More refactoring of heapgettup() and heapgettup_pagemode()
Here we further simplify the code in heapgettup() and heapgettup_pagemode() to make better use of the helper functions added in the previous recent refactors in this area. In passing, remove an unneeded cast added in 8ca6d49f6. Author: Melanie Plageman Reviewed-by: Andres Freund, David Rowley Discussion: https://postgr.es/m/CAAKRu_YSOnhKsDyFcqJsKtBSrd32DP-jjXmv7hL0BPD-z0TGXQ@mail.gmail.com
This commit is contained in:
David Rowley
parent
9ba37b2cb6
commit
cfcf56f923
@ -567,7 +567,7 @@ heapgettup_start_page(HeapScanDesc scan, ScanDirection dir, int *linesleft,
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TestForOldSnapshot(scan->rs_base.rs_snapshot, scan->rs_base.rs_rd, page);
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*linesleft = PageGetMaxOffsetNumber((Page) page) - FirstOffsetNumber + 1;
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*linesleft = PageGetMaxOffsetNumber(page) - FirstOffsetNumber + 1;
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if (ScanDirectionIsForward(dir))
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*lineoff = FirstOffsetNumber;
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@ -732,34 +732,17 @@ heapgettup(HeapScanDesc scan,
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ScanKey key)
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{
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HeapTuple tuple = &(scan->rs_ctup);
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bool backward = ScanDirectionIsBackward(dir);
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BlockNumber block;
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Page page;
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OffsetNumber lineoff;
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int linesleft;
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ItemId lpp;
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if (unlikely(!scan->rs_inited))
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{
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block = heapgettup_initial_block(scan, dir);
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/*
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* Check if we have reached the end of the scan already. This could
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* happen if the table is empty or if the parallel workers have
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* already finished the scan before we did anything ourselves
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*/
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if (block == InvalidBlockNumber)
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{
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Assert(!BufferIsValid(scan->rs_cbuf));
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tuple->t_data = NULL;
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return;
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}
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/* ensure rs_cbuf is invalid when we get InvalidBlockNumber */
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Assert(block != InvalidBlockNumber || !BufferIsValid(scan->rs_cbuf));
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scan->rs_inited = true;
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heapgetpage((TableScanDesc) scan, block);
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LockBuffer(scan->rs_cbuf, BUFFER_LOCK_SHARE);
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page = heapgettup_start_page(scan, dir, &linesleft, &lineoff);
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}
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else
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{
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@ -768,15 +751,20 @@ heapgettup(HeapScanDesc scan,
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LockBuffer(scan->rs_cbuf, BUFFER_LOCK_SHARE);
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page = heapgettup_continue_page(scan, dir, &linesleft, &lineoff);
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goto continue_page;
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}
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/*
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* advance the scan until we find a qualifying tuple or run out of stuff
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* to scan
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*/
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lpp = PageGetItemId(page, lineoff);
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for (;;)
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while (block != InvalidBlockNumber)
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{
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heapgetpage((TableScanDesc) scan, block);
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LockBuffer(scan->rs_cbuf, BUFFER_LOCK_SHARE);
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page = heapgettup_start_page(scan, dir, &linesleft, &lineoff);
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continue_page:
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/*
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* Only continue scanning the page while we have lines left.
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*
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@ -784,53 +772,39 @@ heapgettup(HeapScanDesc scan,
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* PageGetMaxOffsetNumber(); both for forward scans when we resume the
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* table scan, and for when we start scanning a new page.
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*/
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while (linesleft > 0)
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for (; linesleft > 0; linesleft--, lineoff += dir)
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{
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if (ItemIdIsNormal(lpp))
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{
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bool valid;
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bool visible;
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ItemId lpp = PageGetItemId(page, lineoff);
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tuple->t_data = (HeapTupleHeader) PageGetItem(page, lpp);
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tuple->t_len = ItemIdGetLength(lpp);
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ItemPointerSet(&(tuple->t_self), block, lineoff);
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if (!ItemIdIsNormal(lpp))
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continue;
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/*
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* if current tuple qualifies, return it.
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*/
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valid = HeapTupleSatisfiesVisibility(tuple,
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scan->rs_base.rs_snapshot,
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scan->rs_cbuf);
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tuple->t_data = (HeapTupleHeader) PageGetItem(page, lpp);
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tuple->t_len = ItemIdGetLength(lpp);
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ItemPointerSet(&(tuple->t_self), block, lineoff);
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HeapCheckForSerializableConflictOut(valid, scan->rs_base.rs_rd,
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tuple, scan->rs_cbuf,
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scan->rs_base.rs_snapshot);
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visible = HeapTupleSatisfiesVisibility(tuple,
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scan->rs_base.rs_snapshot,
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scan->rs_cbuf);
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if (valid && key != NULL)
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valid = HeapKeyTest(tuple, RelationGetDescr(scan->rs_base.rs_rd),
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nkeys, key);
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HeapCheckForSerializableConflictOut(visible, scan->rs_base.rs_rd,
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tuple, scan->rs_cbuf,
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scan->rs_base.rs_snapshot);
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if (valid)
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{
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LockBuffer(scan->rs_cbuf, BUFFER_LOCK_UNLOCK);
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scan->rs_coffset = lineoff;
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return;
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}
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}
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/* skip tuples not visible to this snapshot */
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if (!visible)
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continue;
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/*
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* otherwise move to the next item on the page
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*/
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--linesleft;
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if (backward)
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{
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--lpp; /* move back in this page's ItemId array */
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--lineoff;
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}
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else
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{
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++lpp; /* move forward in this page's ItemId array */
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++lineoff;
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}
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/* skip any tuples that don't match the scan key */
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if (key != NULL &&
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!HeapKeyTest(tuple, RelationGetDescr(scan->rs_base.rs_rd),
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nkeys, key))
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continue;
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LockBuffer(scan->rs_cbuf, BUFFER_LOCK_UNLOCK);
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scan->rs_coffset = lineoff;
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return;
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}
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/*
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@ -841,40 +815,16 @@ heapgettup(HeapScanDesc scan,
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/* get the BlockNumber to scan next */
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block = heapgettup_advance_block(scan, block, dir);
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/*
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* return NULL if we've exhausted all the pages
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*/
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if (block == InvalidBlockNumber)
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{
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if (BufferIsValid(scan->rs_cbuf))
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ReleaseBuffer(scan->rs_cbuf);
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scan->rs_cbuf = InvalidBuffer;
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scan->rs_cblock = InvalidBlockNumber;
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tuple->t_data = NULL;
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scan->rs_inited = false;
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return;
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}
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heapgetpage((TableScanDesc) scan, block);
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LockBuffer(scan->rs_cbuf, BUFFER_LOCK_SHARE);
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page = BufferGetPage(scan->rs_cbuf);
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TestForOldSnapshot(scan->rs_base.rs_snapshot, scan->rs_base.rs_rd,
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page);
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linesleft = PageGetMaxOffsetNumber(page);
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if (backward)
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{
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lineoff = linesleft;
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lpp = PageGetItemId(page, linesleft);
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}
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else
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{
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lineoff = FirstOffsetNumber;
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lpp = PageGetItemId(page, FirstOffsetNumber);
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}
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}
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/* end of scan */
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if (BufferIsValid(scan->rs_cbuf))
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ReleaseBuffer(scan->rs_cbuf);
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scan->rs_cbuf = InvalidBuffer;
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scan->rs_cblock = InvalidBlockNumber;
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tuple->t_data = NULL;
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scan->rs_inited = false;
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}
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/* ----------------
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@ -897,35 +847,16 @@ heapgettup_pagemode(HeapScanDesc scan,
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ScanKey key)
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{
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HeapTuple tuple = &(scan->rs_ctup);
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bool backward = ScanDirectionIsBackward(dir);
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BlockNumber block;
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Page page;
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int lineindex;
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OffsetNumber lineoff;
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int linesleft;
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ItemId lpp;
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if (unlikely(!scan->rs_inited))
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{
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block = heapgettup_initial_block(scan, dir);
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/*
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* Check if we have reached the end of the scan already. This could
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* happen if the table is empty or if the other workers in a parallel
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* scan have already finished the scan.
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*/
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if (block == InvalidBlockNumber)
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{
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Assert(!BufferIsValid(scan->rs_cbuf));
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tuple->t_data = NULL;
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return;
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}
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heapgetpage((TableScanDesc) scan, block);
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page = BufferGetPage(scan->rs_cbuf);
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TestForOldSnapshot(scan->rs_base.rs_snapshot, scan->rs_base.rs_rd, page);
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linesleft = scan->rs_ntuples;
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lineindex = ScanDirectionIsForward(dir) ? 0 : linesleft - 1;
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/* ensure rs_cbuf is invalid when we get InvalidBlockNumber */
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Assert(block != InvalidBlockNumber || !BufferIsValid(scan->rs_cbuf));
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scan->rs_inited = true;
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}
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else
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@ -940,16 +871,31 @@ heapgettup_pagemode(HeapScanDesc scan,
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linesleft = scan->rs_ntuples - lineindex;
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else
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linesleft = scan->rs_cindex;
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/* lineindex now references the next or previous visible tid */
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goto continue_page;
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}
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/*
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* advance the scan until we find a qualifying tuple or run out of stuff
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* to scan
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*/
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for (;;)
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while (block != InvalidBlockNumber)
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{
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while (linesleft > 0)
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heapgetpage((TableScanDesc) scan, block);
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page = BufferGetPage(scan->rs_cbuf);
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TestForOldSnapshot(scan->rs_base.rs_snapshot, scan->rs_base.rs_rd, page);
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linesleft = scan->rs_ntuples;
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lineindex = ScanDirectionIsForward(dir) ? 0 : linesleft - 1;
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/* lineindex now references the next or previous visible tid */
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continue_page:
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for (; linesleft > 0; linesleft--, lineindex += dir)
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{
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ItemId lpp;
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OffsetNumber lineoff;
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lineoff = scan->rs_vistuples[lineindex];
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lpp = PageGetItemId(page, lineoff);
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Assert(ItemIdIsNormal(lpp));
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@ -958,64 +904,27 @@ heapgettup_pagemode(HeapScanDesc scan,
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tuple->t_len = ItemIdGetLength(lpp);
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ItemPointerSet(&(tuple->t_self), block, lineoff);
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/*
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* if current tuple qualifies, return it.
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*/
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if (key != NULL)
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{
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bool valid;
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/* skip any tuples that don't match the scan key */
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if (key != NULL &&
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!HeapKeyTest(tuple, RelationGetDescr(scan->rs_base.rs_rd),
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nkeys, key))
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continue;
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valid = HeapKeyTest(tuple, RelationGetDescr(scan->rs_base.rs_rd),
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nkeys, key);
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if (valid)
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{
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scan->rs_cindex = lineindex;
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return;
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}
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}
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else
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{
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scan->rs_cindex = lineindex;
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return;
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}
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/*
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* otherwise move to the next item on the page
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*/
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--linesleft;
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if (backward)
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--lineindex;
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else
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++lineindex;
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scan->rs_cindex = lineindex;
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return;
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}
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/* get the BlockNumber to scan next */
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block = heapgettup_advance_block(scan, block, dir);
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/*
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* return NULL if we've exhausted all the pages
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*/
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if (block == InvalidBlockNumber)
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{
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if (BufferIsValid(scan->rs_cbuf))
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ReleaseBuffer(scan->rs_cbuf);
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scan->rs_cbuf = InvalidBuffer;
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scan->rs_cblock = InvalidBlockNumber;
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tuple->t_data = NULL;
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scan->rs_inited = false;
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return;
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}
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heapgetpage((TableScanDesc) scan, block);
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page = BufferGetPage(scan->rs_cbuf);
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TestForOldSnapshot(scan->rs_base.rs_snapshot, scan->rs_base.rs_rd, page);
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linesleft = scan->rs_ntuples;
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if (backward)
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lineindex = linesleft - 1;
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else
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lineindex = 0;
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}
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/* end of scan */
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if (BufferIsValid(scan->rs_cbuf))
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ReleaseBuffer(scan->rs_cbuf);
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scan->rs_cbuf = InvalidBuffer;
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scan->rs_cblock = InvalidBlockNumber;
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tuple->t_data = NULL;
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scan->rs_inited = false;
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}
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