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Add TupleTableSlotOps.is_current_xact_tuple() method

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This allows us to abstract how/whether table AM uses transaction identifiers.
A custom table AM can use a custom slot, which may not store xmin directly,
but determine the tuple belonging to the current transaction in the other way.

Discussion: https://postgr.es/m/CAPpHfdurb9ycV8udYqM%3Do0sPS66PJ4RCBM1g-bBpvzUfogY0EA%40mail.gmail.com
Reviewed-by: Matthias van de Meent, Mark Dilger, Pavel Borisov
Reviewed-by: Nikita Malakhov, Japin Li
This commit is contained in:
Alexander Korotkov
2024-03-21 23:00:43 +02:00
parent c35a3fb5e0
commit 0997e0af27
3 changed files with 101 additions and 7 deletions
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79
src/backend/executor/execTuples.c
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@@ -60,6 +60,7 @@
#include "access/heaptoast.h"
#include "access/htup_details.h"
#include "access/tupdesc_details.h"
#include "access/xact.h"
#include "catalog/pg_type.h"
#include "funcapi.h"
#include "nodes/nodeFuncs.h"
@@ -148,6 +149,22 @@ tts_virtual_getsysattr(TupleTableSlot *slot, int attnum, bool *isnull)
return 0; /* silence compiler warnings */
}
/*
* VirtualTupleTableSlots never have storage tuples. We generally
* shouldn't get here, but provide a user-friendly message if we do.
*/
static bool
tts_virtual_is_current_xact_tuple(TupleTableSlot *slot)
{
Assert(!TTS_EMPTY(slot));
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("don't have a storage tuple in this context")));
return false; /* silence compiler warnings */
}
/*
* To materialize a virtual slot all the datums that aren't passed by value
* have to be copied into the slot's memory context. To do so, compute the
@@ -354,6 +371,29 @@ tts_heap_getsysattr(TupleTableSlot *slot, int attnum, bool *isnull)
slot->tts_tupleDescriptor, isnull);
}
static bool
tts_heap_is_current_xact_tuple(TupleTableSlot *slot)
{
HeapTupleTableSlot *hslot = (HeapTupleTableSlot *) slot;
TransactionId xmin;
Assert(!TTS_EMPTY(slot));
/*
* In some code paths it's possible to get here with a non-materialized
* slot, in which case we can't check if tuple is created by the current
* transaction.
*/
if (!hslot->tuple)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("don't have a storage tuple in this context")));
xmin = HeapTupleHeaderGetRawXmin(hslot->tuple->t_data);
return TransactionIdIsCurrentTransactionId(xmin);
}
static void
tts_heap_materialize(TupleTableSlot *slot)
{
@@ -521,6 +561,18 @@ tts_minimal_getsysattr(TupleTableSlot *slot, int attnum, bool *isnull)
return 0; /* silence compiler warnings */
}
static bool
tts_minimal_is_current_xact_tuple(TupleTableSlot *slot)
{
Assert(!TTS_EMPTY(slot));
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("don't have a storage tuple in this context")));
return false; /* silence compiler warnings */
}
static void
tts_minimal_materialize(TupleTableSlot *slot)
{
@@ -714,6 +766,29 @@ tts_buffer_heap_getsysattr(TupleTableSlot *slot, int attnum, bool *isnull)
slot->tts_tupleDescriptor, isnull);
}
static bool
tts_buffer_is_current_xact_tuple(TupleTableSlot *slot)
{
BufferHeapTupleTableSlot *bslot = (BufferHeapTupleTableSlot *) slot;
TransactionId xmin;
Assert(!TTS_EMPTY(slot));
/*
* In some code paths it's possible to get here with a non-materialized
* slot, in which case we can't check if tuple is created by the current
* transaction.
*/
if (!bslot->base.tuple)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("don't have a storage tuple in this context")));
xmin = HeapTupleHeaderGetRawXmin(bslot->base.tuple->t_data);
return TransactionIdIsCurrentTransactionId(xmin);
}
static void
tts_buffer_heap_materialize(TupleTableSlot *slot)
{
@@ -1029,6 +1104,7 @@ const TupleTableSlotOps TTSOpsVirtual = {
.getsomeattrs = tts_virtual_getsomeattrs,
.getsysattr = tts_virtual_getsysattr,
.materialize = tts_virtual_materialize,
.is_current_xact_tuple = tts_virtual_is_current_xact_tuple,
.copyslot = tts_virtual_copyslot,
/*
@@ -1048,6 +1124,7 @@ const TupleTableSlotOps TTSOpsHeapTuple = {
.clear = tts_heap_clear,
.getsomeattrs = tts_heap_getsomeattrs,
.getsysattr = tts_heap_getsysattr,
.is_current_xact_tuple = tts_heap_is_current_xact_tuple,
.materialize = tts_heap_materialize,
.copyslot = tts_heap_copyslot,
.get_heap_tuple = tts_heap_get_heap_tuple,
@@ -1065,6 +1142,7 @@ const TupleTableSlotOps TTSOpsMinimalTuple = {
.clear = tts_minimal_clear,
.getsomeattrs = tts_minimal_getsomeattrs,
.getsysattr = tts_minimal_getsysattr,
.is_current_xact_tuple = tts_minimal_is_current_xact_tuple,
.materialize = tts_minimal_materialize,
.copyslot = tts_minimal_copyslot,
@@ -1082,6 +1160,7 @@ const TupleTableSlotOps TTSOpsBufferHeapTuple = {
.clear = tts_buffer_heap_clear,
.getsomeattrs = tts_buffer_heap_getsomeattrs,
.getsysattr = tts_buffer_heap_getsysattr,
.is_current_xact_tuple = tts_buffer_is_current_xact_tuple,
.materialize = tts_buffer_heap_materialize,
.copyslot = tts_buffer_heap_copyslot,
.get_heap_tuple = tts_buffer_heap_get_heap_tuple,