From e5adcb789d80ba565ccacb1ed4341a7c29085238 Mon Sep 17 00:00:00 2001
From: Peter Geoghegan <pg@bowt.ie>
Date: Wed, 20 Mar 2019 09:30:57 -0700
Subject: [PATCH] Refactor nbtree insertion scankeys.
Use dedicated struct to represent nbtree insertion scan keys. Having a
dedicated struct makes the difference between search type scankeys and
insertion scankeys a lot clearer, and simplifies the signature of
several related functions. This is based on a suggestion by Andrey
Lepikhov.
Streamline how unique index insertions cache binary search progress.
Cache the state of in-progress binary searches within _bt_check_unique()
for later instead of having callers avoid repeating the binary search in
an ad-hoc manner. This makes it easy to add a new optimization:
_bt_check_unique() now falls out of its loop immediately in the common
case where it's already clear that there couldn't possibly be a
duplicate.
The new _bt_check_unique() scheme makes it a lot easier to manage cached
binary search effort afterwards, from within _bt_findinsertloc(). This
is needed for the upcoming patch to make nbtree tuples unique by
treating heap TID as a final tiebreaker column. Unique key binary
searches need to restore lower and upper bounds. They cannot simply
continue to use the >= lower bound as the offset to insert at, because
the heap TID tiebreaker column must be used in comparisons for the
restored binary search (unlike the original _bt_check_unique() binary
search, where scankey's heap TID column must be omitted).
Author: Peter Geoghegan, Heikki Linnakangas
Reviewed-By: Heikki Linnakangas, Andrey Lepikhov
Discussion: https://postgr.es/m/CAH2-WzmE6AhUdk9NdWBf4K3HjWXZBX3+umC7mH7+WDrKcRtsOw@mail.gmail.com
---
contrib/amcheck/verify_nbtree.c | 52 ++--
src/backend/access/nbtree/README | 29 +-
src/backend/access/nbtree/nbtinsert.c | 400 ++++++++++++++------------
src/backend/access/nbtree/nbtpage.c | 12 +-
src/backend/access/nbtree/nbtsearch.c | 227 ++++++++++-----
src/backend/access/nbtree/nbtsort.c | 8 +-
src/backend/access/nbtree/nbtutils.c | 94 ++----
src/backend/utils/sort/tuplesort.c | 16 +-
src/include/access/nbtree.h | 78 ++++-
9 files changed, 529 insertions(+), 387 deletions(-)
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index bb6442de82d..5426bfd8d87 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -127,9 +127,9 @@ static void bt_check_every_level(Relation rel, Relation heaprel,
static BtreeLevel bt_check_level_from_leftmost(BtreeCheckState *state,
BtreeLevel level);
static void bt_target_page_check(BtreeCheckState *state);
-static ScanKey bt_right_page_check_scankey(BtreeCheckState *state);
-static void bt_downlink_check(BtreeCheckState *state, BlockNumber childblock,
- ScanKey targetkey);
+static BTScanInsert bt_right_page_check_scankey(BtreeCheckState *state);
+static void bt_downlink_check(BtreeCheckState *state, BTScanInsert targetkey,
+ BlockNumber childblock);
static void bt_downlink_missing_check(BtreeCheckState *state);
static void bt_tuple_present_callback(Relation index, HeapTuple htup,
Datum *values, bool *isnull,
@@ -139,14 +139,14 @@ static IndexTuple bt_normalize_tuple(BtreeCheckState *state,
static inline bool offset_is_negative_infinity(BTPageOpaque opaque,
OffsetNumber offset);
static inline bool invariant_leq_offset(BtreeCheckState *state,
- ScanKey key,
+ BTScanInsert key,
OffsetNumber upperbound);
static inline bool invariant_geq_offset(BtreeCheckState *state,
- ScanKey key,
+ BTScanInsert key,
OffsetNumber lowerbound);
static inline bool invariant_leq_nontarget_offset(BtreeCheckState *state,
- Page other,
- ScanKey key,
+ BTScanInsert key,
+ Page nontarget,
OffsetNumber upperbound);
static Page palloc_btree_page(BtreeCheckState *state, BlockNumber blocknum);
@@ -838,8 +838,8 @@ bt_target_page_check(BtreeCheckState *state)
{
ItemId itemid;
IndexTuple itup;
- ScanKey skey;
size_t tupsize;
+ BTScanInsert skey;
CHECK_FOR_INTERRUPTS();
@@ -1030,7 +1030,7 @@ bt_target_page_check(BtreeCheckState *state)
*/
else if (offset == max)
{
- ScanKey rightkey;
+ BTScanInsert rightkey;
/* Get item in next/right page */
rightkey = bt_right_page_check_scankey(state);
@@ -1082,7 +1082,7 @@ bt_target_page_check(BtreeCheckState *state)
{
BlockNumber childblock = BTreeInnerTupleGetDownLink(itup);
- bt_downlink_check(state, childblock, skey);
+ bt_downlink_check(state, skey, childblock);
}
}
@@ -1111,11 +1111,12 @@ bt_target_page_check(BtreeCheckState *state)
* Note that !readonly callers must reverify that target page has not
* been concurrently deleted.
*/
-static ScanKey
+static BTScanInsert
bt_right_page_check_scankey(BtreeCheckState *state)
{
BTPageOpaque opaque;
ItemId rightitem;
+ IndexTuple firstitup;
BlockNumber targetnext;
Page rightpage;
OffsetNumber nline;
@@ -1303,8 +1304,8 @@ bt_right_page_check_scankey(BtreeCheckState *state)
* Return first real item scankey. Note that this relies on right page
* memory remaining allocated.
*/
- return _bt_mkscankey(state->rel,
- (IndexTuple) PageGetItem(rightpage, rightitem));
+ firstitup = (IndexTuple) PageGetItem(rightpage, rightitem);
+ return _bt_mkscankey(state->rel, firstitup);
}
/*
@@ -1317,8 +1318,8 @@ bt_right_page_check_scankey(BtreeCheckState *state)
* verification this way around is much more practical.
*/
static void
-bt_downlink_check(BtreeCheckState *state, BlockNumber childblock,
- ScanKey targetkey)
+bt_downlink_check(BtreeCheckState *state, BTScanInsert targetkey,
+ BlockNumber childblock)
{
OffsetNumber offset;
OffsetNumber maxoffset;
@@ -1423,8 +1424,7 @@ bt_downlink_check(BtreeCheckState *state, BlockNumber childblock,
if (offset_is_negative_infinity(copaque, offset))
continue;
- if (!invariant_leq_nontarget_offset(state, child,
- targetkey, offset))
+ if (!invariant_leq_nontarget_offset(state, targetkey, child, offset))
ereport(ERROR,
(errcode(ERRCODE_INDEX_CORRUPTED),
errmsg("down-link lower bound invariant violated for index \"%s\"",
@@ -1864,13 +1864,12 @@ offset_is_negative_infinity(BTPageOpaque opaque, OffsetNumber offset)
* to corruption.
*/
static inline bool
-invariant_leq_offset(BtreeCheckState *state, ScanKey key,
+invariant_leq_offset(BtreeCheckState *state, BTScanInsert key,
OffsetNumber upperbound)
{
- int16 nkeyatts = IndexRelationGetNumberOfKeyAttributes(state->rel);
int32 cmp;
- cmp = _bt_compare(state->rel, nkeyatts, key, state->target, upperbound);
+ cmp = _bt_compare(state->rel, key, state->target, upperbound);
return cmp <= 0;
}
@@ -1883,13 +1882,12 @@ invariant_leq_offset(BtreeCheckState *state, ScanKey key,
* to corruption.
*/
static inline bool
-invariant_geq_offset(BtreeCheckState *state, ScanKey key,
+invariant_geq_offset(BtreeCheckState *state, BTScanInsert key,
OffsetNumber lowerbound)
{
- int16 nkeyatts = IndexRelationGetNumberOfKeyAttributes(state->rel);
int32 cmp;
- cmp = _bt_compare(state->rel, nkeyatts, key, state->target, lowerbound);
+ cmp = _bt_compare(state->rel, key, state->target, lowerbound);
return cmp >= 0;
}
@@ -1905,14 +1903,12 @@ invariant_geq_offset(BtreeCheckState *state, ScanKey key,
* to corruption.
*/
static inline bool
-invariant_leq_nontarget_offset(BtreeCheckState *state,
- Page nontarget, ScanKey key,
- OffsetNumber upperbound)
+invariant_leq_nontarget_offset(BtreeCheckState *state, BTScanInsert key,
+ Page nontarget, OffsetNumber upperbound)
{
- int16 nkeyatts = IndexRelationGetNumberOfKeyAttributes(state->rel);
int32 cmp;
- cmp = _bt_compare(state->rel, nkeyatts, key, nontarget, upperbound);
+ cmp = _bt_compare(state->rel, key, nontarget, upperbound);
return cmp <= 0;
}
diff --git a/src/backend/access/nbtree/README b/src/backend/access/nbtree/README
index b0b4ab8b766..a295a7a286d 100644
--- a/src/backend/access/nbtree/README
+++ b/src/backend/access/nbtree/README
@@ -598,19 +598,22 @@ scankey point to comparison functions that return boolean, such as int4lt.
There might be more than one scankey entry for a given index column, or
none at all. (We require the keys to appear in index column order, but
the order of multiple keys for a given column is unspecified.) An
-insertion scankey uses the same array-of-ScanKey data structure, but the
-sk_func pointers point to btree comparison support functions (ie, 3-way
-comparators that return int4 values interpreted as <0, =0, >0). In an
-insertion scankey there is exactly one entry per index column. Insertion
-scankeys are built within the btree code (eg, by _bt_mkscankey()) and are
-used to locate the starting point of a scan, as well as for locating the
-place to insert a new index tuple. (Note: in the case of an insertion
-scankey built from a search scankey, there might be fewer keys than
-index columns, indicating that we have no constraints for the remaining
-index columns.) After we have located the starting point of a scan, the
-original search scankey is consulted as each index entry is sequentially
-scanned to decide whether to return the entry and whether the scan can
-stop (see _bt_checkkeys()).
+insertion scankey ("BTScanInsert" data structure) uses a similar
+array-of-ScanKey data structure, but the sk_func pointers point to btree
+comparison support functions (ie, 3-way comparators that return int4 values
+interpreted as <0, =0, >0). In an insertion scankey there is at most one
+entry per index column. There is also other data about the rules used to
+locate where to begin the scan, such as whether or not the scan is a
+"nextkey" scan. Insertion scankeys are built within the btree code (eg, by
+_bt_mkscankey()) and are used to locate the starting point of a scan, as
+well as for locating the place to insert a new index tuple. (Note: in the
+case of an insertion scankey built from a search scankey or built from a
+truncated pivot tuple, there might be fewer keys than index columns,
+indicating that we have no constraints for the remaining index columns.)
+After we have located the starting point of a scan, the original search
+scankey is consulted as each index entry is sequentially scanned to decide
+whether to return the entry and whether the scan can stop (see
+_bt_checkkeys()).
We use term "pivot" index tuples to distinguish tuples which don't point
to heap tuples, but rather used for tree navigation. Pivot tuples includes
diff --git a/src/backend/access/nbtree/nbtinsert.c b/src/backend/access/nbtree/nbtinsert.c
index 2997b1111a2..1facd0535d8 100644
--- a/src/backend/access/nbtree/nbtinsert.c
+++ b/src/backend/access/nbtree/nbtinsert.c
@@ -51,19 +51,16 @@ typedef struct
static Buffer _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf);
-static TransactionId _bt_check_unique(Relation rel, IndexTuple itup,
- Relation heapRel, Buffer buf, OffsetNumber offset,
- ScanKey itup_scankey,
+static TransactionId _bt_check_unique(Relation rel, BTInsertState insertstate,
+ Relation heapRel,
IndexUniqueCheck checkUnique, bool *is_unique,
uint32 *speculativeToken);
-static void _bt_findinsertloc(Relation rel,
- Buffer *bufptr,
- OffsetNumber *offsetptr,
- int keysz,
- ScanKey scankey,
- IndexTuple newtup,
+static OffsetNumber _bt_findinsertloc(Relation rel,
+ BTInsertState insertstate,
+ bool checkingunique,
BTStack stack,
Relation heapRel);
+static void _bt_stepright(Relation rel, BTInsertState insertstate, BTStack stack);
static void _bt_insertonpg(Relation rel, Buffer buf, Buffer cbuf,
BTStack stack,
IndexTuple itup,
@@ -83,8 +80,8 @@ static void _bt_checksplitloc(FindSplitData *state,
int dataitemstoleft, Size firstoldonrightsz);
static bool _bt_pgaddtup(Page page, Size itemsize, IndexTuple itup,
OffsetNumber itup_off);
-static bool _bt_isequal(TupleDesc itupdesc, Page page, OffsetNumber offnum,
- int keysz, ScanKey scankey);
+static bool _bt_isequal(TupleDesc itupdesc, BTScanInsert itup_key,
+ Page page, OffsetNumber offnum);
static void _bt_vacuum_one_page(Relation rel, Buffer buffer, Relation heapRel);
/*
@@ -110,18 +107,26 @@ _bt_doinsert(Relation rel, IndexTuple itup,
IndexUniqueCheck checkUnique, Relation heapRel)
{
bool is_unique = false;
- int indnkeyatts;
- ScanKey itup_scankey;
+ BTInsertStateData insertstate;
+ BTScanInsert itup_key;
BTStack stack = NULL;
Buffer buf;
- OffsetNumber offset;
bool fastpath;
-
- indnkeyatts = IndexRelationGetNumberOfKeyAttributes(rel);
- Assert(indnkeyatts != 0);
+ bool checkingunique = (checkUnique != UNIQUE_CHECK_NO);
/* we need an insertion scan key to do our search, so build one */
- itup_scankey = _bt_mkscankey(rel, itup);
+ itup_key = _bt_mkscankey(rel, itup);
+
+ /*
+ * Fill in the BTInsertState working area, to track the current page and
+ * position within the page to insert on
+ */
+ insertstate.itup = itup;
+ /* PageAddItem will MAXALIGN(), but be consistent */
+ insertstate.itemsz = MAXALIGN(IndexTupleSize(itup));
+ insertstate.itup_key = itup_key;
+ insertstate.bounds_valid = false;
+ insertstate.buf = InvalidBuffer;
/*
* It's very common to have an index on an auto-incremented or
@@ -144,10 +149,8 @@ _bt_doinsert(Relation rel, IndexTuple itup,
*/
top:
fastpath = false;
- offset = InvalidOffsetNumber;
if (RelationGetTargetBlock(rel) != InvalidBlockNumber)
{
- Size itemsz;
Page page;
BTPageOpaque lpageop;
@@ -166,9 +169,6 @@ top:
page = BufferGetPage(buf);
lpageop = (BTPageOpaque) PageGetSpecialPointer(page);
- itemsz = IndexTupleSize(itup);
- itemsz = MAXALIGN(itemsz); /* be safe, PageAddItem will do this
- * but we need to be consistent */
/*
* Check if the page is still the rightmost leaf page, has enough
@@ -177,10 +177,9 @@ top:
*/
if (P_ISLEAF(lpageop) && P_RIGHTMOST(lpageop) &&
!P_IGNORE(lpageop) &&
- (PageGetFreeSpace(page) > itemsz) &&
+ (PageGetFreeSpace(page) > insertstate.itemsz) &&
PageGetMaxOffsetNumber(page) >= P_FIRSTDATAKEY(lpageop) &&
- _bt_compare(rel, indnkeyatts, itup_scankey, page,
- P_FIRSTDATAKEY(lpageop)) > 0)
+ _bt_compare(rel, itup_key, page, P_FIRSTDATAKEY(lpageop)) > 0)
{
/*
* The right-most block should never have an incomplete split.
@@ -219,10 +218,12 @@ top:
* Find the first page containing this key. Buffer returned by
* _bt_search() is locked in exclusive mode.
*/
- stack = _bt_search(rel, indnkeyatts, itup_scankey, false, &buf, BT_WRITE,
- NULL);
+ stack = _bt_search(rel, itup_key, &buf, BT_WRITE, NULL);
}
+ insertstate.buf = buf;
+ buf = InvalidBuffer; /* insertstate.buf now owns the buffer */
+
/*
* If we're not allowing duplicates, make sure the key isn't already in
* the index.
@@ -244,19 +245,19 @@ top:
* let the tuple in and return false for possibly non-unique, or true for
* definitely unique.
*/
- if (checkUnique != UNIQUE_CHECK_NO)
+ if (checkingunique)
{
TransactionId xwait;
uint32 speculativeToken;
- offset = _bt_binsrch(rel, buf, indnkeyatts, itup_scankey, false);
- xwait = _bt_check_unique(rel, itup, heapRel, buf, offset, itup_scankey,
- checkUnique, &is_unique, &speculativeToken);
+ xwait = _bt_check_unique(rel, &insertstate, heapRel, checkUnique,
+ &is_unique, &speculativeToken);
if (TransactionIdIsValid(xwait))
{
/* Have to wait for the other guy ... */
- _bt_relbuf(rel, buf);
+ _bt_relbuf(rel, insertstate.buf);
+ insertstate.buf = InvalidBuffer;
/*
* If it's a speculative insertion, wait for it to finish (ie. to
@@ -277,6 +278,8 @@ top:
if (checkUnique != UNIQUE_CHECK_EXISTING)
{
+ OffsetNumber newitemoff;
+
/*
* The only conflict predicate locking cares about for indexes is when
* an index tuple insert conflicts with an existing lock. Since the
@@ -286,22 +289,28 @@ top:
* This reasoning also applies to INCLUDE indexes, whose extra
* attributes are not considered part of the key space.
*/
- CheckForSerializableConflictIn(rel, NULL, buf);
- /* do the insertion */
- _bt_findinsertloc(rel, &buf, &offset, indnkeyatts, itup_scankey, itup,
- stack, heapRel);
- _bt_insertonpg(rel, buf, InvalidBuffer, stack, itup, offset, false);
+ CheckForSerializableConflictIn(rel, NULL, insertstate.buf);
+
+ /*
+ * Do the insertion. Note that insertstate contains cached binary
+ * search bounds established within _bt_check_unique when insertion is
+ * checkingunique.
+ */
+ newitemoff = _bt_findinsertloc(rel, &insertstate, checkingunique,
+ stack, heapRel);
+ _bt_insertonpg(rel, insertstate.buf, InvalidBuffer, stack, itup,
+ newitemoff, false);
}
else
{
/* just release the buffer */
- _bt_relbuf(rel, buf);
+ _bt_relbuf(rel, insertstate.buf);
}
/* be tidy */
if (stack)
_bt_freestack(stack);
- _bt_freeskey(itup_scankey);
+ pfree(itup_key);
return is_unique;
}
@@ -309,10 +318,6 @@ top:
/*
* _bt_check_unique() -- Check for violation of unique index constraint
*
- * offset points to the first possible item that could conflict. It can
- * also point to end-of-page, which means that the first tuple to check
- * is the first tuple on the next page.
- *
* Returns InvalidTransactionId if there is no conflict, else an xact ID
* we must wait for to see if it commits a conflicting tuple. If an actual
* conflict is detected, no return --- just ereport(). If an xact ID is
@@ -324,16 +329,21 @@ top:
* InvalidTransactionId because we don't want to wait. In this case we
* set *is_unique to false if there is a potential conflict, and the
* core code must redo the uniqueness check later.
+ *
+ * As a side-effect, sets state in insertstate that can later be used by
+ * _bt_findinsertloc() to reuse most of the binary search work we do
+ * here.
*/
static TransactionId
-_bt_check_unique(Relation rel, IndexTuple itup, Relation heapRel,
- Buffer buf, OffsetNumber offset, ScanKey itup_scankey,
+_bt_check_unique(Relation rel, BTInsertState insertstate, Relation heapRel,
IndexUniqueCheck checkUnique, bool *is_unique,
uint32 *speculativeToken)
{
TupleDesc itupdesc = RelationGetDescr(rel);
- int indnkeyatts = IndexRelationGetNumberOfKeyAttributes(rel);
+ IndexTuple itup = insertstate->itup;
+ BTScanInsert itup_key = insertstate->itup_key;
SnapshotData SnapshotDirty;
+ OffsetNumber offset;
OffsetNumber maxoff;
Page page;
BTPageOpaque opaque;
@@ -345,13 +355,22 @@ _bt_check_unique(Relation rel, IndexTuple itup, Relation heapRel,
InitDirtySnapshot(SnapshotDirty);
- page = BufferGetPage(buf);
+ page = BufferGetPage(insertstate->buf);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
maxoff = PageGetMaxOffsetNumber(page);
+ /*
+ * Find the first tuple with the same key.
+ *
+ * This also saves the binary search bounds in insertstate. We use them
+ * in the fastpath below, but also in the _bt_findinsertloc() call later.
+ */
+ offset = _bt_binsrch_insert(rel, insertstate);
+
/*
* Scan over all equal tuples, looking for live conflicts.
*/
+ Assert(!insertstate->bounds_valid || insertstate->low == offset);
for (;;)
{
ItemId curitemid;
@@ -364,21 +383,40 @@ _bt_check_unique(Relation rel, IndexTuple itup, Relation heapRel,
*/
if (offset <= maxoff)
{
+ /*
+ * Fastpath: In most cases, we can use cached search bounds to
+ * limit our consideration to items that are definitely
+ * duplicates. This fastpath doesn't apply when the original page
+ * is empty, or when initial offset is past the end of the
+ * original page, which may indicate that we need to examine a
+ * second or subsequent page.
+ *
+ * Note that this optimization avoids calling _bt_isequal()
+ * entirely when there are no duplicates, as long as the offset
+ * where the key will go is not at the end of the page.
+ */
+ if (nbuf == InvalidBuffer && offset == insertstate->stricthigh)
+ {
+ Assert(insertstate->bounds_valid);
+ Assert(insertstate->low >= P_FIRSTDATAKEY(opaque));
+ Assert(insertstate->low <= insertstate->stricthigh);
+ Assert(!_bt_isequal(itupdesc, itup_key, page, offset));
+ break;
+ }
+
curitemid = PageGetItemId(page, offset);
/*
* We can skip items that are marked killed.
*
- * Formerly, we applied _bt_isequal() before checking the kill
- * flag, so as to fall out of the item loop as soon as possible.
- * However, in the presence of heavy update activity an index may
- * contain many killed items with the same key; running
- * _bt_isequal() on each killed item gets expensive. Furthermore
- * it is likely that the non-killed version of each key appears
- * first, so that we didn't actually get to exit any sooner
- * anyway. So now we just advance over killed items as quickly as
- * we can. We only apply _bt_isequal() when we get to a non-killed
- * item or the end of the page.
+ * In the presence of heavy update activity an index may contain
+ * many killed items with the same key; running _bt_isequal() on
+ * each killed item gets expensive. Just advance over killed
+ * items as quickly as we can. We only apply _bt_isequal() when
+ * we get to a non-killed item. Even those comparisons could be
+ * avoided (in the common case where there is only one page to
+ * visit) by reusing bounds, but just skipping dead items is fast
+ * enough.
*/
if (!ItemIdIsDead(curitemid))
{
@@ -391,7 +429,7 @@ _bt_check_unique(Relation rel, IndexTuple itup, Relation heapRel,
* in real comparison, but only for ordering/finding items on
* pages. - vadim 03/24/97
*/
- if (!_bt_isequal(itupdesc, page, offset, indnkeyatts, itup_scankey))
+ if (!_bt_isequal(itupdesc, itup_key, page, offset))
break; /* we're past all the equal tuples */
/* okay, we gotta fetch the heap tuple ... */
@@ -488,7 +526,7 @@ _bt_check_unique(Relation rel, IndexTuple itup, Relation heapRel,
* otherwise be masked by this unique constraint
* violation.
*/
- CheckForSerializableConflictIn(rel, NULL, buf);
+ CheckForSerializableConflictIn(rel, NULL, insertstate->buf);
/*
* This is a definite conflict. Break the tuple down into
@@ -500,7 +538,8 @@ _bt_check_unique(Relation rel, IndexTuple itup, Relation heapRel,
*/
if (nbuf != InvalidBuffer)
_bt_relbuf(rel, nbuf);
- _bt_relbuf(rel, buf);
+ _bt_relbuf(rel, insertstate->buf);
+ insertstate->buf = InvalidBuffer;
{
Datum values[INDEX_MAX_KEYS];
@@ -540,7 +579,7 @@ _bt_check_unique(Relation rel, IndexTuple itup, Relation heapRel,
if (nbuf != InvalidBuffer)
MarkBufferDirtyHint(nbuf, true);
else
- MarkBufferDirtyHint(buf, true);
+ MarkBufferDirtyHint(insertstate->buf, true);
}
}
}
@@ -552,11 +591,14 @@ _bt_check_unique(Relation rel, IndexTuple itup, Relation heapRel,
offset = OffsetNumberNext(offset);
else
{
+ int highkeycmp;
+
/* If scankey == hikey we gotta check the next page too */
if (P_RIGHTMOST(opaque))
break;
- if (!_bt_isequal(itupdesc, page, P_HIKEY,
- indnkeyatts, itup_scankey))
+ highkeycmp = _bt_compare(rel, itup_key, page, P_HIKEY);
+ Assert(highkeycmp <= 0);
+ if (highkeycmp != 0)
break;
/* Advance to next non-dead page --- there must be one */
for (;;)
@@ -600,57 +642,41 @@ _bt_check_unique(Relation rel, IndexTuple itup, Relation heapRel,
/*
* _bt_findinsertloc() -- Finds an insert location for a tuple
*
+ * On entry, insertstate buffer contains the first legal page the new
+ * tuple could be inserted to. It is exclusive-locked and pinned by the
+ * caller.
+ *
* If the new key is equal to one or more existing keys, we can
* legitimately place it anywhere in the series of equal keys --- in fact,
* if the new key is equal to the page's "high key" we can place it on
* the next page. If it is equal to the high key, and there's not room
* to insert the new tuple on the current page without splitting, then
* we can move right hoping to find more free space and avoid a split.
- * (We should not move right indefinitely, however, since that leads to
- * O(N^2) insertion behavior in the presence of many equal keys.)
- * Once we have chosen the page to put the key on, we'll insert it before
- * any existing equal keys because of the way _bt_binsrch() works.
- *
- * If there's not enough room in the space, we try to make room by
- * removing any LP_DEAD tuples.
+ * Furthermore, if there's not enough room on a page, we try to make
+ * room by removing any LP_DEAD tuples.
*
- * On entry, *bufptr and *offsetptr point to the first legal position
- * where the new tuple could be inserted. The caller should hold an
- * exclusive lock on *bufptr. *offsetptr can also be set to
- * InvalidOffsetNumber, in which case the function will search for the
- * right location within the page if needed. On exit, they point to the
- * chosen insert location. If _bt_findinsertloc decides to move right,
- * the lock and pin on the original page will be released and the new
- * page returned to the caller is exclusively locked instead.
+ * On exit, insertstate buffer contains the chosen insertion page, and
+ * the offset within that page is returned. If _bt_findinsertloc needed
+ * to move right, the lock and pin on the original page are released, and
+ * the new buffer is exclusively locked and pinned instead.
*
- * newtup is the new tuple we're inserting, and scankey is an insertion
- * type scan key for it.
+ * If insertstate contains cached binary search bounds, we will take
+ * advantage of them. This avoids repeating comparisons that we made in
+ * _bt_check_unique() already.
*/
-static void
+static OffsetNumber
_bt_findinsertloc(Relation rel,
- Buffer *bufptr,
- OffsetNumber *offsetptr,
- int keysz,
- ScanKey scankey,
- IndexTuple newtup,
+ BTInsertState insertstate,
+ bool checkingunique,
BTStack stack,
Relation heapRel)
{
- Buffer buf = *bufptr;
- Page page = BufferGetPage(buf);
- Size itemsz;
+ BTScanInsert itup_key = insertstate->itup_key;
+ Page page = BufferGetPage(insertstate->buf);
BTPageOpaque lpageop;
- bool movedright,
- vacuumed;
- OffsetNumber newitemoff;
- OffsetNumber firstlegaloff = *offsetptr;
lpageop = (BTPageOpaque) PageGetSpecialPointer(page);
- itemsz = IndexTupleSize(newtup);
- itemsz = MAXALIGN(itemsz); /* be safe, PageAddItem will do this but we
- * need to be consistent */
-
/*
* Check whether the item can fit on a btree page at all. (Eventually, we
* ought to try to apply TOAST methods if not.) We actually need to be
@@ -660,11 +686,11 @@ _bt_findinsertloc(Relation rel,
*
* NOTE: if you change this, see also the similar code in _bt_buildadd().
*/
- if (itemsz > BTMaxItemSize(page))
+ if (insertstate->itemsz > BTMaxItemSize(page))
ereport(ERROR,
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("index row size %zu exceeds maximum %zu for index \"%s\"",
- itemsz, BTMaxItemSize(page),
+ insertstate->itemsz, BTMaxItemSize(page),
RelationGetRelationName(rel)),
errhint("Values larger than 1/3 of a buffer page cannot be indexed.\n"
"Consider a function index of an MD5 hash of the value, "
@@ -690,100 +716,113 @@ _bt_findinsertloc(Relation rel,
* excellent job of preventing O(N^2) behavior with many equal keys.
*----------
*/
- movedright = false;
- vacuumed = false;
- while (PageGetFreeSpace(page) < itemsz)
- {
- Buffer rbuf;
- BlockNumber rblkno;
+ Assert(P_ISLEAF(lpageop) && !P_INCOMPLETE_SPLIT(lpageop));
+ Assert(!insertstate->bounds_valid || checkingunique);
+ while (PageGetFreeSpace(page) < insertstate->itemsz)
+ {
/*
* before considering moving right, see if we can obtain enough space
* by erasing LP_DEAD items
*/
- if (P_ISLEAF(lpageop) && P_HAS_GARBAGE(lpageop))
+ if (P_HAS_GARBAGE(lpageop))
{
- _bt_vacuum_one_page(rel, buf, heapRel);
+ _bt_vacuum_one_page(rel, insertstate->buf, heapRel);
+ insertstate->bounds_valid = false;
- /*
- * remember that we vacuumed this page, because that makes the
- * hint supplied by the caller invalid
- */
- vacuumed = true;
-
- if (PageGetFreeSpace(page) >= itemsz)
+ if (PageGetFreeSpace(page) >= insertstate->itemsz)
break; /* OK, now we have enough space */
}
/*
- * nope, so check conditions (b) and (c) enumerated above
+ * Nope, so check conditions (b) and (c) enumerated above
+ *
+ * The earlier _bt_check_unique() call may well have established a
+ * strict upper bound on the offset for the new item. If it's not the
+ * last item of the page (i.e. if there is at least one tuple on the
+ * page that's greater than the tuple we're inserting to) then we know
+ * that the tuple belongs on this page. We can skip the high key
+ * check.
*/
+ if (insertstate->bounds_valid &&
+ insertstate->low <= insertstate->stricthigh &&
+ insertstate->stricthigh <= PageGetMaxOffsetNumber(page))
+ break;
+
if (P_RIGHTMOST(lpageop) ||
- _bt_compare(rel, keysz, scankey, page, P_HIKEY) != 0 ||
+ _bt_compare(rel, itup_key, page, P_HIKEY) != 0 ||
random() <= (MAX_RANDOM_VALUE / 100))
break;
- /*
- * step right to next non-dead page
- *
- * must write-lock that page before releasing write lock on current
- * page; else someone else's _bt_check_unique scan could fail to see
- * our insertion. write locks on intermediate dead pages won't do
- * because we don't know when they will get de-linked from the tree.
- */
- rbuf = InvalidBuffer;
+ _bt_stepright(rel, insertstate, stack);
+ /* Update local state after stepping right */
+ page = BufferGetPage(insertstate->buf);
+ lpageop = (BTPageOpaque) PageGetSpecialPointer(page);
+ }
- rblkno = lpageop->btpo_next;
- for (;;)
- {
- rbuf = _bt_relandgetbuf(rel, rbuf, rblkno, BT_WRITE);
- page = BufferGetPage(rbuf);
- lpageop = (BTPageOpaque) PageGetSpecialPointer(page);
+ /*
+ * We should now be on the correct page. Find the offset within the page
+ * for the new tuple. (Possibly reusing earlier search bounds.)
+ */
+ Assert(P_RIGHTMOST(lpageop) ||
+ _bt_compare(rel, itup_key, page, P_HIKEY) <= 0);
- /*
- * If this page was incompletely split, finish the split now. We
- * do this while holding a lock on the left sibling, which is not
- * good because finishing the split could be a fairly lengthy
- * operation. But this should happen very seldom.
- */
- if (P_INCOMPLETE_SPLIT(lpageop))
- {
- _bt_finish_split(rel, rbuf, stack);
- rbuf = InvalidBuffer;
- continue;
- }
+ return _bt_binsrch_insert(rel, insertstate);
+}
- if (!P_IGNORE(lpageop))
- break;
- if (P_RIGHTMOST(lpageop))
- elog(ERROR, "fell off the end of index \"%s\"",
- RelationGetRelationName(rel));
+/*
+ * Step right to next non-dead page, during insertion.
+ *
+ * This is a bit more complicated than moving right in a search. We must
+ * write-lock the target page before releasing write lock on current page;
+ * else someone else's _bt_check_unique scan could fail to see our insertion.
+ * Write locks on intermediate dead pages won't do because we don't know when
+ * they will get de-linked from the tree.
+ */
+static void
+_bt_stepright(Relation rel, BTInsertState insertstate, BTStack stack)
+{
+ Page page;
+ BTPageOpaque lpageop;
+ Buffer rbuf;
+ BlockNumber rblkno;
+
+ page = BufferGetPage(insertstate->buf);
+ lpageop = (BTPageOpaque) PageGetSpecialPointer(page);
+
+ rbuf = InvalidBuffer;
+ rblkno = lpageop->btpo_next;
+ for (;;)
+ {
+ rbuf = _bt_relandgetbuf(rel, rbuf, rblkno, BT_WRITE);
+ page = BufferGetPage(rbuf);
+ lpageop = (BTPageOpaque) PageGetSpecialPointer(page);
- rblkno = lpageop->btpo_next;
+ /*
+ * If this page was incompletely split, finish the split now. We do
+ * this while holding a lock on the left sibling, which is not good
+ * because finishing the split could be a fairly lengthy operation.
+ * But this should happen very seldom.
+ */
+ if (P_INCOMPLETE_SPLIT(lpageop))
+ {
+ _bt_finish_split(rel, rbuf, stack);
+ rbuf = InvalidBuffer;
+ continue;
}
- _bt_relbuf(rel, buf);
- buf = rbuf;
- movedright = true;
- vacuumed = false;
- }
- /*
- * Now we are on the right page, so find the insert position. If we moved
- * right at all, we know we should insert at the start of the page. If we
- * didn't move right, we can use the firstlegaloff hint if the caller
- * supplied one, unless we vacuumed the page which might have moved tuples
- * around making the hint invalid. If we didn't move right or can't use
- * the hint, find the position by searching.
- */
- if (movedright)
- newitemoff = P_FIRSTDATAKEY(lpageop);
- else if (firstlegaloff != InvalidOffsetNumber && !vacuumed)
- newitemoff = firstlegaloff;
- else
- newitemoff = _bt_binsrch(rel, buf, keysz, scankey, false);
+ if (!P_IGNORE(lpageop))
+ break;
+ if (P_RIGHTMOST(lpageop))
+ elog(ERROR, "fell off the end of index \"%s\"",
+ RelationGetRelationName(rel));
- *bufptr = buf;
- *offsetptr = newitemoff;
+ rblkno = lpageop->btpo_next;
+ }
+ /* rbuf locked; unlock buf, update state for caller */
+ _bt_relbuf(rel, insertstate->buf);
+ insertstate->buf = rbuf;
+ insertstate->bounds_valid = false;
}
/*----------
@@ -2312,24 +2351,21 @@ _bt_pgaddtup(Page page,
* Rule is simple: NOT_NULL not equal NULL, NULL not equal NULL too.
*/
static bool
-_bt_isequal(TupleDesc itupdesc, Page page, OffsetNumber offnum,
- int keysz, ScanKey scankey)
+_bt_isequal(TupleDesc itupdesc, BTScanInsert itup_key, Page page,
+ OffsetNumber offnum)
{
IndexTuple itup;
+ ScanKey scankey;
int i;
- /* Better be comparing to a leaf item */
+ /* Better be comparing to a non-pivot item */
Assert(P_ISLEAF((BTPageOpaque) PageGetSpecialPointer(page)));
+ Assert(offnum >= P_FIRSTDATAKEY((BTPageOpaque) PageGetSpecialPointer(page)));
+ scankey = itup_key->scankeys;
itup = (IndexTuple) PageGetItem(page, PageGetItemId(page, offnum));
- /*
- * It's okay that we might perform a comparison against a truncated page
- * high key when caller needs to determine if _bt_check_unique scan must
- * continue on to the next page. Caller never asks us to compare non-key
- * attributes within an INCLUDE index.
- */
- for (i = 1; i <= keysz; i++)
+ for (i = 1; i <= itup_key->keysz; i++)
{
AttrNumber attno;
Datum datum;
@@ -2377,6 +2413,8 @@ _bt_vacuum_one_page(Relation rel, Buffer buffer, Relation heapRel)
Page page = BufferGetPage(buffer);
BTPageOpaque opaque = (BTPageOpaque) PageGetSpecialPointer(page);
+ Assert(P_ISLEAF(opaque));
+
/*
* Scan over all items to see which ones need to be deleted according to
* LP_DEAD flags.
diff --git a/src/backend/access/nbtree/nbtpage.c b/src/backend/access/nbtree/nbtpage.c
index 9c785bca95e..56041c3d383 100644
--- a/src/backend/access/nbtree/nbtpage.c
+++ b/src/backend/access/nbtree/nbtpage.c
@@ -1371,7 +1371,7 @@ _bt_pagedel(Relation rel, Buffer buf)
*/
if (!stack)
{
- ScanKey itup_scankey;
+ BTScanInsert itup_key;
ItemId itemid;
IndexTuple targetkey;
Buffer lbuf;
@@ -1421,12 +1421,10 @@ _bt_pagedel(Relation rel, Buffer buf)
}
/* we need an insertion scan key for the search, so build one */
- itup_scankey = _bt_mkscankey(rel, targetkey);
- /* find the leftmost leaf page containing this key */
- stack = _bt_search(rel,
- IndexRelationGetNumberOfKeyAttributes(rel),
- itup_scankey, false, &lbuf, BT_READ, NULL);
- /* don't need a pin on the page */
+ itup_key = _bt_mkscankey(rel, targetkey);
+ /* get stack to leaf page by searching index */
+ stack = _bt_search(rel, itup_key, &lbuf, BT_READ, NULL);
+ /* don't need a lock or second pin on the page */
_bt_relbuf(rel, lbuf);
/*
diff --git a/src/backend/access/nbtree/nbtsearch.c b/src/backend/access/nbtree/nbtsearch.c
index a0d78b6d682..5a5c30abc3a 100644
--- a/src/backend/access/nbtree/nbtsearch.c
+++ b/src/backend/access/nbtree/nbtsearch.c
@@ -25,6 +25,7 @@
static void _bt_drop_lock_and_maybe_pin(IndexScanDesc scan, BTScanPos sp);
+static OffsetNumber _bt_binsrch(Relation rel, BTScanInsert key, Buffer buf);
static bool _bt_readpage(IndexScanDesc scan, ScanDirection dir,
OffsetNumber offnum);
static void _bt_saveitem(BTScanOpaque so, int itemIndex,
@@ -70,13 +71,9 @@ _bt_drop_lock_and_maybe_pin(IndexScanDesc scan, BTScanPos sp)
* _bt_search() -- Search the tree for a particular scankey,
* or more precisely for the first leaf page it could be on.
*
- * The passed scankey must be an insertion-type scankey (see nbtree/README),
+ * The passed scankey is an insertion-type scankey (see nbtree/README),
* but it can omit the rightmost column(s) of the index.
*
- * When nextkey is false (the usual case), we are looking for the first
- * item >= scankey. When nextkey is true, we are looking for the first
- * item strictly greater than scankey.
- *
* Return value is a stack of parent-page pointers. *bufP is set to the
* address of the leaf-page buffer, which is read-locked and pinned.
* No locks are held on the parent pages, however!
@@ -92,8 +89,8 @@ _bt_drop_lock_and_maybe_pin(IndexScanDesc scan, BTScanPos sp)
* during the search will be finished.
*/
BTStack
-_bt_search(Relation rel, int keysz, ScanKey scankey, bool nextkey,
- Buffer *bufP, int access, Snapshot snapshot)
+_bt_search(Relation rel, BTScanInsert key, Buffer *bufP, int access,
+ Snapshot snapshot)
{
BTStack stack_in = NULL;
int page_access = BT_READ;
@@ -129,8 +126,7 @@ _bt_search(Relation rel, int keysz, ScanKey scankey, bool nextkey,
* if the leaf page is split and we insert to the parent page). But
* this is a good opportunity to finish splits of internal pages too.
*/
- *bufP = _bt_moveright(rel, *bufP, keysz, scankey, nextkey,
- (access == BT_WRITE), stack_in,
+ *bufP = _bt_moveright(rel, key, *bufP, (access == BT_WRITE), stack_in,
page_access, snapshot);
/* if this is a leaf page, we're done */
@@ -143,7 +139,7 @@ _bt_search(Relation rel, int keysz, ScanKey scankey, bool nextkey,
* Find the appropriate item on the internal page, and get the child
* page that it points to.
*/
- offnum = _bt_binsrch(rel, *bufP, keysz, scankey, nextkey);
+ offnum = _bt_binsrch(rel, key, *bufP);
itemid = PageGetItemId(page, offnum);
itup = (IndexTuple) PageGetItem(page, itemid);
blkno = BTreeInnerTupleGetDownLink(itup);
@@ -197,8 +193,8 @@ _bt_search(Relation rel, int keysz, ScanKey scankey, bool nextkey,
* need to move right in the tree. See Lehman and Yao for an
* excruciatingly precise description.
*/
- *bufP = _bt_moveright(rel, *bufP, keysz, scankey, nextkey,
- true, stack_in, BT_WRITE, snapshot);
+ *bufP = _bt_moveright(rel, key, *bufP, true, stack_in, BT_WRITE,
+ snapshot);
}
return stack_in;
@@ -214,16 +210,17 @@ _bt_search(Relation rel, int keysz, ScanKey scankey, bool nextkey,
* or strictly to the right of it.
*
* This routine decides whether or not we need to move right in the
- * tree by examining the high key entry on the page. If that entry
- * is strictly less than the scankey, or <= the scankey in the nextkey=true
- * case, then we followed the wrong link and we need to move right.
+ * tree by examining the high key entry on the page. If that entry is
+ * strictly less than the scankey, or <= the scankey in the
+ * key.nextkey=true case, then we followed the wrong link and we need
+ * to move right.
*
- * The passed scankey must be an insertion-type scankey (see nbtree/README),
- * but it can omit the rightmost column(s) of the index.
+ * The passed insertion-type scankey can omit the rightmost column(s) of the
+ * index. (see nbtree/README)
*
- * When nextkey is false (the usual case), we are looking for the first
- * item >= scankey. When nextkey is true, we are looking for the first
- * item strictly greater than scankey.
+ * When key.nextkey is false (the usual case), we are looking for the first
+ * item >= key. When key.nextkey is true, we are looking for the first item
+ * strictly greater than key.
*
* If forupdate is true, we will attempt to finish any incomplete splits
* that we encounter. This is required when locking a target page for an
@@ -240,10 +237,8 @@ _bt_search(Relation rel, int keysz, ScanKey scankey, bool nextkey,
*/
Buffer
_bt_moveright(Relation rel,
+ BTScanInsert key,
Buffer buf,
- int keysz,
- ScanKey scankey,
- bool nextkey,
bool forupdate,
BTStack stack,
int access,
@@ -268,7 +263,7 @@ _bt_moveright(Relation rel,
* We also have to move right if we followed a link that brought us to a
* dead page.
*/
- cmpval = nextkey ? 0 : 1;
+ cmpval = key->nextkey ? 0 : 1;
for (;;)
{
@@ -303,7 +298,7 @@ _bt_moveright(Relation rel,
continue;
}
- if (P_IGNORE(opaque) || _bt_compare(rel, keysz, scankey, page, P_HIKEY) >= cmpval)
+ if (P_IGNORE(opaque) || _bt_compare(rel, key, page, P_HIKEY) >= cmpval)
{
/* step right one page */
buf = _bt_relandgetbuf(rel, buf, opaque->btpo_next, access);
@@ -323,13 +318,6 @@ _bt_moveright(Relation rel,
/*
* _bt_binsrch() -- Do a binary search for a key on a particular page.
*
- * The passed scankey must be an insertion-type scankey (see nbtree/README),
- * but it can omit the rightmost column(s) of the index.
- *
- * When nextkey is false (the usual case), we are looking for the first
- * item >= scankey. When nextkey is true, we are looking for the first
- * item strictly greater than scankey.
- *
* On a leaf page, _bt_binsrch() returns the OffsetNumber of the first
* key >= given scankey, or > scankey if nextkey is true. (NOTE: in
* particular, this means it is possible to return a value 1 greater than the
@@ -347,12 +335,10 @@ _bt_moveright(Relation rel,
* the given page. _bt_binsrch() has no lock or refcount side effects
* on the buffer.
*/
-OffsetNumber
+static OffsetNumber
_bt_binsrch(Relation rel,
- Buffer buf,
- int keysz,
- ScanKey scankey,
- bool nextkey)
+ BTScanInsert key,
+ Buffer buf)
{
Page page;
BTPageOpaque opaque;
@@ -374,7 +360,7 @@ _bt_binsrch(Relation rel,
* This can never happen on an internal page, however, since they are
* never empty (an internal page must have children).
*/
- if (high < low)
+ if (unlikely(high < low))
return low;
/*
@@ -391,7 +377,7 @@ _bt_binsrch(Relation rel,
*/
high++; /* establish the loop invariant for high */
- cmpval = nextkey ? 0 : 1; /* select comparison value */
+ cmpval = key->nextkey ? 0 : 1; /* select comparison value */
while (high > low)
{
@@ -399,7 +385,7 @@ _bt_binsrch(Relation rel,
/* We have low <= mid < high, so mid points at a real slot */
- result = _bt_compare(rel, keysz, scankey, page, mid);
+ result = _bt_compare(rel, key, page, mid);
if (result >= cmpval)
low = mid + 1;
@@ -426,14 +412,120 @@ _bt_binsrch(Relation rel,
return OffsetNumberPrev(low);
}
-/*----------
- * _bt_compare() -- Compare scankey to a particular tuple on the page.
+/*
*
- * The passed scankey must be an insertion-type scankey (see nbtree/README),
- * but it can omit the rightmost column(s) of the index.
+ * bt_binsrch_insert() -- Cacheable, incremental leaf page binary search.
+ *
+ * Like _bt_binsrch(), but with support for caching the binary search
+ * bounds. Only used during insertion, and only on the leaf page that it
+ * looks like caller will insert tuple on. Exclusive-locked and pinned
+ * leaf page is contained within insertstate.
+ *
+ * Caches the bounds fields in insertstate so that a subsequent call can
+ * reuse the low and strict high bounds of original binary search. Callers
+ * that use these fields directly must be prepared for the case where low
+ * and/or stricthigh are not on the same page (one or both exceed maxoff
+ * for the page). The case where there are no items on the page (high <
+ * low) makes bounds invalid.
+ *
+ * Caller is responsible for invalidating bounds when it modifies the page
+ * before calling here a second time.
+ */
+OffsetNumber
+_bt_binsrch_insert(Relation rel, BTInsertState insertstate)
+{
+ BTScanInsert key = insertstate->itup_key;
+ Page page;
+ BTPageOpaque opaque;
+ OffsetNumber low,
+ high,
+ stricthigh;
+ int32 result,
+ cmpval;
+
+ page = BufferGetPage(insertstate->buf);
+ opaque = (BTPageOpaque) PageGetSpecialPointer(page);
+
+ Assert(P_ISLEAF(opaque));
+ Assert(!key->nextkey);
+
+ if (!insertstate->bounds_valid)
+ {
+ /* Start new binary search */
+ low = P_FIRSTDATAKEY(opaque);
+ high = PageGetMaxOffsetNumber(page);
+ }
+ else
+ {
+ /* Restore result of previous binary search against same page */
+ low = insertstate->low;
+ high = insertstate->stricthigh;
+ }
+
+ /* If there are no keys on the page, return the first available slot */
+ if (unlikely(high < low))
+ {
+ /* Caller can't reuse bounds */
+ insertstate->low = InvalidOffsetNumber;
+ insertstate->stricthigh = InvalidOffsetNumber;
+ insertstate->bounds_valid = false;
+ return low;
+ }
+
+ /*
+ * Binary search to find the first key on the page >= scan key. (nextkey
+ * is always false when inserting).
+ *
+ * The loop invariant is: all slots before 'low' are < scan key, all slots
+ * at or after 'high' are >= scan key. 'stricthigh' is > scan key, and is
+ * maintained to save additional search effort for caller.
+ *
+ * We can fall out when high == low.
+ */
+ if (!insertstate->bounds_valid)
+ high++; /* establish the loop invariant for high */
+ stricthigh = high; /* high initially strictly higher */
+
+ cmpval = 1; /* !nextkey comparison value */
+
+ while (high > low)
+ {
+ OffsetNumber mid = low + ((high - low) / 2);
+
+ /* We have low <= mid < high, so mid points at a real slot */
+
+ result = _bt_compare(rel, key, page, mid);
+
+ if (result >= cmpval)
+ low = mid + 1;
+ else
+ {
+ high = mid;
+ if (result != 0)
+ stricthigh = high;
+ }
+ }
+
+ /*
+ * On a leaf page, a binary search always returns the first key >= scan
+ * key (at least in !nextkey case), which could be the last slot + 1. This
+ * is also the lower bound of cached search.
+ *
+ * stricthigh may also be the last slot + 1, which prevents caller from
+ * using bounds directly, but is still useful to us if we're called a
+ * second time with cached bounds (cached low will be < stricthigh when
+ * that happens).
+ */
+ insertstate->low = low;
+ insertstate->stricthigh = stricthigh;
+ insertstate->bounds_valid = true;
+
+ return low;
+}
+
+/*----------
+ * _bt_compare() -- Compare insertion-type scankey to tuple on a page.
*
- * keysz: number of key conditions to be checked (might be less than the
- * number of index columns!)
* page/offnum: location of btree item to be compared to.
*
* This routine returns:
@@ -446,25 +538,26 @@ _bt_binsrch(Relation rel,
*
* CRUCIAL NOTE: on a non-leaf page, the first data key is assumed to be
* "minus infinity": this routine will always claim it is less than the
- * scankey. The actual key value stored (if any, which there probably isn't)
- * does not matter. This convention allows us to implement the Lehman and
- * Yao convention that the first down-link pointer is before the first key.
- * See backend/access/nbtree/README for details.
+ * scankey. The actual key value stored is explicitly truncated to 0
+ * attributes (explicitly minus infinity) with version 3+ indexes, but
+ * that isn't relied upon. This allows us to implement the Lehman and
+ * Yao convention that the first down-link pointer is before the first
+ * key. See backend/access/nbtree/README for details.
*----------
*/
int32
_bt_compare(Relation rel,
- int keysz,
- ScanKey scankey,
+ BTScanInsert key,
Page page,
OffsetNumber offnum)
{
TupleDesc itupdesc = RelationGetDescr(rel);
BTPageOpaque opaque = (BTPageOpaque) PageGetSpecialPointer(page);
IndexTuple itup;
- int i;
+ ScanKey scankey;
Assert(_bt_check_natts(rel, page, offnum));
+ Assert(key->keysz <= IndexRelationGetNumberOfKeyAttributes(rel));
/*
* Force result ">" if target item is first data item on an internal page
@@ -487,7 +580,8 @@ _bt_compare(Relation rel,
* _bt_first).
*/
- for (i = 1; i <= keysz; i++)
+ scankey = key->scankeys;
+ for (int i = 1; i <= key->keysz; i++)
{
Datum datum;
bool isNull;
@@ -573,8 +667,8 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
StrategyNumber strat;
bool nextkey;
bool goback;
+ BTScanInsertData inskey;
ScanKey startKeys[INDEX_MAX_KEYS];
- ScanKeyData scankeys[INDEX_MAX_KEYS];
ScanKeyData notnullkeys[INDEX_MAX_KEYS];
int keysCount = 0;
int i;
@@ -820,8 +914,9 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
/*
* We want to start the scan somewhere within the index. Set up an
* insertion scankey we can use to search for the boundary point we
- * identified above. The insertion scankey is built in the local
- * scankeys[] array, using the keys identified by startKeys[].
+ * identified above. The insertion scankey is built using the keys
+ * identified by startKeys[]. (Remaining insertion scankey fields are
+ * initialized after initial-positioning strategy is finalized.)
*/
Assert(keysCount <= INDEX_MAX_KEYS);
for (i = 0; i < keysCount; i++)
@@ -849,7 +944,7 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
_bt_parallel_done(scan);
return false;
}
- memcpy(scankeys + i, subkey, sizeof(ScanKeyData));
+ memcpy(inskey.scankeys + i, subkey, sizeof(ScanKeyData));
/*
* If the row comparison is the last positioning key we accepted,
@@ -881,7 +976,8 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
if (subkey->sk_flags & SK_ISNULL)
break; /* can't use null keys */
Assert(keysCount < INDEX_MAX_KEYS);
- memcpy(scankeys + keysCount, subkey, sizeof(ScanKeyData));
+ memcpy(inskey.scankeys + keysCount, subkey,
+ sizeof(ScanKeyData));
keysCount++;
if (subkey->sk_flags & SK_ROW_END)
{
@@ -927,7 +1023,7 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
FmgrInfo *procinfo;
procinfo = index_getprocinfo(rel, cur->sk_attno, BTORDER_PROC);
- ScanKeyEntryInitializeWithInfo(scankeys + i,
+ ScanKeyEntryInitializeWithInfo(inskey.scankeys + i,
cur->sk_flags,
cur->sk_attno,
InvalidStrategy,
@@ -948,7 +1044,7 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
elog(ERROR, "missing support function %d(%u,%u) for attribute %d of index \"%s\"",
BTORDER_PROC, rel->rd_opcintype[i], cur->sk_subtype,
cur->sk_attno, RelationGetRelationName(rel));
- ScanKeyEntryInitialize(scankeys + i,
+ ScanKeyEntryInitialize(inskey.scankeys + i,
cur->sk_flags,
cur->sk_attno,
InvalidStrategy,
@@ -1051,12 +1147,15 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
return false;
}
+ /* Initialize remaining insertion scan key fields */
+ inskey.nextkey = nextkey;
+ inskey.keysz = keysCount;
+
/*
* Use the manufactured insertion scan key to descend the tree and
* position ourselves on the target leaf page.
*/
- stack = _bt_search(rel, keysCount, scankeys, nextkey, &buf, BT_READ,
- scan->xs_snapshot);
+ stack = _bt_search(rel, &inskey, &buf, BT_READ, scan->xs_snapshot);
/* don't need to keep the stack around... */
_bt_freestack(stack);
@@ -1085,7 +1184,7 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
_bt_initialize_more_data(so, dir);
/* position to the precise item on the page */
- offnum = _bt_binsrch(rel, buf, keysCount, scankeys, nextkey);
+ offnum = _bt_binsrch(rel, &inskey, buf);
/*
* If nextkey = false, we are positioned at the first item >= scan key, or
diff --git a/src/backend/access/nbtree/nbtsort.c b/src/backend/access/nbtree/nbtsort.c
index 363dceb5b1c..a0e2e70cefc 100644
--- a/src/backend/access/nbtree/nbtsort.c
+++ b/src/backend/access/nbtree/nbtsort.c
@@ -263,6 +263,7 @@ typedef struct BTWriteState
{
Relation heap;
Relation index;
+ BTScanInsert inskey; /* generic insertion scankey */
bool btws_use_wal; /* dump pages to WAL? */
BlockNumber btws_pages_alloced; /* # pages allocated */
BlockNumber btws_pages_written; /* # pages written out */
@@ -540,6 +541,7 @@ _bt_leafbuild(BTSpool *btspool, BTSpool *btspool2)
wstate.heap = btspool->heap;
wstate.index = btspool->index;
+ wstate.inskey = _bt_mkscankey(wstate.index, NULL);
/*
* We need to log index creation in WAL iff WAL archiving/streaming is
@@ -1085,7 +1087,6 @@ _bt_load(BTWriteState *wstate, BTSpool *btspool, BTSpool *btspool2)
TupleDesc tupdes = RelationGetDescr(wstate->index);
int i,
keysz = IndexRelationGetNumberOfKeyAttributes(wstate->index);
- ScanKey indexScanKey = NULL;
SortSupport sortKeys;
if (merge)
@@ -1098,7 +1099,6 @@ _bt_load(BTWriteState *wstate, BTSpool *btspool, BTSpool *btspool2)
/* the preparation of merge */
itup = tuplesort_getindextuple(btspool->sortstate, true);
itup2 = tuplesort_getindextuple(btspool2->sortstate, true);
- indexScanKey = _bt_mkscankey_nodata(wstate->index);
/* Prepare SortSupport data for each column */
sortKeys = (SortSupport) palloc0(keysz * sizeof(SortSupportData));
@@ -1106,7 +1106,7 @@ _bt_load(BTWriteState *wstate, BTSpool *btspool, BTSpool *btspool2)
for (i = 0; i < keysz; i++)
{
SortSupport sortKey = sortKeys + i;
- ScanKey scanKey = indexScanKey + i;
+ ScanKey scanKey = wstate->inskey->scankeys + i;
int16 strategy;
sortKey->ssup_cxt = CurrentMemoryContext;
@@ -1125,8 +1125,6 @@ _bt_load(BTWriteState *wstate, BTSpool *btspool, BTSpool *btspool2)
PrepareSortSupportFromIndexRel(wstate->index, strategy, sortKey);
}
- _bt_freeskey(indexScanKey);
-
for (;;)
{
load1 = true; /* load BTSpool next ? */
diff --git a/src/backend/access/nbtree/nbtutils.c b/src/backend/access/nbtree/nbtutils.c
index 2c05fb5e451..0250e089a65 100644
--- a/src/backend/access/nbtree/nbtutils.c
+++ b/src/backend/access/nbtree/nbtutils.c
@@ -56,34 +56,37 @@ static bool _bt_check_rowcompare(ScanKey skey,
* Build an insertion scan key that contains comparison data from itup
* as well as comparator routines appropriate to the key datatypes.
*
- * The result is intended for use with _bt_compare().
+ * Result is intended for use with _bt_compare(). Callers that don't
+ * need to fill out the insertion scankey arguments (e.g. they use an
+ * ad-hoc comparison routine) can pass a NULL index tuple.
*/
-ScanKey
+BTScanInsert
_bt_mkscankey(Relation rel, IndexTuple itup)
{
+ BTScanInsert key;
ScanKey skey;
TupleDesc itupdesc;
- int indnatts PG_USED_FOR_ASSERTS_ONLY;
int indnkeyatts;
int16 *indoption;
+ int tupnatts;
int i;
itupdesc = RelationGetDescr(rel);
- indnatts = IndexRelationGetNumberOfAttributes(rel);
indnkeyatts = IndexRelationGetNumberOfKeyAttributes(rel);
indoption = rel->rd_indoption;
+ tupnatts = itup ? BTreeTupleGetNAtts(itup, rel) : 0;
- Assert(indnkeyatts > 0);
- Assert(indnkeyatts <= indnatts);
- Assert(BTreeTupleGetNAtts(itup, rel) == indnatts ||
- BTreeTupleGetNAtts(itup, rel) == indnkeyatts);
+ Assert(tupnatts <= IndexRelationGetNumberOfAttributes(rel));
/*
* We'll execute search using scan key constructed on key columns. Non-key
* (INCLUDE index) columns are always omitted from scan keys.
*/
- skey = (ScanKey) palloc(indnkeyatts * sizeof(ScanKeyData));
-
+ key = palloc(offsetof(BTScanInsertData, scankeys) +
+ sizeof(ScanKeyData) * indnkeyatts);
+ key->nextkey = false;
+ key->keysz = Min(indnkeyatts, tupnatts);
+ skey = key->scankeys;
for (i = 0; i < indnkeyatts; i++)
{
FmgrInfo *procinfo;
@@ -96,56 +99,20 @@ _bt_mkscankey(Relation rel, IndexTuple itup)
* comparison can be needed.
*/
procinfo = index_getprocinfo(rel, i + 1, BTORDER_PROC);
- arg = index_getattr(itup, i + 1, itupdesc, &null);
- flags = (null ? SK_ISNULL : 0) | (indoption[i] << SK_BT_INDOPTION_SHIFT);
- ScanKeyEntryInitializeWithInfo(&skey[i],
- flags,
- (AttrNumber) (i + 1),
- InvalidStrategy,
- InvalidOid,
- rel->rd_indcollation[i],
- procinfo,
- arg);
- }
-
- return skey;
-}
-
-/*
- * _bt_mkscankey_nodata
- * Build an insertion scan key that contains 3-way comparator routines
- * appropriate to the key datatypes, but no comparison data. The
- * comparison data ultimately used must match the key datatypes.
- *
- * The result cannot be used with _bt_compare(), unless comparison
- * data is first stored into the key entries. Currently this
- * routine is only called by nbtsort.c and tuplesort.c, which have
- * their own comparison routines.
- */
-ScanKey
-_bt_mkscankey_nodata(Relation rel)
-{
- ScanKey skey;
- int indnkeyatts;
- int16 *indoption;
- int i;
-
- indnkeyatts = IndexRelationGetNumberOfKeyAttributes(rel);
- indoption = rel->rd_indoption;
-
- skey = (ScanKey) palloc(indnkeyatts * sizeof(ScanKeyData));
-
- for (i = 0; i < indnkeyatts; i++)
- {
- FmgrInfo *procinfo;
- int flags;
/*
- * We can use the cached (default) support procs since no cross-type
- * comparison can be needed.
+ * Key arguments built when caller provides no tuple are
+ * defensively represented as NULL values. They should never be
+ * used.
*/
- procinfo = index_getprocinfo(rel, i + 1, BTORDER_PROC);
- flags = SK_ISNULL | (indoption[i] << SK_BT_INDOPTION_SHIFT);
+ if (i < tupnatts)
+ arg = index_getattr(itup, i + 1, itupdesc, &null);
+ else
+ {
+ arg = (Datum) 0;
+ null = true;
+ }
+ flags = (null ? SK_ISNULL : 0) | (indoption[i] << SK_BT_INDOPTION_SHIFT);
ScanKeyEntryInitializeWithInfo(&skey[i],
flags,
(AttrNumber) (i + 1),
@@ -153,19 +120,10 @@ _bt_mkscankey_nodata(Relation rel)
InvalidOid,
rel->rd_indcollation[i],
procinfo,
- (Datum) 0);
+ arg);
}
- return skey;
-}
-
-/*
- * free a scan key made by either _bt_mkscankey or _bt_mkscankey_nodata.
- */
-void
-_bt_freeskey(ScanKey skey)
-{
- pfree(skey);
+ return key;
}
/*
diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 2946b47b465..16bda5c586a 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -884,7 +884,7 @@ tuplesort_begin_cluster(TupleDesc tupDesc,
{
Tuplesortstate *state = tuplesort_begin_common(workMem, coordinate,
randomAccess);
- ScanKey indexScanKey;
+ BTScanInsert indexScanKey;
MemoryContext oldcontext;
int i;
@@ -919,7 +919,7 @@ tuplesort_begin_cluster(TupleDesc tupDesc,
state->tupDesc = tupDesc; /* assume we need not copy tupDesc */
- indexScanKey = _bt_mkscankey_nodata(indexRel);
+ indexScanKey = _bt_mkscankey(indexRel, NULL);
if (state->indexInfo->ii_Expressions != NULL)
{
@@ -945,7 +945,7 @@ tuplesort_begin_cluster(TupleDesc tupDesc,
for (i = 0; i < state->nKeys; i++)
{
SortSupport sortKey = state->sortKeys + i;
- ScanKey scanKey = indexScanKey + i;
+ ScanKey scanKey = indexScanKey->scankeys + i;
int16 strategy;
sortKey->ssup_cxt = CurrentMemoryContext;
@@ -964,7 +964,7 @@ tuplesort_begin_cluster(TupleDesc tupDesc,
PrepareSortSupportFromIndexRel(indexRel, strategy, sortKey);
}
- _bt_freeskey(indexScanKey);
+ pfree(indexScanKey);
MemoryContextSwitchTo(oldcontext);
@@ -981,7 +981,7 @@ tuplesort_begin_index_btree(Relation heapRel,
{
Tuplesortstate *state = tuplesort_begin_common(workMem, coordinate,
randomAccess);
- ScanKey indexScanKey;
+ BTScanInsert indexScanKey;
MemoryContext oldcontext;
int i;
@@ -1014,7 +1014,7 @@ tuplesort_begin_index_btree(Relation heapRel,
state->indexRel = indexRel;
state->enforceUnique = enforceUnique;
- indexScanKey = _bt_mkscankey_nodata(indexRel);
+ indexScanKey = _bt_mkscankey(indexRel, NULL);
/* Prepare SortSupport data for each column */
state->sortKeys = (SortSupport) palloc0(state->nKeys *
@@ -1023,7 +1023,7 @@ tuplesort_begin_index_btree(Relation heapRel,
for (i = 0; i < state->nKeys; i++)
{
SortSupport sortKey = state->sortKeys + i;
- ScanKey scanKey = indexScanKey + i;
+ ScanKey scanKey = indexScanKey->scankeys + i;
int16 strategy;
sortKey->ssup_cxt = CurrentMemoryContext;
@@ -1042,7 +1042,7 @@ tuplesort_begin_index_btree(Relation heapRel,
PrepareSortSupportFromIndexRel(indexRel, strategy, sortKey);
}
- _bt_freeskey(indexScanKey);
+ pfree(indexScanKey);
MemoryContextSwitchTo(oldcontext);
diff --git a/src/include/access/nbtree.h b/src/include/access/nbtree.h
index 60622ea7906..8b3c9dea256 100644
--- a/src/include/access/nbtree.h
+++ b/src/include/access/nbtree.h
@@ -319,6 +319,64 @@ typedef struct BTStackData
typedef BTStackData *BTStack;
+/*
+ * BTScanInsert is the btree-private state needed to find an initial position
+ * for an indexscan, or to insert new tuples -- an "insertion scankey" (not to
+ * be confused with a search scankey). It's used to descend a B-Tree using
+ * _bt_search.
+ *
+ * When nextkey is false (the usual case), _bt_search and _bt_binsrch will
+ * locate the first item >= scankey. When nextkey is true, they will locate
+ * the first item > scan key.
+ *
+ * scankeys is an array of scan key entries for attributes that are compared.
+ * keysz is the size of the array. During insertion, there must be a scan key
+ * for every attribute, but when starting a regular index scan some can be
+ * omitted. The array is used as a flexible array member, though it's sized
+ * in a way that makes it possible to use stack allocations. See
+ * nbtree/README for full details.
+ */
+typedef struct BTScanInsertData
+{
+ bool nextkey;
+ int keysz; /* Size of scankeys array */
+ ScanKeyData scankeys[INDEX_MAX_KEYS]; /* Must appear last */
+} BTScanInsertData;
+
+typedef BTScanInsertData *BTScanInsert;
+
+/*
+ * BTInsertStateData is a working area used during insertion.
+ *
+ * This is filled in after descending the tree to the first leaf page the new
+ * tuple might belong on. Tracks the current position while performing
+ * uniqueness check, before we have determined which exact page to insert
+ * to.
+ *
+ * (This should be private to nbtinsert.c, but it's also used by
+ * _bt_binsrch_insert)
+ */
+typedef struct BTInsertStateData
+{
+ IndexTuple itup; /* Item we're inserting */
+ Size itemsz; /* Size of itup -- should be MAXALIGN()'d */
+ BTScanInsert itup_key; /* Insertion scankey */
+
+ /* Buffer containing leaf page we're likely to insert itup on */
+ Buffer buf;
+
+ /*
+ * Cache of bounds within the current buffer. Only used for insertions
+ * where _bt_check_unique is called. See _bt_binsrch_insert and
+ * _bt_findinsertloc for details.
+ */
+ bool bounds_valid;
+ OffsetNumber low;
+ OffsetNumber stricthigh;
+} BTInsertStateData;
+
+typedef BTInsertStateData *BTInsertState;
+
/*
* BTScanOpaqueData is the btree-private state needed for an indexscan.
* This consists of preprocessed scan keys (see _bt_preprocess_keys() for
@@ -558,16 +616,12 @@ extern int _bt_pagedel(Relation rel, Buffer buf);
/*
* prototypes for functions in nbtsearch.c
*/
-extern BTStack _bt_search(Relation rel,
- int keysz, ScanKey scankey, bool nextkey,
- Buffer *bufP, int access, Snapshot snapshot);
-extern Buffer _bt_moveright(Relation rel, Buffer buf, int keysz,
- ScanKey scankey, bool nextkey, bool forupdate, BTStack stack,
- int access, Snapshot snapshot);
-extern OffsetNumber _bt_binsrch(Relation rel, Buffer buf, int keysz,
- ScanKey scankey, bool nextkey);
-extern int32 _bt_compare(Relation rel, int keysz, ScanKey scankey,
- Page page, OffsetNumber offnum);
+extern BTStack _bt_search(Relation rel, BTScanInsert key, Buffer *bufP,
+ int access, Snapshot snapshot);
+extern Buffer _bt_moveright(Relation rel, BTScanInsert key, Buffer buf,
+ bool forupdate, BTStack stack, int access, Snapshot snapshot);
+extern OffsetNumber _bt_binsrch_insert(Relation rel, BTInsertState insertstate);
+extern int32 _bt_compare(Relation rel, BTScanInsert key, Page page, OffsetNumber offnum);
extern bool _bt_first(IndexScanDesc scan, ScanDirection dir);
extern bool _bt_next(IndexScanDesc scan, ScanDirection dir);
extern Buffer _bt_get_endpoint(Relation rel, uint32 level, bool rightmost,
@@ -576,9 +630,7 @@ extern Buffer _bt_get_endpoint(Relation rel, uint32 level, bool rightmost,
/*
* prototypes for functions in nbtutils.c
*/
-extern ScanKey _bt_mkscankey(Relation rel, IndexTuple itup);
-extern ScanKey _bt_mkscankey_nodata(Relation rel);
-extern void _bt_freeskey(ScanKey skey);
+extern BTScanInsert _bt_mkscankey(Relation rel, IndexTuple itup);
extern void _bt_freestack(BTStack stack);
extern void _bt_preprocess_array_keys(IndexScanDesc scan);
extern void _bt_start_array_keys(IndexScanDesc scan, ScanDirection dir);
--
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