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Create new routines systable_beginscan_ordered, systable_getnext_ordered,

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systable_endscan_ordered that have API similar to systable_beginscan etc
(in particular, the passed-in scankeys have heap not index attnums),
but guarantee ordered output, unlike the existing functions.  For the moment
these are just very thin wrappers around index_beginscan/index_getnext/etc.
Someday they might need to get smarter; but for now this is just a code
refactoring exercise to reduce the number of direct callers of index_getnext,
in preparation for changing that function's API.

In passing, remove index_getnext_indexitem, which has been dead code for
quite some time, and will have even less use than that in the presence
of run-time-lossy indexes.
This commit is contained in:
Tom Lane
2008-04-12 23:14:21 +00:00
parent 00832809a0
commit ec498cdcbb
9 changed files with 168 additions and 124 deletions
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51
src/backend/storage/large_object/inv_api.c
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@@ -24,7 +24,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/large_object/inv_api.c,v 1.131 2008/03/26 21:10:38 alvherre Exp $
* $PostgreSQL: pgsql/src/backend/storage/large_object/inv_api.c,v 1.132 2008/04/12 23:14:21 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -201,7 +201,8 @@ inv_create(Oid lobjId)
{
open_lo_relation();
lobjId = GetNewOidWithIndex(lo_heap_r, lo_index_r);
lobjId = GetNewOidWithIndex(lo_heap_r, LargeObjectLOidPNIndexId,
Anum_pg_largeobject_loid);
}
/*
@@ -311,7 +312,7 @@ inv_getsize(LargeObjectDesc *obj_desc)
bool found = false;
uint32 lastbyte = 0;
ScanKeyData skey[1];
IndexScanDesc sd;
SysScanDesc sd;
HeapTuple tuple;
Assert(PointerIsValid(obj_desc));
@@ -323,8 +324,8 @@ inv_getsize(LargeObjectDesc *obj_desc)
BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(obj_desc->id));
sd = index_beginscan(lo_heap_r, lo_index_r,
obj_desc->snapshot, 1, skey);
sd = systable_beginscan_ordered(lo_heap_r, lo_index_r,
obj_desc->snapshot, 1, skey);
/*
* Because the pg_largeobject index is on both loid and pageno, but we
@@ -332,7 +333,7 @@ inv_getsize(LargeObjectDesc *obj_desc)
* large object in reverse pageno order. So, it's sufficient to examine
* the first valid tuple (== last valid page).
*/
while ((tuple = index_getnext(sd, BackwardScanDirection)) != NULL)
while ((tuple = systable_getnext_ordered(sd, BackwardScanDirection)) != NULL)
{
Form_pg_largeobject data;
bytea *datafield;
@@ -356,7 +357,7 @@ inv_getsize(LargeObjectDesc *obj_desc)
break;
}
index_endscan(sd);
systable_endscan_ordered(sd);
if (!found)
ereport(ERROR,
@@ -415,7 +416,7 @@ inv_read(LargeObjectDesc *obj_desc, char *buf, int nbytes)
int32 pageno = (int32) (obj_desc->offset / LOBLKSIZE);
uint32 pageoff;
ScanKeyData skey[2];
IndexScanDesc sd;
SysScanDesc sd;
HeapTuple tuple;
Assert(PointerIsValid(obj_desc));
@@ -436,10 +437,10 @@ inv_read(LargeObjectDesc *obj_desc, char *buf, int nbytes)
BTGreaterEqualStrategyNumber, F_INT4GE,
Int32GetDatum(pageno));
sd = index_beginscan(lo_heap_r, lo_index_r,
obj_desc->snapshot, 2, skey);
sd = systable_beginscan_ordered(lo_heap_r, lo_index_r,
obj_desc->snapshot, 2, skey);
while ((tuple = index_getnext(sd, ForwardScanDirection)) != NULL)
while ((tuple = systable_getnext_ordered(sd, ForwardScanDirection)) != NULL)
{
Form_pg_largeobject data;
bytea *datafield;
@@ -450,7 +451,7 @@ inv_read(LargeObjectDesc *obj_desc, char *buf, int nbytes)
data = (Form_pg_largeobject) GETSTRUCT(tuple);
/*
* We assume the indexscan will deliver pages in order. However,
* We expect the indexscan will deliver pages in order. However,
* there may be missing pages if the LO contains unwritten "holes". We
* want missing sections to read out as zeroes.
*/
@@ -495,7 +496,7 @@ inv_read(LargeObjectDesc *obj_desc, char *buf, int nbytes)
break;
}
index_endscan(sd);
systable_endscan_ordered(sd);
return nread;
}
@@ -509,7 +510,7 @@ inv_write(LargeObjectDesc *obj_desc, const char *buf, int nbytes)
int len;
int32 pageno = (int32) (obj_desc->offset / LOBLKSIZE);
ScanKeyData skey[2];
IndexScanDesc sd;
SysScanDesc sd;
HeapTuple oldtuple;
Form_pg_largeobject olddata;
bool neednextpage;
@@ -555,8 +556,8 @@ inv_write(LargeObjectDesc *obj_desc, const char *buf, int nbytes)
BTGreaterEqualStrategyNumber, F_INT4GE,
Int32GetDatum(pageno));
sd = index_beginscan(lo_heap_r, lo_index_r,
obj_desc->snapshot, 2, skey);
sd = systable_beginscan_ordered(lo_heap_r, lo_index_r,
obj_desc->snapshot, 2, skey);
oldtuple = NULL;
olddata = NULL;
@@ -565,12 +566,12 @@ inv_write(LargeObjectDesc *obj_desc, const char *buf, int nbytes)
while (nwritten < nbytes)
{
/*
* If possible, get next pre-existing page of the LO. We assume the
* If possible, get next pre-existing page of the LO. We expect the
* indexscan will deliver these in order --- but there may be holes.
*/
if (neednextpage)
{
if ((oldtuple = index_getnext(sd, ForwardScanDirection)) != NULL)
if ((oldtuple = systable_getnext_ordered(sd, ForwardScanDirection)) != NULL)
{
if (HeapTupleHasNulls(oldtuple)) /* paranoia */
elog(ERROR, "null field found in pg_largeobject");
@@ -685,7 +686,7 @@ inv_write(LargeObjectDesc *obj_desc, const char *buf, int nbytes)
pageno++;
}
index_endscan(sd);
systable_endscan_ordered(sd);
CatalogCloseIndexes(indstate);
@@ -704,7 +705,7 @@ inv_truncate(LargeObjectDesc *obj_desc, int len)
int32 pageno = (int32) (len / LOBLKSIZE);
int off;
ScanKeyData skey[2];
IndexScanDesc sd;
SysScanDesc sd;
HeapTuple oldtuple;
Form_pg_largeobject olddata;
struct
@@ -743,15 +744,15 @@ inv_truncate(LargeObjectDesc *obj_desc, int len)
BTGreaterEqualStrategyNumber, F_INT4GE,
Int32GetDatum(pageno));
sd = index_beginscan(lo_heap_r, lo_index_r,
obj_desc->snapshot, 2, skey);
sd = systable_beginscan_ordered(lo_heap_r, lo_index_r,
obj_desc->snapshot, 2, skey);
/*
* If possible, get the page the truncation point is in. The truncation
* point may be beyond the end of the LO or in a hole.
*/
olddata = NULL;
if ((oldtuple = index_getnext(sd, ForwardScanDirection)) != NULL)
if ((oldtuple = systable_getnext_ordered(sd, ForwardScanDirection)) != NULL)
{
if (HeapTupleHasNulls(oldtuple)) /* paranoia */
elog(ERROR, "null field found in pg_largeobject");
@@ -846,12 +847,12 @@ inv_truncate(LargeObjectDesc *obj_desc, int len)
/*
* Delete any pages after the truncation point
*/
while ((oldtuple = index_getnext(sd, ForwardScanDirection)) != NULL)
while ((oldtuple = systable_getnext_ordered(sd, ForwardScanDirection)) != NULL)
{
simple_heap_delete(lo_heap_r, &oldtuple->t_self);
}
index_endscan(sd);
systable_endscan_ordered(sd);
CatalogCloseIndexes(indstate);