From 3d0a4636aa4c976e971c05c77e162fc70c61f40b Mon Sep 17 00:00:00 2001
From: Andres Freund <andres@anarazel.de>
Date: Sat, 24 Jul 2021 20:14:03 -0700
Subject: [PATCH] Deduplicate choice of horizon for a relation procarray.c.
5a1e1d83022 was a minimal bug fix for dc7420c2c92. To avoid future bugs of
that kind, deduplicate the choice of a relation's horizon into a new helper,
GlobalVisHorizonKindForRel().
As the code in question was only introduced in dc7420c2c92 it seems worth
backpatching this change as well, otherwise 14 will look different from all
other branches.
A different approach to this was suggested by Matthias van de Meent.
Author: Andres Freund
Discussion: https://postgr.es/m/20210621122919.2qhu3pfugxxp3cji@alap3.anarazel.de
Backpatch: 14, like 5a1e1d83022
---
src/backend/storage/ipc/procarray.c | 98 +++++++++++++++++++----------
1 file changed, 64 insertions(+), 34 deletions(-)
diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c
index 793df973b4..aa3e1419a9 100644
--- a/src/backend/storage/ipc/procarray.c
+++ b/src/backend/storage/ipc/procarray.c
@@ -246,6 +246,17 @@ typedef struct ComputeXidHorizonsResult
} ComputeXidHorizonsResult;
+/*
+ * Return value for GlobalVisHorizonKindForRel().
+ */
+typedef enum GlobalVisHorizonKind
+{
+ VISHORIZON_SHARED,
+ VISHORIZON_CATALOG,
+ VISHORIZON_DATA,
+ VISHORIZON_TEMP
+} GlobalVisHorizonKind;
+
static ProcArrayStruct *procArray;
@@ -1952,6 +1963,33 @@ ComputeXidHorizons(ComputeXidHorizonsResult *h)
GlobalVisUpdateApply(h);
}
+/*
+ * Determine what kind of visibility horizon needs to be used for a
+ * relation. If rel is NULL, the most conservative horizon is used.
+ */
+static inline GlobalVisHorizonKind
+GlobalVisHorizonKindForRel(Relation rel)
+{
+ /*
+ * Other relkkinds currently don't contain xids, nor always the necessary
+ * logical decoding markers.
+ */
+ Assert(!rel ||
+ rel->rd_rel->relkind == RELKIND_RELATION ||
+ rel->rd_rel->relkind == RELKIND_MATVIEW ||
+ rel->rd_rel->relkind == RELKIND_TOASTVALUE);
+
+ if (rel == NULL || rel->rd_rel->relisshared || RecoveryInProgress())
+ return VISHORIZON_SHARED;
+ else if (IsCatalogRelation(rel) ||
+ RelationIsAccessibleInLogicalDecoding(rel))
+ return VISHORIZON_CATALOG;
+ else if (!RELATION_IS_LOCAL(rel))
+ return VISHORIZON_DATA;
+ else
+ return VISHORIZON_TEMP;
+}
+
/*
* Return the oldest XID for which deleted tuples must be preserved in the
* passed table.
@@ -1970,16 +2008,19 @@ GetOldestNonRemovableTransactionId(Relation rel)
ComputeXidHorizons(&horizons);
- /* select horizon appropriate for relation */
- if (rel == NULL || rel->rd_rel->relisshared || RecoveryInProgress())
- return horizons.shared_oldest_nonremovable;
- else if (IsCatalogRelation(rel) ||
- RelationIsAccessibleInLogicalDecoding(rel))
- return horizons.catalog_oldest_nonremovable;
- else if (RELATION_IS_LOCAL(rel))
- return horizons.temp_oldest_nonremovable;
- else
- return horizons.data_oldest_nonremovable;
+ switch (GlobalVisHorizonKindForRel(rel))
+ {
+ case VISHORIZON_SHARED:
+ return horizons.shared_oldest_nonremovable;
+ case VISHORIZON_CATALOG:
+ return horizons.catalog_oldest_nonremovable;
+ case VISHORIZON_DATA:
+ return horizons.data_oldest_nonremovable;
+ case VISHORIZON_TEMP:
+ return horizons.temp_oldest_nonremovable;
+ }
+
+ return InvalidTransactionId;
}
/*
@@ -3986,38 +4027,27 @@ DisplayXidCache(void)
GlobalVisState *
GlobalVisTestFor(Relation rel)
{
- bool need_shared;
- bool need_catalog;
GlobalVisState *state;
/* XXX: we should assert that a snapshot is pushed or registered */
Assert(RecentXmin);
- if (!rel)
- need_shared = need_catalog = true;
- else
+ switch (GlobalVisHorizonKindForRel(rel))
{
- /*
- * Other kinds currently don't contain xids, nor always the necessary
- * logical decoding markers.
- */
- Assert(rel->rd_rel->relkind == RELKIND_RELATION ||
- rel->rd_rel->relkind == RELKIND_MATVIEW ||
- rel->rd_rel->relkind == RELKIND_TOASTVALUE);
-
- need_shared = rel->rd_rel->relisshared || RecoveryInProgress();
- need_catalog = IsCatalogRelation(rel) || RelationIsAccessibleInLogicalDecoding(rel);
+ case VISHORIZON_SHARED:
+ state = &GlobalVisSharedRels;
+ break;
+ case VISHORIZON_CATALOG:
+ state = &GlobalVisCatalogRels;
+ break;
+ case VISHORIZON_DATA:
+ state = &GlobalVisDataRels;
+ break;
+ case VISHORIZON_TEMP:
+ state = &GlobalVisTempRels;
+ break;
}
- if (need_shared)
- state = &GlobalVisSharedRels;
- else if (need_catalog)
- state = &GlobalVisCatalogRels;
- else if (RELATION_IS_LOCAL(rel))
- state = &GlobalVisTempRels;
- else
- state = &GlobalVisDataRels;
-
Assert(FullTransactionIdIsValid(state->definitely_needed) &&
FullTransactionIdIsValid(state->maybe_needed));
--
2.24.1