggregatedupto++;
ExecClearTuple(agg_row_slot);
}
/*
* finalize aggregates and fill result/isnull fields.
*/
for (i = 0; i < numaggs; i++)
{
Datum *result;
bool *isnull;
peraggstate = &winstate->peragg[i];
wfuncno = peraggstate->wfuncno;
result = &econtext->ecxt_aggvalues[wfuncno];
isnull = &econtext->ecxt_aggnulls[wfuncno];
finalize_windowaggregate(winstate,
&winstate->perfunc[wfuncno],
peraggstate,
result, isnull);
/*
* save the result in case next row shares the same frame.
*
* XXX in some framing modes, eg ROWS/END_CURRENT_ROW, we can know in
* advance that the next row can't possibly share the same frame. Is
* it worth detecting that and skipping this code?
*/
if (!peraggstate->resulttypeByVal)
{
/*
* clear old resultValue in order not to leak memory. (Note: the
* new result can't possibly be the same datum as old resultValue,
* because we never passed it to the trans function.)
*/
if (!peraggstate->resultValueIsNull)
pfree(DatumGetPointer(peraggstate->resultValue));
/*
* If pass-by-ref, copy it into our aggregate context.
*/
if (!*isnull)
{
oldContext = MemoryContextSwitchTo(winstate->aggcontext);
peraggstate->resultValue =
datumCopy(*result,
peraggstate->resulttypeByVal,
peraggstate->resulttypeLen);
MemoryContextSwitchTo(oldContext);
}
}
else
{
peraggstate->resultValue = *result;
}
peraggstate->resultValueIsNull = *isnull;
}
}
/*
* eval_windowfunction
*
* Arguments of window functions are not evaluated here, because a window
* function can need random access to arbitrary rows in the partition.
* The window function uses the special WinGetFuncArgInPartition and
* WinGetFuncArgInFrame functions to evaluate the arguments for the rows
* it wants.
*/
static void
eval_windowfunction(WindowAggState *winstate, WindowStatePerFunc perfuncstate,
Datum *result, bool *isnull)
{
FunctionCallInfoData fcinfo;
MemoryContext oldContext;
oldContext = MemoryContextSwitchTo(winstate->ss.ps.ps_ExprContext->ecxt_per_tuple_memory);
/*
* We don't pass any normal arguments to a window function, but we do pass
* it the number of arguments, in order to permit window function
* implementations to support varying numbers of arguments. The real info
* goes through the WindowObject, which is passed via fcinfo->context.
*/
InitFunctionCallInfoData(fcinfo, &(perfuncstate->flinfo),
perfuncstate->numArguments,
(void *) perfuncstate->winobj, NULL);
/* Just in case, make all the regular argument slots be null */
memset(fcinfo.argnull, true, perfuncstate->numArguments);
*result = FunctionCallInvoke(&fcinfo);
*isnull = fcinfo.isnull;
/*
* Make sure pass-by-ref data is allocated in the appropriate context. (We
* need this in case the function returns a pointer into some short-lived
* tuple, as is entirely possible.)
*/
if (!perfuncstate->resulttypeByVal && !fcinfo.isnull &&
!MemoryContextContains(CurrentMemoryContext,
DatumGetPointer(*result)))
*result = datumCopy(*result,
perfuncstate->resulttypeByVal,
perfuncstate->resulttypeLen);
MemoryContextSwitchTo(oldContext);
}
/*
* begin_partition
* Start buffering rows of the next partition.
*/
static void
begin_partition(WindowAggState *winstate)
{
PlanState *outerPlan = outerPlanState(winstate);
int numfuncs = winstate->numfuncs;
int i;
winstate->partition_spooled = false;
winstate->framehead_valid = false;
winstate->frametail_valid = false;
winstate->spooled_rows = 0;
winstate->currentpos = 0;
winstate->frameheadpos = 0;
winstate->frametailpos = -1;
ExecClearTuple(winstate->agg_row_slot);
/*
* If this is the very first partition, we need to fetch the first input
* row to store in first_part_slot.
*/
if (TupIsNull(winstate->first_part_slot))
{
TupleTableSlot *outerslot = ExecProcNode(outerPlan);
if (!TupIsNull(outerslot))
ExecCopySlot(winstate->first_part_slot, outerslot);
else
{
/* outer plan is empty, so we have nothing to do */
winstate->partition_spooled = true;
winstate->more_partitions = false;
return;
}
}
/* Create new tuplestore for this partition */
winstate->buffer = tuplestore_begin_heap(false, false, work_mem);
/*
* Set up read pointers for the tuplestore. The current pointer doesn't
* need BACKWARD capability, but the per-window-function read pointers do,
* and the aggregate pointer does if frame start is movable.
*/
winstate->current_ptr = 0; /* read pointer 0 is pre-allocated */
/* reset default REWIND capability bit for current ptr */
tuplestore_set_eflags(winstate->buffer, 0);
/* create read pointers for aggregates, if needed */
if (winstate->numaggs > 0)
{
WindowObject agg_winobj = winstate->agg_winobj;
int readptr_flags = 0;
/* If the frame head is potentially movable ... */
if (!(winstate->frameOptions & FRAMEOPTION_START_UNBOUNDED_PRECEDING))
{
/* ... create a mark pointer to track the frame head */
agg_winobj->markptr = tuplestore_alloc_read_pointer(winstate->buffer, 0);
/* and the read pointer will need BACKWARD capability */
readptr_flags |= EXEC_FLAG_BACKWARD;
}
agg_winobj->readptr = tuplestore_alloc_read_pointer(winstate->buffer,
readptr_flags);
agg_winobj->markpos = -1;
agg_winobj->seekpos = -1;
/* Also reset the row counters for aggregates */
winstate->aggregatedbase = 0;
winstate->aggregatedupto = 0;
}
/* create mark and read pointers for each real window function */
for (i = 0; i < numfuncs; i++)
{
WindowStatePerFunc perfuncstate = &(winstate->perfunc[i]);
if (!perfuncstate->plain_agg)
{
WindowObject winobj = perfuncstate->winobj;
winobj->markptr = tuplestore_alloc_read_pointer(winstate->buffer,
0);
winobj->readptr = tuplestore_alloc_read_pointer(winstate->buffer,
EXEC_FLAG_BACKWARD);
winobj->markpos = -1;
winobj->seekpos = -1;
}
}
/*
* Store the first tuple into the tuplestore (it's always available now;
* we either read it above, or saved it at the end of previous partition)
*/
tuplestore_puttupleslot(winstate->buffer, winstate->first_part_slot);
winstate->spooled_rows++;
}
/*
* Read tuples from the outer node, up to and including position 'pos', and
* store them into the tuplestore. If pos is -1, reads the whole partition.
*/
static void
spool_tuples(WindowAggState *winstate, int64 pos)
{
WindowAgg *node = (WindowAgg *) winstate->ss.ps.plan;
PlanState *outerPlan;
TupleTableSlot *outerslot;
MemoryContext oldcontext;
if (!winstate->buffer)
return; /* just a safety check */
if (winstate->partition_spooled)
return; /* whole partition done already */
/*
* If the tuplestore has spilled to disk, alternate reading and writing
* becomes quite expensive due to frequent buffer flushes. It's cheaper
* to force the entire partition to get spooled in one go.
*
* XXX this is a horrid kluge --- it'd be better to fix the performance
* problem inside tuplestore. FIXME
*/
if (!tuplestore_in_memory(winstate->buffer))
pos = -1;
outerPlan = outerPlanState(winstate);
/* Must be in query context to call outerplan */
oldcontext = MemoryContextSwitchTo(winstate->ss.ps.ps_ExprContext->ecxt_per_query_memory);
while (winstate->spooled_rows <= pos || pos == -1)
{
outerslot = ExecProcNode(outerPlan);
if (TupIsNull(outerslot))
{
/* reached the end of the last partition */
winstate->partition_spooled = true;
winstate->more_partitions = false;
break;
}
if (node->partNumCols > 0)
{
/* Check if this tuple still belongs to the current partition */
if (!execTuplesMatch(winstate->first_part_slot,
outerslot,
node->partNumCols, node->partColIdx,
winstate->partEqfunctions,
winstate->tmpcontext->ecxt_per_tuple_memory))
{
/*
* end of partition; copy the tuple for the next cycle.
*/
ExecCopySlot(winstate->first_part_slot, outerslot);
winstate->partition_spooled = true;
winstate->more_partitions = true;
break;
}
}
/* Still in partition, so save it into the tuplestore */
tuplestore_puttupleslot(winstate->buffer, outerslot);
winstate->spooled_rows++;
}
MemoryContextSwitchTo(oldcontext);
}
/*
* release_partition
* clear information kept within a partition, including
* tuplestore and aggregate results.
*/
static void
release_partition(WindowAggState *winstate)
{
int i;
for (i = 0; i < winstate->numfuncs; i++)
{
WindowStatePerFunc perfuncstate = &(winstate->perfunc[i]);
/* Release any partition-local state of this window function */
if (perfuncstate->winobj)
perfuncstate->winobj->localmem = NULL;
}
/*
* Release all partition-local memory (in particular, any partition-local
* state that we might have trashed our pointers to in the above loop, and
* any aggregate temp data). We don't rely on retail pfree because some
* aggregates might have allocated data we don't have direct pointers to.
*/
MemoryContextResetAndDeleteChildren(winstate->partcontext);
MemoryContextResetAndDeleteChildren(winstate->aggcontext);
if (winstate->buffer)
tuplestore_end(winstate->buffer);
winstate->buffer = NULL;
winstate->partition_spooled = false;
}
/*
* row_is_in_frame
* Determine whether a row is in the current row's window frame according
* to our window framing rule
*
* The caller must have already determined that the row is in the partition
* and fetched it into a slot. This function just encapsulates the framing
* rules.
*/
static bool
row_is_in_frame(WindowAggState *winstate, int64 pos, TupleTableSlot *slot)
{
int frameOptions = winstate->frameOptions;
Assert(pos >= 0); /* else caller error */
/* First, check frame starting conditions */
if (frameOptions & FRAMEOPTION_START_CURRENT_ROW)
{
if (frameOptions & FRAMEOPTION_ROWS)
{
/* rows before current row are out of frame */
if (pos < winstate->currentpos)
return false;
}
else if (frameOptions & FRAMEOPTION_RANGE)
{
/* preceding row that is not peer is out of frame */
if (pos < winstate->currentpos &&
!are_peers(winstate, slot, winstate->ss.ss_ScanTupleSlot))
return false;
}
else
Assert(false);
}
else if (frameOptions & FRAMEOPTION_START_VALUE)
{
if (frameOptions & FRAMEOPTION_ROWS)
{
int64 offset = DatumGetInt64(winstate->startOffsetValue);
/* rows before current row + offset are out of frame */
if (frameOptions & FRAMEOPTION_START_VALUE_PRECEDING)
offset = -offset;
if (pos < winstate->currentpos + offset)
return false;
}
else if (frameOptions & FRAMEOPTION_RANGE)
{
/* parser should have rejected this */
elog(ERROR, "window frame with value offset is not implemented");
}
else
Assert(false);
}
/* Okay so far, now check frame ending conditions */
if (frameOptions & FRAMEOPTION_END_CURRENT_ROW)
{
if (frameOptions & FRAMEOPTION_ROWS)
{
/* rows after current row are out of frame */
if (pos > winstate->currentpos)
return false;
}
else if (frameOptions & FRAMEOPTION_RANGE)
{
/* following row that is not peer is out of frame */
if (pos > winstate->currentpos &&
!are_peers(winstate, slot, winstate->ss.ss_ScanTupleSlot))
return false;
}
else
Assert(false);
}
else if (frameOptions & FRAMEOPTION_END_VALUE)
{
if (frameOptions & FRAMEOPTION_ROWS)
{
int64 offset = DatumGetInt64(winstate->endOffsetValue);
/* rows after current row + offset are out of frame */
if (frameOptions & FRAMEOPTION_END_VALUE_PRECEDING)
offset = -offset;
if (pos > winstate->currentpos + offset)
return false;
}
else if (frameOptions & FRAMEOPTION_RANGE)
{
/* parser should have rejected this */
elog(ERROR, "window frame with value offset is not implemented");
}
else
Assert(false);
}
/* If we get here, it's in frame */
return true;
}
/*
* update_frameheadpos
* make frameheadpos valid for the current row
*
* Uses the winobj's read pointer for any required fetches; hence, if the
* frame mode is one that requires row comparisons, the winobj's mark must
* not be past the currently known frame head. Also uses the specified slot
* for any required fetches.
*/
static void
update_frameheadpos(WindowObject winobj, TupleTableSlot *slot)
{
WindowAggState *winstate = winobj->winstate;
WindowAgg *node = (WindowAgg *) winstate->ss.ps.plan;
int frameOptions = winstate->frameOptions;
if (winstate->framehead_valid)
return; /* already known for current row */
if (frameOptions & FRAMEOPTION_START_UNBOUNDED_PRECEDING)
{
/* In UNBOUNDED PRECEDING mode, frame head is always row 0 */
winstate->frameheadpos = 0;
winstate->framehead_valid = true;
}
else if (frameOptions & FRAMEOPTION_START_CURRENT_ROW)
{
if (frameOptions & FRAMEOPTION_ROWS)
{
/* In ROWS mode, frame head is the same as current */
winstate->frameheadpos = winstate->currentpos;
winstate->framehead_valid = true;
}
else if (frameOptions & FRAMEOPTION_RANGE)
{
int64 fhprev;
/* If no ORDER BY, all rows are peers with each other */
if (node->ordNumCols == 0)
{
winstate->frameheadpos = 0;
winstate->framehead_valid = true;
return;
}
/*
* In RANGE START_CURRENT mode, frame head is the first row that
* is a peer of current row. We search backwards from current,
* which could be a bit inefficient if peer sets are large. Might
* be better to have a separate read pointer that moves forward
* tracking the frame head.
*/
fhprev = winstate->currentpos - 1;
for (;;)
{
/* assume the frame head can't go backwards */
if (fhprev < winstate->frameheadpos)
break;
if (!window_gettupleslot(winobj, fhprev, slot))
break; /* start of partition */
if (!are_peers(winstate, slot, winstate->ss.ss_ScanTupleSlot))
break; /* not peer of current row */
fhprev--;
}
winstate->frameheadpos = fhprev + 1;
winstate->framehead_valid = true;
}
else
Assert(false);
}
else if (frameOptions & FRAMEOPTION_START_VALUE)
{
if (frameOptions & FRAMEOPTION_ROWS)
{
/* In ROWS mode, bound is physically n before/after current */
int64 offset = DatumGetInt64(winstate->startOffsetValue);
if (frameOptions & FRAMEOPTION_START_VALUE_PRECEDING)
offset = -offset;
winstate->frameheadpos = winstate->currentpos + offset;
/* frame head can't go before first row */
if (winstate->frameheadpos < 0)
winstate->frameheadpos = 0;
else if (winstate->frameheadpos > winstate->currentpos)
{
/* make sure frameheadpos is not past end of partition */
spool_tuples(winstate, winstate->frameheadpos - 1);
if (winstate->frameheadpos > winstate->spooled_rows)
winstate->frameheadpos = winstate->spooled_rows;
}
winstate->framehead_valid = true;
}
else if (frameOptions & FRAMEOPTION_RANGE)
{
/* parser should have rejected this */
elog(ERROR, "window frame with value offset is not implemented");
}
else
Assert(false);
}
else
Assert(false);
}
/*
* update_frametailpos
* make frametailpos valid for the current row
*
* Uses the winobj's read pointer for any required fetches; hence, if the
* frame mode is one that requires row comparisons, the winobj's mark must
* not be past the currently known frame tail. Also uses the specified slot
* for any required fetches.
*/
static void
update_frametailpos(WindowObject winobj, TupleTableSlot *slot)
{
WindowAggState *winstate = winobj->winstate;
WindowAgg *node = (WindowAgg *) winstate->ss.ps.plan;
int frameOptions = winstate->frameOptions;
if (winstate->frametail_valid)
return; /* already known for current row */
if (frameOptions & FRAMEOPTION_END_UNBOUNDED_FOLLOWING)
{
/* In UNBOUNDED FOLLOWING mode, all partition rows are in frame */
spool_tuples(winstate, -1);
winstate->frametailpos = winstate->spooled_rows - 1;
winstate->frametail_valid = true;
}
else if (frameOptions & FRAMEOPTION_END_CURRENT_ROW)
{
if (frameOptions & FRAMEOPTION_ROWS)
{
/* In ROWS mode, exactly the rows up to current are in frame */
winstate->frametailpos = winstate->currentpos;
winstate->frametail_valid = true;
}
else if (frameOptions & FRAMEOPTION_RANGE)
{
int64 ftnext;
/* If no ORDER BY, all rows are peers with each other */
if (node->ordNumCols == 0)
{
spool_tuples(winstate, -1);
winstate->frametailpos = winstate->spooled_rows - 1;
winstate->frametail_valid = true;
return;
}
/*
* Else we have to search for the first non-peer of the current
* row. We assume the current value of frametailpos is a lower
* bound on the possible frame tail location, ie, frame tail never
* goes backward, and that currentpos is also a lower bound, ie,
* frame end always >= current row.
*/
ftnext = Max(winstate->frametailpos, winstate->currentpos) + 1;
for (;;)
{
if (!window_gettupleslot(winobj, ftnext, slot))
break; /* end of partition */
if (!are_peers(winstate, slot, winstate->ss.ss_ScanTupleSlot))
break; /* not peer of current row */
ftnext++;
}
winstate->frametailpos = ftnext - 1;
winstate->frametail_valid = true;
}
else
Assert(false);
}
else if (frameOptions & FRAMEOPTION_END_VALUE)
{
if (frameOptions & FRAMEOPTION_ROWS)
{
/* In ROWS mode, bound is physically n before/after current */
int64 offset = DatumGetInt64(winstate->endOffsetValue);
if (frameOptions & FRAMEOPTION_END_VALUE_PRECEDING)
offset = -offset;
winstate->frametailpos = winstate->currentpos + offset;
/* smallest allowable value of frametailpos is -1 */
if (winstate->frametailpos < 0)
winstate->frametailpos = -1;
else if (winstate->frametailpos > winstate->currentpos)
{
/* make sure frametailpos is not past last row of partition */
spool_tuples(winstate, winstate->frametailpos);
if (winstate->frametailpos >= winstate->spooled_rows)
winstate->frametailpos = winstate->spooled_rows - 1;
}
winstate->frametail_valid = true;
}
else if (frameOptions & FRAMEOPTION_RANGE)
{
/* parser should have rejected this */
elog(ERROR, "window frame with value offset is not implemented");
}
else
Assert(false);
}
else
Assert(false);
}
/* -----------------
* ExecWindowAgg
*
* ExecWindowAgg receives tuples from its outer subplan and
* stores them into a tuplestore, then processes window functions.
* This node doesn't reduce nor qualify any row so the number of
* returned rows is exactly the same as its outer subplan's result
* (ignoring the case of SRFs in the targetlist, that is).
* -----------------
*/
TupleTableSlot *
ExecWindowAgg(WindowAggState *winstate)
{
TupleTableSlot *result;
ExprDoneCond isDone;
ExprContext *econtext;
int i;
int numfuncs;
if (winstate->all_done)
return NULL;
/*
* Check to see if we're still projecting out tuples from a previous
* output tuple (because there is a function-returning-set in the
* projection expressions). If so, try to project another one.
*/
if (winstate->ss.ps.ps_TupFromTlist)
{
TupleTableSlot *result;
ExprDoneCond isDone;
result = ExecProject(winstate->ss.ps.ps_ProjInfo, &isDone);
if (isDone == ExprMultipleResult)
return result;
/* Done with that source tuple... */
winstate->ss.ps.ps_TupFromTlist = false;
}
/*
* Compute frame offset values, if any, during first call.
*/
if (winstate->all_first)
{
int frameOptions = winstate->frameOptions;
ExprContext *econtext = winstate->ss.ps.ps_ExprContext;
Datum value;
bool isnull;
int16 len;
bool byval;
if (frameOptions & FRAMEOPTION_START_VALUE)
{
Assert(winstate->startOffset != NULL);
value = ExecEvalExprSwitchContext(winstate->startOffset,
econtext,
&isnull,
NULL);
if (isnull)
ereport(ERROR,
(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
errmsg("frame starting offset must not be null")));
/* copy value into query-lifespan context */
get_typlenbyval(exprType((Node *) winstate->startOffset->expr),
&len, &byval);
winstate->startOffsetValue = datumCopy(value, byval, len);
if (frameOptions & FRAMEOPTION_ROWS)
{
/* value is known to be int8 */
int64 offset = DatumGetInt64(value);
if (offset < 0)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("frame starting offset must not be negative")));
}
}
if (frameOptions & FRAMEOPTION_END_VALUE)
{
Assert(winstate->endOffset != NULL);
value = ExecEvalExprSwitchContext(winstate->endOffset,
econtext,
&isnull,
NULL);
if (isnull)
ereport(ERROR,
(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
errmsg("frame ending offset must not be null")));
/* copy value into query-lifespan context */
get_typlenbyval(exprType((Node *) winstate->endOffset->expr),
&len, &byval);
winstate->endOffsetValue = datumCopy(value, byval, len);
if (frameOptions & FRAMEOPTION_ROWS)
{
/* value is known to be int8 */
int64 offset = DatumGetInt64(value);
if (offset < 0)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("frame ending offset must not be negative")));
}
}
winstate->all_first = false;
}
restart:
if (winstate->buffer == NULL)
{
/* Initialize for first partition and set current row = 0 */
begin_partition(winstate);
/* If there are no input rows, we'll detect that and exit below */
}
else
{
/* Advance current row within partition */
winstate->currentpos++;
/* This might mean that the frame moves, too */
winstate->framehead_valid = false;
winstate->frametail_valid = false;
}
/*
* Spool all tuples up to and including the current row, if we haven't
* already
*/
spool_tuples(winstate, winstate->currentpos);
/* Move to the next partition if we reached the end of this partition */
if (winstate->partition_spooled &&
winstate->currentpos >= winstate->spooled_rows)
{
release_partition(winstate);
if (winstate->more_partitions)
{
begin_partition(winstate);
Assert(winstate->spooled_rows > 0);
}
else
{
winstate->all_done = true;
return NULL;
}
}
/* final output execution is in ps_ExprContext */
econtext = winstate->ss.ps.ps_ExprContext;
/* Clear the per-output-tuple context for current row */
ResetExprContext(econtext);
/*
* Read the current row from the tuplestore, and save in ScanTupleSlot.
* (We can't rely on the outerplan's output slot because we may have to
* read beyond the current row. Also, we have to actually copy the row
* out of the tuplestore, since window function evaluation might cause the
* tuplestore to dump its state to disk.)
*
* Current row must be in the tuplestore, since we spooled it above.
*/
tuplestore_select_read_pointer(winstate->buffer, winstate->current_ptr);
if (!tuplestore_gettupleslot(winstate->buffer, true, true,
winstate->ss.ss_ScanTupleSlot))
elog(ERROR, "unexpected end of tuplestore");
/*
* Evaluate true window functions
*/
numfuncs = winstate->numfuncs;
for (i = 0; i < numfuncs; i++)
{
WindowStatePerFunc perfuncstate = &(winstate->perfunc[i]);
if (perfuncstate->plain_agg)
continue;
eval_windowfunction(winstate, perfuncstate,
&(econtext->ecxt_aggvalues[perfuncstate->wfuncstate->wfuncno]),
&(econtext->ecxt_aggnulls[perfuncstate->wfuncstate->wfuncno]));
}
/*
* Evaluate aggregates
*/
if (winstate->numaggs > 0)
eval_windowaggregates(winstate);
/*
* Truncate any no-longer-needed rows from the tuplestore.
*/
tuplestore_trim(winstate->buffer);
/*
* Form and return a projection tuple using the windowfunc results and the
* current row. Setting ecxt_outertuple arranges that any Vars will be
* evaluated with respect to that row.
*/
econtext->ecxt_outertuple = winstate->ss.ss_ScanTupleSlot;
result = ExecProject(winstate->ss.ps.ps_ProjInfo, &isDone);
if (isDone == ExprEndResult)
{
/* SRF in tlist returned no rows, so advance to next input tuple */
goto restart;
}
winstate->ss.ps.ps_TupFromTlist =
(isDone == ExprMultipleResult);
return result;
}
/* -----------------
* ExecInitWindowAgg
*
* Creates the run-time information for the WindowAgg node produced by the
* planner and initializes its outer subtree
* -----------------
*/
WindowAggState *
ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
{
WindowAggState *winstate;
Plan *outerPlan;
ExprContext *econtext;
ExprContext *tmpcontext;
WindowStatePerFunc perfunc;
WindowStatePerAgg peragg;
int numfuncs,
wfuncno,
numaggs,
aggno;
ListCell *l;
/* check for unsupported flags */
Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
/*
* create state structure
*/
winstate = makeNode(WindowAggState);
winstate->ss.ps.plan = (Plan *) node;
winstate->ss.ps.state = estate;
/*
* Create expression contexts. We need two, one for per-input-tuple
* processing and one for per-output-tuple processing. We cheat a little
* by using ExecAssignExprContext() to build both.
*/
ExecAssignExprContext(estate, &winstate->ss.ps);
tmpcontext = winstate->ss.ps.ps_ExprContext;
winstate->tmpcontext = tmpcontext;
ExecAssignExprContext(estate, &winstate->ss.ps);
/* Create long-lived context for storage of partition-local memory etc */
winstate->partcontext =
AllocSetContextCreate(CurrentMemoryContext,
"WindowAgg_Partition",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
/* Create mid-lived context for aggregate trans values etc */
winstate->aggcontext =
AllocSetContextCreate(CurrentMemoryContext,
"WindowAgg_Aggregates",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
/*
* tuple table initialization
*/
ExecInitScanTupleSlot(estate, &winstate->ss);
ExecInitResultTupleSlot(estate, &winstate->ss.ps);
winstate->first_part_slot = ExecInitExtraTupleSlot(estate);
winstate->agg_row_slot = ExecInitExtraTupleSlot(estate);
winstate->temp_slot_1 = ExecInitExtraTupleSlot(estate);
winstate->temp_slot_2 = ExecInitExtraTupleSlot(estate);
winstate->ss.ps.targetlist = (List *)
ExecInitExpr((Expr *) node->plan.targetlist,
(PlanState *) winstate);
/*
* WindowAgg nodes never have quals, since they can only occur at the
* logical top level of a query (ie, after any WHERE or HAVING filters)
*/
Assert(node->plan.qual == NIL);
winstate->ss.ps.qual = NIL;
/*
* initialize child nodes
*/
outerPlan = outerPlan(node);
outerPlanState(winstate) = ExecInitNode(outerPlan, estate, eflags);
/*
* initialize source tuple type (which is also the tuple type that we'll
* store in the tuplestore and use in all our working slots).
*/
ExecAssignScanTypeFromOuterPlan(&winstate->ss);
ExecSetSlotDescriptor(winstate->first_part_slot,
winstate->ss.ss_ScanTupleSlot->tts_tupleDescriptor);
ExecSetSlotDescriptor(winstate->agg_row_slot,
winstate->ss.ss_ScanTupleSlot->tts_tupleDescriptor);
ExecSetSlotDescriptor(winstate->temp_slot_1,
winstate->ss.ss_ScanTupleSlot->tts_tupleDescriptor);
ExecSetSlotDescriptor(winstate->temp_slot_2,
winstate->ss.ss_ScanTupleSlot->tts_tupleDescriptor);
/*
* Initialize result tuple type and projection info.
*/
ExecAssignResultTypeFromTL(&winstate->ss.ps);
ExecAssignProjectionInfo(&winstate->ss.ps, NULL);
winstate->ss.ps.ps_TupFromTlist = false;
/* Set up data for comparing tuples */
if (node->partNumCols > 0)
winstate->partEqfunctions = execTuplesMatchPrepare(node->partNumCols,
node->partOperators);
if (node->ordNumCols > 0)
winstate->ordEqfunctions = execTuplesMatchPrepare(node->ordNumCols,
node->ordOperators);
/*
* WindowAgg nodes use aggvalues and aggnulls as well as Agg nodes.
*/
numfuncs = winstate->numfuncs;
numaggs = winstate->numaggs;
econtext = winstate->ss.ps.ps_ExprContext;
econtext->ecxt_aggvalues = (Datum *) palloc0(sizeof(Datum) * numfuncs);
econtext->ecxt_aggnulls = (bool *) palloc0(sizeof(bool) * numfuncs);
/*
* allocate per-wfunc/per-agg state information.
*/
perfunc = (WindowStatePerFunc) palloc0(sizeof(WindowStatePerFuncData) * numfuncs);
peragg = (WindowStatePerAgg) palloc0(sizeof(WindowStatePerAggData) * numaggs);
winstate->perfunc = perfunc;
winstate->peragg = peragg;
wfuncno = -1;
aggno = -1;
foreach(l, winstate->funcs)
{
WindowFuncExprState *wfuncstate = (WindowFuncExprState *) lfirst(l);
WindowFunc *wfunc = (WindowFunc *) wfuncstate->xprstate.expr;
WindowStatePerFunc perfuncstate;
AclResult aclresult;
int i;
if (wfunc->winref != node->winref) /* planner screwed up? */
elog(ERROR, "WindowFunc with winref %u assigned to WindowAgg with winref %u",
wfunc->winref, node->winref);
/* Look for a previous duplicate window function */
for (i = 0; i <= wfuncno; i++)
{
if (equal(wfunc, perfunc[i].wfunc) &&
!contain_volatile_functions((Node *) wfunc))
break;
}
if (i <= wfuncno)
{
/* Found a match to an existing entry, so just mark it */
wfuncstate->wfuncno = i;
continue;
}
/* Nope, so assign a new PerAgg record */
perfuncstate = &perfunc[++wfuncno];
/* Mark WindowFunc state node with assigned index in the result array */
wfuncstate->wfuncno = wfuncno;
/* Check permission to call window function */
aclresult = pg_proc_aclcheck(wfunc->winfnoid, GetUserId(),
ACL_EXECUTE);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, ACL_KIND_PROC,
get_func_name(wfunc->winfnoid));
/* Fill in the perfuncstate data */
perfuncstate->wfuncstate = wfuncstate;
perfuncstate->wfunc = wfunc;
perfuncstate->numArguments = list_length(wfuncstate->args);
fmgr_info_cxt(wfunc->winfnoid, &perfuncstate->flinfo,
econtext->ecxt_per_query_memory);
fmgr_info_expr((Node *) wfunc, &perfuncstate->flinfo);
get_typlenbyval(wfunc->wintype,
&perfuncstate->resulttypeLen,
&perfuncstate->resulttypeByVal);
/*
* If it's really just a plain aggregate function, we'll emulate the
* Agg environment for it.
*/
perfuncstate->plain_agg = wfunc->winagg;
if (wfunc->winagg)
{
WindowStatePerAgg peraggstate;
perfuncstate->aggno = ++aggno;
peraggstate = &winstate->peragg[aggno];
initialize_peragg(winstate, wfunc, peraggstate);
peraggstate->wfuncno = wfuncno;
}
else
{
WindowObject winobj = makeNode(WindowObjectData);
winobj->winstate = winstate;
winobj->argstates = wfuncstate->args;
winobj->localmem = NULL;
perfuncstate->winobj = winobj;
}
}
/* Update numfuncs, numaggs to match number of unique functions found */
winstate->numfuncs = wfuncno + 1;
winstate->numaggs = aggno + 1;
/* Set up WindowObject for aggregates, if needed */
if (winstate->numaggs > 0)
{
WindowObject agg_winobj = makeNode(WindowObjectData);
agg_winobj->winstate = winstate;
agg_winobj->argstates = NIL;
agg_winobj->localmem = NULL;
/* make sure markptr = -1 to invalidate. It may not get used */
agg_winobj->markptr = -1;
agg_winobj->readptr = -1;
winstate->agg_winobj = agg_winobj;
}
/* copy frame options to state node for easy access */
winstate->frameOptions = node->frameOptions;
/* initialize frame bound offset expressions */
winstate->startOffset = ExecInitExpr((Expr *) node->startOffset,
(PlanState *) winstate);
winstate->endOffset = ExecInitExpr((Expr *) node->endOffset,
(PlanState *) winstate);
winstate->all_first = true;
winstate->partition_spooled = false;
winstate->more_partitions = false;
return winstate;
}
/* -----------------
* ExecEndWindowAgg
* -----------------
*/
void
ExecEndWindowAgg(WindowAggState *node)
{
PlanState *outerPlan;
release_partition(node);
pfree(node->perfunc);
pfree(node->peragg);
ExecClearTuple(node->ss.ss_ScanTupleSlot);
ExecClearTuple(node->first_part_slot);
ExecClearTuple(node->agg_row_slot);
ExecClearTuple(node->temp_slot_1);
ExecClearTuple(node->temp_slot_2);
/*
* Free both the expr contexts.
*/
ExecFreeExprContext(&node->ss.ps);
node->ss.ps.ps_ExprContext = node->tmpcontext;
ExecFreeExprContext(&node->ss.ps);
MemoryContextDelete(node->partcontext);
MemoryContextDelete(node->aggcontext);
outerPlan = outerPlanState(node);
ExecEndNode(outerPlan);
}
/* -----------------
* ExecRescanWindowAgg
* -----------------
*/
void
ExecReScanWindowAgg(WindowAggState *node)
{
ExprContext *econtext = node->ss.ps.ps_ExprContext;
node->all_done = false;
node->ss.ps.ps_TupFromTlist = false;
node->all_first = true;
/* release tuplestore et al */
release_partition(node);
/* release all temp tuples, but especially first_part_slot */
ExecClearTuple(node->ss.ss_ScanTupleSlot);
ExecClearTuple(node->first_part_slot);
ExecClearTuple(node->agg_row_slot);
ExecClearTuple(node->temp_slot_1);
ExecClearTuple(node->temp_slot_2);
/* Forget current wfunc values */
MemSet(econtext->ecxt_aggvalues, 0, sizeof(Datum) * node->numfuncs);
MemSet(econtext->ecxt_aggnulls, 0, sizeof(bool) * node->numfuncs);
/*
* if chgParam of subnode is not null then plan will be re-scanned by
* first ExecProcNode.
*/
if (node->ss.ps.lefttree->chgParam == NULL)
ExecReScan(node->ss.ps.lefttree);
}
/*
* initialize_peragg
*
* Almost same as in nodeAgg.c, except we don't support DISTINCT currently.
*/
static WindowStatePerAggData *
initialize_peragg(WindowAggState *winstate, WindowFunc *wfunc,
WindowStatePerAgg peraggstate)
{
Oid inputTypes[FUNC_MAX_ARGS];
int numArguments;
HeapTuple aggTuple;
Form_pg_aggregate aggform;
Oid aggtranstype;
AclResult aclresult;
Oid transfn_oid,
finalfn_oid;
Expr *transfnexpr,
*finalfnexpr;
Datum textInitVal;
int i;
ListCell *lc;
numArguments = list_length(wfunc->args);
i = 0;
foreach(lc, wfunc->args)
{
inputTypes[i++] = exprType((Node *) lfirst(lc));
}
aggTuple = SearchSysCache1(AGGFNOID, ObjectIdGetDatum(wfunc->winfnoid));
if (!HeapTupleIsValid(aggTuple))
elog(ERROR, "cache lookup failed for aggregate %u",
wfunc->winfnoid);
aggform = (Form_pg_aggregate) GETSTRUCT(aggTuple);
/*
* ExecInitWindowAgg already checked permission to call aggregate function
* ... but we still need to check the component functions
*/
peraggstate->transfn_oid = transfn_oid = aggform->aggtransfn;
peraggstate->finalfn_oid = finalfn_oid = aggform->aggfinalfn;
/* Check that aggregate owner has permission to call component fns */
{
HeapTuple procTuple;
Oid aggOwner;
procTuple = SearchSysCache1(PROCOID,
ObjectIdGetDatum(wfunc->winfnoid));
if (!HeapTupleIsValid(procTuple))
elog(ERROR, "cache lookup failed for function %u",
wfunc->winfnoid);
aggOwner = ((Form_pg_proc) GETSTRUCT(procTuple))->proowner;
ReleaseSysCache(procTuple);
aclresult = pg_proc_aclcheck(transfn_oid, aggOwner,
ACL_EXECUTE);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, ACL_KIND_PROC,
get_func_name(transfn_oid));
if (OidIsValid(finalfn_oid))
{
aclresult = pg_proc_aclcheck(finalfn_oid, aggOwner,
ACL_EXECUTE);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, ACL_KIND_PROC,
get_func_name(finalfn_oid));
}
}
/* resolve actual type of transition state, if polymorphic */
aggtranstype = aggform->aggtranstype;
if (IsPolymorphicType(aggtranstype))
{
/* have to fetch the agg's declared input types... */
Oid *declaredArgTypes;
int agg_nargs;
get_func_signature(wfunc->winfnoid,
&declaredArgTypes, &agg_nargs);
Assert(agg_nargs == numArguments);
aggtranstype = enforce_generic_type_consistency(inputTypes,
declaredArgTypes,
agg_nargs,
aggtranstype,
false);
pfree(declaredArgTypes);
}
/* build expression trees using actual argument & result types */
build_aggregate_fnexprs(inputTypes,
numArguments,
aggtranstype,
wfunc->wintype,
transfn_oid,
finalfn_oid,
wfunc->collid,
&transfnexpr,
&finalfnexpr);
fmgr_info(transfn_oid, &peraggstate->transfn);
fmgr_info_expr((Node *) transfnexpr, &peraggstate->transfn);
if (OidIsValid(finalfn_oid))
{
fmgr_info(finalfn_oid, &peraggstate->finalfn);
fmgr_info_expr((Node *) finalfnexpr, &peraggstate->finalfn);
}
get_typlenbyval(wfunc->wintype,
&peraggstate->resulttypeLen,
&peraggstate->resulttypeByVal);
get_typlenbyval(aggtranstype,
&peraggstate->transtypeLen,
&peraggstate->transtypeByVal);
/*
* initval is potentially null, so don't try to access it as a struct
* field. Must do it the hard way with SysCacheGetAttr.
*/
textInitVal = SysCacheGetAttr(AGGFNOID, aggTuple,
Anum_pg_aggregate_agginitval,
&peraggstate->initValueIsNull);
if (peraggstate->initValueIsNull)
peraggstate->initValue = (Datum) 0;
else
peraggstate->initValue = GetAggInitVal(textInitVal,
aggtranstype);
/*
* If the transfn is strict and the initval is NULL, make sure input type
* and transtype are the same (or at least binary-compatible), so that
* it's OK to use the first input value as the initial transValue. This
* should have been checked at agg definition time, but just in case...
*/
if (peraggstate->transfn.fn_strict && peraggstate->initValueIsNull)
{
if (numArguments < 1 ||
!IsBinaryCoercible(inputTypes[0], aggtranstype))
ereport(ERROR,
(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
errmsg("aggregate %u needs to have compatible input type and transition type",
wfunc->winfnoid)));
}
ReleaseSysCache(aggTuple);
return peraggstate;
}
static Datum
GetAggInitVal(Datum textInitVal, Oid transtype)
{
Oid typinput,
typioparam;
char *strInitVal;
Datum initVal;
getTypeInputInfo(transtype, &typinput, &typioparam);
strInitVal = TextDatumGetCString(textInitVal);
initVal = OidInputFunctionCall(typinput, strInitVal,
typioparam, -1);
pfree(strInitVal);
return initVal;
}
/*
* are_peers
* compare two rows to see if they are equal according to the ORDER BY clause
*
* NB: this does not consider the window frame mode.
*/
static bool
are_peers(WindowAggState *winstate, TupleTableSlot *slot1,
TupleTableSlot *slot2)
{
WindowAgg *node = (WindowAgg *) winstate->ss.ps.plan;
/* If no ORDER BY, all rows are peers with each other */
if (node->ordNumCols == 0)
return true;
return execTuplesMatch(slot1, slot2,
node->ordNumCols, node->ordColIdx,
winstate->ordEqfunctions,
winstate->tmpcontext->ecxt_per_tuple_memory);
}
/*
* window_gettupleslot
* Fetch the pos'th tuple of the current partition into the slot,
* using the winobj's read pointer
*
* Returns true if successful, false if no such row
*/
static bool
window_gettupleslot(WindowObject winobj, int64 pos, TupleTableSlot *slot)
{
WindowAggState *winstate = winobj->winstate;
MemoryContext oldcontext;
/* Don't allow passing -1 to spool_tuples here */
if (pos < 0)
return false;
/* If necessary, fetch the tuple into the spool */
spool_tuples(winstate, pos);
if (pos >= winstate->spooled_rows)
return false;
if (pos < winobj->markpos)
elog(ERROR, "cannot fetch row before WindowObject's mark position");
oldcontext = MemoryContextSwitchTo(winstate->ss.ps.ps_ExprContext->ecxt_per_query_memory);
tuplestore_select_read_pointer(winstate->buffer, winobj->readptr);
/*
* There's no API to refetch the tuple at the current position. We have to
* move one tuple forward, and then one backward. (We don't do it the
* other way because we might try to fetch the row before our mark, which
* isn't allowed.) XXX this case could stand to be optimized.
*/
if (winobj->seekpos == pos)
{
tuplestore_advance(winstate->buffer, true);
winobj->seekpos++;
}
while (winobj->seekpos > pos)
{
if (!tuplestore_gettupleslot(winstate->buffer, false, true, slot))
elog(ERROR, "unexpected end of tuplestore");
winobj->seekpos--;
}
while (winobj->seekpos < pos)
{
if (!tuplestore_gettupleslot(winstate->buffer, true, true, slot))
elog(ERROR, "unexpected end of tuplestore");
winobj->seekpos++;
}
MemoryContextSwitchTo(oldcontext);
return true;
}
/***********************************************************************
* API exposed to window functions
***********************************************************************/
/*
* WinGetPartitionLocalMemory
* Get working memory that lives till end of partition processing
*
* On first call within a given partition, this allocates and zeroes the
* requested amount of space. Subsequent calls just return the same chunk.
*
* Memory obtained this way is normally used to hold state that should be
* automatically reset for each new partition. If a window function wants
* to hold state across the whole query, fcinfo->fn_extra can be used in the
* usual way for that.
*/
void *
WinGetPartitionLocalMemory(WindowObject winobj, Size sz)
{
Assert(WindowObjectIsValid(winobj));
if (winobj->localmem == NULL)
winobj->localmem =
MemoryContextAllocZero(winobj->winstate->partcontext, sz);
return winobj->localmem;
}
/*
* WinGetCurrentPosition
* Return the current row's position (counting from 0) within the current
* partition.
*/
int64
WinGetCurrentPosition(WindowObject winobj)
{
Assert(WindowObjectIsValid(winobj));
return winobj->winstate->currentpos;
}
/*
* WinGetPartitionRowCount
* Return total number of rows contained in the current partition.
*
* Note: this is a relatively expensive operation because it forces the
* whole partition to be "spooled" into the tuplestore at once. Once
* executed, however, additional calls within the same partition are cheap.
*/
int64
WinGetPartitionRowCount(WindowObject winobj)
{
Assert(WindowObjectIsValid(winobj));
spool_tuples(winobj->winstate, -1);
return winobj->winstate->spooled_rows;
}
/*
* WinSetMarkPosition
* Set the "mark" position for the window object, which is the oldest row
* number (counting from 0) it is allowed to fetch during all subsequent
* operations within the current partition.
*
* Window functions do not have to call this, but are encouraged to move the
* mark forward when possible to keep the tuplestore size down and prevent
* having to spill rows to disk.
*/
void
WinSetMarkPosition(WindowObject winobj, int64 markpos)
{
WindowAggState *winstate;
Assert(WindowObjectIsValid(winobj));
winstate = winobj->winstate;
if (markpos < winobj->markpos)
elog(ERROR, "cannot move WindowObject's mark position backward");
tuplestore_select_read_pointer(winstate->buffer, winobj->markptr);
while (markpos > winobj->markpos)
{
tuplestore_advance(winstate->buffer, true);
winobj->markpos++;
}
tuplestore_select_read_pointer(winstate->buffer, winobj->readptr);
while (markpos > winobj->seekpos)
{
tuplestore_advance(winstate->buffer, true);
winobj->seekpos++;
}
}
/*
* WinRowsArePeers
* Compare two rows (specified by absolute position in window) to see
* if they are equal according to the ORDER BY clause.
*
* NB: this does not consider the window frame mode.
*/
bool
WinRowsArePeers(WindowObject winobj, int64 pos1, int64 pos2)
{
WindowAggState *winstate;
WindowAgg *node;
TupleTableSlot *slot1;
TupleTableSlot *slot2;
bool res;
Assert(WindowObjectIsValid(winobj));
winstate = winobj->winstate;
node = (WindowAgg *) winstate->ss.ps.plan;
/* If no ORDER BY, all rows are peers; don't bother to fetch them */
if (node->ordNumCols == 0)
return true;
slot1 = winstate->temp_slot_1;
slot2 = winstate->temp_slot_2;
if (!window_gettupleslot(winobj, pos1, slot1))
elog(ERROR, "specified position is out of window: " INT64_FORMAT,
pos1);
if (!window_gettupleslot(winobj, pos2, slot2))
elog(ERROR, "specified position is out of window: " INT64_FORMAT,
pos2);
res = are_peers(winstate, slot1, slot2);
ExecClearTuple(slot1);
ExecClearTuple(slot2);
return res;
}
/*
* WinGetFuncArgInPartition
* Evaluate a window function's argument expression on a specified
* row of the partition. The row is identified in lseek(2) style,
* i.e. relative to the current, first, or last row.
*
* argno: argument number to evaluate (counted from 0)
* relpos: signed rowcount offset from the seek position
* seektype: WINDOW_SEEK_CURRENT, WINDOW_SEEK_HEAD, or WINDOW_SEEK_TAIL
* set_mark: If the row is found and set_mark is true, the mark is moved to
* the row as a side-effect.
* isnull: output argument, receives isnull status of result
* isout: output argument, set to indicate whether target row position
* is out of partition (can pass NULL if caller doesn't care about this)
*
* Specifying a nonexistent row is not an error, it just causes a null result
* (plus setting *isout true, if isout isn't NULL).
*/
Datum
WinGetFuncArgInPartition(WindowObject winobj, int argno,
int relpos, int seektype, bool set_mark,
bool *isnull, bool *isout)
{
WindowAggState *winstate;
ExprContext *econtext;
TupleTableSlot *slot;
bool gottuple;
int64 abs_pos;
Assert(WindowObjectIsValid(winobj));
winstate = winobj->winstate;
econtext = winstate->ss.ps.ps_ExprContext;
slot = winstate->temp_slot_1;
switch (seektype)
{
case WINDOW_SEEK_CURRENT:
abs_pos = winstate->currentpos + relpos;
break;
case WINDOW_SEEK_HEAD:
abs_pos = relpos;
break;
case WINDOW_SEEK_TAIL:
spool_tuples(winstate, -1);
abs_pos = winstate->spooled_rows - 1 + relpos;
break;
default:
elog(ERROR, "unrecognized window seek type: %d", seektype);
abs_pos = 0; /* keep compiler quiet */
break;
}
gottuple = window_gettupleslot(winobj, abs_pos, slot);
if (!gottuple)
{
if (isout)
*isout = true;
*isnull = true;
return (Datum) 0;
}
else
{
if (isout)
*isout = false;
if (set_mark)
{
int frameOptions = winstate->frameOptions;
int64 mark_pos = abs_pos;
/*
* In RANGE mode with a moving frame head, we must not let the
* mark advance past frameheadpos, since that row has to be
* fetchable during future update_frameheadpos calls.
*
* XXX it is very ugly to pollute window functions' marks with
* this consideration; it could for instance mask a logic bug that
* lets a window function fetch rows before what it had claimed
* was its mark. Perhaps use a separate mark for frame head
* probes?
*/
if ((frameOptions & FRAMEOPTION_RANGE) &&
!(frameOptions & FRAMEOPTION_START_UNBOUNDED_PRECEDING))
{
update_frameheadpos(winobj, winstate->temp_slot_2);
if (mark_pos > winstate->frameheadpos)
mark_pos = winstate->frameheadpos;
}
WinSetMarkPosition(winobj, mark_pos);
}
econtext->ecxt_outertuple = slot;
return ExecEvalExpr((ExprState *) list_nth(winobj->argstates, argno),
econtext, isnull, NULL);
}
}
/*
* WinGetFuncArgInFrame
* Evaluate a window function's argument expression on a specified
* row of the window frame. The row is identified in lseek(2) style,
* i.e. relative to the current, first, or last row.
*
* argno: argument number to evaluate (counted from 0)
* relpos: signed rowcount offset from the seek position
* seektype: WINDOW_SEEK_CURRENT, WINDOW_SEEK_HEAD, or WINDOW_SEEK_TAIL
* set_mark: If the row is found and set_mark is true, the mark is moved to
* the row as a side-effect.
* isnull: output argument, receives isnull status of result
* isout: output argument, set to indicate whether target row position
* is out of frame (can pass NULL if caller doesn't care about this)
*
* Specifying a nonexistent row is not an error, it just causes a null result
* (plus setting *isout true, if isout isn't NULL).
*/
Datum
WinGetFuncArgInFrame(WindowObject winobj, int argno,
int relpos, int seektype, bool set_mark,
bool *isnull, bool *isout)
{
WindowAggState *winstate;
ExprContext *econtext;
TupleTableSlot *slot;
bool gottuple;
int64 abs_pos;
Assert(WindowObjectIsValid(winobj));
winstate = winobj->winstate;
econtext = winstate->ss.ps.ps_ExprContext;
slot = winstate->temp_slot_1;
switch (seektype)
{
case WINDOW_SEEK_CURRENT:
abs_pos = winstate->currentpos + relpos;
break;
case WINDOW_SEEK_HEAD:
update_frameheadpos(winobj, slot);
abs_pos = winstate->frameheadpos + relpos;
break;
case WINDOW_SEEK_TAIL:
update_frametailpos(winobj, slot);
abs_pos = winstate->frametailpos + relpos;
break;
default:
elog(ERROR, "unrecognized window seek type: %d", seektype);
abs_pos = 0; /* keep compiler quiet */
break;
}
gottuple = window_gettupleslot(winobj, abs_pos, slot);
if (gottuple)
gottuple = row_is_in_frame(winstate, abs_pos, slot);
if (!gottuple)
{
if (isout)
*isout = true;
*isnull = true;
return (Datum) 0;
}
else
{
if (isout)
*isout = false;
if (set_mark)
{
int frameOptions = winstate->frameOptions;
int64 mark_pos = abs_pos;
/*
* In RANGE mode with a moving frame head, we must not let the
* mark advance past frameheadpos, since that row has to be
* fetchable during future update_frameheadpos calls.
*
* XXX it is very ugly to pollute window functions' marks with
* this consideration; it could for instance mask a logic bug that
* lets a window function fetch rows before what it had claimed
* was its mark. Perhaps use a separate mark for frame head
* probes?
*/
if ((frameOptions & FRAMEOPTION_RANGE) &&
!(frameOptions & FRAMEOPTION_START_UNBOUNDED_PRECEDING))
{
update_frameheadpos(winobj, winstate->temp_slot_2);
if (mark_pos > winstate->frameheadpos)
mark_pos = winstate->frameheadpos;
}
WinSetMarkPosition(winobj, mark_pos);
}
econtext->ecxt_outertuple = slot;
return ExecEvalExpr((ExprState *) list_nth(winobj->argstates, argno),
econtext, isnull, NULL);
}
}
/*
* WinGetFuncArgCurrent
* Evaluate a window function's argument expression on the current row.
*
* argno: argument number to evaluate (counted from 0)
* isnull: output argument, receives isnull status of result
*
* Note: this isn't quite equivalent to WinGetFuncArgInPartition or
* WinGetFuncArgInFrame targeting the current row, because it will succeed
* even if the WindowObject's mark has been set beyond the current row.
* This should generally be used for "ordinary" arguments of a window
* function, such as the offset argument of lead() or lag().
*/
Datum
WinGetFuncArgCurrent(WindowObject winobj, int argno, bool *isnull)
{
WindowAggState *winstate;
ExprContext *econtext;
Assert(WindowObjectIsValid(winobj));
winstate = winobj->winstate;
econtext = winstate->ss.ps.ps_ExprContext;
econtext->ecxt_outertuple = winstate->ss.ss_ScanTupleSlot;
return ExecEvalExpr((ExprState *) list_nth(winobj->argstates, argno),
econtext, isnull, NULL);
}