/*
* Initialize a BrinBuildState appropriate to create tuples on the given index.
*/
static BrinBuildState *
initialize_brin_buildstate(Relation idxRel, BrinRevmap *revmap,
BlockNumber pagesPerRange)
{
BrinBuildState *state;
state = palloc(sizeof(BrinBuildState));
state->bs_irel = idxRel;
state->bs_numtuples = 0;
state->bs_currentInsertBuf = InvalidBuffer;
state->bs_pagesPerRange = pagesPerRange;
state->bs_currRangeStart = 0;
state->bs_rmAccess = revmap;
state->bs_bdesc = brin_build_desc(idxRel);
state->bs_dtuple = brin_new_memtuple(state->bs_bdesc);
brin_memtuple_initialize(state->bs_dtuple, state->bs_bdesc);
return state;
}
/*
* Convert a BrinTuple back to a BrinMemTuple. This is the reverse of
* brin_form_tuple.
*
* As an optimization, the caller can pass a previously allocated 'dMemtuple'.
* This avoids having to allocate it here, which can be useful when this
* function is called many times in a loop. It is caller's responsibility
* that the given BrinMemTuple matches what we need here.
*
* Note we don't need the "on disk tupdesc" here; we rely on our own routine to
* deconstruct the tuple from the on-disk format.
*/
BrinMemTuple *
brin_deform_tuple(BrinDesc *brdesc, BrinTuple *tuple, BrinMemTuple *dMemtuple)
{
BrinMemTuple *dtup;
Datum *values;
bool *allnulls;
bool *hasnulls;
char *tp;
bits8 *nullbits;
int keyno;
int valueno;
MemoryContext oldcxt;
dtup = dMemtuple ? brin_memtuple_initialize(dMemtuple, brdesc) :
brin_new_memtuple(brdesc);
if (BrinTupleIsPlaceholder(tuple))
dtup->bt_placeholder = true;
dtup->bt_blkno = tuple->bt_blkno;
values = dtup->bt_values;
allnulls = dtup->bt_allnulls;
hasnulls = dtup->bt_hasnulls;
tp = (char *) tuple + BrinTupleDataOffset(tuple);
if (BrinTupleHasNulls(tuple))
nullbits = (bits8 *) ((char *) tuple + SizeOfBrinTuple);
else
nullbits = NULL;
brin_deconstruct_tuple(brdesc,
tp, nullbits, BrinTupleHasNulls(tuple),
values, allnulls, hasnulls);
/*
* Iterate to assign each of the values to the corresponding item in the
* values array of each column. The copies occur in the tuple's context.
*/
oldcxt = MemoryContextSwitchTo(dtup->bt_context);
for (valueno = 0, keyno = 0; keyno < brdesc->bd_tupdesc->natts; keyno++)
{
int i;
if (allnulls[keyno])
{
valueno += brdesc->bd_info[keyno]->oi_nstored;
continue;
}
/*
* We would like to skip datumCopy'ing the values datum in some cases,
* caller permitting ...
*/
for (i = 0; i < brdesc->bd_info[keyno]->oi_nstored; i++)
dtup->bt_columns[keyno].bv_values[i] =
datumCopy(values[valueno++],
brdesc->bd_info[keyno]->oi_typcache[i]->typbyval,
brdesc->bd_info[keyno]->oi_typcache[i]->typlen);
dtup->bt_columns[keyno].bv_hasnulls = hasnulls[keyno];
dtup->bt_columns[keyno].bv_allnulls = false;
}
MemoryContextSwitchTo(oldcxt);
return dtup;
}
/*
* Execute the index scan.
*
* This works by reading index TIDs from the revmap, and obtaining the index
* tuples pointed to by them; the summary values in the index tuples are
* compared to the scan keys. We return into the TID bitmap all the pages in
* ranges corresponding to index tuples that match the scan keys.
*
* If a TID from the revmap is read as InvalidTID, we know that range is
* unsummarized. Pages in those ranges need to be returned regardless of scan
* keys.
*/
int64
bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm)
{
Relation idxRel = scan->indexRelation;
Buffer buf = InvalidBuffer;
BrinDesc *bdesc;
Oid heapOid;
Relation heapRel;
BrinOpaque *opaque;
BlockNumber nblocks;
BlockNumber heapBlk;
int totalpages = 0;
FmgrInfo *consistentFn;
MemoryContext oldcxt;
MemoryContext perRangeCxt;
BrinMemTuple *dtup;
BrinTuple *btup = NULL;
Size btupsz = 0;
opaque = (BrinOpaque *) scan->opaque;
bdesc = opaque->bo_bdesc;
pgstat_count_index_scan(idxRel);
/*
* We need to know the size of the table so that we know how long to
* iterate on the revmap.
*/
heapOid = IndexGetRelation(RelationGetRelid(idxRel), false);
heapRel = table_open(heapOid, AccessShareLock);
nblocks = RelationGetNumberOfBlocks(heapRel);
table_close(heapRel, AccessShareLock);
/*
* Make room for the consistent support procedures of indexed columns. We
* don't look them up here; we do that lazily the first time we see a scan
* key reference each of them. We rely on zeroing fn_oid to InvalidOid.
*/
consistentFn = palloc0(sizeof(FmgrInfo) * bdesc->bd_tupdesc->natts);
/* allocate an initial in-memory tuple, out of the per-range memcxt */
dtup = brin_new_memtuple(bdesc);
/*
* Setup and use a per-range memory context, which is reset every time we
* loop below. This avoids having to free the tuples within the loop.
*/
perRangeCxt = AllocSetContextCreate(CurrentMemoryContext,
"bringetbitmap cxt",
ALLOCSET_DEFAULT_SIZES);
oldcxt = MemoryContextSwitchTo(perRangeCxt);
/*
* Now scan the revmap. We start by querying for heap page 0,
* incrementing by the number of pages per range; this gives us a full
* view of the table.
*/
for (heapBlk = 0; heapBlk < nblocks; heapBlk += opaque->bo_pagesPerRange)
{
bool addrange;
bool gottuple = false;
BrinTuple *tup;
OffsetNumber off;
Size size;
CHECK_FOR_INTERRUPTS();
MemoryContextResetAndDeleteChildren(perRangeCxt);
tup = brinGetTupleForHeapBlock(opaque->bo_rmAccess, heapBlk, &buf,
&off, &size, BUFFER_LOCK_SHARE,
scan->xs_snapshot);
if (tup)
{
gottuple = true;
btup = brin_copy_tuple(tup, size, btup, &btupsz);
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
}
/*
* For page ranges with no indexed tuple, we must return the whole
* range; otherwise, compare it to the scan keys.
*/
if (!gottuple)
{
addrange = true;
}
else
{
dtup = brin_deform_tuple(bdesc, btup, dtup);
if (dtup->bt_placeholder)
{
/*
* Placeholder tuples are always returned, regardless of the
* values stored in them.
*/
addrange = true;
}
else
{
int keyno;
/*
* Compare scan keys with summary values stored for the range.
* If scan keys are matched, the page range must be added to
* the bitmap. We initially assume the range needs to be
* added; in particular this serves the case where there are
* no keys.
*/
addrange = true;
for (keyno = 0; keyno < scan->numberOfKeys; keyno++)
{
ScanKey key = &scan->keyData[keyno];
AttrNumber keyattno = key->sk_attno;
BrinValues *bval = &dtup->bt_columns[keyattno - 1];
Datum add;
/*
* The collation of the scan key must match the collation
* used in the index column (but only if the search is not
* IS NULL/ IS NOT NULL). Otherwise we shouldn't be using
* this index ...
*/
Assert((key->sk_flags & SK_ISNULL) ||
(key->sk_collation ==
TupleDescAttr(bdesc->bd_tupdesc,
keyattno - 1)->attcollation));
/* First time this column? look up consistent function */
if (consistentFn[keyattno - 1].fn_oid == InvalidOid)
{
FmgrInfo *tmp;
tmp = index_getprocinfo(idxRel, keyattno,
BRIN_PROCNUM_CONSISTENT);
fmgr_info_copy(&consistentFn[keyattno - 1], tmp,
CurrentMemoryContext);
}
/*
* Check whether the scan key is consistent with the page
* range values; if so, have the pages in the range added
* to the output bitmap.
*
* When there are multiple scan keys, failure to meet the
* criteria for a single one of them is enough to discard
* the range as a whole, so break out of the loop as soon
* as a false return value is obtained.
*/
add = FunctionCall3Coll(&consistentFn[keyattno - 1],
key->sk_collation,
PointerGetDatum(bdesc),
PointerGetDatum(bval),
PointerGetDatum(key));
addrange = DatumGetBool(add);
if (!addrange)
break;
}
}
}
/* add the pages in the range to the output bitmap, if needed */
if (addrange)
{
BlockNumber pageno;
for (pageno = heapBlk;
pageno <= heapBlk + opaque->bo_pagesPerRange - 1;
pageno++)
{
MemoryContextSwitchTo(oldcxt);
tbm_add_page(tbm, pageno);
totalpages++;
MemoryContextSwitchTo(perRangeCxt);
}
}
}
MemoryContextSwitchTo(oldcxt);
MemoryContextDelete(perRangeCxt);
if (buf != InvalidBuffer)
ReleaseBuffer(buf);
/*
* XXX We have an approximation of the number of *pages* that our scan
* returns, but we don't have a precise idea of the number of heap tuples
* involved.
*/
return totalpages * 10;
}
