/* ----------------------------------------------------------------
* ValuesNext
*
* This is a workhorse for ExecValuesScan
* ----------------------------------------------------------------
*/
static TupleTableSlot *
ValuesNext(ValuesScanState *node)
{
TupleTableSlot *slot;
EState *estate;
ExprContext *econtext;
ScanDirection direction;
List *exprlist;
/*
* get information from the estate and scan state
*/
estate = node->ss.ps.state;
direction = estate->es_direction;
slot = node->ss.ss_ScanTupleSlot;
econtext = node->rowcontext;
/*
* Get the next tuple. Return NULL if no more tuples.
*/
if (ScanDirectionIsForward(direction))
{
if (node->curr_idx < node->array_len)
node->curr_idx++;
if (node->curr_idx < node->array_len)
exprlist = node->exprlists[node->curr_idx];
else
exprlist = NIL;
}
else
{
if (node->curr_idx >= 0)
node->curr_idx--;
if (node->curr_idx >= 0)
exprlist = node->exprlists[node->curr_idx];
else
exprlist = NIL;
}
/*
* Always clear the result slot; this is appropriate if we are at the end
* of the data, and if we're not, we still need it as the first step of
* the store-virtual-tuple protocol. It seems wise to clear the slot
* before we reset the context it might have pointers into.
*/
ExecClearTuple(slot);
if (exprlist)
{
MemoryContext oldContext;
List *exprstatelist;
Datum *values;
bool *isnull;
Form_pg_attribute *att;
ListCell *lc;
int resind;
/*
* Get rid of any prior cycle's leftovers. We use ReScanExprContext
* not just ResetExprContext because we want any registered shutdown
* callbacks to be called.
*/
ReScanExprContext(econtext);
/*
* Build the expression eval state in the econtext's per-tuple memory.
* This is a tad unusual, but we want to delete the eval state again
* when we move to the next row, to avoid growth of memory
* requirements over a long values list.
*/
oldContext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
/*
* Pass NULL, not my plan node, because we don't want anything in this
* transient state linking into permanent state. The only possibility
* is a SubPlan, and there shouldn't be any (any subselects in the
* VALUES list should be InitPlans).
*/
exprstatelist = ExecInitExprList(exprlist, NULL);
/* parser should have checked all sublists are the same length */
Assert(list_length(exprstatelist) == slot->tts_tupleDescriptor->natts);
/*
* Compute the expressions and build a virtual result tuple. We
* already did ExecClearTuple(slot).
*/
values = slot->tts_values;
isnull = slot->tts_isnull;
att = slot->tts_tupleDescriptor->attrs;
resind = 0;
foreach(lc, exprstatelist)
{
ExprState *estate = (ExprState *) lfirst(lc);
values[resind] = ExecEvalExpr(estate,
econtext,
&isnull[resind]);
/*
* We must force any R/W expanded datums to read-only state, in
* case they are multiply referenced in the plan node's output
* expressions, or in case we skip the output projection and the
* output column is multiply referenced in higher plan nodes.
*/
values[resind] = MakeExpandedObjectReadOnly(values[resind],
isnull[resind],
att[resind]->attlen);
resind++;
}
MemoryContextSwitchTo(oldContext);
/*
* And return the virtual tuple.
*/
ExecStoreVirtualTuple(slot);
}
/* ----------------------------------------------------------------
* ValuesNext
*
* This is a workhorse for ExecValuesScan
* ----------------------------------------------------------------
*/
static TupleTableSlot *
ValuesNext(ValuesScanState *node)
{
TupleTableSlot *slot;
EState *estate;
ExprContext *econtext;
ScanDirection direction;
List *exprlist;
/*
* get information from the estate and scan state
*/
estate = node->ss.ps.state;
direction = estate->es_direction;
slot = node->ss.ss_ScanTupleSlot;
econtext = node->rowcontext;
/*
* Get the next tuple. Return NULL if no more tuples.
*/
if (ScanDirectionIsForward(direction))
{
if (node->curr_idx < node->array_len)
node->curr_idx++;
if (node->curr_idx < node->array_len)
exprlist = node->exprlists[node->curr_idx];
else
exprlist = NIL;
}
else
{
if (node->curr_idx >= 0)
node->curr_idx--;
if (node->curr_idx >= 0)
exprlist = node->exprlists[node->curr_idx];
else
exprlist = NIL;
}
/*
* Always clear the result slot; this is appropriate if we are at the end
* of the data, and if we're not, we still need it as the first step of
* the store-virtual-tuple protocol. It seems wise to clear the slot
* before we reset the context it might have pointers into.
*/
ExecClearTuple(slot);
if (exprlist)
{
MemoryContext oldContext;
List *oldsubplans;
List *exprstatelist;
Datum *values;
bool *isnull;
ListCell *lc;
int resind;
int saved_jit_flags;
/*
* Get rid of any prior cycle's leftovers. We use ReScanExprContext
* not just ResetExprContext because we want any registered shutdown
* callbacks to be called.
*/
ReScanExprContext(econtext);
/*
* Build the expression eval state in the econtext's per-tuple memory.
* This is a tad unusual, but we want to delete the eval state again
* when we move to the next row, to avoid growth of memory
* requirements over a long values list.
*/
oldContext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
/*
* The expressions might contain SubPlans (this is currently only
* possible if there's a sub-select containing a LATERAL reference,
* otherwise sub-selects in a VALUES list should be InitPlans). Those
* subplans will want to hook themselves into our subPlan list, which
* would result in a corrupted list after we delete the eval state. We
* can work around this by saving and restoring the subPlan list.
* (There's no need for the functionality that would be enabled by
* having the list entries, since the SubPlans aren't going to be
* re-executed anyway.)
*/
oldsubplans = node->ss.ps.subPlan;
node->ss.ps.subPlan = NIL;
/*
* As the expressions are only ever used once, disable JIT for them.
* This is worthwhile because it's common to insert significant
* amounts of data via VALUES().
*/
saved_jit_flags = econtext->ecxt_estate->es_jit_flags;
econtext->ecxt_estate->es_jit_flags = PGJIT_NONE;
exprstatelist = ExecInitExprList(exprlist, &node->ss.ps);
econtext->ecxt_estate->es_jit_flags = saved_jit_flags;
node->ss.ps.subPlan = oldsubplans;
/* parser should have checked all sublists are the same length */
Assert(list_length(exprstatelist) == slot->tts_tupleDescriptor->natts);
/*
* Compute the expressions and build a virtual result tuple. We
* already did ExecClearTuple(slot).
*/
values = slot->tts_values;
isnull = slot->tts_isnull;
resind = 0;
foreach(lc, exprstatelist)
{
ExprState *estate = (ExprState *) lfirst(lc);
Form_pg_attribute attr = TupleDescAttr(slot->tts_tupleDescriptor,
resind);
values[resind] = ExecEvalExpr(estate,
econtext,
&isnull[resind]);
/*
* We must force any R/W expanded datums to read-only state, in
* case they are multiply referenced in the plan node's output
* expressions, or in case we skip the output projection and the
* output column is multiply referenced in higher plan nodes.
*/
values[resind] = MakeExpandedObjectReadOnly(values[resind],
isnull[resind],
attr->attlen);
resind++;
}
MemoryContextSwitchTo(oldContext);
/*
* And return the virtual tuple.
*/
ExecStoreVirtualTuple(slot);
}
