database/postgres
database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-04-22 23:02:54 +03:00
Code

Allow buffer tuple table slots to materialize after ExecStoreVirtualTuple().

Browse Source 
While not common, it can be useful to store a virtual tuple into a
buffer tuple table slot, and then materialize that slot. So far we've
asserted out, which surprisingly wasn't a problem for anything in
core. But that seems fragile, and it also breaks redis_fdw after
ff11e7f4b9.

Thus, allow materializing a virtual tuple stored in a buffer tuple
table slot.

Author: Andres Freund
Discussion:
    https://postgr.es/m/20190227181621.xholonj7ff7ohxsg@alap3.anarazel.de
    https://postgr.es/m/20180703070645.wchpu5muyto5n647@alap3.anarazel.de
This commit is contained in:
Andres Freund 2019-02-28 12:27:58 -08:00
parent 19455c9f56
commit f414abd62d
1 changed files with 31 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

48
src/backend/executor/execTuples.c
View File

@ -700,25 +700,36 @@ tts_buffer_heap_materialize(TupleTableSlot *slot)
slot->tts_flags |= TTS_FLAG_SHOULDFREE; slot->tts_flags |= TTS_FLAG_SHOULDFREE;
/*
* A heap tuple stored in a BufferHeapTupleTableSlot should have a buffer
* associated with it, unless it's materialized (which would've returned
* above).
*/
Assert(bslot->base.tuple);
oldContext = MemoryContextSwitchTo(slot->tts_mcxt); oldContext = MemoryContextSwitchTo(slot->tts_mcxt);
bslot->base.tuple = heap_copytuple(bslot->base.tuple);
MemoryContextSwitchTo(oldContext);
/* if (!bslot->base.tuple)
* A heap tuple stored in a BufferHeapTupleTableSlot should have a buffer {
* associated with it, unless it's materialized. /*
*/ * Normally BufferHeapTupleTableSlot should have a tuple + buffer
Assert(BufferIsValid(bslot->buffer)); * associated with it, unless it's materialized (which would've
if (likely(BufferIsValid(bslot->buffer))) * returned above). But when it's useful to allow storing virtual
ReleaseBuffer(bslot->buffer); * tuples in a buffer slot, which then also needs to be
bslot->buffer = InvalidBuffer; * materializable.
*/
bslot->base.tuple = heap_form_tuple(slot->tts_tupleDescriptor,
slot->tts_values,
slot->tts_isnull);
}
else
{
bslot->base.tuple = heap_copytuple(bslot->base.tuple);
/*
* A heap tuple stored in a BufferHeapTupleTableSlot should have a
* buffer associated with it, unless it's materialized or virtual.
*/
Assert(BufferIsValid(bslot->buffer));
if (likely(BufferIsValid(bslot->buffer)))
ReleaseBuffer(bslot->buffer);
bslot->buffer = InvalidBuffer;
}
MemoryContextSwitchTo(oldContext);
/* /*
* Have to deform from scratch, otherwise tts_values[] entries could point * Have to deform from scratch, otherwise tts_values[] entries could point
@ -752,6 +763,9 @@ tts_buffer_heap_copyslot(TupleTableSlot *dstslot, TupleTableSlot *srcslot)
} }
else else
{ {
if (!bsrcslot->base.tuple)
tts_buffer_heap_materialize(srcslot);
tts_buffer_heap_store_tuple(dstslot, bsrcslot->base.tuple, tts_buffer_heap_store_tuple(dstslot, bsrcslot->base.tuple,
bsrcslot->buffer, false); bsrcslot->buffer, false);