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refactor a bit to make it easier to support lossy bitmap results

pull/5273/head
Nils Dijk 2021-09-10 15:34:32 +02:00
parent 01f6c48944
commit 3f89a505d1
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GPG Key ID: CA1177EF9434F241
1 changed files with 36 additions and 12 deletions
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48
src/backend/columnar/columnar_tableam.c
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@ -84,7 +84,7 @@ typedef struct ColumnarScanDescData
Bitmapset *attr_needed;
List *scanQual;
int tupleindex;
Bitmapset *offsets;
} ColumnarScanDescData;
typedef struct ColumnarScanDescData *ColumnarScanDesc;
@ -2072,7 +2072,35 @@ static bool
columnar_bitmap_next_block(TableScanDesc scan, TBMIterateResult *tbmres)
{
ColumnarScanDesc cscan = (ColumnarScanDesc) scan;
cscan->tupleindex = 0;
/* remove any previously left over set of offsets */
if (cscan->offsets != NULL)
{
bms_free(cscan->offsets);
cscan->offsets = NULL;
}
/*
* Load all unique offset numbers of the tid to load for the current block described
* in the tbmres. During the iteration of the block we simply consume the offset
* numbers till they are depleted. These offset numbers will be combined with the
* block number to construct the tid's.
*/
Bitmapset *offsets = NULL;
if (tbmres->ntuples >= 0)
{
for (int i = 0; i < tbmres->ntuples; i++)
{
offsets = bms_add_member(offsets, tbmres->offsets[i]);
}
}
else
{
/* TODO page is lossy, we should add all valid offsets to the bms */
Assert(false);
}
cscan->offsets = offsets;
return tbmres->blockno == 0;
}
@ -2083,16 +2111,16 @@ columnar_bitmap_next_tuple(TableScanDesc scan, TBMIterateResult *tbmres,
TupleTableSlot *slot)
{
ColumnarScanDesc cscan = (ColumnarScanDesc) scan;
if (cscan->tupleindex >= tbmres->ntuples)
if (bms_is_empty(cscan->offsets))
{
/* offsets are empty, we have returned all the tuples for this page */
return false;
}
/* since we already did an empty check we know we will read a valid OffsetNumber */
OffsetNumber offset = bms_first_member(cscan->offsets);
ItemPointerData tid = { 0 };
ItemPointerSet(&tid, tbmres->blockno, tbmres->offsets[cscan->tupleindex]);
cscan->tupleindex++;
ItemPointerSet(&tid, tbmres->blockno, offset);
ExecClearTuple(slot);
@ -2101,15 +2129,11 @@ columnar_bitmap_next_tuple(TableScanDesc scan, TBMIterateResult *tbmres,
/* initialize read state for the first row */
if (cscan->cs_readState == NULL)
{
/* we need all columns */
int natts = rel->rd_att->natts;
Bitmapset *attr_needed = bms_add_range(NULL, 0, natts - 1);
/* no quals for index scan */
List *scanQual = NIL;
cscan->cs_readState = init_columnar_read_state(rel, slot->tts_tupleDescriptor,
attr_needed, scanQual,
cscan->attr_needed, scanQual,
cscan->scanContext,
cscan->cs_base.rs_snapshot);
}