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Commit3f50ba2

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Create infrastructure for 'MinimalTuple' representation of in-memory
tuples with less header overhead than a regular HeapTuple, per myrecent proposal. Teach TupleTableSlot code how to deal with these.As proof of concept, change tuplestore.c to store MinimalTuples insteadof HeapTuples. Future patches will expand the concept to other placeswhere it is useful.
1 parentfe491fb commit3f50ba2

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13 files changed

+558
-129
lines changed

13 files changed

+558
-129
lines changed

‎contrib/tablefunc/tablefunc.c‎

Lines changed: 8 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -934,19 +934,16 @@ get_crosstab_tuplestore(char *sql,
934934
*/
935935
if (lastrowid!=NULL)
936936
{
937-
/*
938-
* switch to appropriate context while storing the tuple
939-
*/
940-
SPIcontext=MemoryContextSwitchTo(per_query_ctx);
941-
942937
/* rowid changed, flush the previous output row */
943938
tuple=BuildTupleFromCStrings(attinmeta,values);
939+
940+
/* switch to appropriate context while storing the tuple */
941+
SPIcontext=MemoryContextSwitchTo(per_query_ctx);
944942
tuplestore_puttuple(tupstore,tuple);
943+
MemoryContextSwitchTo(SPIcontext);
944+
945945
for (j=0;j<result_ncols;j++)
946946
xpfree(values[j]);
947-
948-
/* now reset the context */
949-
MemoryContextSwitchTo(SPIcontext);
950947
}
951948

952949
values[0]=rowid;
@@ -970,16 +967,13 @@ get_crosstab_tuplestore(char *sql,
970967
lastrowid=pstrdup(rowid);
971968
}
972969

973-
/* switch to appropriate context while storing the tuple */
974-
SPIcontext=MemoryContextSwitchTo(per_query_ctx);
975-
976970
/* flush the last output row */
977971
tuple=BuildTupleFromCStrings(attinmeta,values);
978-
tuplestore_puttuple(tupstore,tuple);
979972

980-
/* now reset the context */
973+
/* switch to appropriate context while storing the tuple */
974+
SPIcontext=MemoryContextSwitchTo(per_query_ctx);
975+
tuplestore_puttuple(tupstore,tuple);
981976
MemoryContextSwitchTo(SPIcontext);
982-
983977
}
984978

985979
if (SPI_finish()!=SPI_OK_FINISH)

‎src/backend/access/common/heaptuple.c‎

Lines changed: 174 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -16,7 +16,7 @@
1616
*
1717
*
1818
* IDENTIFICATION
19-
* $PostgreSQL: pgsql/src/backend/access/common/heaptuple.c,v 1.106 2006/03/05 15:58:20 momjian Exp $
19+
* $PostgreSQL: pgsql/src/backend/access/common/heaptuple.c,v 1.107 2006/06/27 02:51:39 tgl Exp $
2020
*
2121
*-------------------------------------------------------------------------
2222
*/
@@ -1295,6 +1295,8 @@ slot_getattr(TupleTableSlot *slot, int attnum, bool *isnull)
12951295
{
12961296
if (tuple==NULL)/* internal error */
12971297
elog(ERROR,"cannot extract system attribute from virtual tuple");
1298+
if (slot->tts_mintuple)/* internal error */
1299+
elog(ERROR,"cannot extract system attribute from minimal tuple");
12981300
returnheap_getsysattr(tuple,attnum,tupleDesc,isnull);
12991301
}
13001302

@@ -1479,6 +1481,8 @@ slot_attisnull(TupleTableSlot *slot, int attnum)
14791481
{
14801482
if (tuple==NULL)/* internal error */
14811483
elog(ERROR,"cannot extract system attribute from virtual tuple");
1484+
if (slot->tts_mintuple)/* internal error */
1485+
elog(ERROR,"cannot extract system attribute from minimal tuple");
14821486
returnheap_attisnull(tuple,attnum);
14831487
}
14841488

@@ -1505,9 +1509,8 @@ slot_attisnull(TupleTableSlot *slot, int attnum)
15051509
returnheap_attisnull(tuple,attnum);
15061510
}
15071511

1508-
/* ----------------
1509-
*heap_freetuple
1510-
* ----------------
1512+
/*
1513+
* heap_freetuple
15111514
*/
15121515
void
15131516
heap_freetuple(HeapTuplehtup)
@@ -1516,6 +1519,173 @@ heap_freetuple(HeapTuple htup)
15161519
}
15171520

15181521

1522+
/*
1523+
* heap_form_minimal_tuple
1524+
*construct a MinimalTuple from the given values[] and isnull[] arrays,
1525+
*which are of the length indicated by tupleDescriptor->natts
1526+
*
1527+
* This is exactly like heap_form_tuple() except that the result is a
1528+
* "minimal" tuple lacking a HeapTupleData header as well as room for system
1529+
* columns.
1530+
*
1531+
* The result is allocated in the current memory context.
1532+
*/
1533+
MinimalTuple
1534+
heap_form_minimal_tuple(TupleDesctupleDescriptor,
1535+
Datum*values,
1536+
bool*isnull)
1537+
{
1538+
MinimalTupletuple;/* return tuple */
1539+
unsigned longlen;
1540+
inthoff;
1541+
boolhasnull= false;
1542+
Form_pg_attribute*att=tupleDescriptor->attrs;
1543+
intnumberOfAttributes=tupleDescriptor->natts;
1544+
inti;
1545+
1546+
if (numberOfAttributes>MaxTupleAttributeNumber)
1547+
ereport(ERROR,
1548+
(errcode(ERRCODE_TOO_MANY_COLUMNS),
1549+
errmsg("number of columns (%d) exceeds limit (%d)",
1550+
numberOfAttributes,MaxTupleAttributeNumber)));
1551+
1552+
/*
1553+
* Check for nulls and embedded tuples; expand any toasted attributes in
1554+
* embedded tuples. This preserves the invariant that toasting can only
1555+
* go one level deep.
1556+
*
1557+
* We can skip calling toast_flatten_tuple_attribute() if the attribute
1558+
* couldn't possibly be of composite type. All composite datums are
1559+
* varlena and have alignment 'd'; furthermore they aren't arrays. Also,
1560+
* if an attribute is already toasted, it must have been sent to disk
1561+
* already and so cannot contain toasted attributes.
1562+
*/
1563+
for (i=0;i<numberOfAttributes;i++)
1564+
{
1565+
if (isnull[i])
1566+
hasnull= true;
1567+
elseif (att[i]->attlen==-1&&
1568+
att[i]->attalign=='d'&&
1569+
att[i]->attndims==0&&
1570+
!VARATT_IS_EXTENDED(values[i]))
1571+
{
1572+
values[i]=toast_flatten_tuple_attribute(values[i],
1573+
att[i]->atttypid,
1574+
att[i]->atttypmod);
1575+
}
1576+
}
1577+
1578+
/*
1579+
* Determine total space needed
1580+
*/
1581+
len= offsetof(MinimalTupleData,t_bits);
1582+
1583+
if (hasnull)
1584+
len+=BITMAPLEN(numberOfAttributes);
1585+
1586+
if (tupleDescriptor->tdhasoid)
1587+
len+=sizeof(Oid);
1588+
1589+
hoff=len=MAXALIGN(len);/* align user data safely */
1590+
1591+
len+=heap_compute_data_size(tupleDescriptor,values,isnull);
1592+
1593+
/*
1594+
* Allocate and zero the space needed.
1595+
*/
1596+
tuple= (MinimalTuple)palloc0(len);
1597+
1598+
/*
1599+
* And fill in the information.
1600+
*/
1601+
tuple->t_len=len;
1602+
tuple->t_natts=numberOfAttributes;
1603+
tuple->t_hoff=hoff+MINIMAL_TUPLE_OFFSET;
1604+
1605+
if (tupleDescriptor->tdhasoid)/* else leave infomask = 0 */
1606+
tuple->t_infomask=HEAP_HASOID;
1607+
1608+
heap_fill_tuple(tupleDescriptor,
1609+
values,
1610+
isnull,
1611+
(char*)tuple+hoff,
1612+
&tuple->t_infomask,
1613+
(hasnull ?tuple->t_bits :NULL));
1614+
1615+
returntuple;
1616+
}
1617+
1618+
/*
1619+
* heap_free_minimal_tuple
1620+
*/
1621+
void
1622+
heap_free_minimal_tuple(MinimalTuplemtup)
1623+
{
1624+
pfree(mtup);
1625+
}
1626+
1627+
/*
1628+
* heap_copy_minimal_tuple
1629+
*copy a MinimalTuple
1630+
*
1631+
* The result is allocated in the current memory context.
1632+
*/
1633+
MinimalTuple
1634+
heap_copy_minimal_tuple(MinimalTuplemtup)
1635+
{
1636+
MinimalTupleresult;
1637+
1638+
result= (MinimalTuple)palloc(mtup->t_len);
1639+
memcpy(result,mtup,mtup->t_len);
1640+
returnresult;
1641+
}
1642+
1643+
/*
1644+
* heap_tuple_from_minimal_tuple
1645+
*create a HeapTuple by copying from a MinimalTuple;
1646+
*system columns are filled with zeroes
1647+
*
1648+
* The result is allocated in the current memory context.
1649+
* The HeapTuple struct, tuple header, and tuple data are all allocated
1650+
* as a single palloc() block.
1651+
*/
1652+
HeapTuple
1653+
heap_tuple_from_minimal_tuple(MinimalTuplemtup)
1654+
{
1655+
HeapTupleresult;
1656+
uint32len=mtup->t_len+MINIMAL_TUPLE_OFFSET;
1657+
1658+
result= (HeapTuple)palloc(HEAPTUPLESIZE+len);
1659+
result->t_len=len;
1660+
ItemPointerSetInvalid(&(result->t_self));
1661+
result->t_tableOid=InvalidOid;
1662+
result->t_data= (HeapTupleHeader) ((char*)result+HEAPTUPLESIZE);
1663+
memcpy((char*)result->t_data+MINIMAL_TUPLE_OFFSET,mtup,mtup->t_len);
1664+
memset(result->t_data,0, offsetof(HeapTupleHeaderData,t_natts));
1665+
returnresult;
1666+
}
1667+
1668+
/*
1669+
* minimal_tuple_from_heap_tuple
1670+
*create a MinimalTuple by copying from a HeapTuple
1671+
*
1672+
* The result is allocated in the current memory context.
1673+
*/
1674+
MinimalTuple
1675+
minimal_tuple_from_heap_tuple(HeapTuplehtup)
1676+
{
1677+
MinimalTupleresult;
1678+
uint32len;
1679+
1680+
Assert(htup->t_len>MINIMAL_TUPLE_OFFSET);
1681+
len=htup->t_len-MINIMAL_TUPLE_OFFSET;
1682+
result= (MinimalTuple)palloc(len);
1683+
memcpy(result, (char*)htup->t_data+MINIMAL_TUPLE_OFFSET,len);
1684+
result->t_len=len;
1685+
returnresult;
1686+
}
1687+
1688+
15191689
/* ----------------
15201690
*heap_addheader
15211691
*

‎src/backend/commands/portalcmds.c‎

Lines changed: 2 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -14,7 +14,7 @@
1414
*
1515
*
1616
* IDENTIFICATION
17-
* $PostgreSQL: pgsql/src/backend/commands/portalcmds.c,v 1.46 2006/03/05 15:58:24 momjian Exp $
17+
* $PostgreSQL: pgsql/src/backend/commands/portalcmds.c,v 1.47 2006/06/27 02:51:39 tgl Exp $
1818
*
1919
*-------------------------------------------------------------------------
2020
*/
@@ -411,17 +411,8 @@ PersistHoldablePortal(Portal portal)
411411

412412
for (store_pos=0;store_pos<portal->portalPos;store_pos++)
413413
{
414-
HeapTupletup;
415-
boolshould_free;
416-
417-
tup=tuplestore_gettuple(portal->holdStore, true,
418-
&should_free);
419-
420-
if (tup==NULL)
414+
if (!tuplestore_advance(portal->holdStore, true))
421415
elog(ERROR,"unexpected end of tuple stream");
422-
423-
if (should_free)
424-
pfree(tup);
425416
}
426417
}
427418
}

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