/* ----------------
* heap_attisnull - returns TRUE iff tuple attribute is not present
* ----------------
*/
bool
heap_attisnull(HeapTuple tup, int attnum)
{
if (attnum > (int) HeapTupleHeaderGetNatts(tup->t_data))
return true;
if (attnum > 0)
{
if (HeapTupleNoNulls(tup))
return false;
return att_isnull(attnum - 1, tup->t_data->t_bits);
}
switch (attnum)
{
case TableOidAttributeNumber:
case SelfItemPointerAttributeNumber:
case ObjectIdAttributeNumber:
case MinTransactionIdAttributeNumber:
case MinCommandIdAttributeNumber:
case MaxTransactionIdAttributeNumber:
case MaxCommandIdAttributeNumber:
/* these are never null */
break;
default:
elog(ERROR, "invalid attnum: %d", attnum);
}
return false;
}
bool
heap_attisnull_normalattr(HeapTuple tup, int attnum)
{
Assert(attnum > 0);
if (HeapTupleNoNulls(tup))
return false;
return att_isnull(attnum - 1, tup->t_data->t_bits);
}
/* ----------------
* nocachegetattr
*
* This only gets called from fastgetattr() macro, in cases where
* we can't use a cacheoffset and the value is not null.
*
* This caches attribute offsets in the attribute descriptor.
*
* An alternative way to speed things up would be to cache offsets
* with the tuple, but that seems more difficult unless you take
* the storage hit of actually putting those offsets into the
* tuple you send to disk. Yuck.
*
* This scheme will be slightly slower than that, but should
* perform well for queries which hit large #'s of tuples. After
* you cache the offsets once, examining all the other tuples using
* the same attribute descriptor will go much quicker. -cim 5/4/91
*
* NOTE: if you need to change this code, see also heap_deform_tuple.
* Also see nocache_index_getattr, which is the same code for index
* tuples.
* ----------------
*/
Datum
nocachegetattr(HeapTuple tuple,
int attnum,
TupleDesc tupleDesc)
{
HeapTupleHeader tup = tuple->t_data;
Form_pg_attribute *att = tupleDesc->attrs;
char *tp; /* ptr to data part of tuple */
bits8 *bp = tup->t_bits; /* ptr to null bitmap in tuple */
bool slow = false; /* do we have to walk attrs? */
int off; /* current offset within data */
/* ----------------
* Three cases:
*
* 1: No nulls and no variable-width attributes.
* 2: Has a null or a var-width AFTER att.
* 3: Has nulls or var-widths BEFORE att.
* ----------------
*/
attnum--;
if (!HeapTupleNoNulls(tuple))
{
/*
* there's a null somewhere in the tuple
*
* check to see if any preceding bits are null...
*/
int byte = attnum >> 3;
int finalbit = attnum & 0x07;
/* check for nulls "before" final bit of last byte */
if ((~bp[byte]) & ((1 << finalbit) - 1))
slow = true;
else
{
/* check for nulls in any "earlier" bytes */
int i;
for (i = 0; i < byte; i++)
{
if (bp[i] != 0xFF)
{
slow = true;
break;
}
}
}
}
/* ----------------
* heap_attisnull - returns true iff tuple attribute is not present
* ----------------
*/
bool
heap_attisnull(HeapTuple tup, int attnum, TupleDesc tupleDesc)
{
/*
* We allow a NULL tupledesc for relations not expected to have missing
* values, such as catalog relations and indexes.
*/
Assert(!tupleDesc || attnum <= tupleDesc->natts);
if (attnum > (int) HeapTupleHeaderGetNatts(tup->t_data))
{
if (tupleDesc && TupleDescAttr(tupleDesc, attnum - 1)->atthasmissing)
return false;
else
return true;
}
if (attnum > 0)
{
if (HeapTupleNoNulls(tup))
return false;
return att_isnull(attnum - 1, tup->t_data->t_bits);
}
switch (attnum)
{
case TableOidAttributeNumber:
case SelfItemPointerAttributeNumber:
case MinTransactionIdAttributeNumber:
case MinCommandIdAttributeNumber:
case MaxTransactionIdAttributeNumber:
case MaxCommandIdAttributeNumber:
/* these are never null */
break;
default:
elog(ERROR, "invalid attnum: %d", attnum);
}
return false;
}
/* ----------------
* nocachegetattr
*
* This only gets called from fastgetattr() macro, in cases where
* we can't use a cacheoffset and the value is not null.
*
* This caches attribute offsets in the attribute descriptor.
*
* An alternative way to speed things up would be to cache offsets
* with the tuple, but that seems more difficult unless you take
* the storage hit of actually putting those offsets into the
* tuple you send to disk. Yuck.
*
* This scheme will be slightly slower than that, but should
* perform well for queries which hit large #'s of tuples. After
* you cache the offsets once, examining all the other tuples using
* the same attribute descriptor will go much quicker. -cim 5/4/91
*
* NOTE: if you need to change this code, see also heap_deform_tuple.
* Also see nocache_index_getattr, which is the same code for index
* tuples.
* ----------------
*/
Datum
nocachegetattr(HeapTuple tuple,
int attnum,
TupleDesc tupleDesc)
{
HeapTupleHeader tup = tuple->t_data;
Form_pg_attribute *att = tupleDesc->attrs;
char *tp; /* ptr to data part of tuple */
bits8 *bp = tup->t_bits; /* ptr to null bitmap in tuple */
bool slow = false; /* do we have to walk attrs? */
int off; /* current offset within data */
Assert(!is_heaptuple_memtuple(tuple));
/* ----------------
* Three cases:
*
* 1: No nulls and no variable-width attributes.
* 2: Has a null or a var-width AFTER att.
* 3: Has nulls or var-widths BEFORE att.
* ----------------
*/
#ifdef IN_MACRO
/* This is handled in the macro */
Assert(attnum > 0);
if (isnull)
*isnull = false;
#endif
attnum--;
if (HeapTupleNoNulls(tuple))
{
#ifdef IN_MACRO
/* This is handled in the macro */
if (att[attnum]->attcacheoff >= 0)
{
return fetchatt(att[attnum],
(char *) tup + tup->t_hoff +
att[attnum]->attcacheoff);
}
#endif
}
else
{
/*
* there's a null somewhere in the tuple
*
* check to see if desired att is null
*/
#ifdef IN_MACRO
/* This is handled in the macro */
if (att_isnull(attnum, bp))
{
if (isnull)
*isnull = true;
return (Datum) NULL;
}
#endif
/*
* Now check to see if any preceding bits are null...
*/
{
int byte = attnum >> 3;
int finalbit = attnum & 0x07;
/* check for nulls "before" final bit of last byte */
if ((~bp[byte]) & ((1 << finalbit) - 1))
slow = true;
else
{
/* check for nulls in any "earlier" bytes */
int i;
for (i = 0; i < byte; i++)
{
if (bp[i] != 0xFF)
{
slow = true;
break;
}
}
}
}
}
tp = (char *) tup + tup->t_hoff;
if (!slow)
{
/*
* If we get here, there are no nulls up to and including the target
* attribute. If we have a cached offset, we can use it.
*/
if (att[attnum]->attcacheoff >= 0)
{
return fetchatt(att[attnum],
tp + att[attnum]->attcacheoff);
}
/*
* Otherwise, check for non-fixed-length attrs up to and including
* target. If there aren't any, it's safe to cheaply initialize the
* cached offsets for these attrs.
*/
if (HeapTupleHasVarWidth(tuple))
{
int j;
for (j = 0; j <= attnum; j++)
{
if (att[j]->attlen <= 0)
{
slow = true;
break;
}
}
}
}
if (!slow)
{
int natts = tupleDesc->natts;
int j = 1;
/*
* If we get here, we have a tuple with no nulls or var-widths up to
* and including the target attribute, so we can use the cached offset
* ... only we don't have it yet, or we'd not have got here. Since
* it's cheap to compute offsets for fixed-width columns, we take the
* opportunity to initialize the cached offsets for *all* the leading
* fixed-width columns, in hope of avoiding future visits to this
* routine.
*/
att[0]->attcacheoff = 0;
/* we might have set some offsets in the slow path previously */
while (j < natts && att[j]->attcacheoff > 0)
j++;
off = att[j - 1]->attcacheoff + att[j - 1]->attlen;
for (; j < natts; j++)
{
if (att[j]->attlen <= 0)
break;
off = att_align_nominal(off, att[j]->attalign);
att[j]->attcacheoff = off;
off += att[j]->attlen;
}
Assert(j > attnum);
off = att[attnum]->attcacheoff;
}
else
{
bool usecache = true;
int i;
/* this is always true */
att[0]->attcacheoff = 0;
/*
* Now we know that we have to walk the tuple CAREFULLY. But we still
* might be able to cache some offsets for next time.
*
* Note - This loop is a little tricky. For each non-null attribute,
* we have to first account for alignment padding before the attr,
* then advance over the attr based on its length. Nulls have no
* storage and no alignment padding either. We can use/set
* attcacheoff until we reach either a null or a var-width attribute.
*/
off = 0;
for (i = 0;; i++) /* loop exit is at "break" */
{
if (HeapTupleHasNulls(tuple) && att_isnull(i, bp))
{
usecache = false;
continue; /* this cannot be the target att */
}
/* If we know the next offset, we can skip the rest */
if (usecache && att[i]->attcacheoff >= 0)
off = att[i]->attcacheoff;
else if (att[i]->attlen == -1)
{
/*
* We can only cache the offset for a varlena attribute if the
* offset is already suitably aligned, so that there would be
* no pad bytes in any case: then the offset will be valid for
* either an aligned or unaligned value.
*/
if (usecache &&
off == att_align_nominal(off, att[i]->attalign))
att[i]->attcacheoff = off;
else
{
off = att_align_pointer(off, att[i]->attalign, -1,
tp + off);
usecache = false;
}
}
else
{
/* not varlena, so safe to use att_align_nominal */
off = att_align_nominal(off, att[i]->attalign);
if (usecache)
att[i]->attcacheoff = off;
}
if (i == attnum)
break;
off = att_addlength_pointer(off, att[i]->attlen, tp + off);
if (usecache && att[i]->attlen <= 0)
usecache = false;
}
}
return fetchatt(att[attnum], tp + off);
}
/* ----------------
* nocachegetattr
*
* This only gets called from fastgetattr() macro, in cases where
* we can't use a cacheoffset and the value is not null.
*
* This caches attribute offsets in the attribute descriptor.
*
* An alternative way to speed things up would be to cache offsets
* with the tuple, but that seems more difficult unless you take
* the storage hit of actually putting those offsets into the
* tuple you send to disk. Yuck.
*
* This scheme will be slightly slower than that, but should
* perform well for queries which hit large #'s of tuples. After
* you cache the offsets once, examining all the other tuples using
* the same attribute descriptor will go much quicker. -cim 5/4/91
*
* NOTE: if you need to change this code, see also heap_deform_tuple.
* Also see nocache_index_getattr, which is the same code for index
* tuples.
* ----------------
*/
Datum
nocachegetattr(HeapTuple tuple,
int attnum,
TupleDesc tupleDesc)
{
HeapTupleHeader tup = tuple->t_data;
Form_pg_attribute *att = tupleDesc->attrs;
char *tp; /* ptr to att in tuple */
bits8 *bp = tup->t_bits; /* ptr to null bitmap in tuple */
bool slow = false; /* do we have to walk nulls? */
Assert(!is_heaptuple_memtuple(tuple));
/* If any cached offsets are there we can check that they make sense, but
* there may not be any at all, so pass -1 for the attnum we know is valid */
#ifdef IN_MACRO
/* This is handled in the macro */
Assert(attnum > 0);
if (isnull)
*isnull = false;
#endif
attnum--;
/* ----------------
* Three cases:
*
* 1: No nulls and no variable-width attributes.
* 2: Has a null or a var-width AFTER att.
* 3: Has nulls or var-widths BEFORE att.
* ----------------
*/
if (HeapTupleNoNulls(tuple))
{
#ifdef IN_MACRO
/* This is handled in the macro */
if (att[attnum]->attcacheoff != -1)
{
return fetchatt(att[attnum],
(char *) tup + tup->t_hoff +
att[attnum]->attcacheoff);
}
#endif
}
else
{
/*
* there's a null somewhere in the tuple
*
* check to see if desired att is null
*/
#ifdef IN_MACRO
/* This is handled in the macro */
if (att_isnull(attnum, bp))
{
if (isnull)
*isnull = true;
return (Datum) NULL;
}
#endif
/*
* Now check to see if any preceding bits are null...
*/
{
int byte = attnum >> 3;
int finalbit = attnum & 0x07;
/* check for nulls "before" final bit of last byte */
if ((~bp[byte]) & ((1 << finalbit) - 1))
slow = true;
else
{
/* check for nulls in any "earlier" bytes */
int i;
for (i = 0; i < byte; i++)
{
if (bp[i] != 0xFF)
{
slow = true;
break;
}
}
}
}
}
tp = (char *) tup + tup->t_hoff;
/*
* now check for any non-fixed length attrs before our attribute
*/
if (!slow)
{
/*
* If we get here, there are no nulls up to and including the target
* attribute. If we have a cached offset, we can use it.
*/
if (att[attnum]->attcacheoff >= 0)
{
return fetchatt(att[attnum],
tp + att[attnum]->attcacheoff);
}
/*
* Otherwise, check for non-fixed-length attrs up to and including
* target. If there aren't any, it's safe to cheaply initialize the
* cached offsets for these attrs.
*/
if (HeapTupleHasVarWidth(tuple))
{
int j;
/*
* In for(), we test <= and not < because we want to see if we can
* go past it in initializing offsets.
*/
for (j = 0; j <= attnum; j++)
{
if (att[j]->attlen <= 0)
{
slow = true;
break;
}
}
}
}
/*
* If slow is false, and we got here, we know that we have a tuple with no
* nulls or var-widths before the target attribute. If possible, we also
* want to initialize the remainder of the attribute cached offset values.
*/
if (!slow)
{
int j = 1;
long off;
int natts = HeapTupleHeaderGetNatts(tup);
/*
* If we get here, we have a tuple with no nulls or var-widths up to
* and including the target attribute, so we can use the cached offset
* ... only we don't have it yet, or we'd not have got here. Since
* it's cheap to compute offsets for fixed-width columns, we take the
* opportunity to initialize the cached offsets for *all* the leading
* fixed-width columns, in hope of avoiding future visits to this
* routine.
*/
/* this is always true */
att[0]->attcacheoff = 0;
while (j < attnum && att[j]->attcacheoff > 0)
j++;
off = att[j - 1]->attcacheoff + att[j - 1]->attlen;
for (; j <= attnum ||
/* Can we compute more? We will probably need them */
(j < natts &&
att[j]->attcacheoff == -1 &&
(HeapTupleNoNulls(tuple) || !att_isnull(j, bp)) &&
(HeapTupleAllFixed(tuple) || att[j]->attlen > 0)); j++)
{
/* don't need to worry about shortvarlenas here since we're only
* looking at non-varlenas. Note that it's important that we check
* that the target attribute itself is a nonvarlena too since we
* can't use cached offsets for even the first varlena any more. */
off = att_align(off, att[j]->attalign);
att[j]->attcacheoff = off;
off = att_addlength(off, att[j]->attlen, PointerGetDatum(tp + off));
}
return fetchatt(att[attnum], tp + att[attnum]->attcacheoff);
}
else
{
bool usecache = true;
int off = 0;
int i;
/* this is always true */
att[0]->attcacheoff = 0;
/*
* Now we know that we have to walk the tuple CAREFULLY.
*
* Note - This loop is a little tricky. For each non-null attribute,
* we have to first account for alignment padding before the attr,
* then advance over the attr based on its length. Nulls have no
* storage and no alignment padding either. We can use/set
* attcacheoff until we reach either a null or a var-width attribute.
*/
for (i = 0; i < attnum; i++)
{
if (HeapTupleHasNulls(tuple) && att_isnull(i, bp))
{
usecache = false;
continue;
}
/* If we know the next offset, we can skip the alignment calc */
if (usecache && att[i]->attcacheoff != -1)
off = att[i]->attcacheoff;
else
{
/* if it's a varlena it may or may not be aligned, so check for
* something that looks like a padding byte before aligning. If
* we're already aligned it may be the leading byte of a 4-byte
* header but then the att_align is harmless. Don't bother
* looking if it's not a varlena though.*/
if (att[i]->attlen != -1 || !tp[off])
off = att_align(off, att[i]->attalign);
if (usecache && att[i]->attlen != -1)
att[i]->attcacheoff = off;
}
if (att[i]->attlen < 0)
usecache = false;
off = att_addlength(off, att[i]->attlen, PointerGetDatum(tp + off));
}
if (att[attnum]->attlen != -1 || !tp[off])
off = att_align(off, att[attnum]->attalign);
return fetchatt(att[attnum], tp + off);
}
}
