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-rw-r--r--src/backend/access/heap/tuptoaster.c110
1 files changed, 90 insertions, 20 deletions
diff --git a/src/backend/access/heap/tuptoaster.c b/src/backend/access/heap/tuptoaster.c
index fc37ceb4a3e..445a7ed9fbc 100644
--- a/src/backend/access/heap/tuptoaster.c
+++ b/src/backend/access/heap/tuptoaster.c
@@ -44,9 +44,6 @@
#undef TOAST_DEBUG
-/* Size of an EXTERNAL datum that contains a standard TOAST pointer */
-#define TOAST_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(struct varatt_external))
-
/*
* Testing whether an externally-stored value is compressed now requires
* comparing extsize (the actual length of the external data) to rawsize
@@ -87,11 +84,11 @@ static struct varlena *toast_fetch_datum_slice(struct varlena * attr,
* heap_tuple_fetch_attr -
*
* Public entry point to get back a toasted value from
- * external storage (possibly still in compressed format).
+ * external source (possibly still in compressed format).
*
* This will return a datum that contains all the data internally, ie, not
- * relying on external storage, but it can still be compressed or have a short
- * header.
+ * relying on external storage or memory, but it can still be compressed or
+ * have a short header.
----------
*/
struct varlena *
@@ -99,13 +96,35 @@ heap_tuple_fetch_attr(struct varlena * attr)
{
struct varlena *result;
- if (VARATT_IS_EXTERNAL(attr))
+ if (VARATT_IS_EXTERNAL_ONDISK(attr))
{
/*
* This is an external stored plain value
*/
result = toast_fetch_datum(attr);
}
+ else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+ {
+ /*
+ * copy into the caller's memory context. That's not required in all
+ * cases but sufficient for now since this is mainly used when we need
+ * to persist a Datum for unusually long time, like in a HOLD cursor.
+ */
+ struct varatt_indirect redirect;
+ VARATT_EXTERNAL_GET_POINTER(redirect, attr);
+ attr = (struct varlena *)redirect.pointer;
+
+ /* nested indirect Datums aren't allowed */
+ Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
+
+ /* doesn't make much sense, but better handle it */
+ if (VARATT_IS_EXTERNAL_ONDISK(attr))
+ return heap_tuple_fetch_attr(attr);
+
+ /* copy datum verbatim */
+ result = (struct varlena *) palloc(VARSIZE_ANY(attr));
+ memcpy(result, attr, VARSIZE_ANY(attr));
+ }
else
{
/*
@@ -128,7 +147,7 @@ heap_tuple_fetch_attr(struct varlena * attr)
struct varlena *
heap_tuple_untoast_attr(struct varlena * attr)
{
- if (VARATT_IS_EXTERNAL(attr))
+ if (VARATT_IS_EXTERNAL_ONDISK(attr))
{
/*
* This is an externally stored datum --- fetch it back from there
@@ -145,6 +164,17 @@ heap_tuple_untoast_attr(struct varlena * attr)
pfree(tmp);
}
}
+ else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+ {
+ struct varatt_indirect redirect;
+ VARATT_EXTERNAL_GET_POINTER(redirect, attr);
+ attr = (struct varlena *)redirect.pointer;
+
+ /* nested indirect Datums aren't allowed */
+ Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
+
+ attr = heap_tuple_untoast_attr(attr);
+ }
else if (VARATT_IS_COMPRESSED(attr))
{
/*
@@ -191,7 +221,7 @@ heap_tuple_untoast_attr_slice(struct varlena * attr,
char *attrdata;
int32 attrsize;
- if (VARATT_IS_EXTERNAL(attr))
+ if (VARATT_IS_EXTERNAL_ONDISK(attr))
{
struct varatt_external toast_pointer;
@@ -204,6 +234,17 @@ heap_tuple_untoast_attr_slice(struct varlena * attr,
/* fetch it back (compressed marker will get set automatically) */
preslice = toast_fetch_datum(attr);
}
+ else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+ {
+ struct varatt_indirect redirect;
+ VARATT_EXTERNAL_GET_POINTER(redirect, attr);
+
+ /* nested indirect Datums aren't allowed */
+ Assert(!VARATT_IS_EXTERNAL_INDIRECT(redirect.pointer));
+
+ return heap_tuple_untoast_attr_slice(redirect.pointer,
+ sliceoffset, slicelength);
+ }
else
preslice = attr;
@@ -267,7 +308,7 @@ toast_raw_datum_size(Datum value)
struct varlena *attr = (struct varlena *) DatumGetPointer(value);
Size result;
- if (VARATT_IS_EXTERNAL(attr))
+ if (VARATT_IS_EXTERNAL_ONDISK(attr))
{
/* va_rawsize is the size of the original datum -- including header */
struct varatt_external toast_pointer;
@@ -275,6 +316,16 @@ toast_raw_datum_size(Datum value)
VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
result = toast_pointer.va_rawsize;
}
+ else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+ {
+ struct varatt_indirect toast_pointer;
+ VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+ /* nested indirect Datums aren't allowed */
+ Assert(!VARATT_IS_EXTERNAL_INDIRECT(toast_pointer.pointer));
+
+ return toast_raw_datum_size(PointerGetDatum(toast_pointer.pointer));
+ }
else if (VARATT_IS_COMPRESSED(attr))
{
/* here, va_rawsize is just the payload size */
@@ -308,7 +359,7 @@ toast_datum_size(Datum value)
struct varlena *attr = (struct varlena *) DatumGetPointer(value);
Size result;
- if (VARATT_IS_EXTERNAL(attr))
+ if (VARATT_IS_EXTERNAL_ONDISK(attr))
{
/*
* Attribute is stored externally - return the extsize whether
@@ -320,6 +371,16 @@ toast_datum_size(Datum value)
VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
result = toast_pointer.va_extsize;
}
+ else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+ {
+ struct varatt_indirect toast_pointer;
+ VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+ /* nested indirect Datums aren't allowed */
+ Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
+
+ return toast_datum_size(PointerGetDatum(toast_pointer.pointer));
+ }
else if (VARATT_IS_SHORT(attr))
{
result = VARSIZE_SHORT(attr);
@@ -387,8 +448,12 @@ toast_delete(Relation rel, HeapTuple oldtup)
{
Datum value = toast_values[i];
- if (!toast_isnull[i] && VARATT_IS_EXTERNAL(PointerGetDatum(value)))
+ if (toast_isnull[i])
+ continue;
+ else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
toast_delete_datum(rel, value);
+ else if (VARATT_IS_EXTERNAL_INDIRECT(PointerGetDatum(value)))
+ elog(ERROR, "attempt to delete tuple containing indirect datums");
}
}
}
@@ -490,13 +555,13 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
/*
- * If the old value is an external stored one, check if it has
- * changed so we have to delete it later.
+ * If the old value is stored on disk, check if it has changed so
+ * we have to delete it later.
*/
if (att[i]->attlen == -1 && !toast_oldisnull[i] &&
- VARATT_IS_EXTERNAL(old_value))
+ VARATT_IS_EXTERNAL_ONDISK(old_value))
{
- if (toast_isnull[i] || !VARATT_IS_EXTERNAL(new_value) ||
+ if (toast_isnull[i] || !VARATT_IS_EXTERNAL_ONDISK(new_value) ||
memcmp((char *) old_value, (char *) new_value,
VARSIZE_EXTERNAL(old_value)) != 0)
{
@@ -1258,6 +1323,8 @@ toast_save_datum(Relation rel, Datum value,
int32 data_todo;
Pointer dval = DatumGetPointer(value);
+ Assert(!VARATT_IS_EXTERNAL(value));
+
/*
* Open the toast relation and its index. We can use the index to check
* uniqueness of the OID we assign to the toasted item, even though it has
@@ -1341,7 +1408,7 @@ toast_save_datum(Relation rel, Datum value,
{
struct varatt_external old_toast_pointer;
- Assert(VARATT_IS_EXTERNAL(oldexternal));
+ Assert(VARATT_IS_EXTERNAL_ONDISK(oldexternal));
/* Must copy to access aligned fields */
VARATT_EXTERNAL_GET_POINTER(old_toast_pointer, oldexternal);
if (old_toast_pointer.va_toastrelid == rel->rd_toastoid)
@@ -1456,7 +1523,7 @@ toast_save_datum(Relation rel, Datum value,
* Create the TOAST pointer value that we'll return
*/
result = (struct varlena *) palloc(TOAST_POINTER_SIZE);
- SET_VARSIZE_EXTERNAL(result, TOAST_POINTER_SIZE);
+ SET_VARTAG_EXTERNAL(result, VARTAG_ONDISK);
memcpy(VARDATA_EXTERNAL(result), &toast_pointer, sizeof(toast_pointer));
return PointerGetDatum(result);
@@ -1480,7 +1547,7 @@ toast_delete_datum(Relation rel, Datum value)
SysScanDesc toastscan;
HeapTuple toasttup;
- if (!VARATT_IS_EXTERNAL(attr))
+ if (!VARATT_IS_EXTERNAL_ONDISK(attr))
return;
/* Must copy to access aligned fields */
@@ -1608,6 +1675,9 @@ toast_fetch_datum(struct varlena * attr)
char *chunkdata;
int32 chunksize;
+ if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+ elog(ERROR, "shouldn't be called for indirect tuples");
+
/* Must copy to access aligned fields */
VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
@@ -1775,7 +1845,7 @@ toast_fetch_datum_slice(struct varlena * attr, int32 sliceoffset, int32 length)
int32 chcpystrt;
int32 chcpyend;
- Assert(VARATT_IS_EXTERNAL(attr));
+ Assert(VARATT_IS_EXTERNAL_ONDISK(attr));
/* Must copy to access aligned fields */
VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
generated by cgit v1.2.3 (git 2.39.1) at 2025-08-01 03:53:28 +0000