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TOAST needs to do at least minimal time-qual checking in order not to

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mess up after an aborted VACUUM FULL, per today's pghackers discussion.
Add a suitable HeapTupleSatisfiesToast routine.  Remove useless special-
case test in HeapTupleSatisfiesVisibility macro for xmax =
BootstrapTransactionId; perhaps that was needed at one time, but it's
a waste of cycles now, not to mention actively wrong for SnapshotAny.
Along the way, add some much-needed comments to tqual.c, and simplify
toast_fetch_datum, which no longer needs to assume it may see chunks
out-of-order.
This commit is contained in:
Tom Lane
2002-01-16 20:29:02 +00:00
parent 0f2d949c1e
commit cf97080fa4
3 changed files with 158 additions and 59 deletions
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48
src/backend/access/heap/tuptoaster.c
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@@ -4,11 +4,11 @@
* Support routines for external and compressed storage of
* variable size attributes.
*
* Copyright (c) 2000, PostgreSQL Global Development Group
* Copyright (c) 2000-2002, PostgreSQL Global Development Group
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/access/heap/tuptoaster.c,v 1.26 2001/11/05 17:46:23 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/access/heap/tuptoaster.c,v 1.27 2002/01/16 20:29:01 tgl Exp $
*
*
* INTERFACE ROUTINES
@@ -921,7 +921,7 @@ toast_delete_datum(Relation rel, Datum value)
while ((indexRes = index_getnext(toastscan, ForwardScanDirection)) != NULL)
{
toasttup.t_self = indexRes->heap_iptr;
heap_fetch(toastrel, SnapshotAny, &toasttup, &buffer, toastscan);
heap_fetch(toastrel, SnapshotToast, &toasttup, &buffer, toastscan);
pfree(indexRes);
if (!toasttup.t_data)
@@ -963,26 +963,18 @@ toast_fetch_datum(varattrib *attr)
TupleDesc toasttupDesc;
RetrieveIndexResult indexRes;
Buffer buffer;
varattrib *result;
int32 ressize;
int32 residx;
int numchunks;
int32 residx,
nextidx;
int32 numchunks;
Pointer chunk;
bool isnull;
int32 chunksize;
char *chunks_found;
char *chunks_expected;
ressize = attr->va_content.va_external.va_extsize;
numchunks = ((ressize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
chunks_found = palloc(numchunks);
chunks_expected = palloc(numchunks);
memset(chunks_found, 0, numchunks);
memset(chunks_expected, 1, numchunks);
result = (varattrib *) palloc(ressize + VARHDRSZ);
VARATT_SIZEP(result) = ressize + VARHDRSZ;
if (VARATT_IS_COMPRESSED(attr))
@@ -1008,13 +1000,17 @@ toast_fetch_datum(varattrib *attr)
/*
* Read the chunks by index
*
* Note we will not necessarily see the chunks in sequence-number order.
* Note that because the index is actually on (valueid, chunkidx)
* we will see the chunks in chunkidx order, even though we didn't
* explicitly ask for it.
*/
nextidx = 0;
toastscan = index_beginscan(toastidx, false, 1, &toastkey);
while ((indexRes = index_getnext(toastscan, ForwardScanDirection)) != NULL)
{
toasttup.t_self = indexRes->heap_iptr;
heap_fetch(toastrel, SnapshotAny, &toasttup, &buffer, toastscan);
heap_fetch(toastrel, SnapshotToast, &toasttup, &buffer, toastscan);
pfree(indexRes);
if (toasttup.t_data == NULL)
@@ -1033,9 +1029,9 @@ toast_fetch_datum(varattrib *attr)
/*
* Some checks on the data we've found
*/
if (residx < 0 || residx >= numchunks)
elog(ERROR, "unexpected chunk number %d for toast value %u",
residx,
if (residx != nextidx)
elog(ERROR, "unexpected chunk number %d (expected %d) for toast value %u",
residx, nextidx,
attr->va_content.va_external.va_valueid);
if (residx < numchunks - 1)
{
@@ -1044,15 +1040,15 @@ toast_fetch_datum(varattrib *attr)
chunksize, residx,
attr->va_content.va_external.va_valueid);
}
else
else if (residx < numchunks)
{
if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != ressize)
elog(ERROR, "unexpected chunk size %d in chunk %d for toast value %u",
chunksize, residx,
attr->va_content.va_external.va_valueid);
}
if (chunks_found[residx]++ > 0)
elog(ERROR, "chunk %d for toast value %u appears multiple times",
else
elog(ERROR, "unexpected chunk number %d for toast value %u",
residx,
attr->va_content.va_external.va_valueid);
@@ -1064,16 +1060,16 @@ toast_fetch_datum(varattrib *attr)
chunksize);
ReleaseBuffer(buffer);
nextidx++;
}
/*
* Final checks that we successfully fetched the datum
*/
if (memcmp(chunks_found, chunks_expected, numchunks) != 0)
elog(ERROR, "not all toast chunks found for value %u",
if (nextidx != numchunks)
elog(ERROR, "missing chunk number %d for toast value %u",
nextidx,
attr->va_content.va_external.va_valueid);
pfree(chunks_expected);
pfree(chunks_found);
/*
* End scan and close relations