/*
* Check to see whether the table needs a TOAST table. It does only if
* (1) there are any toastable attributes, and (2) the maximum length
* of a tuple could exceed TOAST_TUPLE_THRESHOLD. (We don't want to
* create a toast table for something like "f1 varchar(20)".)
* No need to create a TOAST table for partitioned tables.
*/
static bool
needs_toast_table(Relation rel)
{
int32 data_length = 0;
bool maxlength_unknown = false;
bool has_toastable_attrs = false;
TupleDesc tupdesc;
int32 tuple_length;
int i;
if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
return false;
tupdesc = rel->rd_att;
for (i = 0; i < tupdesc->natts; i++)
{
Form_pg_attribute att = TupleDescAttr(tupdesc, i);
if (att->attisdropped)
continue;
data_length = att_align_nominal(data_length, att->attalign);
if (att->attlen > 0)
{
/* Fixed-length types are never toastable */
data_length += att->attlen;
}
else
{
int32 maxlen = type_maximum_size(att->atttypid,
att->atttypmod);
if (maxlen < 0)
maxlength_unknown = true;
else
data_length += maxlen;
if (att->attstorage != 'p')
has_toastable_attrs = true;
}
}
if (!has_toastable_attrs)
return false; /* nothing to toast? */
if (maxlength_unknown)
return true; /* any unlimited-length attrs? */
tuple_length = MAXALIGN(SizeofHeapTupleHeader +
BITMAPLEN(tupdesc->natts)) +
MAXALIGN(data_length);
return (tuple_length > TOAST_TUPLE_THRESHOLD);
}
/*
* Check to see whether the table needs a TOAST table. It does only if
* (1) there are any toastable attributes, and (2) the maximum length
* of a tuple could exceed TOAST_TUPLE_THRESHOLD. (We don't want to
* create a toast table for something like "f1 varchar(20)".)
*/
bool
RelationNeedsToastTable(Relation rel)
{
int32 data_length = 0;
bool maxlength_unknown = false;
bool has_toastable_attrs = false;
TupleDesc tupdesc;
Form_pg_attribute *att;
int32 tuple_length;
int i;
if(RelationIsExternal(rel))
return false;
tupdesc = rel->rd_att;
att = tupdesc->attrs;
for (i = 0; i < tupdesc->natts; i++)
{
if (att[i]->attisdropped)
continue;
data_length = att_align_nominal(data_length, att[i]->attalign);
if (att[i]->attlen > 0)
{
/* Fixed-length types are never toastable */
data_length += att[i]->attlen;
}
else
{
int32 maxlen = type_maximum_size(att[i]->atttypid,
att[i]->atttypmod);
if (maxlen < 0)
maxlength_unknown = true;
else
data_length += maxlen;
if (att[i]->attstorage != 'p')
has_toastable_attrs = true;
}
}
if (!has_toastable_attrs)
return false; /* nothing to toast? */
if (maxlength_unknown)
return true; /* any unlimited-length attrs? */
tuple_length = MAXALIGN(offsetof(HeapTupleHeaderData, t_bits) +
BITMAPLEN(tupdesc->natts)) +
MAXALIGN(data_length);
return (tuple_length > TOAST_TUPLE_THRESHOLD);
}
/*
* get_typavgwidth
*
* Given a type OID and a typmod value (pass -1 if typmod is unknown),
* estimate the average width of values of the type. This is used by
* the planner, which doesn't require absolutely correct results;
* it's OK (and expected) to guess if we don't know for sure.
*/
int32
get_typavgwidth(Oid typid, int32 typmod)
{
int typlen = get_typlen(typid);
int32 maxwidth;
/*
* Easy if it's a fixed-width type
*/
if (typlen > 0)
return typlen;
/*
* type_maximum_size knows the encoding of typmod for some datatypes;
* don't duplicate that knowledge here.
*/
maxwidth = type_maximum_size(typid, typmod);
if (maxwidth > 0)
{
/*
* For BPCHAR, the max width is also the only width. Otherwise we
* need to guess about the typical data width given the max. A sliding
* scale for percentage of max width seems reasonable.
*/
if (typid == BPCHAROID)
return maxwidth;
if (maxwidth <= 32)
return maxwidth; /* assume full width */
if (maxwidth < 1000)
return 32 + (maxwidth - 32) / 2; /* assume 50% */
/*
* Beyond 1000, assume we're looking at something like
* "varchar(10000)" where the limit isn't actually reached often, and
* use a fixed estimate.
*/
return 32 + (1000 - 32) / 2;
}
/*
* Ooops, we have no idea ... wild guess time.
*/
return 32;
}
/*
* Check to see whether the table needs a TOAST table. It does only if
* (1) there are any toastable attributes, and (2) the maximum length
* of a tuple could exceed TOAST_TUPLE_THRESHOLD. (We don't want to
* create a toast table for something like "f1 varchar(20)".)
*/
static bool
needs_toast_table(Relation rel)
{
int32 data_length = 0;
bool maxlength_unknown = false;
bool has_toastable_attrs = false;
TupleDesc tupdesc;
int32 tuple_length;
int i;
/*
* No need to create a TOAST table for partitioned tables.
*/
if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
return false;
/*
* We cannot allow toasting a shared relation after initdb (because
* there's no way to mark it toasted in other databases' pg_class).
*/
if (rel->rd_rel->relisshared && !IsBootstrapProcessingMode())
return false;
/*
* Ignore attempts to create toast tables on catalog tables after initdb.
* Which catalogs get toast tables is explicitly chosen in
* catalog/toasting.h. (We could get here via some ALTER TABLE command if
* the catalog doesn't have a toast table.)
*/
if (IsCatalogRelation(rel) && !IsBootstrapProcessingMode())
return false;
tupdesc = rel->rd_att;
for (i = 0; i < tupdesc->natts; i++)
{
Form_pg_attribute att = TupleDescAttr(tupdesc, i);
if (att->attisdropped)
continue;
data_length = att_align_nominal(data_length, att->attalign);
if (att->attlen > 0)
{
/* Fixed-length types are never toastable */
data_length += att->attlen;
}
else
{
int32 maxlen = type_maximum_size(att->atttypid,
att->atttypmod);
if (maxlen < 0)
maxlength_unknown = true;
else
data_length += maxlen;
if (att->attstorage != 'p')
has_toastable_attrs = true;
}
}
if (!has_toastable_attrs)
return false; /* nothing to toast? */
if (maxlength_unknown)
return true; /* any unlimited-length attrs? */
tuple_length = MAXALIGN(SizeofHeapTupleHeader +
BITMAPLEN(tupdesc->natts)) +
MAXALIGN(data_length);
return (tuple_length > TOAST_TUPLE_THRESHOLD);
}
