24.07.2019 4:22, Peter Geoghegan wrote:
Attached is a revised version of your v2 that fixes this issue -- I'll
call this v3. In general, my goal for the revision was to make sure
that all of my old tests from the v12 work passed, and to make sure
that amcheck can detect almost any possible problem. I tested the
amcheck changes by corrupting random state in a test index using
pg_hexedit, then making sure that amcheck actually complained in each
case.
I also fixed one or two bugs in passing, including the bug that caused
an assertion failure in _bt_truncate(). That was down to a subtle
off-by-one issue within _bt_insertonpg_in_posting(). Overall, I didn't
make that many changes to your v2. There are probably some things
about the patch that I still don't understand, or things that I have
misunderstood.
Thank you for this review and fixes.
* Changed the custom binary search code within _bt_compare_posting()
to look more like _bt_binsrch() and _bt_binsrch_insert(). Do you know
of any reason not to do it that way?
It's ok to update it. There was no particular reason, just my habit.
* Added quite a few "FIXME"/"XXX" comments at various points, to
indicate where I have general concerns that need more discussion.
+ * FIXME: The calls to BTreeGetNthTupleOfPosting() allocate
memory,
If we only need to check TIDs, we don't need BTreeGetNthTupleOfPosting(),
we can use BTreeTupleGetPostingN() instead and iterate over TIDs, not
tuples.
Fixed in version 4.
* Included my own pageinspect hack to visualize the minimum TIDs in
posting lists. It's broken out into a separate patch file. The code is
very rough, but it might help someone else, so I thought I'd include
it.
Cool, I think we should add it to the final patchset,
probably, as separate function by analogy with tuple_data_split.
I also have some new concerns about the code in the patch that I will
point out now (though only as something to think about a solution on
-- I am unsure myself):
* It's a bad sign that compression involves calls to PageAddItem()
that are allowed to fail (we just give up on compression when that
happens). For one thing, all existing calls to PageAddItem() in
Postgres are never expected to fail -- if they do fail we get a "can't
happen" error that suggests corruption. It was a good idea to take
this approach to get the patch to work, and to prove the general idea,
but we now need to fully work out all the details about the use of
space. This includes complicated new questions around how alignment is
supposed to work.
The main reason to implement this gentle error handling is the fact that
deduplication could cause storage overhead, which leads to running out
of space
on the page.
First of all, it is a legacy of the previous versions where
BTreeFormPostingTuple was not able to form non-posting tuple even in case
where a number of posting items is 1.
Another case that was in my mind is the situation where we have 2 tuples:
t_tid | t_info | key + t_tid | t_info | key
and compressed result is:
t_tid | t_info | key | t_tid | t_tid
If sizeof(t_info) + sizeof(key) < sizeof(t_tid), resulting posting tuple
can be
larger. It may happen if keysize <= 4 byte.
In this situation original tuples must have been aligned to size 16
bytes each,
and resulting tuple is at most 24 bytes (6+2+4+6+6). So this case is
also safe.
I changed DEBUG message to ERROR in v4 and it passes all regression tests.
I doubt that it covers all corner cases, so I'll try to add more special
tests.
Alignment in nbtree is already complicated today -- you're supposed to
MAXALIGN() everything in nbtree, so that the MAXALIGN() within
bufpage.c routines cannot be different to the lp_len/IndexTupleSize()
length (note that heapam can have tuples whose lp_len isn't aligned,
so nbtree could do it differently if it proved useful). Code within
nbtsplitloc.c fully understands the space requirements for the
bufpage.c routines, and is very careful about it. (The bufpage.c
details are supposed to be totally hidden from code like
nbtsplitloc.c, but I guess that that ideal isn't quite possible in
reality. Code comments don't really explain the situation today.)
I'm not sure what it would look like for this patch to be as precise
about free space as nbtsplitloc.c already is, even though that seems
desirable (I just know that it would mean you would trust
PageAddItem() to work in all cases). The patch is different to what we
already have today in that it tries to add *less than* a single
MAXALIGN() quantum at a time in some places (when a posting list needs
to grow by one item). The devil is in the details.
* As you know, the current approach to WAL logging is very
inefficient. It's okay for now, but we'll need a fine-grained approach
for the patch to be commitable. I think that this is subtly related to
the last item (i.e. the one about alignment). I have done basic
performance tests using unlogged tables. The patch seems to either
make big INSERT queries run as fast or faster than before when
inserting into unlogged tables, which is a very good start.
* Since we can now split a posting list in two, we may also have to
reconsider BTMaxItemSize, or some similar mechanism that worries about
extreme cases where it becomes impossible to split because even two
pages are not enough to fit everything. Think of what happens when
there is a tuple with a single large datum, that gets split in two
(the tuple is split, not the page), with each half receiving its own
copy of the datum. I haven't proven to myself that this is broken, but
that may just be because I haven't spent any time on it. OTOH, maybe
you already have it right, in which case it seems like it should be
explained somewhere. Possibly in nbtree.h. This is tricky stuff.
Hmm, I can't get the problem.
In current implementation each posting tuple is smaller than BTMaxItemSize,
so no split can lead to having tuple of larger size.
* I agree with all of your existing TODO items -- most of them seem
very important to me.
* Do we really need to keep BTreeTupleGetHeapTID(), now that we have
BTreeTupleGetMinTID()? Can't we combine the two macros into one, so
that callers don't need to think about the pivot vs posting list thing
themselves? See the new code added to _bt_mkscankey() by v3, for
example. It now handles both cases/macros at once, in order to keep
its amcheck caller happy. amcheck's verify_nbtree.c received similar
ugly code in v3.
No, we don't need them both. I don't mind combining them into one macro.
Actually, we never needed BTreeTupleGetMinTID(),
since its functionality is covered by BTreeTupleGetHeapTID.
On the other hand, in some cases BTreeTupleGetMinTID() looks more readable.
For example here:
> Assert(ItemPointerCompare(BTreeTupleGetMaxTID(lefttup),
BTreeTupleGetMinTID(righttup)) < 0);
* We should at least experiment with applying compression when
inserting into unique indexes. Like Alexander, I think that
compression in unique indexes might work well, given how they must
work in Postgres.
The main reason why I decided to avoid applying compression to unique
indexes
is the performance of microvacuum. It is not applied to items inside a
posting
tuple. And I expect it to be important for unique indexes, which ideally
contain only a few live values.
One more thing I want to discuss:
/*
* We do not expect to meet any DEAD items, since this function is
* called right after _bt_vacuum_one_page(). If for some reason we
* found dead item, don't compress it, to allow upcoming microvacuum
* or vacuum clean it up.
*/
if (ItemIdIsDead(itemId))
continue;
In the previous review Rafia asked about "some reason".
Trying to figure out if this situation possible, I changed this line to
Assert(!ItemIdIsDead(itemId)) in our test version. And it failed in a
performance
test. Unfortunately, I was not able to reproduce it.
The explanation I see is that page had DEAD items, but for some reason
BTP_HAS_GARBAGE was not set so _bt_vacuum_one_page() was not called.
I find it difficult to understand what could lead to this situation,
so probably we need to inspect it closer to exclude the possibility of a
bug.
--
Anastasia Lubennikova
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 55a3a4b..b8c1d03 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -889,6 +889,7 @@ bt_target_page_check(BtreeCheckState *state)
size_t tupsize;
BTScanInsert skey;
bool lowersizelimit;
+ ItemPointer scantid;
CHECK_FOR_INTERRUPTS();
@@ -959,29 +960,73 @@ bt_target_page_check(BtreeCheckState *state)
/*
* Readonly callers may optionally verify that non-pivot tuples can
- * each be found by an independent search that starts from the root
+ * each be found by an independent search that starts from the root.
+ * Note that we deliberately don't do individual searches for each
+ * "logical" posting list tuple, since the posting list itself is
+ * validated by other checks.
*/
if (state->rootdescend && P_ISLEAF(topaque) &&
!bt_rootdescend(state, itup))
{
char *itid,
*htid;
+ ItemPointer tid = BTreeTupleGetMinTID(itup);
itid = psprintf("(%u,%u)", state->targetblock, offset);
htid = psprintf("(%u,%u)",
- ItemPointerGetBlockNumber(&(itup->t_tid)),
- ItemPointerGetOffsetNumber(&(itup->t_tid)));
+ ItemPointerGetBlockNumber(tid),
+ ItemPointerGetOffsetNumber(tid));
ereport(ERROR,
(errcode(ERRCODE_INDEX_CORRUPTED),
errmsg("could not find tuple using search from root page in index \"%s\"",
RelationGetRelationName(state->rel)),
- errdetail_internal("Index tid=%s points to heap tid=%s page lsn=%X/%X.",
+ errdetail_internal("Index tid=%s min heap tid=%s page lsn=%X/%X.",
itid, htid,
(uint32) (state->targetlsn >> 32),
(uint32) state->targetlsn)));
}
+ /*
+ * If tuple is actually a posting list, make sure posting list TIDs
+ * are in order.
+ */
+ if (BTreeTupleIsPosting(itup))
+ {
+ ItemPointerData last;
+ ItemPointer current;
+
+ ItemPointerCopy(BTreeTupleGetMinTID(itup), &last);
+
+ for (int i = 1; i < BTreeTupleGetNPosting(itup); i++)
+ {
+
+ current = BTreeTupleGetPostingN(itup, i);
+
+ if (ItemPointerCompare(current, &last) <= 0)
+ {
+ char *itid,
+ *htid;
+
+ itid = psprintf("(%u,%u)", state->targetblock, offset);
+ htid = psprintf("(%u,%u)",
+ ItemPointerGetBlockNumberNoCheck(current),
+ ItemPointerGetOffsetNumberNoCheck(current));
+
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("posting list heap TIDs out of order in index \"%s\"",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Index tid=%s min heap tid=%s page lsn=%X/%X.",
+ itid, htid,
+ (uint32) (state->targetlsn >> 32),
+ (uint32) state->targetlsn)));
+ }
+
+ ItemPointerCopy(current, &last);
+ }
+ }
+
/* Build insertion scankey for current page offset */
skey = bt_mkscankey_pivotsearch(state->rel, itup);
@@ -1039,12 +1084,33 @@ bt_target_page_check(BtreeCheckState *state)
{
IndexTuple norm;
- norm = bt_normalize_tuple(state, itup);
- bloom_add_element(state->filter, (unsigned char *) norm,
- IndexTupleSize(norm));
- /* Be tidy */
- if (norm != itup)
- pfree(norm);
+ if (BTreeTupleIsPosting(itup))
+ {
+ IndexTuple onetup;
+
+ /* Fingerprint all elements of posting tuple one by one */
+ for (int i = 0; i < BTreeTupleGetNPosting(itup); i++)
+ {
+ onetup = BTreeGetNthTupleOfPosting(itup, i);
+
+ norm = bt_normalize_tuple(state, onetup);
+ bloom_add_element(state->filter, (unsigned char *) norm,
+ IndexTupleSize(norm));
+ /* Be tidy */
+ if (norm != onetup)
+ pfree(norm);
+ pfree(onetup);
+ }
+ }
+ else
+ {
+ norm = bt_normalize_tuple(state, itup);
+ bloom_add_element(state->filter, (unsigned char *) norm,
+ IndexTupleSize(norm));
+ /* Be tidy */
+ if (norm != itup)
+ pfree(norm);
+ }
}
/*
@@ -1052,7 +1118,8 @@ bt_target_page_check(BtreeCheckState *state)
*
* If there is a high key (if this is not the rightmost page on its
* entire level), check that high key actually is upper bound on all
- * page items.
+ * page items. If this is a posting list tuple, we'll need to set
+ * scantid to be highest TID in posting list.
*
* We prefer to check all items against high key rather than checking
* just the last and trusting that the operator class obeys the
@@ -1092,6 +1159,9 @@ bt_target_page_check(BtreeCheckState *state)
* tuple. (See also: "Notes About Data Representation" in the nbtree
* README.)
*/
+ scantid = skey->scantid;
+ if (!BTreeTupleIsPivot(itup))
+ skey->scantid = BTreeTupleGetMaxTID(itup);
if (!P_RIGHTMOST(topaque) &&
!(P_ISLEAF(topaque) ? invariant_leq_offset(state, skey, P_HIKEY) :
invariant_l_offset(state, skey, P_HIKEY)))
@@ -1115,6 +1185,7 @@ bt_target_page_check(BtreeCheckState *state)
(uint32) (state->targetlsn >> 32),
(uint32) state->targetlsn)));
}
+ skey->scantid = scantid;
/*
* * Item order check *
@@ -1129,11 +1200,16 @@ bt_target_page_check(BtreeCheckState *state)
*htid,
*nitid,
*nhtid;
+ ItemPointer tid;
itid = psprintf("(%u,%u)", state->targetblock, offset);
+ if (!BTreeTupleIsPivot(itup))
+ tid = BTreeTupleGetMinTID(itup);
+ else
+ tid = BTreeTupleGetHeapTID(itup);
htid = psprintf("(%u,%u)",
- ItemPointerGetBlockNumberNoCheck(&(itup->t_tid)),
- ItemPointerGetOffsetNumberNoCheck(&(itup->t_tid)));
+ ItemPointerGetBlockNumberNoCheck(tid),
+ ItemPointerGetOffsetNumberNoCheck(tid));
nitid = psprintf("(%u,%u)", state->targetblock,
OffsetNumberNext(offset));
@@ -1142,9 +1218,14 @@ bt_target_page_check(BtreeCheckState *state)
state->target,
OffsetNumberNext(offset));
itup = (IndexTuple) PageGetItem(state->target, itemid);
+
+ if (!BTreeTupleIsPivot(itup))
+ tid = BTreeTupleGetMinTID(itup);
+ else
+ tid = BTreeTupleGetHeapTID(itup);
nhtid = psprintf("(%u,%u)",
- ItemPointerGetBlockNumberNoCheck(&(itup->t_tid)),
- ItemPointerGetOffsetNumberNoCheck(&(itup->t_tid)));
+ ItemPointerGetBlockNumberNoCheck(tid),
+ ItemPointerGetOffsetNumberNoCheck(tid));
ereport(ERROR,
(errcode(ERRCODE_INDEX_CORRUPTED),
@@ -1154,10 +1235,10 @@ bt_target_page_check(BtreeCheckState *state)
"higher index tid=%s (points to %s tid=%s) "
"page lsn=%X/%X.",
itid,
- P_ISLEAF(topaque) ? "heap" : "index",
+ P_ISLEAF(topaque) ? "min heap" : "index",
htid,
nitid,
- P_ISLEAF(topaque) ? "heap" : "index",
+ P_ISLEAF(topaque) ? "min heap" : "index",
nhtid,
(uint32) (state->targetlsn >> 32),
(uint32) state->targetlsn)));
@@ -1918,10 +1999,11 @@ bt_tuple_present_callback(Relation index, HeapTuple htup, Datum *values,
* verification. In particular, it won't try to normalize opclass-equal
* datums with potentially distinct representations (e.g., btree/numeric_ops
* index datums will not get their display scale normalized-away here).
- * Normalization may need to be expanded to handle more cases in the future,
- * though. For example, it's possible that non-pivot tuples could in the
- * future have alternative logically equivalent representations due to using
- * the INDEX_ALT_TID_MASK bit to implement intelligent deduplication.
+ * Caller does normalization for non-pivot tuples that have their own posting
+ * list, since dummy CREATE INDEX callback code generates new tuples with the
+ * same normalized representation. Compression is performed
+ * opportunistically, and in general there is no guarantee about how or when
+ * compression will be applied.
*/
static IndexTuple
bt_normalize_tuple(BtreeCheckState *state, IndexTuple itup)
@@ -2525,14 +2607,20 @@ static inline ItemPointer
BTreeTupleGetHeapTIDCareful(BtreeCheckState *state, IndexTuple itup,
bool nonpivot)
{
- ItemPointer result = BTreeTupleGetHeapTID(itup);
+ ItemPointer result;
BlockNumber targetblock = state->targetblock;
- if (result == NULL && nonpivot)
+ if (BTreeTupleIsPivot(itup) == nonpivot)
ereport(ERROR,
(errcode(ERRCODE_INDEX_CORRUPTED),
errmsg("block %u or its right sibling block or child block in index \"%s\" contains non-pivot tuple that lacks a heap TID",
targetblock, RelationGetRelationName(state->rel))));
+ /* XXX: Again, I wonder if we need both of these macros... */
+ if (!BTreeTupleIsPivot(itup))
+ result = BTreeTupleGetMinTID(itup);
+ else
+ result = BTreeTupleGetHeapTID(itup);
+
return result;
}
diff --git a/src/backend/access/nbtree/nbtinsert.c b/src/backend/access/nbtree/nbtinsert.c
index 602f884..57b6bb5 100644
--- a/src/backend/access/nbtree/nbtinsert.c
+++ b/src/backend/access/nbtree/nbtinsert.c
@@ -41,6 +41,17 @@ static OffsetNumber _bt_findinsertloc(Relation rel,
BTStack stack,
Relation heapRel);
static void _bt_stepright(Relation rel, BTInsertState insertstate, BTStack stack);
+static void _bt_delete_and_insert(Relation rel,
+ Buffer buf,
+ IndexTuple newitup,
+ OffsetNumber newitemoff);
+static void _bt_insertonpg_in_posting(Relation rel, BTScanInsert itup_key,
+ Buffer buf,
+ Buffer cbuf,
+ BTStack stack,
+ IndexTuple itup,
+ OffsetNumber newitemoff,
+ bool split_only_page, int in_posting_offset);
static void _bt_insertonpg(Relation rel, BTScanInsert itup_key,
Buffer buf,
Buffer cbuf,
@@ -56,6 +67,8 @@ static void _bt_insert_parent(Relation rel, Buffer buf, Buffer rbuf,
static bool _bt_pgaddtup(Page page, Size itemsize, IndexTuple itup,
OffsetNumber itup_off);
static void _bt_vacuum_one_page(Relation rel, Buffer buffer, Relation heapRel);
+static void insert_itupprev_to_page(Page page, BTCompressState *compressState);
+static void _bt_compress_one_page(Relation rel, Buffer buffer, Relation heapRel);
/*
* _bt_doinsert() -- Handle insertion of a single index tuple in the tree.
@@ -297,10 +310,17 @@ top:
* search bounds established within _bt_check_unique when insertion is
* checkingunique.
*/
+ insertstate.in_posting_offset = 0;
newitemoff = _bt_findinsertloc(rel, &insertstate, checkingunique,
stack, heapRel);
- _bt_insertonpg(rel, itup_key, insertstate.buf, InvalidBuffer, stack,
- itup, newitemoff, false);
+
+ if (insertstate.in_posting_offset)
+ _bt_insertonpg_in_posting(rel, itup_key, insertstate.buf,
+ InvalidBuffer, stack, itup, newitemoff,
+ false, insertstate.in_posting_offset);
+ else
+ _bt_insertonpg(rel, itup_key, insertstate.buf, InvalidBuffer,
+ stack, itup, newitemoff, false);
}
else
{
@@ -759,6 +779,12 @@ _bt_findinsertloc(Relation rel,
_bt_vacuum_one_page(rel, insertstate->buf, heapRel);
insertstate->bounds_valid = false;
}
+
+ /*
+ * If the target page is full, try to compress the page
+ */
+ if (PageGetFreeSpace(page) < insertstate->itemsz)
+ _bt_compress_one_page(rel, insertstate->buf, heapRel);
}
else
{
@@ -900,6 +926,191 @@ _bt_stepright(Relation rel, BTInsertState insertstate, BTStack stack)
insertstate->bounds_valid = false;
}
+/*
+ * Delete tuple on newitemoff offset and insert newitup at the same offset.
+ * All checks of free space must have been done before calling this function.
+ *
+ * For use in posting tuple's update.
+ */
+static void
+_bt_delete_and_insert(Relation rel,
+ Buffer buf,
+ IndexTuple newitup,
+ OffsetNumber newitemoff)
+{
+ Page page = BufferGetPage(buf);
+ Size newitupsz = IndexTupleSize(newitup);
+
+ newitupsz = MAXALIGN(newitupsz);
+
+ START_CRIT_SECTION();
+
+ PageIndexTupleDelete(page, newitemoff);
+
+ if (!_bt_pgaddtup(page, newitupsz, newitup, newitemoff))
+ elog(ERROR, "failed to insert compressed item in index \"%s\"",
+ RelationGetRelationName(rel));
+
+ MarkBufferDirty(buf);
+
+ /* Xlog stuff */
+ if (RelationNeedsWAL(rel))
+ {
+ xl_btree_insert xlrec;
+ XLogRecPtr recptr;
+
+ xlrec.offnum = newitemoff;
+
+ XLogBeginInsert();
+ XLogRegisterData((char *) &xlrec, SizeOfBtreeInsert);
+
+ Assert(P_ISLEAF((BTPageOpaque) PageGetSpecialPointer(page)));
+
+ /*
+ * Force full page write to keep code simple
+ *
+ * TODO: think of using XLOG_BTREE_INSERT_LEAF with a new tuple's data
+ */
+ XLogRegisterBuffer(0, buf, REGBUF_STANDARD | REGBUF_FORCE_IMAGE);
+ recptr = XLogInsert(RM_BTREE_ID, XLOG_BTREE_INSERT_LEAF);
+ PageSetLSN(page, recptr);
+ }
+
+ END_CRIT_SECTION();
+}
+
+/*
+ * _bt_insertonpg_in_posting() --
+ * Insert a tuple on a particular page in the index
+ * (compression aware version).
+ *
+ * If new tuple's key is equal to the key of a posting tuple that already
+ * exists on the page and it's TID falls inside the min/max range of
+ * existing posting list, update the posting tuple.
+ *
+ * It only can happen on leaf page.
+ *
+ * newitemoff - offset of the posting tuple we must update
+ * in_posting_offset - position of the new tuple's TID in posting list
+ *
+ * If necessary, split the page.
+ */
+static void
+_bt_insertonpg_in_posting(Relation rel,
+ BTScanInsert itup_key,
+ Buffer buf,
+ Buffer cbuf,
+ BTStack stack,
+ IndexTuple itup,
+ OffsetNumber newitemoff,
+ bool split_only_page,
+ int in_posting_offset)
+{
+ IndexTuple origtup;
+ IndexTuple lefttup;
+ IndexTuple righttup;
+ ItemPointerData *ipd;
+ IndexTuple newitup;
+ Page page;
+ int nipd,
+ nipd_right;
+
+ page = BufferGetPage(buf);
+ /* get old posting tuple */
+ origtup = (IndexTuple) PageGetItem(page, PageGetItemId(page, newitemoff));
+ Assert(BTreeTupleIsPosting(origtup));
+ nipd = BTreeTupleGetNPosting(origtup);
+ Assert(in_posting_offset < nipd);
+ Assert(itup_key->scantid != NULL);
+ Assert(itup_key->heapkeyspace);
+
+ elog(DEBUG4, "(%u,%u) is min, (%u,%u) is max, (%u,%u) is new",
+ ItemPointerGetBlockNumberNoCheck(BTreeTupleGetMinTID(origtup)),
+ ItemPointerGetOffsetNumberNoCheck(BTreeTupleGetMinTID(origtup)),
+ ItemPointerGetBlockNumberNoCheck(BTreeTupleGetMaxTID(origtup)),
+ ItemPointerGetOffsetNumberNoCheck(BTreeTupleGetMaxTID(origtup)),
+ ItemPointerGetBlockNumberNoCheck(BTreeTupleGetMaxTID(itup)),
+ ItemPointerGetOffsetNumberNoCheck(BTreeTupleGetMaxTID(itup)));
+
+ /*
+ * At first, check if the new itempointer fits into the tuple's posting
+ * list.
+ *
+ * Also check if new itempointer fits into the page.
+ *
+ * If not, posting tuple's split is required in both cases.
+ *
+ * XXX: Think some more about alignment - pg
+ */
+ if (BTMaxItemSize(page) < MAXALIGN(IndexTupleSize(origtup)) + MAXALIGN(sizeof(ItemPointerData)) ||
+ PageGetFreeSpace(page) < MAXALIGN(IndexTupleSize(origtup)) + MAXALIGN(sizeof(ItemPointerData)))
+ {
+ /*
+ * Split posting tuple into two halves.
+ *
+ * Left tuple contains all item pointes less than the new one and
+ * right tuple contains new item pointer and all to the right.
+ *
+ * TODO Probably we can come up with more clever algorithm.
+ */
+ lefttup = BTreeFormPostingTuple(origtup, BTreeTupleGetPosting(origtup),
+ in_posting_offset);
+
+ nipd_right = nipd - in_posting_offset + 1;
+ ipd = palloc0(sizeof(ItemPointerData) * nipd_right);
+ /* insert new item pointer */
+ memcpy(ipd, itup, sizeof(ItemPointerData));
+ /* copy item pointers from original tuple that belong on right */
+ memcpy(ipd + 1,
+ BTreeTupleGetPostingN(origtup, in_posting_offset),
+ sizeof(ItemPointerData) * (nipd - in_posting_offset));
+
+ righttup = BTreeFormPostingTuple(origtup, ipd, nipd_right);
+ elog(DEBUG4, "inserting inside posting list with split due to no space orig elements %d new off %d",
+ nipd, in_posting_offset);
+
+ Assert(ItemPointerCompare(BTreeTupleGetMaxTID(lefttup),
+ BTreeTupleGetMinTID(righttup)) < 0);
+
+ /*
+ * Replace old tuple with a left tuple on a page.
+ *
+ * And insert righttuple using ordinary _bt_insertonpg() function If
+ * split is required, _bt_insertonpg will handle it.
+ */
+ _bt_delete_and_insert(rel, buf, lefttup, newitemoff);
+ _bt_insertonpg(rel, itup_key, buf, InvalidBuffer,
+ stack, righttup, newitemoff + 1, false);
+
+ pfree(ipd);
+ pfree(lefttup);
+ pfree(righttup);
+ }
+ else
+ {
+ ipd = palloc0(sizeof(ItemPointerData) * (nipd + 1));
+ elog(DEBUG4, "inserting inside posting list due to apparent overlap");
+
+ /* copy item pointers from original tuple into ipd */
+ memcpy(ipd, BTreeTupleGetPosting(origtup),
+ sizeof(ItemPointerData) * in_posting_offset);
+ /* add item pointer of the new tuple into ipd */
+ memcpy(ipd + in_posting_offset, itup, sizeof(ItemPointerData));
+ /* copy item pointers from old tuple into ipd */
+ memcpy(ipd + in_posting_offset + 1,
+ BTreeTupleGetPostingN(origtup, in_posting_offset),
+ sizeof(ItemPointerData) * (nipd - in_posting_offset));
+
+ newitup = BTreeFormPostingTuple(itup, ipd, nipd + 1);
+
+ _bt_delete_and_insert(rel, buf, newitup, newitemoff);
+
+ pfree(ipd);
+ pfree(newitup);
+ _bt_relbuf(rel, buf);
+ }
+}
+
/*----------
* _bt_insertonpg() -- Insert a tuple on a particular page in the index.
*
@@ -2286,3 +2497,221 @@ _bt_vacuum_one_page(Relation rel, Buffer buffer, Relation heapRel)
* the page.
*/
}
+
+/*
+ * Add new item (compressed or not) to the page, while compressing it.
+ * If insertion failed, return false.
+ * Caller should consider this as compression failure and
+ * leave page uncompressed.
+ */
+static void
+insert_itupprev_to_page(Page page, BTCompressState *compressState)
+{
+ IndexTuple to_insert;
+ OffsetNumber offnum = PageGetMaxOffsetNumber(page);
+
+ if (compressState->ntuples == 0)
+ to_insert = compressState->itupprev;
+ else
+ {
+ IndexTuple postingtuple;
+
+ /* form a tuple with a posting list */
+ postingtuple = BTreeFormPostingTuple(compressState->itupprev,
+ compressState->ipd,
+ compressState->ntuples);
+ to_insert = postingtuple;
+ pfree(compressState->ipd);
+ }
+
+ /* Add the new item into the page */
+ offnum = OffsetNumberNext(offnum);
+
+ elog(DEBUG4, "insert_itupprev_to_page. compressState->ntuples %d IndexTupleSize %zu free %zu",
+ compressState->ntuples, IndexTupleSize(to_insert), PageGetFreeSpace(page));
+
+ if (PageAddItem(page, (Item) to_insert, IndexTupleSize(to_insert),
+ offnum, false, false) == InvalidOffsetNumber)
+ {
+ if (compressState->ntuples > 0)
+ pfree(to_insert);
+ elog(ERROR, "failed to add tuple to page while compresing it");
+ }
+
+ if (compressState->ntuples > 0)
+ pfree(to_insert);
+ compressState->ntuples = 0;
+}
+
+/*
+ * Before splitting the page, try to compress items to free some space.
+ * If compression didn't succeed, buffer will contain old state of the page.
+ * This function should be called after lp_dead items
+ * were removed by _bt_vacuum_one_page().
+ */
+static void
+_bt_compress_one_page(Relation rel, Buffer buffer, Relation heapRel)
+{
+ OffsetNumber offnum,
+ minoff,
+ maxoff;
+ Page page = BufferGetPage(buffer);
+ Page newpage;
+ BTPageOpaque opaque = (BTPageOpaque) PageGetSpecialPointer(page);
+ bool use_compression = false;
+ BTCompressState *compressState = NULL;
+ int n_posting_on_page = 0;
+ int natts = IndexRelationGetNumberOfAttributes(rel);
+
+ /*
+ * Don't use compression for indexes with INCLUDEd columns and unique
+ * indexes.
+ */
+ use_compression = (IndexRelationGetNumberOfKeyAttributes(rel) ==
+ IndexRelationGetNumberOfAttributes(rel) &&
+ !rel->rd_index->indisunique);
+ if (!use_compression)
+ return;
+
+ /* init compress state needed to build posting tuples */
+ compressState = (BTCompressState *) palloc0(sizeof(BTCompressState));
+ compressState->ipd = NULL;
+ compressState->ntuples = 0;
+ compressState->itupprev = NULL;
+ compressState->maxitemsize = BTMaxItemSize(page);
+ compressState->maxpostingsize = 0;
+
+ /*
+ * Scan over all items to see which ones can be compressed
+ */
+ minoff = P_FIRSTDATAKEY(opaque);
+ maxoff = PageGetMaxOffsetNumber(page);
+
+ /*
+ * Heuristic to avoid trying to compress page that has already contain
+ * mostly compressed items
+ */
+ for (offnum = minoff;
+ offnum <= maxoff;
+ offnum = OffsetNumberNext(offnum))
+ {
+ ItemId itemid = PageGetItemId(page, P_HIKEY);
+ IndexTuple item = (IndexTuple) PageGetItem(page, itemid);
+
+ if (BTreeTupleIsPosting(item))
+ n_posting_on_page++;
+ }
+
+ /*
+ * If we have only a few uncompressed items on the full page, it isn't
+ * worth to compress them
+ */
+ if (maxoff - n_posting_on_page < BT_COMPRESS_THRESHOLD)
+ return;
+
+ newpage = PageGetTempPageCopySpecial(page);
+ elog(DEBUG4, "_bt_compress_one_page rel: %s,blkno: %u",
+ RelationGetRelationName(rel), BufferGetBlockNumber(buffer));
+
+ /* Copy High Key if any */
+ if (!P_RIGHTMOST(opaque))
+ {
+ ItemId itemid = PageGetItemId(page, P_HIKEY);
+ Size itemsz = ItemIdGetLength(itemid);
+ IndexTuple item = (IndexTuple) PageGetItem(page, itemid);
+
+ if (PageAddItem(newpage, (Item) item, itemsz, P_HIKEY,
+ false, false) == InvalidOffsetNumber)
+ {
+ /*
+ * Should never happen. Anyway, fallback gently to scenario of
+ * incompressible page and just return from function.
+ */
+ elog(DEBUG4, "_bt_compress_one_page. failed to insert highkey to newpage");
+ return;
+ }
+ }
+
+ /*
+ * Iterate over tuples on the page, try to compress them into posting
+ * lists and insert into new page.
+ */
+ for (offnum = minoff;
+ offnum <= maxoff;
+ offnum = OffsetNumberNext(offnum))
+ {
+ ItemId itemId = PageGetItemId(page, offnum);
+ IndexTuple itup = (IndexTuple) PageGetItem(page, itemId);
+
+ /*
+ * We do not expect to meet any DEAD items, since this function is
+ * called right after _bt_vacuum_one_page(). If for some reason we
+ * found dead item, don't compress it, to allow upcoming microvacuum
+ * or vacuum clean it up.
+ */
+ if (ItemIdIsDead(itemId))
+ continue;
+
+ if (compressState->itupprev != NULL)
+ {
+ int n_equal_atts =
+ _bt_keep_natts_fast(rel, compressState->itupprev, itup);
+ int itup_ntuples = BTreeTupleIsPosting(itup) ?
+ BTreeTupleGetNPosting(itup) : 1;
+
+ if (n_equal_atts > natts)
+ {
+ /*
+ * When tuples are equal, create or update posting.
+ *
+ * If posting is too big, insert it on page and continue.
+ */
+ if (compressState->maxitemsize >
+ MAXALIGN(((IndexTupleSize(compressState->itupprev)
+ + (compressState->ntuples + itup_ntuples + 1) * sizeof(ItemPointerData)))))
+ {
+ _bt_add_posting_item(compressState, itup);
+ }
+ else
+ {
+ insert_itupprev_to_page(newpage, compressState);
+ }
+ }
+ else
+ {
+ insert_itupprev_to_page(newpage, compressState);
+ }
+ }
+
+ /*
+ * Copy the tuple into temp variable itupprev to compare it with the
+ * following tuple and maybe unite them into a posting tuple
+ */
+ if (compressState->itupprev)
+ pfree(compressState->itupprev);
+ compressState->itupprev = CopyIndexTuple(itup);
+
+ Assert(IndexTupleSize(compressState->itupprev) <= compressState->maxitemsize);
+ }
+
+ /* Handle the last item. */
+ insert_itupprev_to_page(newpage, compressState);
+
+ START_CRIT_SECTION();
+
+ PageRestoreTempPage(newpage, page);
+ MarkBufferDirty(buffer);
+
+ /* Log full page write */
+ if (RelationNeedsWAL(rel))
+ {
+ XLogRecPtr recptr;
+
+ recptr = log_newpage_buffer(buffer, true);
+ PageSetLSN(page, recptr);
+ }
+
+ END_CRIT_SECTION();
+
+ elog(DEBUG4, "_bt_compress_one_page. success");
+}
diff --git a/src/backend/access/nbtree/nbtpage.c b/src/backend/access/nbtree/nbtpage.c
index 5962126..707a5d0 100644
--- a/src/backend/access/nbtree/nbtpage.c
+++ b/src/backend/access/nbtree/nbtpage.c
@@ -983,14 +983,52 @@ _bt_page_recyclable(Page page)
void
_bt_delitems_vacuum(Relation rel, Buffer buf,
OffsetNumber *itemnos, int nitems,
+ OffsetNumber *remainingoffset,
+ IndexTuple *remaining, int nremaining,
BlockNumber lastBlockVacuumed)
{
Page page = BufferGetPage(buf);
BTPageOpaque opaque;
+ Size itemsz;
+ Size remaining_sz = 0;
+ char *remaining_buf = NULL;
+
+ /* XLOG stuff, buffer for remainings */
+ if (nremaining && RelationNeedsWAL(rel))
+ {
+ Size offset = 0;
+
+ for (int i = 0; i < nremaining; i++)
+ remaining_sz += MAXALIGN(IndexTupleSize(remaining[i]));
+
+ remaining_buf = palloc0(remaining_sz);
+ for (int i = 0; i < nremaining; i++)
+ {
+ itemsz = IndexTupleSize(remaining[i]);
+ memcpy(remaining_buf + offset, (char *) remaining[i], itemsz);
+ offset += MAXALIGN(itemsz);
+ }
+ Assert(offset == remaining_sz);
+ }
/* No ereport(ERROR) until changes are logged */
START_CRIT_SECTION();
+ /* Handle posting tuples here */
+ for (int i = 0; i < nremaining; i++)
+ {
+ /* At first, delete the old tuple. */
+ PageIndexTupleDelete(page, remainingoffset[i]);
+
+ itemsz = IndexTupleSize(remaining[i]);
+ itemsz = MAXALIGN(itemsz);
+
+ /* Add tuple with remaining ItemPointers to the page. */
+ if (PageAddItem(page, (Item) remaining[i], itemsz, remainingoffset[i],
+ false, false) == InvalidOffsetNumber)
+ elog(ERROR, "failed to rewrite compressed item in index while doing vacuum");
+ }
+
/* Fix the page */
if (nitems > 0)
PageIndexMultiDelete(page, itemnos, nitems);
@@ -1020,6 +1058,8 @@ _bt_delitems_vacuum(Relation rel, Buffer buf,
xl_btree_vacuum xlrec_vacuum;
xlrec_vacuum.lastBlockVacuumed = lastBlockVacuumed;
+ xlrec_vacuum.nremaining = nremaining;
+ xlrec_vacuum.ndeleted = nitems;
XLogBeginInsert();
XLogRegisterBuffer(0, buf, REGBUF_STANDARD);
@@ -1033,6 +1073,19 @@ _bt_delitems_vacuum(Relation rel, Buffer buf,
if (nitems > 0)
XLogRegisterBufData(0, (char *) itemnos, nitems * sizeof(OffsetNumber));
+ /*
+ * Here we should save offnums and remaining tuples themselves. It's
+ * important to restore them in correct order. At first, we must
+ * handle remaining tuples and only after that other deleted items.
+ */
+ if (nremaining > 0)
+ {
+ Assert(remaining_buf != NULL);
+ XLogRegisterBufData(0, (char *) remainingoffset,
+ nremaining * sizeof(OffsetNumber));
+ XLogRegisterBufData(0, remaining_buf, remaining_sz);
+ }
+
recptr = XLogInsert(RM_BTREE_ID, XLOG_BTREE_VACUUM);
PageSetLSN(page, recptr);
diff --git a/src/backend/access/nbtree/nbtree.c b/src/backend/access/nbtree/nbtree.c
index 4cfd528..22fb228 100644
--- a/src/backend/access/nbtree/nbtree.c
+++ b/src/backend/access/nbtree/nbtree.c
@@ -97,6 +97,8 @@ static void btvacuumscan(IndexVacuumInfo *info, IndexBulkDeleteResult *stats,
BTCycleId cycleid, TransactionId *oldestBtpoXact);
static void btvacuumpage(BTVacState *vstate, BlockNumber blkno,
BlockNumber orig_blkno);
+static ItemPointer btreevacuumPosting(BTVacState *vstate, IndexTuple itup,
+ int *nremaining);
/*
@@ -1069,7 +1071,8 @@ btvacuumscan(IndexVacuumInfo *info, IndexBulkDeleteResult *stats,
RBM_NORMAL, info->strategy);
LockBufferForCleanup(buf);
_bt_checkpage(rel, buf);
- _bt_delitems_vacuum(rel, buf, NULL, 0, vstate.lastBlockVacuumed);
+ _bt_delitems_vacuum(rel, buf, NULL, 0, NULL, NULL, 0,
+ vstate.lastBlockVacuumed);
_bt_relbuf(rel, buf);
}
@@ -1193,6 +1196,9 @@ restart:
OffsetNumber offnum,
minoff,
maxoff;
+ IndexTuple remaining[MaxOffsetNumber];
+ OffsetNumber remainingoffset[MaxOffsetNumber];
+ int nremaining;
/*
* Trade in the initial read lock for a super-exclusive write lock on
@@ -1229,6 +1235,7 @@ restart:
* callback function.
*/
ndeletable = 0;
+ nremaining = 0;
minoff = P_FIRSTDATAKEY(opaque);
maxoff = PageGetMaxOffsetNumber(page);
if (callback)
@@ -1242,31 +1249,78 @@ restart:
itup = (IndexTuple) PageGetItem(page,
PageGetItemId(page, offnum));
- htup = &(itup->t_tid);
- /*
- * During Hot Standby we currently assume that
- * XLOG_BTREE_VACUUM records do not produce conflicts. That is
- * only true as long as the callback function depends only
- * upon whether the index tuple refers to heap tuples removed
- * in the initial heap scan. When vacuum starts it derives a
- * value of OldestXmin. Backends taking later snapshots could
- * have a RecentGlobalXmin with a later xid than the vacuum's
- * OldestXmin, so it is possible that row versions deleted
- * after OldestXmin could be marked as killed by other
- * backends. The callback function *could* look at the index
- * tuple state in isolation and decide to delete the index
- * tuple, though currently it does not. If it ever did, we
- * would need to reconsider whether XLOG_BTREE_VACUUM records
- * should cause conflicts. If they did cause conflicts they
- * would be fairly harsh conflicts, since we haven't yet
- * worked out a way to pass a useful value for
- * latestRemovedXid on the XLOG_BTREE_VACUUM records. This
- * applies to *any* type of index that marks index tuples as
- * killed.
- */
- if (callback(htup, callback_state))
- deletable[ndeletable++] = offnum;
+ if (BTreeTupleIsPosting(itup))
+ {
+ int nnewipd = 0;
+ ItemPointer newipd = NULL;
+
+ newipd = btreevacuumPosting(vstate, itup, &nnewipd);
+
+ if (nnewipd == 0)
+ {
+ /*
+ * All TIDs from posting list must be deleted, we can
+ * delete whole tuple in a regular way.
+ */
+ deletable[ndeletable++] = offnum;
+ }
+ else if (nnewipd == BTreeTupleGetNPosting(itup))
+ {
+ /*
+ * All TIDs from posting tuple must remain. Do
+ * nothing, just cleanup.
+ */
+ pfree(newipd);
+ }
+ else if (nnewipd < BTreeTupleGetNPosting(itup))
+ {
+ /* Some TIDs from posting tuple must remain. */
+ Assert(nnewipd > 0);
+ Assert(newipd != NULL);
+
+ /*
+ * Form new tuple that contains only remaining TIDs.
+ * Remember this tuple and the offset of the old tuple
+ * to update it in place.
+ */
+ remainingoffset[nremaining] = offnum;
+ remaining[nremaining] = BTreeFormPostingTuple(itup, newipd, nnewipd);
+ nremaining++;
+ pfree(newipd);
+
+ Assert(IndexTupleSize(itup) <= BTMaxItemSize(page));
+ }
+ }
+ else
+ {
+ htup = &(itup->t_tid);
+
+ /*
+ * During Hot Standby we currently assume that
+ * XLOG_BTREE_VACUUM records do not produce conflicts.
+ * That is only true as long as the callback function
+ * depends only upon whether the index tuple refers to
+ * heap tuples removed in the initial heap scan. When
+ * vacuum starts it derives a value of OldestXmin.
+ * Backends taking later snapshots could have a
+ * RecentGlobalXmin with a later xid than the vacuum's
+ * OldestXmin, so it is possible that row versions deleted
+ * after OldestXmin could be marked as killed by other
+ * backends. The callback function *could* look at the
+ * index tuple state in isolation and decide to delete the
+ * index tuple, though currently it does not. If it ever
+ * did, we would need to reconsider whether
+ * XLOG_BTREE_VACUUM records should cause conflicts. If
+ * they did cause conflicts they would be fairly harsh
+ * conflicts, since we haven't yet worked out a way to
+ * pass a useful value for latestRemovedXid on the
+ * XLOG_BTREE_VACUUM records. This applies to *any* type
+ * of index that marks index tuples as killed.
+ */
+ if (callback(htup, callback_state))
+ deletable[ndeletable++] = offnum;
+ }
}
}
@@ -1274,7 +1328,7 @@ restart:
* Apply any needed deletes. We issue just one _bt_delitems_vacuum()
* call per page, so as to minimize WAL traffic.
*/
- if (ndeletable > 0)
+ if (ndeletable > 0 || nremaining > 0)
{
/*
* Notice that the issued XLOG_BTREE_VACUUM WAL record includes
@@ -1291,6 +1345,7 @@ restart:
* that.
*/
_bt_delitems_vacuum(rel, buf, deletable, ndeletable,
+ remainingoffset, remaining, nremaining,
vstate->lastBlockVacuumed);
/*
@@ -1376,6 +1431,41 @@ restart:
}
/*
+ * btreevacuumPosting() -- vacuums a posting tuple.
+ *
+ * Returns new palloc'd posting list with remaining items.
+ * Posting list size is returned via nremaining.
+ *
+ * If all items are dead,
+ * nremaining is 0 and resulting posting list is NULL.
+ */
+static ItemPointer
+btreevacuumPosting(BTVacState *vstate, IndexTuple itup, int *nremaining)
+{
+ int remaining = 0;
+ int nitem = BTreeTupleGetNPosting(itup);
+ ItemPointer tmpitems = NULL,
+ items = BTreeTupleGetPosting(itup);
+
+ /*
+ * Check each tuple in the posting list, save alive tuples into tmpitems
+ */
+ for (int i = 0; i < nitem; i++)
+ {
+ if (vstate->callback(items + i, vstate->callback_state))
+ continue;
+
+ if (tmpitems == NULL)
+ tmpitems = palloc(sizeof(ItemPointerData) * nitem);
+
+ tmpitems[remaining++] = items[i];
+ }
+
+ *nremaining = remaining;
+ return tmpitems;
+}
+
+/*
* btcanreturn() -- Check whether btree indexes support index-only scans.
*
* btrees always do, so this is trivial.
diff --git a/src/backend/access/nbtree/nbtsearch.c b/src/backend/access/nbtree/nbtsearch.c
index c655dad..3e53675 100644
--- a/src/backend/access/nbtree/nbtsearch.c
+++ b/src/backend/access/nbtree/nbtsearch.c
@@ -30,6 +30,9 @@ static bool _bt_readpage(IndexScanDesc scan, ScanDirection dir,
OffsetNumber offnum);
static void _bt_saveitem(BTScanOpaque so, int itemIndex,
OffsetNumber offnum, IndexTuple itup);
+static void _bt_savePostingitem(BTScanOpaque so, int itemIndex,
+ OffsetNumber offnum, ItemPointer iptr,
+ IndexTuple itup, int i);
static bool _bt_steppage(IndexScanDesc scan, ScanDirection dir);
static bool _bt_readnextpage(IndexScanDesc scan, BlockNumber blkno, ScanDirection dir);
static bool _bt_parallel_readpage(IndexScanDesc scan, BlockNumber blkno,
@@ -504,7 +507,8 @@ _bt_binsrch_insert(Relation rel, BTInsertState insertstate)
/* We have low <= mid < high, so mid points at a real slot */
- result = _bt_compare(rel, key, page, mid);
+ result = _bt_compare_posting(rel, key, page, mid,
+ &(insertstate->in_posting_offset));
if (result >= cmpval)
low = mid + 1;
@@ -533,6 +537,55 @@ _bt_binsrch_insert(Relation rel, BTInsertState insertstate)
return low;
}
+/*
+ * Compare insertion-type scankey to tuple on a page,
+ * taking into account posting tuples.
+ * If the key of the posting tuple is equal to scankey,
+ * find exact position inside the posting list,
+ * using TID as extra attribute.
+ */
+int32
+_bt_compare_posting(Relation rel,
+ BTScanInsert key,
+ Page page,
+ OffsetNumber offnum,
+ int *in_posting_offset)
+{
+ IndexTuple itup;
+ int result;
+
+ itup = (IndexTuple) PageGetItem(page, PageGetItemId(page, offnum));
+ result = _bt_compare(rel, key, page, offnum);
+
+ if (BTreeTupleIsPosting(itup) && result == 0)
+ {
+ int low,
+ high,
+ mid,
+ res;
+
+ low = 0;
+ /* "high" is past end of posting list for loop invariant */
+ high = BTreeTupleGetNPosting(itup);
+
+ while (high > low)
+ {
+ mid = low + ((high - low) / 2);
+ res = ItemPointerCompare(key->scantid,
+ BTreeTupleGetPostingN(itup, mid));
+
+ if (res >= 1)
+ low = mid + 1;
+ else
+ high = mid;
+ }
+
+ *in_posting_offset = high;
+ }
+
+ return result;
+}
+
/*----------
* _bt_compare() -- Compare insertion-type scankey to tuple on a page.
*
@@ -665,61 +718,120 @@ _bt_compare(Relation rel,
* Use the heap TID attribute and scantid to try to break the tie. The
* rules are the same as any other key attribute -- only the
* representation differs.
+ *
+ * When itup is a posting tuple, the check becomes more complex. It is
+ * possible that the scankey belongs to the tuple's posting list TID
+ * range.
+ *
+ * _bt_compare() is multipurpose, so it just returns 0 for a fact that key
+ * matches tuple at this offset.
+ *
+ * Use special _bt_compare_posting() wrapper function to handle this case
+ * and perform recheck for posting tuple, finding exact position of the
+ * scankey.
*/
- heapTid = BTreeTupleGetHeapTID(itup);
- if (key->scantid == NULL)
+ if (!BTreeTupleIsPosting(itup))
{
+ heapTid = BTreeTupleGetHeapTID(itup);
+ if (key->scantid == NULL)
+ {
+ /*
+ * Most searches have a scankey that is considered greater than a
+ * truncated pivot tuple if and when the scankey has equal values
+ * for attributes up to and including the least significant
+ * untruncated attribute in tuple.
+ *
+ * For example, if an index has the minimum two attributes (single
+ * user key attribute, plus heap TID attribute), and a page's high
+ * key is ('foo', -inf), and scankey is ('foo', <omitted>), the
+ * search will not descend to the page to the left. The search
+ * will descend right instead. The truncated attribute in pivot
+ * tuple means that all non-pivot tuples on the page to the left
+ * are strictly < 'foo', so it isn't necessary to descend left. In
+ * other words, search doesn't have to descend left because it
+ * isn't interested in a match that has a heap TID value of -inf.
+ *
+ * However, some searches (pivotsearch searches) actually require
+ * that we descend left when this happens. -inf is treated as a
+ * possible match for omitted scankey attribute(s). This is
+ * needed by page deletion, which must re-find leaf pages that are
+ * targets for deletion using their high keys.
+ *
+ * Note: the heap TID part of the test ensures that scankey is
+ * being compared to a pivot tuple with one or more truncated key
+ * attributes.
+ *
+ * Note: pg_upgrade'd !heapkeyspace indexes must always descend to
+ * the left here, since they have no heap TID attribute (and
+ * cannot have any -inf key values in any case, since truncation
+ * can only remove non-key attributes). !heapkeyspace searches
+ * must always be prepared to deal with matches on both sides of
+ * the pivot once the leaf level is reached.
+ */
+ if (key->heapkeyspace && !key->pivotsearch &&
+ key->keysz == ntupatts && heapTid == NULL)
+ return 1;
+
+ /* All provided scankey arguments found to be equal */
+ return 0;
+ }
+
/*
- * Most searches have a scankey that is considered greater than a
- * truncated pivot tuple if and when the scankey has equal values for
- * attributes up to and including the least significant untruncated
- * attribute in tuple.
- *
- * For example, if an index has the minimum two attributes (single
- * user key attribute, plus heap TID attribute), and a page's high key
- * is ('foo', -inf), and scankey is ('foo', <omitted>), the search
- * will not descend to the page to the left. The search will descend
- * right instead. The truncated attribute in pivot tuple means that
- * all non-pivot tuples on the page to the left are strictly < 'foo',
- * so it isn't necessary to descend left. In other words, search
- * doesn't have to descend left because it isn't interested in a match
- * that has a heap TID value of -inf.
- *
- * However, some searches (pivotsearch searches) actually require that
- * we descend left when this happens. -inf is treated as a possible
- * match for omitted scankey attribute(s). This is needed by page
- * deletion, which must re-find leaf pages that are targets for
- * deletion using their high keys.
- *
- * Note: the heap TID part of the test ensures that scankey is being
- * compared to a pivot tuple with one or more truncated key
- * attributes.
- *
- * Note: pg_upgrade'd !heapkeyspace indexes must always descend to the
- * left here, since they have no heap TID attribute (and cannot have
- * any -inf key values in any case, since truncation can only remove
- * non-key attributes). !heapkeyspace searches must always be
- * prepared to deal with matches on both sides of the pivot once the
- * leaf level is reached.
+ * Treat truncated heap TID as minus infinity, since scankey has a key
+ * attribute value (scantid) that would otherwise be compared directly
*/
- if (key->heapkeyspace && !key->pivotsearch &&
- key->keysz == ntupatts && heapTid == NULL)
+ Assert(key->keysz == IndexRelationGetNumberOfKeyAttributes(rel));
+ if (heapTid == NULL)
return 1;
- /* All provided scankey arguments found to be equal */
- return 0;
+ Assert(ntupatts >= IndexRelationGetNumberOfKeyAttributes(rel));
+ return ItemPointerCompare(key->scantid, heapTid);
}
+ else
+ {
+ heapTid = BTreeTupleGetMinTID(itup);
+ if (key->scantid != NULL && heapTid != NULL)
+ {
+ int cmp = ItemPointerCompare(key->scantid, heapTid);
- /*
- * Treat truncated heap TID as minus infinity, since scankey has a key
- * attribute value (scantid) that would otherwise be compared directly
- */
- Assert(key->keysz == IndexRelationGetNumberOfKeyAttributes(rel));
- if (heapTid == NULL)
- return 1;
+ if (cmp == -1 || cmp == 0)
+ {
+ elog(DEBUG4, "offnum %d Scankey (%u,%u) is less than or equal to posting tuple (%u,%u)",
+ offnum, ItemPointerGetBlockNumberNoCheck(key->scantid),
+ ItemPointerGetOffsetNumberNoCheck(key->scantid),
+ ItemPointerGetBlockNumberNoCheck(heapTid),
+ ItemPointerGetOffsetNumberNoCheck(heapTid));
+ return cmp;
+ }
- Assert(ntupatts >= IndexRelationGetNumberOfKeyAttributes(rel));
- return ItemPointerCompare(key->scantid, heapTid);
+ heapTid = BTreeTupleGetMaxTID(itup);
+ cmp = ItemPointerCompare(key->scantid, heapTid);
+ if (cmp == 1)
+ {
+ elog(DEBUG4, "offnum %d Scankey (%u,%u) is greater than posting tuple (%u,%u)",
+ offnum, ItemPointerGetBlockNumberNoCheck(key->scantid),
+ ItemPointerGetOffsetNumberNoCheck(key->scantid),
+ ItemPointerGetBlockNumberNoCheck(heapTid),
+ ItemPointerGetOffsetNumberNoCheck(heapTid));
+ return cmp;
+ }
+
+ /*
+ * if we got here, scantid is inbetween of posting items of the
+ * tuple
+ */
+ elog(DEBUG4, "offnum %d Scankey (%u,%u) is between posting items (%u,%u) and (%u,%u)",
+ offnum, ItemPointerGetBlockNumberNoCheck(key->scantid),
+ ItemPointerGetOffsetNumberNoCheck(key->scantid),
+ ItemPointerGetBlockNumberNoCheck(BTreeTupleGetMinTID(itup)),
+ ItemPointerGetOffsetNumberNoCheck(BTreeTupleGetMinTID(itup)),
+ ItemPointerGetBlockNumberNoCheck(heapTid),
+ ItemPointerGetOffsetNumberNoCheck(heapTid));
+ return 0;
+ }
+ }
+
+ return 0;
}
/*
@@ -1456,6 +1568,7 @@ _bt_readpage(IndexScanDesc scan, ScanDirection dir, OffsetNumber offnum)
/* initialize tuple workspace to empty */
so->currPos.nextTupleOffset = 0;
+ so->currPos.prevTupleOffset = 0;
/*
* Now that the current page has been made consistent, the macro should be
@@ -1490,8 +1603,22 @@ _bt_readpage(IndexScanDesc scan, ScanDirection dir, OffsetNumber offnum)
if (_bt_checkkeys(scan, itup, indnatts, dir, &continuescan))
{
/* tuple passes all scan key conditions, so remember it */
- _bt_saveitem(so, itemIndex, offnum, itup);
- itemIndex++;
+ if (!BTreeTupleIsPosting(itup))
+ {
+ _bt_saveitem(so, itemIndex, offnum, itup);
+ itemIndex++;
+ }
+ else
+ {
+ /* Return posting list "logical" tuples */
+ for (int i = 0; i < BTreeTupleGetNPosting(itup); i++)
+ {
+ _bt_savePostingitem(so, itemIndex, offnum,
+ BTreeTupleGetPostingN(itup, i),
+ itup, i);
+ itemIndex++;
+ }
+ }
}
/* When !continuescan, there can't be any more matches, so stop */
if (!continuescan)
@@ -1524,7 +1651,7 @@ _bt_readpage(IndexScanDesc scan, ScanDirection dir, OffsetNumber offnum)
if (!continuescan)
so->currPos.moreRight = false;
- Assert(itemIndex <= MaxIndexTuplesPerPage);
+ Assert(itemIndex <= MaxPostingIndexTuplesPerPage);
so->currPos.firstItem = 0;
so->currPos.lastItem = itemIndex - 1;
so->currPos.itemIndex = 0;
@@ -1532,7 +1659,7 @@ _bt_readpage(IndexScanDesc scan, ScanDirection dir, OffsetNumber offnum)
else
{
/* load items[] in descending order */
- itemIndex = MaxIndexTuplesPerPage;
+ itemIndex = MaxPostingIndexTuplesPerPage;
offnum = Min(offnum, maxoff);
@@ -1574,8 +1701,23 @@ _bt_readpage(IndexScanDesc scan, ScanDirection dir, OffsetNumber offnum)
if (passes_quals && tuple_alive)
{
/* tuple passes all scan key conditions, so remember it */
- itemIndex--;
- _bt_saveitem(so, itemIndex, offnum, itup);
+ if (!BTreeTupleIsPosting(itup))
+ {
+ itemIndex--;
+ _bt_saveitem(so, itemIndex, offnum, itup);
+ }
+ else
+ {
+ /* Return posting list "logical" tuples */
+ /* XXX: Maybe this loop should be backwards? */
+ for (int i = 0; i < BTreeTupleGetNPosting(itup); i++)
+ {
+ itemIndex--;
+ _bt_savePostingitem(so, itemIndex, offnum,
+ BTreeTupleGetPostingN(itup, i),
+ itup, i);
+ }
+ }
}
if (!continuescan)
{
@@ -1589,8 +1731,8 @@ _bt_readpage(IndexScanDesc scan, ScanDirection dir, OffsetNumber offnum)
Assert(itemIndex >= 0);
so->currPos.firstItem = itemIndex;
- so->currPos.lastItem = MaxIndexTuplesPerPage - 1;
- so->currPos.itemIndex = MaxIndexTuplesPerPage - 1;
+ so->currPos.lastItem = MaxPostingIndexTuplesPerPage - 1;
+ so->currPos.itemIndex = MaxPostingIndexTuplesPerPage - 1;
}
return (so->currPos.firstItem <= so->currPos.lastItem);
@@ -1603,6 +1745,8 @@ _bt_saveitem(BTScanOpaque so, int itemIndex,
{
BTScanPosItem *currItem = &so->currPos.items[itemIndex];
+ Assert(!BTreeTupleIsPosting(itup));
+
currItem->heapTid = itup->t_tid;
currItem->indexOffset = offnum;
if (so->currTuples)
@@ -1615,6 +1759,33 @@ _bt_saveitem(BTScanOpaque so, int itemIndex,
}
}
+/* Save an index item into so->currPos.items[itemIndex] for posting tuples. */
+static void
+_bt_savePostingitem(BTScanOpaque so, int itemIndex, OffsetNumber offnum,
+ ItemPointer iptr, IndexTuple itup, int i)
+{
+ BTScanPosItem *currItem = &so->currPos.items[itemIndex];
+
+ currItem->heapTid = *iptr;
+ currItem->indexOffset = offnum;
+
+ if (so->currTuples)
+ {
+ if (i == 0)
+ {
+ /* save key. the same for all tuples in the posting */
+ Size itupsz = BTreeTupleGetPostingOffset(itup);
+
+ currItem->tupleOffset = so->currPos.nextTupleOffset;
+ memcpy(so->currTuples + so->currPos.nextTupleOffset, itup, itupsz);
+ so->currPos.nextTupleOffset += MAXALIGN(itupsz);
+ so->currPos.prevTupleOffset = currItem->tupleOffset;
+ }
+ else
+ currItem->tupleOffset = so->currPos.prevTupleOffset;
+ }
+}
+
/*
* _bt_steppage() -- Step to next page containing valid data for scan
*
diff --git a/src/backend/access/nbtree/nbtsort.c b/src/backend/access/nbtree/nbtsort.c
index d0b9013..5545465f9 100644
--- a/src/backend/access/nbtree/nbtsort.c
+++ b/src/backend/access/nbtree/nbtsort.c
@@ -288,6 +288,8 @@ static void _bt_sortaddtup(Page page, Size itemsize,
static void _bt_buildadd(BTWriteState *wstate, BTPageState *state,
IndexTuple itup);
static void _bt_uppershutdown(BTWriteState *wstate, BTPageState *state);
+static void _bt_buildadd_posting(BTWriteState *wstate, BTPageState *state,
+ BTCompressState *compressState);
static void _bt_load(BTWriteState *wstate,
BTSpool *btspool, BTSpool *btspool2);
static void _bt_begin_parallel(BTBuildState *buildstate, bool isconcurrent,
@@ -972,6 +974,11 @@ _bt_buildadd(BTWriteState *wstate, BTPageState *state, IndexTuple itup)
* only shift the line pointer array back and forth, and overwrite
* the tuple space previously occupied by oitup. This is fairly
* cheap.
+ *
+ * If lastleft tuple was a posting tuple, we'll truncate its
+ * posting list in _bt_truncate as well. Note that it is also
+ * applicable only to leaf pages, since internal pages never
+ * contain posting tuples.
*/
ii = PageGetItemId(opage, OffsetNumberPrev(last_off));
lastleft = (IndexTuple) PageGetItem(opage, ii);
@@ -1011,6 +1018,7 @@ _bt_buildadd(BTWriteState *wstate, BTPageState *state, IndexTuple itup)
* the minimum key for the new page.
*/
state->btps_minkey = CopyIndexTuple(oitup);
+ Assert(BTreeTupleIsPivot(state->btps_minkey));
/*
* Set the sibling links for both pages.
@@ -1052,6 +1060,7 @@ _bt_buildadd(BTWriteState *wstate, BTPageState *state, IndexTuple itup)
Assert(state->btps_minkey == NULL);
state->btps_minkey = CopyIndexTuple(itup);
/* _bt_sortaddtup() will perform full truncation later */
+ BTreeTupleClearBtIsPosting(state->btps_minkey);
BTreeTupleSetNAtts(state->btps_minkey, 0);
}
@@ -1137,6 +1146,91 @@ _bt_uppershutdown(BTWriteState *wstate, BTPageState *state)
}
/*
+ * Add new tuple (posting or non-posting) to the page while building index.
+ */
+static void
+_bt_buildadd_posting(BTWriteState *wstate, BTPageState *state,
+ BTCompressState *compressState)
+{
+ IndexTuple to_insert;
+
+ /* Return, if there is no tuple to insert */
+ if (state == NULL)
+ return;
+
+ if (compressState->ntuples == 0)
+ to_insert = compressState->itupprev;
+ else
+ {
+ IndexTuple postingtuple;
+
+ /* form a tuple with a posting list */
+ postingtuple = BTreeFormPostingTuple(compressState->itupprev,
+ compressState->ipd,
+ compressState->ntuples);
+ to_insert = postingtuple;
+ pfree(compressState->ipd);
+ }
+
+ _bt_buildadd(wstate, state, to_insert);
+
+ if (compressState->ntuples > 0)
+ pfree(to_insert);
+ compressState->ntuples = 0;
+}
+
+/*
+ * Save item pointer(s) of itup to the posting list in compressState.
+ *
+ * Helper function for _bt_load() and _bt_compress_one_page().
+ *
+ * Note: caller is responsible for size check to ensure that resulting tuple
+ * won't exceed BTMaxItemSize.
+ */
+void
+_bt_add_posting_item(BTCompressState *compressState, IndexTuple itup)
+{
+ int nposting = 0;
+
+ if (compressState->ntuples == 0)
+ {
+ compressState->ipd = palloc0(compressState->maxitemsize);
+
+ if (BTreeTupleIsPosting(compressState->itupprev))
+ {
+ /* if itupprev is posting, add all its TIDs to the posting list */
+ nposting = BTreeTupleGetNPosting(compressState->itupprev);
+ memcpy(compressState->ipd,
+ BTreeTupleGetPosting(compressState->itupprev),
+ sizeof(ItemPointerData) * nposting);
+ compressState->ntuples += nposting;
+ }
+ else
+ {
+ memcpy(compressState->ipd, compressState->itupprev,
+ sizeof(ItemPointerData));
+ compressState->ntuples++;
+ }
+ }
+
+ if (BTreeTupleIsPosting(itup))
+ {
+ /* if tuple is posting, add all its TIDs to the posting list */
+ nposting = BTreeTupleGetNPosting(itup);
+ memcpy(compressState->ipd + compressState->ntuples,
+ BTreeTupleGetPosting(itup),
+ sizeof(ItemPointerData) * nposting);
+ compressState->ntuples += nposting;
+ }
+ else
+ {
+ memcpy(compressState->ipd + compressState->ntuples, itup,
+ sizeof(ItemPointerData));
+ compressState->ntuples++;
+ }
+}
+
+/*
* Read tuples in correct sort order from tuplesort, and load them into
* btree leaves.
*/
@@ -1150,9 +1244,20 @@ _bt_load(BTWriteState *wstate, BTSpool *btspool, BTSpool *btspool2)
bool load1;
TupleDesc tupdes = RelationGetDescr(wstate->index);
int i,
- keysz = IndexRelationGetNumberOfKeyAttributes(wstate->index);
+ keysz = IndexRelationGetNumberOfKeyAttributes(wstate->index),
+ natts = IndexRelationGetNumberOfAttributes(wstate->index);
SortSupport sortKeys;
int64 tuples_done = 0;
+ bool use_compression = false;
+ BTCompressState *compressState = NULL;
+
+ /*
+ * Don't use compression for indexes with INCLUDEd columns and unique
+ * indexes.
+ */
+ use_compression = (IndexRelationGetNumberOfKeyAttributes(wstate->index) ==
+ IndexRelationGetNumberOfAttributes(wstate->index) &&
+ !wstate->index->rd_index->indisunique);
if (merge)
{
@@ -1266,19 +1371,89 @@ _bt_load(BTWriteState *wstate, BTSpool *btspool, BTSpool *btspool2)
}
else
{
- /* merge is unnecessary */
- while ((itup = tuplesort_getindextuple(btspool->sortstate,
- true)) != NULL)
+ if (!use_compression)
{
- /* When we see first tuple, create first index page */
- if (state == NULL)
- state = _bt_pagestate(wstate, 0);
+ /* merge is unnecessary */
+ while ((itup = tuplesort_getindextuple(btspool->sortstate,
+ true)) != NULL)
+ {
+ /* When we see first tuple, create first index page */
+ if (state == NULL)
+ state = _bt_pagestate(wstate, 0);
- _bt_buildadd(wstate, state, itup);
+ _bt_buildadd(wstate, state, itup);
- /* Report progress */
- pgstat_progress_update_param(PROGRESS_CREATEIDX_TUPLES_DONE,
- ++tuples_done);
+ /* Report progress */
+ pgstat_progress_update_param(PROGRESS_CREATEIDX_TUPLES_DONE,
+ ++tuples_done);
+ }
+ }
+ else
+ {
+ /* init compress state needed to build posting tuples */
+ compressState = (BTCompressState *) palloc0(sizeof(BTCompressState));
+ compressState->ipd = NULL;
+ compressState->ntuples = 0;
+ compressState->itupprev = NULL;
+ compressState->maxitemsize = 0;
+ compressState->maxpostingsize = 0;
+
+ while ((itup = tuplesort_getindextuple(btspool->sortstate,
+ true)) != NULL)
+ {
+ /* When we see first tuple, create first index page */
+ if (state == NULL)
+ {
+ state = _bt_pagestate(wstate, 0);
+ compressState->maxitemsize = BTMaxItemSize(state->btps_page);
+ }
+
+ if (compressState->itupprev != NULL)
+ {
+ int n_equal_atts = _bt_keep_natts_fast(wstate->index,
+ compressState->itupprev, itup);
+
+ if (n_equal_atts > natts)
+ {
+ /*
+ * Tuples are equal. Create or update posting.
+ *
+ * Else If posting is too big, insert it on page and
+ * continue.
+ */
+ if ((compressState->ntuples + 1) * sizeof(ItemPointerData) <
+ compressState->maxpostingsize)
+ _bt_add_posting_item(compressState, itup);
+ else
+ _bt_buildadd_posting(wstate, state,
+ compressState);
+ }
+ else
+ {
+ /*
+ * Tuples are not equal. Insert itupprev into index.
+ * Save current tuple for the next iteration.
+ */
+ _bt_buildadd_posting(wstate, state, compressState);
+ }
+ }
+
+ /*
+ * Save the tuple to compare it with the next one and maybe
+ * unite them into a posting tuple.
+ */
+ if (compressState->itupprev)
+ pfree(compressState->itupprev);
+ compressState->itupprev = CopyIndexTuple(itup);
+
+ /* compute max size of posting list */
+ compressState->maxpostingsize = compressState->maxitemsize -
+ IndexInfoFindDataOffset(compressState->itupprev->t_info) -
+ MAXALIGN(IndexTupleSize(compressState->itupprev));
+ }
+
+ /* Handle the last item */
+ _bt_buildadd_posting(wstate, state, compressState);
}
}
diff --git a/src/backend/access/nbtree/nbtsplitloc.c b/src/backend/access/nbtree/nbtsplitloc.c
index a7882fd..fbb12db 100644
--- a/src/backend/access/nbtree/nbtsplitloc.c
+++ b/src/backend/access/nbtree/nbtsplitloc.c
@@ -492,6 +492,13 @@ _bt_recsplitloc(FindSplitData *state,
* adding a heap TID to the left half's new high key when splitting at the
* leaf level. In practice the new high key will often be smaller and
* will rarely be larger, but conservatively assume the worst case.
+ *
+ * FIXME: We can make better choices about split points by being clever
+ * about the BTreeTupleIsPosting() case here. All we need to do is
+ * subtract the whole size of the posting list, then add
+ * MAXALIGN(sizeof(ItemPointerData)), since we know for sure that
+ * _bt_truncate() won't make a final high key that is larger even in the
+ * worst case.
*/
if (state->is_leaf)
leftfree -= (int16) (firstrightitemsz +
diff --git a/src/backend/access/nbtree/nbtutils.c b/src/backend/access/nbtree/nbtutils.c
index 93fab26..a6eee1b 100644
--- a/src/backend/access/nbtree/nbtutils.c
+++ b/src/backend/access/nbtree/nbtutils.c
@@ -111,8 +111,21 @@ _bt_mkscankey(Relation rel, IndexTuple itup)
key->nextkey = false;
key->pivotsearch = false;
key->keysz = Min(indnkeyatts, tupnatts);
- key->scantid = key->heapkeyspace && itup ?
- BTreeTupleGetHeapTID(itup) : NULL;
+
+ /*
+ * XXX: Do we need to have both BTreeTupleGetHeapTID() and
+ * BTreeTupleGetMinTID()?
+ */
+ if (itup && key->heapkeyspace)
+ {
+ if (!BTreeTupleIsPivot(itup))
+ key->scantid = BTreeTupleGetMinTID(itup);
+ else
+ key->scantid = BTreeTupleGetHeapTID(itup);
+ }
+ else
+ key->scantid = NULL;
+
skey = key->scankeys;
for (i = 0; i < indnkeyatts; i++)
{
@@ -1787,7 +1800,9 @@ _bt_killitems(IndexScanDesc scan)
ItemId iid = PageGetItemId(page, offnum);
IndexTuple ituple = (IndexTuple) PageGetItem(page, iid);
- if (ItemPointerEquals(&ituple->t_tid, &kitem->heapTid))
+ /* No microvacuum for posting tuples */
+ if (!BTreeTupleIsPosting(ituple) &&
+ (ItemPointerEquals(&ituple->t_tid, &kitem->heapTid)))
{
/* found the item */
ItemIdMarkDead(iid);
@@ -2145,6 +2160,16 @@ _bt_truncate(Relation rel, IndexTuple lastleft, IndexTuple firstright,
pivot = index_truncate_tuple(itupdesc, firstright, keepnatts);
+ if (BTreeTupleIsPosting(firstright))
+ {
+ BTreeTupleClearBtIsPosting(pivot);
+ BTreeTupleSetNAtts(pivot, keepnatts);
+ pivot->t_info &= ~INDEX_SIZE_MASK;
+ pivot->t_info |= BTreeTupleGetPostingOffset(firstright);
+ }
+
+ Assert(!BTreeTupleIsPosting(pivot));
+
/*
* If there is a distinguishing key attribute within new pivot tuple,
* there is no need to add an explicit heap TID attribute
@@ -2161,6 +2186,8 @@ _bt_truncate(Relation rel, IndexTuple lastleft, IndexTuple firstright,
* attribute to the new pivot tuple.
*/
Assert(natts != nkeyatts);
+ Assert(!BTreeTupleIsPosting(lastleft));
+ Assert(!BTreeTupleIsPosting(firstright));
newsize = IndexTupleSize(pivot) + MAXALIGN(sizeof(ItemPointerData));
tidpivot = palloc0(newsize);
memcpy(tidpivot, pivot, IndexTupleSize(pivot));
@@ -2168,6 +2195,27 @@ _bt_truncate(Relation rel, IndexTuple lastleft, IndexTuple firstright,
pfree(pivot);
pivot = tidpivot;
}
+ else if (BTreeTupleIsPosting(firstright))
+ {
+ /*
+ * No truncation was possible, since key attributes are all equal. But
+ * the tuple is a compressed tuple with a posting list, so we still
+ * must truncate it.
+ *
+ * It's necessary to add a heap TID attribute to the new pivot tuple.
+ */
+ newsize = BTreeTupleGetPostingOffset(firstright) +
+ MAXALIGN(sizeof(ItemPointerData));
+ pivot = palloc0(newsize);
+ memcpy(pivot, firstright, BTreeTupleGetPostingOffset(firstright));
+
+ pivot->t_info &= ~INDEX_SIZE_MASK;
+ pivot->t_info |= newsize;
+ BTreeTupleClearBtIsPosting(pivot);
+ BTreeTupleSetAltHeapTID(pivot);
+
+ Assert(!BTreeTupleIsPosting(pivot));
+ }
else
{
/*
@@ -2205,7 +2253,7 @@ _bt_truncate(Relation rel, IndexTuple lastleft, IndexTuple firstright,
*/
pivotheaptid = (ItemPointer) ((char *) pivot + newsize -
sizeof(ItemPointerData));
- ItemPointerCopy(&lastleft->t_tid, pivotheaptid);
+ ItemPointerCopy(BTreeTupleGetMaxTID(lastleft), pivotheaptid);
/*
* Lehman and Yao require that the downlink to the right page, which is to
@@ -2216,9 +2264,12 @@ _bt_truncate(Relation rel, IndexTuple lastleft, IndexTuple firstright,
* tiebreaker.
*/
#ifndef DEBUG_NO_TRUNCATE
- Assert(ItemPointerCompare(&lastleft->t_tid, &firstright->t_tid) < 0);
- Assert(ItemPointerCompare(pivotheaptid, &lastleft->t_tid) >= 0);
- Assert(ItemPointerCompare(pivotheaptid, &firstright->t_tid) < 0);
+ Assert(ItemPointerCompare(BTreeTupleGetMaxTID(lastleft),
+ BTreeTupleGetMinTID(firstright)) < 0);
+ Assert(ItemPointerCompare(pivotheaptid,
+ BTreeTupleGetMinTID(lastleft)) >= 0);
+ Assert(ItemPointerCompare(pivotheaptid,
+ BTreeTupleGetMinTID(firstright)) < 0);
#else
/*
@@ -2231,7 +2282,7 @@ _bt_truncate(Relation rel, IndexTuple lastleft, IndexTuple firstright,
* attribute values along with lastleft's heap TID value when lastleft's
* TID happens to be greater than firstright's TID.
*/
- ItemPointerCopy(&firstright->t_tid, pivotheaptid);
+ ItemPointerCopy(BTreeTupleGetMinTID(firstright), pivotheaptid);
/*
* Pivot heap TID should never be fully equal to firstright. Note that
@@ -2240,7 +2291,8 @@ _bt_truncate(Relation rel, IndexTuple lastleft, IndexTuple firstright,
*/
ItemPointerSetOffsetNumber(pivotheaptid,
OffsetNumberPrev(ItemPointerGetOffsetNumber(pivotheaptid)));
- Assert(ItemPointerCompare(pivotheaptid, &firstright->t_tid) < 0);
+ Assert(ItemPointerCompare(pivotheaptid,
+ BTreeTupleGetMinTID(firstright)) < 0);
#endif
BTreeTupleSetNAtts(pivot, nkeyatts);
@@ -2330,6 +2382,25 @@ _bt_keep_natts(Relation rel, IndexTuple lastleft, IndexTuple firstright,
* leaving excessive amounts of free space on either side of page split.
* Callers can rely on the fact that attributes considered equal here are
* definitely also equal according to _bt_keep_natts.
+ *
+ * To build a posting tuple we need to ensure that all attributes
+ * of both tuples are equal. Use this function to compare them.
+ * TODO: maybe it's worth to rename the function.
+ *
+ * XXX: Obviously we need infrastructure for making sure it is okay to use
+ * this for posting list stuff. For example, non-deterministic collations
+ * cannot use compression, and will not work with what we have now.
+ *
+ * XXX: Even then, we probably also need to worry about TOAST as a special
+ * case. Don't repeat bugs like the amcheck bug that was fixed in commit
+ * eba775345d23d2c999bbb412ae658b6dab36e3e8. As the test case added in that
+ * commit shows, we need to worry about pg_attribute.attstorage changing in
+ * the underlying table due to an ALTER TABLE (and maybe a few other things
+ * like that). In general, the "TOAST input state" of a TOASTable datum isn't
+ * something that we make many guarantees about today, so even with C
+ * collation text we could in theory get different answers from
+ * _bt_keep_natts_fast() and _bt_keep_natts(). This needs to be nailed down
+ * in some way.
*/
int
_bt_keep_natts_fast(Relation rel, IndexTuple lastleft, IndexTuple firstright)
@@ -2415,7 +2486,7 @@ _bt_check_natts(Relation rel, bool heapkeyspace, Page page, OffsetNumber offnum)
* Non-pivot tuples currently never use alternative heap TID
* representation -- even those within heapkeyspace indexes
*/
- if ((itup->t_info & INDEX_ALT_TID_MASK) != 0)
+ if (BTreeTupleIsPivot(itup))
return false;
/*
@@ -2470,7 +2541,7 @@ _bt_check_natts(Relation rel, bool heapkeyspace, Page page, OffsetNumber offnum)
* that to decide if the tuple is a pre-v11 tuple.
*/
return tupnatts == 0 ||
- ((itup->t_info & INDEX_ALT_TID_MASK) == 0 &&
+ (!BTreeTupleIsPivot(itup) &&
ItemPointerGetOffsetNumber(&(itup->t_tid)) == P_HIKEY);
}
else
@@ -2497,7 +2568,7 @@ _bt_check_natts(Relation rel, bool heapkeyspace, Page page, OffsetNumber offnum)
* heapkeyspace index pivot tuples, regardless of whether or not there are
* non-key attributes.
*/
- if ((itup->t_info & INDEX_ALT_TID_MASK) == 0)
+ if (!BTreeTupleIsPivot(itup))
return false;
/*
@@ -2549,6 +2620,8 @@ _bt_check_third_page(Relation rel, Relation heap, bool needheaptidspace,
if (!needheaptidspace && itemsz <= BTMaxItemSizeNoHeapTid(page))
return;
+ /* TODO correct error messages for posting tuples */
+
/*
* Internal page insertions cannot fail here, because that would mean that
* an earlier leaf level insertion that should have failed didn't
@@ -2575,3 +2648,79 @@ _bt_check_third_page(Relation rel, Relation heap, bool needheaptidspace,
"or use full text indexing."),
errtableconstraint(heap, RelationGetRelationName(rel))));
}
+
+/*
+ * Given a basic tuple that contains key datum and posting list,
+ * build a posting tuple.
+ *
+ * Basic tuple can be a posting tuple, but we only use key part of it,
+ * all ItemPointers must be passed via ipd.
+ *
+ * If nipd == 1 fallback to building a non-posting tuple.
+ * It is necessary to avoid storage overhead after posting tuple was vacuumed.
+ */
+IndexTuple
+BTreeFormPostingTuple(IndexTuple tuple, ItemPointerData *ipd, int nipd)
+{
+ uint32 keysize,
+ newsize = 0;
+ IndexTuple itup;
+
+ /* We only need key part of the tuple */
+ if (BTreeTupleIsPosting(tuple))
+ keysize = BTreeTupleGetPostingOffset(tuple);
+ else
+ keysize = IndexTupleSize(tuple);
+
+ Assert(nipd > 0);
+
+ /* Add space needed for posting list */
+ if (nipd > 1)
+ newsize = SHORTALIGN(keysize) + sizeof(ItemPointerData) * nipd;
+ else
+ newsize = keysize;
+
+ newsize = MAXALIGN(newsize);
+ itup = palloc0(newsize);
+ memcpy(itup, tuple, keysize);
+ itup->t_info &= ~INDEX_SIZE_MASK;
+ itup->t_info |= newsize;
+
+ if (nipd > 1)
+ {
+ /* Form posting tuple, fill posting fields */
+
+ /* Set meta info about the posting list */
+ itup->t_info |= INDEX_ALT_TID_MASK;
+ BTreeSetPostingMeta(itup, nipd, SHORTALIGN(keysize));
+
+ /* sort the list to preserve TID order invariant */
+ qsort((void *) ipd, nipd, sizeof(ItemPointerData),
+ (int (*) (const void *, const void *)) ItemPointerCompare);
+
+ /* Copy posting list into the posting tuple */
+ memcpy(BTreeTupleGetPosting(itup), ipd,
+ sizeof(ItemPointerData) * nipd);
+ }
+ else
+ {
+ /* To finish building of a non-posting tuple, copy TID from ipd */
+ itup->t_info &= ~INDEX_ALT_TID_MASK;
+ ItemPointerCopy(ipd, &itup->t_tid);
+ }
+
+ return itup;
+}
+
+/*
+ * Opposite of BTreeFormPostingTuple.
+ * returns regular tuple that contains the key,
+ * the tid of the new tuple is the nth tid of original tuple's posting list
+ * result tuple palloc'd in a caller's context.
+ */
+IndexTuple
+BTreeGetNthTupleOfPosting(IndexTuple tuple, int n)
+{
+ Assert(BTreeTupleIsPosting(tuple));
+ return BTreeFormPostingTuple(tuple, BTreeTupleGetPostingN(tuple, n), 1);
+}
diff --git a/src/backend/access/nbtree/nbtxlog.c b/src/backend/access/nbtree/nbtxlog.c
index dd5315c..5b30e36 100644
--- a/src/backend/access/nbtree/nbtxlog.c
+++ b/src/backend/access/nbtree/nbtxlog.c
@@ -386,8 +386,8 @@ btree_xlog_vacuum(XLogReaderState *record)
Buffer buffer;
Page page;
BTPageOpaque opaque;
-#ifdef UNUSED
xl_btree_vacuum *xlrec = (xl_btree_vacuum *) XLogRecGetData(record);
+#ifdef UNUSED
/*
* This section of code is thought to be no longer needed, after analysis
@@ -478,14 +478,35 @@ btree_xlog_vacuum(XLogReaderState *record)
if (len > 0)
{
- OffsetNumber *unused;
- OffsetNumber *unend;
+ if (xlrec->nremaining)
+ {
+ int i;
+ OffsetNumber *remainingoffset;
+ IndexTuple remaining;
+ Size itemsz;
+
+ remainingoffset = (OffsetNumber *)
+ (ptr + xlrec->ndeleted * sizeof(OffsetNumber));
+ remaining = (IndexTuple) ((char *) remainingoffset +
+ xlrec->nremaining * sizeof(OffsetNumber));
- unused = (OffsetNumber *) ptr;
- unend = (OffsetNumber *) ((char *) ptr + len);
+ /* Handle posting tuples */
+ for (i = 0; i < xlrec->nremaining; i++)
+ {
+ PageIndexTupleDelete(page, remainingoffset[i]);
+
+ itemsz = MAXALIGN(IndexTupleSize(remaining));
+
+ if (PageAddItem(page, (Item) remaining, itemsz, remainingoffset[i],
+ false, false) == InvalidOffsetNumber)
+ elog(PANIC, "btree_xlog_vacuum: failed to add remaining item");
+
+ remaining = (IndexTuple) ((char *) remaining + itemsz);
+ }
+ }
- if ((unend - unused) > 0)
- PageIndexMultiDelete(page, unused, unend - unused);
+ if (xlrec->ndeleted)
+ PageIndexMultiDelete(page, (OffsetNumber *) ptr, xlrec->ndeleted);
}
/*
diff --git a/src/backend/access/rmgrdesc/nbtdesc.c b/src/backend/access/rmgrdesc/nbtdesc.c
index a14eb79..e4fa99a 100644
--- a/src/backend/access/rmgrdesc/nbtdesc.c
+++ b/src/backend/access/rmgrdesc/nbtdesc.c
@@ -46,8 +46,10 @@ btree_desc(StringInfo buf, XLogReaderState *record)
{
xl_btree_vacuum *xlrec = (xl_btree_vacuum *) rec;
- appendStringInfo(buf, "lastBlockVacuumed %u",
- xlrec->lastBlockVacuumed);
+ appendStringInfo(buf, "lastBlockVacuumed %u; nremaining %u; ndeleted %u",
+ xlrec->lastBlockVacuumed,
+ xlrec->nremaining,
+ xlrec->ndeleted);
break;
}
case XLOG_BTREE_DELETE:
diff --git a/src/include/access/itup.h b/src/include/access/itup.h
index 744ffb6..85ee040 100644
--- a/src/include/access/itup.h
+++ b/src/include/access/itup.h
@@ -141,6 +141,11 @@ typedef IndexAttributeBitMapData * IndexAttributeBitMap;
* On such a page, N tuples could take one MAXALIGN quantum less space than
* estimated here, seemingly allowing one more tuple than estimated here.
* But such a page always has at least MAXALIGN special space, so we're safe.
+ *
+ * Note: btree leaf pages may contain posting tuples, which store duplicates
+ * in a more effective way, so they may contain more tuples.
+ * Use MaxPostingIndexTuplesPerPage instead.
+
*/
#define MaxIndexTuplesPerPage \
((int) ((BLCKSZ - SizeOfPageHeaderData) / \
diff --git a/src/include/access/nbtree.h b/src/include/access/nbtree.h
index 83e0e6c..3127c41 100644
--- a/src/include/access/nbtree.h
+++ b/src/include/access/nbtree.h
@@ -234,8 +234,7 @@ typedef struct BTMetaPageData
* t_tid | t_info | key values | INCLUDE columns, if any
*
* t_tid points to the heap TID, which is a tiebreaker key column as of
- * BTREE_VERSION 4. Currently, the INDEX_ALT_TID_MASK status bit is never
- * set for non-pivot tuples.
+ * BTREE_VERSION 4.
*
* All other types of index tuples ("pivot" tuples) only have key columns,
* since pivot tuples only exist to represent how the key space is
@@ -252,6 +251,39 @@ typedef struct BTMetaPageData
* omitted rather than truncated, since its representation is different to
* the non-pivot representation.)
*
+ * Non-pivot posting tuple format:
+ * t_tid | t_info | key values | INCLUDE columns, if any | posting_list[]
+ *
+ * In order to store duplicated keys more effectively,
+ * we use special format of tuples - posting tuples.
+ * posting_list is an array of ItemPointerData.
+ *
+ * This type of compression never applies to system indexes, unique indexes
+ * or indexes with INCLUDEd columns.
+ *
+ * To differ posting tuples we use INDEX_ALT_TID_MASK flag in t_info and
+ * BT_IS_POSTING flag in t_tid.
+ * These flags redefine the content of the posting tuple's tid:
+ * - t_tid.ip_blkid contains offset of the posting list.
+ * - t_tid offset field contains number of posting items this tuple contain
+ *
+ * The 12 least significant offset bits from t_tid are used to represent
+ * the number of posting items in posting tuples, leaving 4 status
+ * bits (BT_RESERVED_OFFSET_MASK bits), 3 of which that are reserved for
+ * future use.
+ * BT_N_POSTING_OFFSET_MASK is large enough to store any number of posting
+ * tuples, which is constrainted by BTMaxItemSize.
+
+ * If page contains so many duplicates, that they do not fit into one posting
+ * tuple (bounded by BTMaxItemSize), page may contain several posting
+ * tuples with the same key.
+ * Also page can contain both posting and non-posting tuples with the same key.
+ * Currently, posting tuples always contain at least two TIDs in the posting
+ * list.
+ *
+ * Posting tuples always have the same number of attributes as the index has
+ * generally.
+ *
* Pivot tuple format:
*
* t_tid | t_info | key values | [heap TID]
@@ -281,23 +313,157 @@ typedef struct BTMetaPageData
* bits (BT_RESERVED_OFFSET_MASK bits), 3 of which that are reserved for
* future use. BT_N_KEYS_OFFSET_MASK should be large enough to store any
* number of columns/attributes <= INDEX_MAX_KEYS.
+ * BT_IS_POSTING bit must be unset for pivot tuples, since we use it
+ * to distinct posting tuples from pivot tuples.
*
* Note well: The macros that deal with the number of attributes in tuples
- * assume that a tuple with INDEX_ALT_TID_MASK set must be a pivot tuple,
- * and that a tuple without INDEX_ALT_TID_MASK set must be a non-pivot
- * tuple (or must have the same number of attributes as the index has
- * generally in the case of !heapkeyspace indexes). They will need to be
- * updated if non-pivot tuples ever get taught to use INDEX_ALT_TID_MASK
- * for something else.
+ * assume that a tuple with INDEX_ALT_TID_MASK set must be a pivot tuple or
+ * non-pivot posting tuple, and that a tuple without INDEX_ALT_TID_MASK set
+ * must be a non-pivot tuple (or must have the same number of attributes as
+ * the index has generally in the case of !heapkeyspace indexes).
*/
#define INDEX_ALT_TID_MASK INDEX_AM_RESERVED_BIT
/* Item pointer offset bits */
#define BT_RESERVED_OFFSET_MASK 0xF000
#define BT_N_KEYS_OFFSET_MASK 0x0FFF
+#define BT_N_POSTING_OFFSET_MASK 0x0FFF
#define BT_HEAP_TID_ATTR 0x1000
+#define BT_IS_POSTING 0x2000
+
+#define BTreeTupleIsPosting(itup) \
+ ( \
+ ((itup)->t_info & INDEX_ALT_TID_MASK && \
+ ((ItemPointerGetOffsetNumberNoCheck(&(itup)->t_tid) & BT_IS_POSTING) != 0))\
+ )
+
+#define BTreeTupleIsPivot(itup) \
+ ( \
+ ((itup)->t_info & INDEX_ALT_TID_MASK && \
+ ((ItemPointerGetOffsetNumberNoCheck(&(itup)->t_tid) & BT_IS_POSTING) == 0))\
+ )
+
+/*
+ * MaxPostingIndexTuplesPerPage is an upper bound on the number of tuples
+ * that can fit on one btree leaf page.
+ *
+ * Btree leaf pages may contain posting tuples, which store duplicates
+ * in a more effective way, so MaxPostingIndexTuplesPerPage is larger then
+ * MaxIndexTuplesPerPage.
+ *
+ * Each leaf page must contain at least three items, so estimate it as
+ * if we have three posting tuples with minimal size keys.
+ */
+#define MaxPostingIndexTuplesPerPage \
+ ((int) ((BLCKSZ - SizeOfPageHeaderData - \
+ 3*((MAXALIGN(sizeof(IndexTupleData) + 1) + sizeof(ItemIdData))) )) / \
+ (sizeof(ItemPointerData)))
+
+/*
+ * Btree-private state needed to build posting tuples.
+ * ipd is a posting list - an array of ItemPointerData.
+ *
+ * Iterating over tuples during index build or applying compression to a
+ * single page, we remember a tuple in itupprev, then compare the next one
+ * with it. If tuples are equal, save their TIDs in the posting list.
+ * ntuples contains the size of the posting list.
+ *
+ * Use maxitemsize and maxpostingsize to ensure that resulting posting tuple
+ * will satisfy BTMaxItemSize.
+ */
+typedef struct BTCompressState
+{
+ Size maxitemsize;
+ Size maxpostingsize;
+ IndexTuple itupprev;
+ int ntuples;
+ ItemPointerData *ipd;
+} BTCompressState;
+
+/*
+ * For use in _bt_compress_one_page().
+ * If there is only a few uncompressed items on a page,
+ * it isn't worth to apply compression.
+ * Currently it is just a magic number,
+ * proper benchmarking will probably help to choose better value.
+ */
+#define BT_COMPRESS_THRESHOLD 10
+
+/* macros to work with posting tuples *BEGIN* */
+#define BTreeTupleSetBtIsPosting(itup) \
+ do { \
+ Assert((itup)->t_info & INDEX_ALT_TID_MASK); \
+ Assert(!((ItemPointerGetOffsetNumberNoCheck(&(itup)->t_tid) & BT_IS_POSTING) != 0)); \
+ ItemPointerSetOffsetNumber(&(itup)->t_tid, \
+ ItemPointerGetOffsetNumberNoCheck(&(itup)->t_tid) | BT_IS_POSTING); \
+ } while(0)
-/* Get/set downlink block number */
+#define BTreeTupleClearBtIsPosting(itup) \
+ do { \
+ ItemPointerSetOffsetNumber(&(itup)->t_tid, \
+ ItemPointerGetOffsetNumberNoCheck(&(itup)->t_tid) & ~BT_IS_POSTING); \
+ } while(0)
+
+#define BTreeTupleGetNPosting(itup) \
+ ( \
+ ItemPointerGetOffsetNumberNoCheck(&(itup)->t_tid) & BT_N_POSTING_OFFSET_MASK \
+ )
+
+#define BTreeTupleSetNPosting(itup, n) \
+ do { \
+ ItemPointerSetOffsetNumber(&(itup)->t_tid, (n) & BT_N_POSTING_OFFSET_MASK); \
+ BTreeTupleSetBtIsPosting(itup); \
+ } while(0)
+
+/*
+ * If tuple is posting, t_tid.ip_blkid contains offset of the posting list.
+ * Caller is responsible for checking BTreeTupleIsPosting to ensure that
+ * it will get what he expects
+ */
+#define BTreeTupleGetPostingOffset(itup) \
+ ItemPointerGetBlockNumberNoCheck(&((itup)->t_tid))
+#define BTreeTupleSetPostingOffset(itup, offset) \
+ ItemPointerSetBlockNumber(&((itup)->t_tid), (offset))
+
+#define BTreeSetPostingMeta(itup, nposting, off) \
+ do { \
+ BTreeTupleSetNPosting(itup, nposting); \
+ BTreeTupleSetPostingOffset(itup, off); \
+ } while(0)
+
+#define BTreeTupleGetPosting(itup) \
+ (ItemPointerData*) ((char*)(itup) + BTreeTupleGetPostingOffset(itup))
+#define BTreeTupleGetPostingN(itup,n) \
+ (ItemPointerData*) (BTreeTupleGetPosting(itup) + (n))
+
+/*
+ * Posting tuples always contain several TIDs.
+ * Some functions that use TID as a tiebreaker,
+ * to ensure correct order of TID keys they can use two macros below:
+ */
+#define BTreeTupleGetMinTID(itup) \
+ ( \
+ ((itup)->t_info & INDEX_ALT_TID_MASK && \
+ ((ItemPointerGetOffsetNumberNoCheck(&(itup)->t_tid) & BT_IS_POSTING))) ? \
+ ( \
+ (ItemPointer) BTreeTupleGetPosting(itup) \
+ ) \
+ : \
+ (ItemPointer) &((itup)->t_tid) \
+ )
+#define BTreeTupleGetMaxTID(itup) \
+ ( \
+ ((itup)->t_info & INDEX_ALT_TID_MASK && \
+ ((ItemPointerGetOffsetNumberNoCheck(&(itup)->t_tid) & BT_IS_POSTING))) ? \
+ ( \
+ (ItemPointer) (BTreeTupleGetPosting(itup) + (BTreeTupleGetNPosting(itup)-1)) \
+ ) \
+ : \
+ (ItemPointer) &((itup)->t_tid) \
+ )
+/* macros to work with posting tuples *END* */
+
+/* Get/set downlink block number */
#define BTreeInnerTupleGetDownLink(itup) \
ItemPointerGetBlockNumberNoCheck(&((itup)->t_tid))
#define BTreeInnerTupleSetDownLink(itup, blkno) \
@@ -326,7 +492,8 @@ typedef struct BTMetaPageData
*/
#define BTreeTupleGetNAtts(itup, rel) \
( \
- (itup)->t_info & INDEX_ALT_TID_MASK ? \
+ ((itup)->t_info & INDEX_ALT_TID_MASK && \
+ ((ItemPointerGetOffsetNumberNoCheck(&(itup)->t_tid) & BT_IS_POSTING) == 0)) ? \
( \
ItemPointerGetOffsetNumberNoCheck(&(itup)->t_tid) & BT_N_KEYS_OFFSET_MASK \
) \
@@ -335,6 +502,7 @@ typedef struct BTMetaPageData
)
#define BTreeTupleSetNAtts(itup, n) \
do { \
+ Assert(!BTreeTupleIsPosting(itup)); \
(itup)->t_info |= INDEX_ALT_TID_MASK; \
ItemPointerSetOffsetNumber(&(itup)->t_tid, (n) & BT_N_KEYS_OFFSET_MASK); \
} while(0)
@@ -342,6 +510,8 @@ typedef struct BTMetaPageData
/*
* Get tiebreaker heap TID attribute, if any. Macro works with both pivot
* and non-pivot tuples, despite differences in how heap TID is represented.
+ *
+ * For non-pivot posting tuple it returns the first tid from posting list.
*/
#define BTreeTupleGetHeapTID(itup) \
( \
@@ -351,7 +521,10 @@ typedef struct BTMetaPageData
(ItemPointer) (((char *) (itup) + IndexTupleSize(itup)) - \
sizeof(ItemPointerData)) \
) \
- : (itup)->t_info & INDEX_ALT_TID_MASK ? NULL : (ItemPointer) &((itup)->t_tid) \
+ : (itup)->t_info & INDEX_ALT_TID_MASK ? \
+ (((ItemPointerGetOffsetNumberNoCheck(&(itup)->t_tid) & BT_IS_POSTING) != 0) ? \
+ (ItemPointer) BTreeTupleGetPosting(itup) : NULL) \
+ : (ItemPointer) &((itup)->t_tid) \
)
/*
* Set the heap TID attribute for a tuple that uses the INDEX_ALT_TID_MASK
@@ -360,6 +533,7 @@ typedef struct BTMetaPageData
#define BTreeTupleSetAltHeapTID(itup) \
do { \
Assert((itup)->t_info & INDEX_ALT_TID_MASK); \
+ Assert(!((ItemPointerGetOffsetNumberNoCheck(&(itup)->t_tid) & BT_IS_POSTING) != 0)); \
ItemPointerSetOffsetNumber(&(itup)->t_tid, \
ItemPointerGetOffsetNumberNoCheck(&(itup)->t_tid) | BT_HEAP_TID_ATTR); \
} while(0)
@@ -501,6 +675,12 @@ typedef struct BTInsertStateData
Buffer buf;
/*
+ * if _bt_binsrch_insert() found the location inside existing posting
+ * list, save the position inside the list.
+ */
+ int in_posting_offset;
+
+ /*
* 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.
@@ -567,6 +747,8 @@ typedef struct BTScanPosData
* location in the associated tuple storage workspace.
*/
int nextTupleOffset;
+ /* prevTupleOffset is for posting list handling */
+ int prevTupleOffset;
/*
* The items array is always ordered in index order (ie, increasing
@@ -579,7 +761,7 @@ typedef struct BTScanPosData
int lastItem; /* last valid index in items[] */
int itemIndex; /* current index in items[] */
- BTScanPosItem items[MaxIndexTuplesPerPage]; /* MUST BE LAST */
+ BTScanPosItem items[MaxPostingIndexTuplesPerPage]; /* MUST BE LAST */
} BTScanPosData;
typedef BTScanPosData *BTScanPos;
@@ -763,6 +945,8 @@ extern void _bt_delitems_delete(Relation rel, Buffer buf,
OffsetNumber *itemnos, int nitems, Relation heapRel);
extern void _bt_delitems_vacuum(Relation rel, Buffer buf,
OffsetNumber *itemnos, int nitems,
+ OffsetNumber *remainingoffset,
+ IndexTuple *remaining, int nremaining,
BlockNumber lastBlockVacuumed);
extern int _bt_pagedel(Relation rel, Buffer buf);
@@ -775,6 +959,8 @@ 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 int32 _bt_compare_posting(Relation rel, BTScanInsert key, Page page,
+ OffsetNumber offnum, int *in_posting_offset);
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,
@@ -813,6 +999,9 @@ extern bool _bt_check_natts(Relation rel, bool heapkeyspace, Page page,
OffsetNumber offnum);
extern void _bt_check_third_page(Relation rel, Relation heap,
bool needheaptidspace, Page page, IndexTuple newtup);
+extern IndexTuple BTreeFormPostingTuple(IndexTuple tuple, ItemPointerData *ipd,
+ int nipd);
+extern IndexTuple BTreeGetNthTupleOfPosting(IndexTuple tuple, int n);
/*
* prototypes for functions in nbtvalidate.c
@@ -825,5 +1014,7 @@ extern bool btvalidate(Oid opclassoid);
extern IndexBuildResult *btbuild(Relation heap, Relation index,
struct IndexInfo *indexInfo);
extern void _bt_parallel_build_main(dsm_segment *seg, shm_toc *toc);
+extern void _bt_add_posting_item(BTCompressState *compressState,
+ IndexTuple itup);
#endif /* NBTREE_H */
diff --git a/src/include/access/nbtxlog.h b/src/include/access/nbtxlog.h
index 9beccc8..6f60ca5 100644
--- a/src/include/access/nbtxlog.h
+++ b/src/include/access/nbtxlog.h
@@ -173,10 +173,19 @@ typedef struct xl_btree_vacuum
{
BlockNumber lastBlockVacuumed;
- /* TARGET OFFSET NUMBERS FOLLOW */
+ /*
+ * This field helps us to find beginning of the remaining tuples from
+ * postings which follow array of offset numbers.
+ */
+ uint32 nremaining;
+ uint32 ndeleted;
+
+ /* REMAINING OFFSET NUMBERS FOLLOW (nremaining values) */
+ /* REMAINING TUPLES TO INSERT FOLLOW (if nremaining > 0) */
+ /* TARGET OFFSET NUMBERS FOLLOW (if any) */
} xl_btree_vacuum;
-#define SizeOfBtreeVacuum (offsetof(xl_btree_vacuum, lastBlockVacuumed) + sizeof(BlockNumber))
+#define SizeOfBtreeVacuum (offsetof(xl_btree_vacuum, ndeleted) + sizeof(BlockNumber))
/*
* This is what we need to know about marking an empty branch for deletion.
