/*-------------------------------------------------------------------------
*
* tstoreReceiver.c
- * an implementation of DestReceiver that stores the result tuples in
- * a Tuplestore
+ * An implementation of DestReceiver that stores the result tuples in
+ * a Tuplestore.
*
+ * Optionally, we can force detoasting (but not decompression) of out-of-line
+ * toasted values. This is to support cursors WITH HOLD, which must retain
+ * data even if the underlying table is dropped.
*
- * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
+ *
+ * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
#include "postgres.h"
+#include "access/heapam.h"
+#include "access/tuptoaster.h"
#include "executor/tstoreReceiver.h"
typedef struct
{
DestReceiver pub;
- Tuplestorestate *tstore;
- MemoryContext cxt;
+ /* parameters: */
+ Tuplestorestate *tstore; /* where to put the data */
+ MemoryContext cxt; /* context containing tstore */
+ bool detoast; /* were we told to detoast? */
+ /* workspace: */
+ Datum *outvalues; /* values array for result tuple */
+ Datum *tofree; /* temp values to be pfree'd */
} TStoreState;
+static void tstoreReceiveSlot_notoast(TupleTableSlot *slot, DestReceiver *self);
+static void tstoreReceiveSlot_detoast(TupleTableSlot *slot, DestReceiver *self);
+
+
/*
* Prepare to receive tuples from executor.
*/
static void
tstoreStartupReceiver(DestReceiver *self, int operation, TupleDesc typeinfo)
{
- /* do nothing */
+ TStoreState *myState = (TStoreState *) self;
+ bool needtoast = false;
+ Form_pg_attribute *attrs = typeinfo->attrs;
+ int natts = typeinfo->natts;
+ int i;
+
+ /* Check if any columns require detoast work */
+ if (myState->detoast)
+ {
+ for (i = 0; i < natts; i++)
+ {
+ if (attrs[i]->attisdropped)
+ continue;
+ if (attrs[i]->attlen == -1)
+ {
+ needtoast = true;
+ break;
+ }
+ }
+ }
+
+ /* Set up appropriate callback */
+ if (needtoast)
+ {
+ myState->pub.receiveSlot = tstoreReceiveSlot_detoast;
+ /* Create workspace */
+ myState->outvalues = (Datum *)
+ MemoryContextAlloc(myState->cxt, natts * sizeof(Datum));
+ myState->tofree = (Datum *)
+ MemoryContextAlloc(myState->cxt, natts * sizeof(Datum));
+ }
+ else
+ {
+ myState->pub.receiveSlot = tstoreReceiveSlot_notoast;
+ myState->outvalues = NULL;
+ myState->tofree = NULL;
+ }
}
/*
* Receive a tuple from the executor and store it in the tuplestore.
+ * This is for the easy case where we don't have to detoast.
*/
static void
-tstoreReceiveSlot(TupleTableSlot *slot, DestReceiver *self)
+tstoreReceiveSlot_notoast(TupleTableSlot *slot, DestReceiver *self)
{
TStoreState *myState = (TStoreState *) self;
MemoryContext oldcxt = MemoryContextSwitchTo(myState->cxt);
MemoryContextSwitchTo(oldcxt);
}
+/*
+ * Receive a tuple from the executor and store it in the tuplestore.
+ * This is for the case where we have to detoast any toasted values.
+ */
+static void
+tstoreReceiveSlot_detoast(TupleTableSlot *slot, DestReceiver *self)
+{
+ TStoreState *myState = (TStoreState *) self;
+ TupleDesc typeinfo = slot->tts_tupleDescriptor;
+ Form_pg_attribute *attrs = typeinfo->attrs;
+ int natts = typeinfo->natts;
+ int nfree;
+ int i;
+ HeapTuple tuple;
+ MemoryContext oldcxt;
+
+ /* Make sure the tuple is fully deconstructed */
+ slot_getallattrs(slot);
+
+ /*
+ * Fetch back any out-of-line datums. We build the new datums array in
+ * myState->outvalues[] (but we can re-use the slot's isnull array).
+ * Also, remember the fetched values to free afterwards.
+ */
+ nfree = 0;
+ for (i = 0; i < natts; i++)
+ {
+ Datum val = slot->tts_values[i];
+
+ if (!attrs[i]->attisdropped &&
+ attrs[i]->attlen == -1 &&
+ !slot->tts_isnull[i])
+ {
+ if (VARATT_IS_EXTERNAL(DatumGetPointer(val)))
+ {
+ val = PointerGetDatum(heap_tuple_fetch_attr((varattrib *)
+ DatumGetPointer(val)));
+ myState->tofree[nfree++] = val;
+ }
+ }
+
+ myState->outvalues[i] = val;
+ }
+
+ /*
+ * Push the modified tuple into the tuplestore.
+ */
+ tuple = heap_form_tuple(typeinfo,
+ myState->outvalues, slot->tts_isnull);
+ oldcxt = MemoryContextSwitchTo(myState->cxt);
+ tuplestore_puttuple(myState->tstore, tuple);
+ MemoryContextSwitchTo(oldcxt);
+ heap_freetuple(tuple);
+
+ /* And release any temporary detoasted values */
+ for (i = 0; i < nfree; i++)
+ pfree(DatumGetPointer(myState->tofree[i]));
+}
+
/*
* Clean up at end of an executor run
*/
static void
tstoreShutdownReceiver(DestReceiver *self)
{
- /* do nothing */
+ TStoreState *myState = (TStoreState *) self;
+
+ /* Release workspace if any */
+ if (myState->outvalues)
+ pfree(myState->outvalues);
+ myState->outvalues = NULL;
+ if (myState->tofree)
+ pfree(myState->tofree);
+ myState->tofree = NULL;
}
/*
CreateTuplestoreDestReceiver(Tuplestorestate *tStore,
MemoryContext tContext)
{
- TStoreState *self = (TStoreState *) palloc(sizeof(TStoreState));
+ TStoreState *self = (TStoreState *) palloc0(sizeof(TStoreState));
- self->pub.receiveSlot = tstoreReceiveSlot;
+ self->pub.receiveSlot = tstoreReceiveSlot_notoast;
self->pub.rStartup = tstoreStartupReceiver;
self->pub.rShutdown = tstoreShutdownReceiver;
self->pub.rDestroy = tstoreDestroyReceiver;
self->tstore = tStore;
self->cxt = tContext;
+ self->detoast = false;
return (DestReceiver *) self;
}
+
+/*
+ * Set parameters for a TuplestoreDestReceiver
+ */
+void
+SetTuplestoreDestReceiverDeToast(DestReceiver *self,
+ bool detoast)
+{
+ TStoreState *myState = (TStoreState *) self;
+
+ Assert(myState->pub.mydest == DestTuplestore);
+ myState->detoast = detoast;
+}
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