Datum
make_tuple_indirect(PG_FUNCTION_ARGS)
{
HeapTupleHeader rec = PG_GETARG_HEAPTUPLEHEADER(0);
HeapTupleData tuple;
int ncolumns;
Datum *values;
bool *nulls;
Oid tupType;
int32 tupTypmod;
TupleDesc tupdesc;
HeapTuple newtup;
int i;
MemoryContext old_context;
/* Extract type info from the tuple itself */
tupType = HeapTupleHeaderGetTypeId(rec);
tupTypmod = HeapTupleHeaderGetTypMod(rec);
tupdesc = lookup_rowtype_tupdesc(tupType, tupTypmod);
ncolumns = tupdesc->natts;
/* Build a temporary HeapTuple control structure */
tuple.t_len = HeapTupleHeaderGetDatumLength(rec);
ItemPointerSetInvalid(&(tuple.t_self));
tuple.t_tableOid = InvalidOid;
tuple.t_data = rec;
values = (Datum *) palloc(ncolumns * sizeof(Datum));
nulls = (bool *) palloc(ncolumns * sizeof(bool));
heap_deform_tuple(&tuple, tupdesc, values, nulls);
old_context = MemoryContextSwitchTo(TopTransactionContext);
for (i = 0; i < ncolumns; i++)
{
struct varlena *attr;
struct varlena *new_attr;
struct varatt_indirect redirect_pointer;
/* only work on existing, not-null varlenas */
if (TupleDescAttr(tupdesc, i)->attisdropped ||
nulls[i] ||
TupleDescAttr(tupdesc, i)->attlen != -1)
continue;
attr = (struct varlena *) DatumGetPointer(values[i]);
/* don't recursively indirect */
if (VARATT_IS_EXTERNAL_INDIRECT(attr))
continue;
/* copy datum, so it still lives later */
if (VARATT_IS_EXTERNAL_ONDISK(attr))
attr = heap_tuple_fetch_attr(attr);
else
{
struct varlena *oldattr = attr;
attr = palloc0(VARSIZE_ANY(oldattr));
memcpy(attr, oldattr, VARSIZE_ANY(oldattr));
}
/* build indirection Datum */
new_attr = (struct varlena *) palloc0(INDIRECT_POINTER_SIZE);
redirect_pointer.pointer = attr;
SET_VARTAG_EXTERNAL(new_attr, VARTAG_INDIRECT);
memcpy(VARDATA_EXTERNAL(new_attr), &redirect_pointer,
sizeof(redirect_pointer));
values[i] = PointerGetDatum(new_attr);
}
newtup = heap_form_tuple(tupdesc, values, nulls);
pfree(values);
pfree(nulls);
ReleaseTupleDesc(tupdesc);
MemoryContextSwitchTo(old_context);
/*
* We intentionally don't use PG_RETURN_HEAPTUPLEHEADER here, because that
* would cause the indirect toast pointers to be flattened out of the
* tuple immediately, rendering subsequent testing irrelevant. So just
* return the HeapTupleHeader pointer as-is. This violates the general
* rule that composite Datums shouldn't contain toast pointers, but so
* long as the regression test scripts don't insert the result of this
* function into a container type (record, array, etc) it should be OK.
*/
PG_RETURN_POINTER(newtup->t_data);
}
/*
* Write a tuple to the outputstream, in the most efficient format possible.
*/
static void
pglogical_write_tuple(StringInfo out, PGLogicalOutputData *data,
Relation rel, HeapTuple tuple)
{
TupleDesc desc;
Datum values[MaxTupleAttributeNumber];
bool isnull[MaxTupleAttributeNumber];
int i;
uint16 nliveatts = 0;
desc = RelationGetDescr(rel);
pq_sendbyte(out, 'T'); /* sending TUPLE */
for (i = 0; i < desc->natts; i++)
{
if (desc->attrs[i]->attisdropped)
continue;
nliveatts++;
}
pq_sendint(out, nliveatts, 2);
/* try to allocate enough memory from the get go */
enlargeStringInfo(out, tuple->t_len +
nliveatts * (1 + 4));
/*
* XXX: should this prove to be a relevant bottleneck, it might be
* interesting to inline heap_deform_tuple() here, we don't actually need
* the information in the form we get from it.
*/
heap_deform_tuple(tuple, desc, values, isnull);
for (i = 0; i < desc->natts; i++)
{
HeapTuple typtup;
Form_pg_type typclass;
Form_pg_attribute att = desc->attrs[i];
char transfer_type;
/* skip dropped columns */
if (att->attisdropped)
continue;
if (isnull[i])
{
pq_sendbyte(out, 'n'); /* null column */
continue;
}
else if (att->attlen == -1 && VARATT_IS_EXTERNAL_ONDISK(values[i]))
{
pq_sendbyte(out, 'u'); /* unchanged toast column */
continue;
}
typtup = SearchSysCache1(TYPEOID, ObjectIdGetDatum(att->atttypid));
if (!HeapTupleIsValid(typtup))
elog(ERROR, "cache lookup failed for type %u", att->atttypid);
typclass = (Form_pg_type) GETSTRUCT(typtup);
transfer_type = decide_datum_transfer(att, typclass,
data->allow_internal_basetypes,
data->allow_binary_basetypes);
pq_sendbyte(out, transfer_type);
switch (transfer_type)
{
case 'b': /* internal-format binary data follows */
/* pass by value */
if (att->attbyval)
{
pq_sendint(out, att->attlen, 4); /* length */
enlargeStringInfo(out, att->attlen);
store_att_byval(out->data + out->len, values[i],
att->attlen);
out->len += att->attlen;
out->data[out->len] = '\0';
}
/* fixed length non-varlena pass-by-reference type */
else if (att->attlen > 0)
{
pq_sendint(out, att->attlen, 4); /* length */
appendBinaryStringInfo(out, DatumGetPointer(values[i]),
att->attlen);
}
/* varlena type */
else if (att->attlen == -1)
{
char *data = DatumGetPointer(values[i]);
/* send indirect datums inline */
if (VARATT_IS_EXTERNAL_INDIRECT(values[i]))
{
struct varatt_indirect redirect;
VARATT_EXTERNAL_GET_POINTER(redirect, data);
data = (char *) redirect.pointer;
}
Assert(!VARATT_IS_EXTERNAL(data));
pq_sendint(out, VARSIZE_ANY(data), 4); /* length */
appendBinaryStringInfo(out, data, VARSIZE_ANY(data));
}
else
elog(ERROR, "unsupported tuple type");
break;
case 's': /* binary send/recv data follows */
{
bytea *outputbytes;
int len;
outputbytes = OidSendFunctionCall(typclass->typsend,
values[i]);
len = VARSIZE(outputbytes) - VARHDRSZ;
pq_sendint(out, len, 4); /* length */
pq_sendbytes(out, VARDATA(outputbytes), len); /* data */
pfree(outputbytes);
}
break;
default:
{
char *outputstr;
int len;
outputstr = OidOutputFunctionCall(typclass->typoutput,
values[i]);
len = strlen(outputstr) + 1;
pq_sendint(out, len, 4); /* length */
appendBinaryStringInfo(out, outputstr, len); /* data */
pfree(outputstr);
}
}
ReleaseSysCache(typtup);
}
}
/*
* tuple_data_split_internal
*
* Split raw tuple data taken directly from a page into an array of bytea
* elements. This routine does a lookup on NULL values and creates array
* elements accordingly. This is a reimplementation of nocachegetattr()
* in heaptuple.c simplified for educational purposes.
*/
static Datum
tuple_data_split_internal(Oid relid, char *tupdata,
uint16 tupdata_len, uint16 t_infomask,
uint16 t_infomask2, bits8 *t_bits,
bool do_detoast)
{
ArrayBuildState *raw_attrs;
int nattrs;
int i;
int off = 0;
Relation rel;
TupleDesc tupdesc;
/* Get tuple descriptor from relation OID */
rel = relation_open(relid, AccessShareLock);
tupdesc = RelationGetDescr(rel);
raw_attrs = initArrayResult(BYTEAOID, CurrentMemoryContext, false);
nattrs = tupdesc->natts;
if (nattrs < (t_infomask2 & HEAP_NATTS_MASK))
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg("number of attributes in tuple header is greater than number of attributes in tuple descriptor")));
for (i = 0; i < nattrs; i++)
{
Form_pg_attribute attr;
bool is_null;
bytea *attr_data = NULL;
attr = TupleDescAttr(tupdesc, i);
/*
* Tuple header can specify less attributes than tuple descriptor as
* ALTER TABLE ADD COLUMN without DEFAULT keyword does not actually
* change tuples in pages, so attributes with numbers greater than
* (t_infomask2 & HEAP_NATTS_MASK) should be treated as NULL.
*/
if (i >= (t_infomask2 & HEAP_NATTS_MASK))
is_null = true;
else
is_null = (t_infomask & HEAP_HASNULL) && att_isnull(i, t_bits);
if (!is_null)
{
int len;
if (attr->attlen == -1)
{
off = att_align_pointer(off, attr->attalign, -1,
tupdata + off);
/*
* As VARSIZE_ANY throws an exception if it can't properly
* detect the type of external storage in macros VARTAG_SIZE,
* this check is repeated to have a nicer error handling.
*/
if (VARATT_IS_EXTERNAL(tupdata + off) &&
!VARATT_IS_EXTERNAL_ONDISK(tupdata + off) &&
!VARATT_IS_EXTERNAL_INDIRECT(tupdata + off))
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg("first byte of varlena attribute is incorrect for attribute %d", i)));
len = VARSIZE_ANY(tupdata + off);
}
else
{
off = att_align_nominal(off, attr->attalign);
len = attr->attlen;
}
if (tupdata_len < off + len)
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg("unexpected end of tuple data")));
if (attr->attlen == -1 && do_detoast)
attr_data = DatumGetByteaPCopy(tupdata + off);
else
{
attr_data = (bytea *) palloc(len + VARHDRSZ);
SET_VARSIZE(attr_data, len + VARHDRSZ);
memcpy(VARDATA(attr_data), tupdata + off, len);
}
off = att_addlength_pointer(off, attr->attlen,
tupdata + off);
}
raw_attrs = accumArrayResult(raw_attrs, PointerGetDatum(attr_data),
is_null, BYTEAOID, CurrentMemoryContext);
if (attr_data)
pfree(attr_data);
}
if (tupdata_len != off)
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg("end of tuple reached without looking at all its data")));
relation_close(rel, AccessShareLock);
return makeArrayResult(raw_attrs, CurrentMemoryContext);
}
Datum
make_tuple_indirect(PG_FUNCTION_ARGS)
{
HeapTupleHeader rec = PG_GETARG_HEAPTUPLEHEADER(0);
HeapTupleData tuple;
int ncolumns;
Datum *values;
bool *nulls;
Oid tupType;
int32 tupTypmod;
TupleDesc tupdesc;
HeapTuple newtup;
int i;
MemoryContext old_context;
/* Extract type info from the tuple itself */
tupType = HeapTupleHeaderGetTypeId(rec);
tupTypmod = HeapTupleHeaderGetTypMod(rec);
tupdesc = lookup_rowtype_tupdesc(tupType, tupTypmod);
ncolumns = tupdesc->natts;
/* Build a temporary HeapTuple control structure */
tuple.t_len = HeapTupleHeaderGetDatumLength(rec);
ItemPointerSetInvalid(&(tuple.t_self));
tuple.t_tableOid = InvalidOid;
tuple.t_data = rec;
values = (Datum *) palloc(ncolumns * sizeof(Datum));
nulls = (bool *) palloc(ncolumns * sizeof(bool));
heap_deform_tuple(&tuple, tupdesc, values, nulls);
old_context = MemoryContextSwitchTo(TopTransactionContext);
for (i = 0; i < ncolumns; i++)
{
struct varlena *attr;
struct varlena *new_attr;
struct varatt_indirect redirect_pointer;
/* only work on existing, not-null varlenas */
if (tupdesc->attrs[i]->attisdropped ||
nulls[i] ||
tupdesc->attrs[i]->attlen != -1)
continue;
attr = (struct varlena *) DatumGetPointer(values[i]);
/* don't recursively indirect */
if (VARATT_IS_EXTERNAL_INDIRECT(attr))
continue;
/* copy datum, so it still lives later */
if (VARATT_IS_EXTERNAL_ONDISK(attr))
attr = heap_tuple_fetch_attr(attr);
else
{
struct varlena *oldattr = attr;
attr = palloc0(VARSIZE_ANY(oldattr));
memcpy(attr, oldattr, VARSIZE_ANY(oldattr));
}
/* build indirection Datum */
new_attr = (struct varlena *) palloc0(INDIRECT_POINTER_SIZE);
redirect_pointer.pointer = attr;
SET_VARTAG_EXTERNAL(new_attr, VARTAG_INDIRECT);
memcpy(VARDATA_EXTERNAL(new_attr), &redirect_pointer,
sizeof(redirect_pointer));
values[i] = PointerGetDatum(new_attr);
}
newtup = heap_form_tuple(tupdesc, values, nulls);
pfree(values);
pfree(nulls);
ReleaseTupleDesc(tupdesc);
MemoryContextSwitchTo(old_context);
PG_RETURN_HEAPTUPLEHEADER(newtup->t_data);
}