On Tue, Jun 7, 2016 at 10:40 AM, Robert Haas <robertmh...@gmail.com> wrote:
> On Sat, Jun 4, 2016 at 4:21 PM, Kevin Grittner <kgri...@gmail.com> wrote:
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>> the minimal patch to fix behavior in this area would be:
>>
>> diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
>> index 31a1438..6c379da 100644
>> --- a/src/backend/catalog/index.c
>> +++ b/src/backend/catalog/index.c
>> @@ -2268,6 +2268,9 @@ IndexBuildHeapRangeScan(Relation heapRelation,
>> Assert(numblocks == InvalidBlockNumber);
>> }
>>
>> + if (old_snapshot_threshold >= 0)
>> + indexInfo->ii_BrokenHotChain = true;
>> +
>> reltuples = 0;
>>
>> /*
>>
>> Of course, ii_BrokenHotChain should be renamed to something like
>> ii_UnsafeForOldSnapshots, and some comments need to be updated; but
>> the above is the substance of it.
>
> I don't know why we'd want to rename it like that...
If we made the above change, the old name would be misleading, but
I've thought better of that and attach a slightly different
approach (tested but not yet with comment adjustments); attached.
--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 31a1438..945f55c 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -2060,7 +2060,8 @@ index_build(Relation heapRelation,
* about any concurrent readers of the tuple; no other transaction can see
* it yet.
*/
- if (indexInfo->ii_BrokenHotChain && !isreindex &&
+ if ((indexInfo->ii_BrokenHotChain || EarlyVacuumEnabled(indexRelation)) &&
+ !isreindex &&
!indexInfo->ii_Concurrent)
{
Oid indexId = RelationGetRelid(indexRelation);
@@ -3409,9 +3410,10 @@ reindex_index(Oid indexId, bool skip_constraint_checks, char persistence,
!indexForm->indisready ||
!indexForm->indislive);
if (index_bad ||
- (indexForm->indcheckxmin && !indexInfo->ii_BrokenHotChain))
+ (indexForm->indcheckxmin &&
+ !(indexInfo->ii_BrokenHotChain || EarlyVacuumEnabled(iRel))))
{
- if (!indexInfo->ii_BrokenHotChain)
+ if (!(indexInfo->ii_BrokenHotChain || EarlyVacuumEnabled(iRel)))
indexForm->indcheckxmin = false;
else if (index_bad)
indexForm->indcheckxmin = true;
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 8a830d4..4e50b19 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -4290,8 +4290,7 @@ IssuePendingWritebacks(WritebackContext *context)
void
TestForOldSnapshot_impl(Snapshot snapshot, Relation relation)
{
- if (!IsCatalogRelation(relation)
- && !RelationIsAccessibleInLogicalDecoding(relation)
+ if (RelationAllowsEarlyVacuum(relation)
&& (snapshot)->whenTaken < GetOldSnapshotThresholdTimestamp())
ereport(ERROR,
(errcode(ERRCODE_SNAPSHOT_TOO_OLD),
diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c
index f8a2a83..2eabd1c 100644
--- a/src/backend/utils/time/snapmgr.c
+++ b/src/backend/utils/time/snapmgr.c
@@ -1597,10 +1597,7 @@ TransactionIdLimitedForOldSnapshots(TransactionId recentXmin,
{
if (TransactionIdIsNormal(recentXmin)
&& old_snapshot_threshold >= 0
- && RelationNeedsWAL(relation)
- && !IsCatalogRelation(relation)
- && !RelationIsAccessibleInLogicalDecoding(relation)
- && !RelationHasUnloggedIndex(relation))
+ && RelationAllowsEarlyVacuum(relation))
{
int64 ts = GetSnapshotCurrentTimestamp();
TransactionId xlimit = recentXmin;
diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h
index 4270696..effdb0c 100644
--- a/src/include/utils/snapmgr.h
+++ b/src/include/utils/snapmgr.h
@@ -31,6 +31,19 @@
#define OLD_SNAPSHOT_PADDING_ENTRIES 10
#define OLD_SNAPSHOT_TIME_MAP_ENTRIES (old_snapshot_threshold + OLD_SNAPSHOT_PADDING_ENTRIES)
+/*
+ * Common definition of relation properties that allow early pruning/vacuuming
+ * when old_snapshot_threshold >= 0.
+ */
+#define RelationAllowsEarlyVacuum(rel) \
+( \
+ RelationNeedsWAL(rel) \
+ && !IsCatalogRelation(rel) \
+ && !RelationIsAccessibleInLogicalDecoding(rel) \
+ && !RelationHasUnloggedIndex(rel) \
+)
+
+#define EarlyVacuumEnabled(rel) (old_snapshot_threshold >= 0 && RelationAllowsEarlyVacuum(rel))
/* GUC variables */
extern PGDLLIMPORT int old_snapshot_threshold;
--
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