Tweak some nbtree-related code comments.
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@ -1975,7 +1975,7 @@ bt_normalize_tuple(BtreeCheckState *state, IndexTuple itup)
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/*
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* Search for itup in index, starting from fast root page. itup must be a
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* non-pivot tuple. This is only supported with heapkeyspace indexes, since
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* we rely on having fully unique keys to find a match with only a signle
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* we rely on having fully unique keys to find a match with only a single
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* visit to a leaf page, barring an interrupted page split, where we may have
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* to move right. (A concurrent page split is impossible because caller must
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* be readonly caller.)
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@ -182,7 +182,8 @@ _bt_search(Relation rel, BTScanInsert key, Buffer *bufP, int access,
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/*
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* If we're asked to lock leaf in write mode, but didn't manage to, then
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* relock. That may happen when the root page appears to be leaf.
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* relock. This should only happen when the root page is a leaf page (and
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* the only page in the index other than the metapage).
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*/
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if (access == BT_WRITE && page_access == BT_READ)
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{
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@ -835,7 +835,7 @@ _bt_buildadd(BTWriteState *wstate, BTPageState *state, IndexTuple itup)
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* the limit on the size of tuples inserted on the leaf level by the same
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* small amount. Enforce the new v4+ limit on the leaf level, and the old
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* limit on internal levels, since pivot tuples may need to make use of
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* the resered space. This should never fail on internal pages.
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* the reserved space. This should never fail on internal pages.
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*/
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if (unlikely(itupsz > BTMaxItemSize(npage)))
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_bt_check_third_page(wstate->index, wstate->heap,
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@ -907,8 +907,8 @@ _bt_buildadd(BTWriteState *wstate, BTPageState *state, IndexTuple itup)
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* choosing a split point here for a benefit that is bound to be
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* much smaller.
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*
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* Since the truncated tuple is probably smaller than the
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* original, it cannot just be copied in place (besides, we want
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* Since the truncated tuple is often smaller than the original
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* tuple, it cannot just be copied in place (besides, we want
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* to actually save space on the leaf page). We delete the
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* original high key, and add our own truncated high key at the
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* same offset. It's okay if the truncated tuple is slightly
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@ -219,7 +219,6 @@ typedef struct BTMetaPageData
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#define P_FIRSTDATAKEY(opaque) (P_RIGHTMOST(opaque) ? P_HIKEY : P_FIRSTKEY)
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/*
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*
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* Notes on B-Tree tuple format, and key and non-key attributes:
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*
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* INCLUDE B-Tree indexes have non-key attributes. These are extra
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@ -321,7 +320,7 @@ typedef struct BTMetaPageData
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/*
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* Get/set number of attributes within B-tree index tuple.
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*
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* Note that this does not include an implicit tiebreaker heap-TID
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* Note that this does not include an implicit tiebreaker heap TID
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* attribute, if any. Note also that the number of key attributes must be
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* explicitly represented in all heapkeyspace pivot tuples.
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*/
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@ -424,10 +423,10 @@ typedef struct BTStackData
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typedef BTStackData *BTStack;
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/*
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* BTScanInsert is the btree-private state needed to find an initial position
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* for an indexscan, or to insert new tuples -- an "insertion scankey" (not to
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* be confused with a search scankey). It's used to descend a B-Tree using
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* _bt_search.
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* BTScanInsertData is the btree-private state needed to find an initial
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* position for an indexscan, or to insert new tuples -- an "insertion
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* scankey" (not to be confused with a search scankey). It's used to descend
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* a B-Tree using _bt_search.
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*
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* heapkeyspace indicates if we expect all keys in the index to be physically
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* unique because heap TID is used as a tiebreaker attribute, and if index may
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