On Thu, Aug 4, 2016 at 10:58 PM, Robert Haas <[email protected]> wrote:
> On Thu, Aug 4, 2016 at 7:23 PM, Tom Lane <[email protected]> wrote:
>> Robert Haas <[email protected]> writes:
>>> Prevent "snapshot too old" from trying to return pruned TOAST tuples.
>>
>> Looks like this patch broke the build on castoroides. Recommend
>> changing InitToastSnapshot into a macro. (There's a reason why
>> InitDirtySnapshot is a macro.)
>
> What is the reason? We refuse to separate frontend and backend
> headers in any sort of principled way?
That was poorly phrased. I'll try again: I can't see any reason for
using a macro here except that it allows frontend code to compile this
without breaking. But that doesn't seem like a very good way of
solving that problem. There's surely no way for a casual reader of
the code to realize that macros can be used here and inline functions
cannot, especially because this works apparently works fine on most
machines, including mine.
Here's a patch. Is this what you want?
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
diff --git a/src/backend/access/heap/tuptoaster.c b/src/backend/access/heap/tuptoaster.c
index 55b6b41..31b0132 100644
--- a/src/backend/access/heap/tuptoaster.c
+++ b/src/backend/access/heap/tuptoaster.c
@@ -2316,5 +2316,5 @@ init_toast_snapshot(Snapshot toast_snapshot)
if (snapshot == NULL)
elog(ERROR, "no known snapshots");
- InitToastSnapshot(toast_snapshot, snapshot->lsn, snapshot->whenTaken);
+ InitToastSnapshot(*toast_snapshot, snapshot->lsn, snapshot->whenTaken);
}
diff --git a/src/include/utils/tqual.h b/src/include/utils/tqual.h
index 8041e7b..fc7328c 100644
--- a/src/include/utils/tqual.h
+++ b/src/include/utils/tqual.h
@@ -104,12 +104,9 @@ extern bool ResolveCminCmaxDuringDecoding(struct HTAB *tuplecid_data,
* Similarly, some initialization is required for SnapshotToast. We need
* to set lsn and whenTaken correctly to support snapshot_too_old.
*/
-static inline void
-InitToastSnapshot(Snapshot snapshot, XLogRecPtr lsn, int64 whenTaken)
-{
- snapshot->satisfies = HeapTupleSatisfiesToast;
- snapshot->lsn = lsn;
- snapshot->whenTaken = whenTaken;
-}
+#define InitToastSnapshot(snapshotdata, l, w) \
+ ((snapshotdata).satisfies = HeapTupleSatisfiesDirty, \
+ (snapshotdata).lsn = (l), \
+ (snapshotdata).whenTaken = (w))
#endif /* TQUAL_H */
--
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