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Revert buggy optimization of index scans
606c0123d6
attempted to reduce cost of index scans using > and <
strategies, though got that completely wrong in a few complex cases.
Revert whole patch until we find a safe optimization.
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@ -1026,33 +1026,6 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
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if (goback)
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offnum = OffsetNumberPrev(offnum);
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/*
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* By here the scan position is now set for the first key. If all further
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* tuples are expected to match we set the SK_BT_MATCHED flag to avoid
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* re-checking the scan key later. This is a big win for slow key matches
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* though is still significant even for fast datatypes.
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*/
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switch (startKeys[0]->sk_strategy)
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{
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case BTEqualStrategyNumber:
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break;
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case BTGreaterEqualStrategyNumber:
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case BTGreaterStrategyNumber:
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if (ScanDirectionIsForward(dir))
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startKeys[0]->sk_flags |= SK_BT_MATCHED;
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break;
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case BTLessEqualStrategyNumber:
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case BTLessStrategyNumber:
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if (ScanDirectionIsBackward(dir))
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startKeys[0]->sk_flags |= SK_BT_MATCHED;
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break;
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default:
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break;
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}
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/* remember which buffer we have pinned, if any */
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Assert(!BTScanPosIsValid(so->currPos));
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so->currPos.buf = buf;
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@ -1429,13 +1429,6 @@ _bt_checkkeys(IndexScanDesc scan,
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bool isNull;
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Datum test;
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/*
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* If the scan key has already matched we can skip this key, as long
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* as the index tuple does not contain NULL values.
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*/
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if (key->sk_flags & SK_BT_MATCHED && !IndexTupleHasNulls(tuple))
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continue;
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/* row-comparison keys need special processing */
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if (key->sk_flags & SK_ROW_HEADER)
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{
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@ -644,7 +644,6 @@ typedef BTScanOpaqueData *BTScanOpaque;
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*/
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#define SK_BT_REQFWD 0x00010000 /* required to continue forward scan */
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#define SK_BT_REQBKWD 0x00020000 /* required to continue backward scan */
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#define SK_BT_MATCHED 0x00040000 /* required to skip further key match */
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#define SK_BT_INDOPTION_SHIFT 24 /* must clear the above bits */
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#define SK_BT_DESC (INDOPTION_DESC << SK_BT_INDOPTION_SHIFT)
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#define SK_BT_NULLS_FIRST (INDOPTION_NULLS_FIRST << SK_BT_INDOPTION_SHIFT)
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