/* *Askopclasssupportroutinetoprovidedecrementedcopyofexisting *non-NULLsk_argument
*/
dec_sk_argument = array->sksup->decrement(rel, skey->sk_argument, &uflow); if (unlikely(uflow))
{ /* dec_sk_argument has undefined value (so no pfree) */ if (array->null_elem && (skey->sk_flags & SK_BT_NULLS_FIRST))
{
_bt_skiparray_set_isnull(rel, skey, array);
/* Successfully "decremented" array to NULL */ returntrue;
}
/* Cannot decrement to before first array element */ returnfalse;
}
/* *Successfullydecrementedsk_argumenttoanon-NULLvalue.Makesure *thatthedecrementedvalueisstillwithintherangeofthearray.
*/ if (array->low_compare &&
!DatumGetBool(FunctionCall2Coll(&array->low_compare->sk_func,
array->low_compare->sk_collation,
dec_sk_argument,
array->low_compare->sk_argument)))
{ /* Keep existing sk_argument after all */ if (!array->attbyval)
pfree(DatumGetPointer(dec_sk_argument));
/* Cannot decrement to before first array element */ returnfalse;
}
/* Accept value returned by opclass decrement callback */ if (!array->attbyval && skey->sk_argument)
pfree(DatumGetPointer(skey->sk_argument));
skey->sk_argument = dec_sk_argument;
/* *Askopclasssupportroutinetoprovideincrementedcopyofexisting *non-NULLsk_argument
*/
inc_sk_argument = array->sksup->increment(rel, skey->sk_argument, &oflow); if (unlikely(oflow))
{ /* inc_sk_argument has undefined value (so no pfree) */ if (array->null_elem && !(skey->sk_flags & SK_BT_NULLS_FIRST))
{
_bt_skiparray_set_isnull(rel, skey, array);
/* Successfully "incremented" array to NULL */ returntrue;
}
/* Cannot increment past final array element */ returnfalse;
}
/* *Successfullyincrementedsk_argumenttoanon-NULLvalue.Makesure *thattheincrementedvalueisstillwithintherangeofthearray.
*/ if (array->high_compare &&
!DatumGetBool(FunctionCall2Coll(&array->high_compare->sk_func,
array->high_compare->sk_collation,
inc_sk_argument,
array->high_compare->sk_argument)))
{ /* Keep existing sk_argument after all */ if (!array->attbyval)
pfree(DatumGetPointer(inc_sk_argument));
/* Cannot increment past final array element */ returnfalse;
}
/* Accept value returned by opclass increment callback */ if (!array->attbyval && skey->sk_argument)
pfree(DatumGetPointer(skey->sk_argument));
skey->sk_argument = inc_sk_argument;
if (likely(!(cur->sk_flags & (SK_BT_MINVAL | SK_BT_MAXVAL))))
{ /* Scankey has a valid/comparable sk_argument value */
result = _bt_compare_array_skey(&so->orderProcs[ikey],
tupdatum, tupnull,
cur->sk_argument, cur);
if (result == 0)
{ /* *InterpretresultinawaythattakesNEXT/PRIORinto *account
*/ if (cur->sk_flags & SK_BT_NEXT)
result = -1; elseif (cur->sk_flags & SK_BT_PRIOR)
result = 1;
/* Use "beyond end" advancement. See below for an explanation. */
beyond_end_advance = true;
all_satisfied = all_required_satisfied = false;
continue;
}
/*
* Nothing more for us to do with an inequality strategy scan key that
* wasn't the one that _bt_check_compare stopped on, though.
*
* Note: if our later call to _bt_check_compare (to recheck caller's
* tuple) sets continuescan=false due to finding this same inequality
* unsatisfied (possible when it's required in the scan direction),
* we'll deal with it via a recursive "second pass" call.
*/
else if (cur->sk_strategy != BTEqualStrategyNumber)
continue;
/*
* Nothing for us to do with an equality strategy scan key that isn't
* marked required, either -- unless it's a non-required array
*/
else if (!required && !array)
continue;
/*
* Here we perform steps for all array scan keys after a required
* array scan key whose binary search triggered "beyond end of array
* element" array advancement due to encountering a tuple attribute
* value > the closest matching array key (or < for backwards scans).
*/
if (beyond_end_advance)
{
if (array)
_bt_array_set_low_or_high(rel, cur, array,
ScanDirectionIsBackward(dir));
continue;
}
/*
* Here we perform steps for all array scan keys after a required
* array scan key whose tuple attribute was < the closest matching
* array key when we dealt with it (or > for backwards scans).
*
* This earlier required array key already puts us ahead of caller's
* tuple in the key space (for the current scan direction). We must
* make sure that subsequent lower-order array keys do not put us too
* far ahead (ahead of tuples that have yet to be seen by our caller).
* For example, when a tuple "(a, b) = (42, 5)" advances the array
* keys on "a" from 40 to 45, we must also set "b" to whatever the
* first array element for "b" is. It would be wrong to allow "b" to
* be set based on the tuple value.
*
* Perform the same steps with truncated high key attributes. You can
* think of this as a "binary search" for the element closest to the
* value -inf. Again, the arrays must never get ahead of the scan.
*/
if (!all_required_satisfied || cur->sk_attno > tupnatts)
{
if (array)
_bt_array_set_low_or_high(rel, cur, array,
ScanDirectionIsForward(dir));
continue;
}
/*
* Search in scankey's array for the corresponding tuple attribute
* value from caller's tuple
*/
tupdatum = index_getattr(tuple, cur->sk_attno, tupdesc, &tupnull);
/*
* "Binary search" by checking if tupdatum/tupnull are within the
* range of the skip array
*/
if (array->num_elems == -1)
_bt_binsrch_skiparray_skey(cur_elem_trig, dir,
tupdatum, tupnull, array, cur,
&result);
/*
* Binary search for the closest match from the SAOP array
*/
else
set_elem = _bt_binsrch_array_skey(&so->orderProcs[ikey],
cur_elem_trig, dir,
tupdatum, tupnull, array, cur,
&result);
}
else
{
Assert(required);
/*
* This is a required non-array equality strategy scan key, which
* we'll treat as a degenerate single element array.
*
* This scan key's imaginary "array" can't really advance, but it
* can still roll over like any other array. (Actually, this is
* no different to real single value arrays, which never advance
* without rolling over -- they can never truly advance, either.)
*/
result = _bt_compare_array_skey(&so->orderProcs[ikey],
tupdatum, tupnull,
cur->sk_argument, cur);
}
/*
* Consider "beyond end of array element" array advancement.
*
* When the tuple attribute value is > the closest matching array key
* (or < in the backwards scan case), we need to ratchet this array
* forward (backward) by one increment, so that caller's tuple ends up
* being < final array value instead (or > final array value instead).
* This process has to work for all of the arrays, not just this one:
* it must "carry" to higher-order arrays when the set_elem that we
* just found happens to be the final one for the scan's direction.
* Incrementing (decrementing) set_elem itself isn't good enough.
*
* Our approach is to provisionally use set_elem as if it was an exact
* match now, then set each later/less significant array to whatever
* its final element is. Once outside the loop we'll then "increment
* this array's set_elem" by calling _bt_advance_array_keys_increment.
* That way the process rolls over to higher order arrays as needed.
*
* Under this scheme any required arrays only ever ratchet forwards
* (or backwards), and always do so to the maximum possible extent
* that we can know will be safe without seeing the scan's next tuple.
* We don't need any special handling for required scan keys that lack
* a real array to advance, nor for redundant scan keys that couldn't
* be eliminated by _bt_preprocess_keys. It won't matter if some of
* our "true" array scan keys (or even all of them) are non-required.
*/
if (sktrig_required && required &&
((ScanDirectionIsForward(dir) && result > 0) ||
(ScanDirectionIsBackward(dir) && result < 0)))
beyond_end_advance = true;
Assert(all_required_satisfied && all_satisfied);
if (result != 0)
{
/*
* Track whether caller's tuple satisfies our new post-advancement
* qual, for required scan keys, as well as for the entire set of
* interesting scan keys (all required scan keys plus non-required
* array scan keys are considered interesting.)
*/
all_satisfied = false;
if (sktrig_required && required)
all_required_satisfied = false;
else
{
/*
* There's no need to advance the arrays using the best
* available match for a non-required array. Give up now.
* (Though note that sktrig_required calls still have to do
* all the usual post-advancement steps, including the recheck
* call to _bt_check_compare.)
*/
break;
}
}
/* Advance array keys, even when we don't have an exact match */
if (array)
{
if (array->num_elems == -1)
{
/* Skip array's new element is tupdatum (or MINVAL/MAXVAL) */
_bt_skiparray_set_element(rel, cur, array, result,
tupdatum, tupnull);
skip_array_advanced = true;
}
else if (array->cur_elem != set_elem)
{
/* SAOP array's new element is set_elem datum */
array->cur_elem = set_elem;
cur->sk_argument = array->elem_values[set_elem];
}
}
}
/*
* Advance the array keys incrementally whenever "beyond end of array
* element" array advancement happens, so that advancement will carry to
* higher-order arrays (might exhaust all the scan's arrays instead, which
* ends the top-level scan).
*/
if (beyond_end_advance &&
!_bt_advance_array_keys_increment(scan, dir, &skip_array_advanced))
goto end_toplevel_scan;
Assert(_bt_verify_keys_with_arraykeys(scan));
/*
* Maintain a page-level count of the number of times the scan's array
* keys advanced in a way that affected at least one skip array
*/
if (sktrig_required && skip_array_advanced)
pstate->nskipadvances++;
/*
* Does tuple now satisfy our new qual? Recheck with _bt_check_compare.
*
* Calls triggered by an unsatisfied required scan key, whose tuple now
* satisfies all required scan keys, but not all nonrequired array keys,
* will still require a recheck call to _bt_check_compare. They'll still
* need its "second pass" handling of required inequality scan keys.
* (Might have missed a still-unsatisfied required inequality scan key
* that caller didn't detect as the sktrig scan key during its initial
* _bt_check_compare call that used the old/original qual.)
*
* Calls triggered by an unsatisfied nonrequired array scan key never need
* "second pass" handling of required inequalities (nor any other handling
* of any required scan key). All that matters is whether caller's tuple
* satisfies the new qual, so it's safe to just skip the _bt_check_compare
* recheck when we've already determined that it can only return 'false'.
*
* Note: In practice most scan keys are marked required by preprocessing,
* if necessary by generating a preceding skip array. We nevertheless
* often handle array keys marked required as if they were nonrequired.
* This behavior is requested by our _bt_check_compare caller, though only
* when it is passed "forcenonrequired=true" by _bt_checkkeys.
*/
if ((sktrig_required && all_required_satisfied) ||
(!sktrig_required && all_satisfied))
{
int nsktrig = sktrig + 1;
bool continuescan;
Assert(all_required_satisfied);
/* Recheck _bt_check_compare on behalf of caller */
if (_bt_check_compare(scan, dir, tuple, tupnatts, tupdesc, false,
!sktrig_required, &continuescan,
&nsktrig) &&
!so->scanBehind)
{
/* This tuple satisfies the new qual */
Assert(all_satisfied && continuescan);
if (pstate)
pstate->continuescan = true;
return true;
}
/*
* Consider "second pass" handling of required inequalities.
*
* It's possible that our _bt_check_compare call indicated that the
* scan should end due to some unsatisfied inequality that wasn't
* initially recognized as such by us. Handle this by calling
* ourselves recursively, this time indicating that the trigger is the
* inequality that we missed first time around (and using a set of
* required array/equality keys that are now exact matches for tuple).
*
* We make a strong, general guarantee that every _bt_checkkeys call
* here will advance the array keys to the maximum possible extent
* that we can know to be safe based on caller's tuple alone. If we
* didn't perform this step, then that guarantee wouldn't quite hold.
*/
if (unlikely(!continuescan))
{
bool satisfied PG_USED_FOR_ASSERTS_ONLY;
/*
* The tuple must use "beyond end" advancement during the
* recursive call, so we cannot possibly end up back here when
* recursing. We'll consume a small, fixed amount of stack space.
*/
Assert(!beyond_end_advance);
/* Advance the array keys a second time using same tuple */
satisfied = _bt_advance_array_keys(scan, pstate, tuple, tupnatts,
tupdesc, nsktrig, true);
/* This tuple doesn't satisfy the inequality */
Assert(!satisfied);
return false;
}
/*
* Some non-required scan key (from new qual) still not satisfied.
*
* All scan keys required in the current scan direction must still be
* satisfied, though, so we can trust all_required_satisfied below.
*/
}
/*
* When we were called just to deal with "advancing" non-required arrays,
* this is as far as we can go (cannot stop the scan for these callers)
*/
if (!sktrig_required)
{
/* Caller's tuple doesn't match any qual */
return false;
}
/*
* Postcondition array state assertion (for still-unsatisfied tuples).
*
* By here we have established that the scan's required arrays (scan must
* have at least one required array) advanced, without becoming exhausted.
*
* Caller's tuple is now < the newly advanced array keys (or > when this
* is a backwards scan), except in the case where we only got this far due
* to an unsatisfied non-required scan key. Verify that with an assert.
*
* Note: we don't just quit at this point when all required scan keys were
* found to be satisfied because we need to consider edge-cases involving
* scan keys required in the opposite direction only; those aren't tracked
* by all_required_satisfied.
*/
Assert(_bt_tuple_before_array_skeys(scan, dir, tuple, tupdesc, tupnatts,
false, 0, NULL) ==
!all_required_satisfied);
/*
* We generally permit primitive index scans to continue onto the next
* sibling page when the page's finaltup satisfies all required scan keys
* at the point where we're between pages.
*
* If caller's tuple is also the page's finaltup, and we see that required
* scan keys still aren't satisfied, start a new primitive index scan.
*/
if (!all_required_satisfied && pstate->finaltup == tuple)
goto new_prim_scan;
/*
* Proactively check finaltup (don't wait until finaltup is reached by the
* scan) when it might well turn out to not be satisfied later on.
*
* Note: if so->scanBehind hasn't already been set for finaltup by us,
* it'll be set during this call to _bt_tuple_before_array_skeys. Either
* way, it'll be set correctly (for the whole page) after this point.
*/
if (!all_required_satisfied && pstate->finaltup &&
_bt_tuple_before_array_skeys(scan, dir, pstate->finaltup, tupdesc,
BTreeTupleGetNAtts(pstate->finaltup, rel),
false, 0, &so->scanBehind))
goto new_prim_scan;
/*
* When we encounter a truncated finaltup high key attribute, we're
* optimistic about the chances of its corresponding required scan key
* being satisfied when we go on to recheck it against tuples from this
* page's right sibling leaf page. We consider truncated attributes to be
* satisfied by required scan keys, which allows the primitive index scan
* to continue to the next leaf page. We must set so->scanBehind to true
* to remember that the last page's finaltup had "satisfied" required scan
* keys for one or more truncated attribute values (scan keys required in
* _either_ scan direction).
*
* There is a chance that _bt_readpage (which checks so->scanBehind) will
* find that even the sibling leaf page's finaltup is < the new array
* keys. When that happens, our optimistic policy will have incurred a
* single extra leaf page access that could have been avoided.
*
* A pessimistic policy would give backward scans a gratuitous advantage
* over forward scans. We'd punish forward scans for applying more
* accurate information from the high key, rather than just using the
* final non-pivot tuple as finaltup, in the style of backward scans.
* Being pessimistic would also give some scans with non-required arrays a
* perverse advantage over similar scans that use required arrays instead.
*
* This is similar to our scan-level heuristics, below. They also set
* scanBehind to speculatively continue the primscan onto the next page.
*/
if (so->scanBehind)
{
/* Truncated high key -- _bt_scanbehind_checkkeys recheck scheduled */
}
/*
* Handle inequalities marked required in the opposite scan direction.
* They can also signal that we should start a new primitive index scan.
*
* It's possible that the scan is now positioned where "matching" tuples
* begin, and that caller's tuple satisfies all scan keys required in the
* current scan direction. But if caller's tuple still doesn't satisfy
* other scan keys that are required in the opposite scan direction only
* (e.g., a required >= strategy scan key when scan direction is forward),
* it's still possible that there are many leaf pages before the page that
* _bt_first could skip straight to. Groveling through all those pages
* will always give correct answers, but it can be very inefficient. We
* must avoid needlessly scanning extra pages.
*
* Separately, it's possible that _bt_check_compare set continuescan=false
* for a scan key that's required in the opposite direction only. This is
* a special case, that happens only when _bt_check_compare sees that the
* inequality encountered a NULL value. This signals the end of non-NULL
* values in the current scan direction, which is reason enough to end the
* (primitive) scan. If this happens at the start of a large group of
* NULL values, then we shouldn't expect to be called again until after
* the scan has already read indefinitely-many leaf pages full of tuples
* with NULL suffix values. (_bt_first is expected to skip over the group
* of NULLs by applying a similar "deduce NOT NULL" rule of its own, which
* involves consing up an explicit SK_SEARCHNOTNULL key.)
*
* Apply a test against finaltup to detect and recover from the problem:
* if even finaltup doesn't satisfy such an inequality, we just skip by
* starting a new primitive index scan. When we skip, we know for sure
* that all of the tuples on the current page following caller's tuple are
* also before the _bt_first-wise start of tuples for our new qual. That
* at least suggests many more skippable pages beyond the current page.
* (when so->scanBehind and so->oppositeDirCheck are set, this'll happen
* when we test the next page's finaltup/high key instead.)
*/
else if (has_required_opposite_direction_only && pstate->finaltup &&
unlikely(!_bt_oppodir_checkkeys(scan, dir, pstate->finaltup)))
goto new_prim_scan;
continue_scan:
/*
* Stick with the ongoing primitive index scan for now.
*
* It's possible that later tuples will also turn out to have values that
* are still < the now-current array keys (or > the current array keys).
* Our caller will handle this by performing what amounts to a linear
* search of the page, implemented by calling _bt_check_compare and then
* _bt_tuple_before_array_skeys for each tuple.
*
* This approach has various advantages over a binary search of the page.
* Repeated binary searches of the page (one binary search for every array
* advancement) won't outperform a continuous linear search. While there
* are workloads that a naive linear search won't handle well, our caller
* has a "look ahead" fallback mechanism to deal with that problem.
*/
pstate->continuescan = true; /* Override _bt_check_compare */
so->needPrimScan = false; /* _bt_readpage has more tuples to check */
if (so->scanBehind)
{
/*
* Remember if recheck needs to call _bt_oppodir_checkkeys for next
* page's finaltup (see above comments about "Handle inequalities
* marked required in the opposite scan direction" for why).
*/
so->oppositeDirCheck = has_required_opposite_direction_only;
/*
* skip by setting "look ahead" mechanism's offnum for forwards scans
* (backwards scans check scanBehind flag directly instead)
*/
if (ScanDirectionIsForward(dir))
pstate->skip = pstate->maxoff + 1;
}
/* Caller's tuple doesn't match the new qual */
return false;
new_prim_scan:
Assert(pstate->finaltup); /* not on rightmost/leftmost page */
/*
* Looks like another primitive index scan is required. But consider
* continuing the current primscan based on scan-level heuristics.
*
* Continue the ongoing primitive scan (and schedule a recheck for when
* the scan arrives on the next sibling leaf page) when it has already
* read at least one leaf page before the one we're reading now. This
* makes primscan scheduling more efficient when scanning subsets of an
* index with many distinct attribute values matching many array elements.
* It encourages fewer, larger primitive scans where that makes sense.
* This will in turn encourage _bt_readpage to apply the pstate.startikey
* optimization more often.
*
* Also continue the ongoing primitive index scan when it is still on the
* first page if there have been more than NSKIPADVANCES_THRESHOLD calls
* here that each advanced at least one of the scan's skip arrays
* (deliberately ignore advancements that only affected SAOP arrays here).
* A page that cycles through this many skip array elements is quite
* likely to neighbor similar pages, that we'll also need to read.
*
* Note: These heuristics aren't as aggressive as you might think. We're
* conservative about allowing a primitive scan to step from the first
* leaf page it reads to the page's sibling page (we only allow it on
* first pages whose finaltup strongly suggests that it'll work out, as
* well as first pages that have a large number of skip array advances).
* Clearing this first page finaltup hurdle is a strong signal in itself.
*
* Note: The NSKIPADVANCES_THRESHOLD heuristic exists only to avoid
* pathological cases. Specifically, cases where a skip scan should just
* behave like a traditional full index scan, but ends up "skipping" again
* and again, descending to the prior leaf page's direct sibling leaf page
* each time. This misbehavior would otherwise be possible during scans
* that never quite manage to "clear the first page finaltup hurdle".
*/
if (!pstate->firstpage || pstate->nskipadvances > NSKIPADVANCES_THRESHOLD)
{
/* Schedule a recheck once on the next (or previous) page */
so->scanBehind = true;
/* Continue the current primitive scan after all */
goto continue_scan;
}
/*
* End this primitive index scan, but schedule another.
*
* Note: We make a soft assumption that the current scan direction will
* also be used within _bt_next, when it is asked to step off this page.
* It is up to _bt_next to cancel this scheduled primitive index scan
* whenever it steps to a page in the direction opposite currPos.dir.
*/
pstate->continuescan = false; /* Tell _bt_readpage we're done... */
so->needPrimScan = true; /* ...but call _bt_first again */
if (scan->parallel_scan)
_bt_parallel_primscan_schedule(scan, so->currPos.currPage);
/* Caller's tuple doesn't match the new qual */
return false;
end_toplevel_scan:
/*
* End the current primitive index scan, but don't schedule another.
*
* This ends the entire top-level scan in the current scan direction.
*
* Note: The scan's arrays (including any non-required arrays) are now in
* their final positions for the current scan direction. If the scan
* direction happens to change, then the arrays will already be in their
* first positions for what will then be the current scan direction.
*/
pstate->continuescan = false; /* Tell _bt_readpage we're done... */
so->needPrimScan = false; /* ...and don't call _bt_first again */
/* Caller's tuple doesn't match any qual */
return false;
}
#ifdef USE_ASSERT_CHECKING
/*
* Verify that the scan's "so->keyData[]" scan keys are in agreement with
* its array key state
*/
static bool
_bt_verify_keys_with_arraykeys(IndexScanDesc scan)
{
BTScanOpaque so = (BTScanOpaque) scan->opaque;
int last_sk_attno = InvalidAttrNumber,
arrayidx = 0;
bool nonrequiredseen = false;
if (!so->qual_ok)
return false;
for (int ikey = 0; ikey < so->numberOfKeys; ikey++)
{
ScanKey cur = so->keyData + ikey;
BTArrayKeyInfo *array;
if (cur->sk_strategy != BTEqualStrategyNumber ||
!(cur->sk_flags & SK_SEARCHARRAY))
continue;
array = &so->arrayKeys[arrayidx++];
if (array->scan_key != ikey)
return false;
if (array->num_elems == 0 || array->num_elems < -1)
return false;
if (array->num_elems != -1 &&
cur->sk_argument != array->elem_values[array->cur_elem])
return false;
if (cur->sk_flags & (SK_BT_REQFWD | SK_BT_REQBKWD))
{
if (last_sk_attno > cur->sk_attno)
return false;
if (nonrequiredseen)
return false;
}
else
nonrequiredseen = true;
last_sk_attno = cur->sk_attno;
}
if (arrayidx != so->numArrayKeys)
return false;
return true;
}
#endif
/*
* Test whether an indextuple satisfies all the scankey conditions.
*
* Return true if so, false if not. If the tuple fails to pass the qual,
* we also determine whether there's any need to continue the scan beyond
* this tuple, and set pstate.continuescan accordingly. See comments for
* _bt_preprocess_keys() about how this is done.
*
* Forward scan callers can pass a high key tuple in the hopes of having
* us set *continuescan to false, and avoiding an unnecessary visit to
* the page to the right.
*
* Advances the scan's array keys when necessary for arrayKeys=true callers.
* Scans without any array keys must always pass arrayKeys=false.
*
* Also stops and starts primitive index scans for arrayKeys=true callers.
* Scans with array keys are required to set up page state that helps us with
* this. The page's finaltup tuple (the page high key for a forward scan, or
* the page's first non-pivot tuple for a backward scan) must be set in
* pstate.finaltup ahead of the first call here for the page. Set this to
* NULL for rightmost page (or the leftmost page for backwards scans).
*
* scan: index scan descriptor (containing a search-type scankey)
* pstate: page level input and output parameters
* arrayKeys: should we advance the scan's array keys if necessary?
* tuple: index tuple to test
* tupnatts: number of attributes in tupnatts (high key may be truncated)
*/
bool
_bt_checkkeys(IndexScanDesc scan, BTReadPageState *pstate, bool arrayKeys,
IndexTuple tuple, int tupnatts)
{
TupleDesc tupdesc = RelationGetDescr(scan->indexRelation);
BTScanOpaque so = (BTScanOpaque) scan->opaque;
ScanDirection dir = so->currPos.dir;
int ikey = pstate->startikey;
bool res;
/*
* If _bt_check_compare relied on the pstate.startikey optimization, call
* again (in assert-enabled builds) to verify it didn't affect our answer.
*
* Note: we can't do this when !pstate.forcenonrequired, since any arrays
* before pstate.startikey won't have advanced on this page at all.
*/
Assert(!pstate->forcenonrequired || arrayKeys);
#ifdef USE_ASSERT_CHECKING
if (pstate->startikey > 0 && !pstate->forcenonrequired)
{
bool dres,
dcontinuescan;
int dikey = 0;
/*
* Should also get the same ikey result. We need a slightly weaker
* assertion during arrayKeys calls, since they might be using an
* array that couldn't be marked required during preprocessing.
*/
Assert(arrayKeys || ikey == dikey);
Assert(ikey <= dikey);
}
#endif
/*
* Only one _bt_check_compare call is required in the common case where
* there are no equality strategy array scan keys. Otherwise we can only
* accept _bt_check_compare's answer unreservedly when it didn't set
* pstate.continuescan=false.
*/
if (!arrayKeys || pstate->continuescan)
return res;
/*
* _bt_check_compare call set continuescan=false in the presence of
* equality type array keys. This could mean that the tuple is just past
* the end of matches for the current array keys.
*
* It's also possible that the scan is still _before_ the _start_ of
* tuples matching the current set of array keys. Check for that first.
*/
Assert(!pstate->forcenonrequired);
if (_bt_tuple_before_array_skeys(scan, dir, tuple, tupdesc, tupnatts, true,
ikey, NULL))
{
/* Override _bt_check_compare, continue primitive scan */
pstate->continuescan = true;
/*
* We will end up here repeatedly given a group of tuples > the
* previous array keys and < the now-current keys (for a backwards
* scan it's just the same, though the operators swap positions).
*
* We must avoid allowing this linear search process to scan very many
* tuples from well before the start of tuples matching the current
* array keys (or from well before the point where we'll once again
* have to advance the scan's array keys).
*
* We keep the overhead under control by speculatively "looking ahead"
* to later still-unscanned items from this same leaf page. We'll
* only attempt this once the number of tuples that the linear search
* process has examined starts to get out of hand.
*/
pstate->rechecks++;
if (pstate->rechecks >= LOOK_AHEAD_REQUIRED_RECHECKS)
{
/* See if we should skip ahead within the current leaf page */
_bt_checkkeys_look_ahead(scan, pstate, tupnatts, tupdesc);
/*
* Might have set pstate.skip to a later page offset. When that
* happens then _bt_readpage caller will inexpensively skip ahead
* to a later tuple from the same page (the one just after the
* tuple we successfully "looked ahead" to).
*/
}
/* This indextuple doesn't match the current qual, in any case */
return false;
}
/*
* Caller's tuple is >= the current set of array keys and other equality
* constraint scan keys (or <= if this is a backwards scan). It's now
* clear that we _must_ advance any required array keys in lockstep with
* the scan.
*/
return _bt_advance_array_keys(scan, pstate, tuple, tupnatts, tupdesc,
ikey, true);
}
/*
* Test whether caller's finaltup tuple is still before the start of matches
* for the current array keys.
*
* Called at the start of reading a page during a scan with array keys, though
* only when the so->scanBehind flag was set on the scan's prior page.
*
* Returns false if the tuple is still before the start of matches. When that
* happens, caller should cut its losses and start a new primitive index scan.
* Otherwise returns true.
*/
bool
_bt_scanbehind_checkkeys(IndexScanDesc scan, ScanDirection dir,
IndexTuple finaltup)
{
Relation rel = scan->indexRelation;
TupleDesc tupdesc = RelationGetDescr(rel);
BTScanOpaque so = (BTScanOpaque) scan->opaque;
int nfinaltupatts = BTreeTupleGetNAtts(finaltup, rel);
bool scanBehind;
/*
* If scanBehind was set, all of the untruncated attribute values from
* finaltup that correspond to an array match the array's current element,
* but there are other keys associated with truncated suffix attributes.
* Array advancement must have incremented the scan's arrays on the
* previous page, resulting in a set of array keys that happen to be an
* exact match for the current page high key's untruncated prefix values.
*
* This page definitely doesn't contain tuples that the scan will need to
* return. The next page may or may not contain relevant tuples. Handle
* this by cutting our losses and starting a new primscan.
*/
if (scanBehind)
return false;
/*
* Test whether an indextuple fails to satisfy an inequality required in the
* opposite direction only.
*
* Caller's finaltup tuple is the page high key (for forwards scans), or the
* first non-pivot tuple (for backwards scans). Called during scans with
* required array keys and required opposite-direction inequalities.
*
* Returns false if an inequality scan key required in the opposite direction
* only isn't satisfied (and any earlier required scan keys are satisfied).
* Otherwise returns true.
*
* An unsatisfied inequality required in the opposite direction only might
* well enable skipping over many leaf pages, provided another _bt_first call
* takes place. This type of unsatisfied inequality won't usually cause
* _bt_checkkeys to stop the scan to consider array advancement/starting a new
* primitive index scan.
*/
static bool
_bt_oppodir_checkkeys(IndexScanDesc scan, ScanDirection dir,
IndexTuple finaltup)
{
Relation rel = scan->indexRelation;
TupleDesc tupdesc = RelationGetDescr(rel);
BTScanOpaque so = (BTScanOpaque) scan->opaque;
int nfinaltupatts = BTreeTupleGetNAtts(finaltup, rel);
bool continuescan;
ScanDirection flipped = -dir;
int ikey = 0;
if (!continuescan && so->keyData[ikey].sk_strategy != BTEqualStrategyNumber)
return false;
return true;
}
/*
* Determines an offset to the first scan key (an so->keyData[]-wise offset)
* that is _not_ guaranteed to be satisfied by every tuple from pstate.page,
* which is set in pstate.startikey for _bt_checkkeys calls for the page.
* This allows caller to save cycles on comparisons of a prefix of keys while
* reading pstate.page.
*
* Also determines if later calls to _bt_checkkeys (for pstate.page) should be
* forced to treat all required scan keys >= pstate.startikey as nonrequired
* (that is, if they're to be treated as if any SK_BT_REQFWD/SK_BT_REQBKWD
* markings that were set by preprocessing were not set at all, for the
* duration of _bt_checkkeys calls prior to the call for pstate.finaltup).
* This is indicated to caller by setting pstate.forcenonrequired.
*
* Call here at the start of reading a leaf page beyond the first one for the
* primitive index scan. We consider all non-pivot tuples, so it doesn't make
* sense to call here when only a subset of those tuples can ever be read.
* This is also a good idea on performance grounds; not calling here when on
* the first page (first for the current primitive scan) avoids wasting cycles
* during selective point queries. They typically don't stand to gain as much
* when we can set pstate.startikey, and are likely to notice the overhead of
* calling here. (Also, allowing pstate.forcenonrequired to be set on a
* primscan's first page would mislead _bt_advance_array_keys, which expects
* pstate.nskipadvances to be representative of every first page's key space.)
*
* Caller must call _bt_start_array_keys and reset startikey/forcenonrequired
* ahead of the finaltup _bt_checkkeys call when we set forcenonrequired=true.
* This will give _bt_checkkeys the opportunity to call _bt_advance_array_keys
* with sktrig_required=true, restoring the invariant that the scan's required
* arrays always track the scan's progress through the index's key space.
* Caller won't need to do this on the rightmost/leftmost page in the index
* (where pstate.finaltup isn't ever set), since forcenonrequired will never
* be set here in the first place.
*/
void
_bt_set_startikey(IndexScanDesc scan, BTReadPageState *pstate)
{
BTScanOpaque so = (BTScanOpaque) scan->opaque;
Relation rel = scan->indexRelation;
TupleDesc tupdesc = RelationGetDescr(rel);
ItemId iid;
IndexTuple firsttup,
lasttup;
int startikey = 0,
arrayidx = 0,
firstchangingattnum;
bool start_past_saop_eq = false;
/* minoff is an offset to the lowest non-pivot tuple on the page */
iid = PageGetItemId(pstate->page, pstate->minoff);
firsttup = (IndexTuple) PageGetItem(pstate->page, iid);
/* maxoff is an offset to the highest non-pivot tuple on the page */
iid = PageGetItemId(pstate->page, pstate->maxoff);
lasttup = (IndexTuple) PageGetItem(pstate->page, iid);
/* Determine the first attribute whose values change on caller's page */
firstchangingattnum = _bt_keep_natts_fast(rel, firsttup, lasttup);
/*
* Determine if it's safe to set pstate.startikey to an offset to a
* key that comes after this key, by examining this key
*/
if (!(key->sk_flags & (SK_BT_REQFWD | SK_BT_REQBKWD)))
{
/* Scan key isn't marked required (corner case) */
break; /* unsafe */
}
if (key->sk_flags & SK_ROW_HEADER)
{
/* RowCompare inequalities currently aren't supported */
break; /* "unsafe" */
}
if (key->sk_strategy != BTEqualStrategyNumber)
{
/*
* Scalar inequality key.
*
* It's definitely safe for _bt_checkkeys to avoid assessing this
* inequality when the page's first and last non-pivot tuples both
* satisfy the inequality (since the same must also be true of all
* the tuples in between these two).
*
* Unlike the "=" case, it doesn't matter if this attribute has
* more than one distinct value (though it _is_ necessary for any
* and all _prior_ attributes to contain no more than one distinct
* value amongst all of the tuples from pstate.page).
*/
if (key->sk_attno > firstchangingattnum) /* >, not >= */
break; /* unsafe, preceding attr has multiple
* distinct values */
if (key->sk_flags & SK_ISNULL)
{
/* IS NOT NULL key */
Assert(key->sk_flags & SK_SEARCHNOTNULL);
if (firstnull || lastnull)
break; /* unsafe */
/* Safe, IS NOT NULL key satisfied by every tuple */
continue;
}
/* Test firsttup */
if (firstnull ||
!DatumGetBool(FunctionCall2Coll(&key->sk_func,
key->sk_collation, firstdatum,
key->sk_argument)))
break; /* unsafe */
/* Test lasttup */
if (lastnull ||
!DatumGetBool(FunctionCall2Coll(&key->sk_func,
key->sk_collation, lastdatum,
key->sk_argument)))
break; /* unsafe */
/* Safe, scalar inequality satisfied by every tuple */
continue;
}
/* Some = key (could be a scalar = key, could be an array = key) */
Assert(key->sk_strategy == BTEqualStrategyNumber);
if (!(key->sk_flags & SK_SEARCHARRAY))
{
/*
* Scalar = key (possibly an IS NULL key).
*
* It is unsafe to set pstate.startikey to an ikey beyond this
* key, unless the = key is satisfied by every possible tuple on
* the page (possible only when attribute has just one distinct
* value among all tuples on the page).
*/
if (key->sk_attno >= firstchangingattnum)
break; /* unsafe, multiple distinct attr values */
firstdatum = index_getattr(firsttup, key->sk_attno, tupdesc,
&firstnull);
if (key->sk_flags & SK_ISNULL)
{
/* IS NULL key */
Assert(key->sk_flags & SK_SEARCHNULL);
if (!firstnull)
break; /* unsafe */
/* Safe, IS NULL key satisfied by every tuple */
continue;
}
if (firstnull ||
!DatumGetBool(FunctionCall2Coll(&key->sk_func,
key->sk_collation, firstdatum,
key->sk_argument)))
break; /* unsafe */
/* Safe, scalar = key satisfied by every tuple */
continue;
}
/* = array key (could be a SAOP array, could be a skip array) */
array = &so->arrayKeys[arrayidx++];
Assert(array->scan_key == startikey);
if (array->num_elems != -1)
{
/*
* SAOP array = key.
*
* Handle this like we handle scalar = keys (though binary search
* for a matching element, to avoid relying on key's sk_argument).
*/
if (key->sk_attno >= firstchangingattnum)
break; /* unsafe, multiple distinct attr values */
/* Safe, SAOP = key satisfied by every tuple */
start_past_saop_eq = true;
continue;
}
/*
* Skip array = key
*/
Assert(key->sk_flags & SK_BT_SKIP);
if (array->null_elem)
{
/*
* Non-range skip array = key.
*
* Safe, non-range skip array "satisfied" by every tuple on page
* (safe even when "key->sk_attno > firstchangingattnum").
*/
continue;
}
/*
* Range skip array = key.
*
* Handle this like we handle scalar inequality keys (but avoid using
* key's sk_argument directly, as in the SAOP array case).
*/
if (key->sk_attno > firstchangingattnum) /* >, not >= */
break; /* unsafe, preceding attr has multiple
* distinct values */
/* Test firsttup */
_bt_binsrch_skiparray_skey(false, ForwardScanDirection,
firstdatum, firstnull, array, key,
&result);
if (result != 0)
break; /* unsafe */
/* Test lasttup */
_bt_binsrch_skiparray_skey(false, ForwardScanDirection,
lastdatum, lastnull, array, key,
&result);
if (result != 0)
break; /* unsafe */
/* Safe, range skip array satisfied by every tuple on page */
}
/*
* Use of forcenonrequired is typically undesirable, since it'll force
* _bt_readpage caller to read every tuple on the page -- even though, in
* general, it might well be possible to end the scan on an earlier tuple.
* However, caller must use forcenonrequired when start_past_saop_eq=true,
* since the usual required array behavior might fail to roll over to the
* SAOP array.
*
* We always prefer forcenonrequired=true during scans with skip arrays
* (except on the first page of each primitive index scan), though -- even
* when "startikey == 0". That way, _bt_advance_array_keys's low-order
* key precheck optimization can always be used (unless on the first page
* of the scan). It seems slightly preferable to check more tuples when
* that allows us to do significantly less skip array maintenance.
*/
pstate->forcenonrequired = (start_past_saop_eq || so->skipScan);
pstate->startikey = startikey;
/*
* _bt_readpage caller is required to call _bt_checkkeys against page's
* finaltup with forcenonrequired=false whenever we initially set
* forcenonrequired=true. That way the scan's arrays will reliably track
* its progress through the index's key space.
*
* We don't expect this when _bt_readpage caller has no finaltup due to
* its page being the rightmost (or the leftmost, during backwards scans).
* When we see that _bt_readpage has no finaltup, back out of everything.
*/
Assert(!pstate->forcenonrequired || so->numArrayKeys);
if (pstate->forcenonrequired && !pstate->finaltup)
{
pstate->forcenonrequired = false;
pstate->startikey = 0;
}
}
/*
* Test whether an indextuple satisfies current scan condition.
*
* Return true if so, false if not. If not, also sets *continuescan to false
* when it's also not possible for any later tuples to pass the current qual
* (with the scan's current set of array keys, in the current scan direction),
* in addition to setting *ikey to the so->keyData[] subscript/offset for the
* unsatisfied scan key (needed when caller must consider advancing the scan's
* array keys).
*
* This is a subroutine for _bt_checkkeys. We provisionally assume that
* reaching the end of the current set of required keys (in particular the
* current required array keys) ends the ongoing (primitive) index scan.
* Callers without array keys should just end the scan right away when they
* find that continuescan has been set to false here by us. Things are more
* complicated for callers with array keys.
*
* Callers with array keys must first consider advancing the arrays when
* continuescan has been set to false here by us. They must then consider if
* it really does make sense to end the current (primitive) index scan, in
* light of everything that is known at that point. (In general when we set
* continuescan=false for these callers it must be treated as provisional.)
*
* We deal with advancing unsatisfied non-required arrays directly, though.
* This is safe, since by definition non-required keys can't end the scan.
* This is just how we determine if non-required arrays are just unsatisfied
* by the current array key, or if they're truly unsatisfied (that is, if
* they're unsatisfied by every possible array key).
*
* Pass advancenonrequired=false to avoid all array related side effects.
* This allows _bt_advance_array_keys caller to avoid infinite recursion.
*
* Pass forcenonrequired=true to instruct us to treat all keys as nonrequired.
* This is used to make it safe to temporarily stop properly maintaining the
* scan's required arrays. _bt_checkkeys caller (_bt_readpage, actually)
* determines a prefix of keys that must satisfy every possible corresponding
* index attribute value from its page, which is passed to us via *ikey arg
* (this is the first key that might be unsatisfied by tuples on the page).
* Obviously, we won't maintain any array keys from before *ikey, so it's
* quite possible for such arrays to "fall behind" the index's keyspace.
* Caller will need to "catch up" by passing forcenonrequired=true (alongside
* an *ikey=0) once the page's finaltup is reached.
*
* Note: it's safe to pass an *ikey > 0 with forcenonrequired=false, but only
* when caller determines that it won't affect array maintenance.
*/
static bool
_bt_check_compare(IndexScanDesc scan, ScanDirection dir,
IndexTuple tuple, int tupnatts, TupleDesc tupdesc,
bool advancenonrequired, bool forcenonrequired,
bool *continuescan, int *ikey)
{
BTScanOpaque so = (BTScanOpaque) scan->opaque;
/*
* Check if the key is required in the current scan direction, in the
* opposite scan direction _only_, or in neither direction (except
* when we're forced to treat all scan keys as nonrequired)
*/
if (forcenonrequired)
{
/* treating scan's keys as non-required */
}
else if (((key->sk_flags & SK_BT_REQFWD) && ScanDirectionIsForward(dir)) ||
((key->sk_flags & SK_BT_REQBKWD) && ScanDirectionIsBackward(dir)))
requiredSameDir = true;
else if (((key->sk_flags & SK_BT_REQFWD) && ScanDirectionIsBackward(dir)) ||
((key->sk_flags & SK_BT_REQBKWD) && ScanDirectionIsForward(dir)))
requiredOppositeDirOnly = true;
if (key->sk_attno > tupnatts)
{
/*
* This attribute is truncated (must be high key). The value for
* this attribute in the first non-pivot tuple on the page to the
* right could be any possible value. Assume that truncated
* attribute passes the qual.
*/
Assert(BTreeTupleIsPivot(tuple));
continue;
}
/*
* A skip array scan key uses one of several sentinel values. We just
* fall back on _bt_tuple_before_array_skeys when we see such a value.
*/
if (key->sk_flags & (SK_BT_MINVAL | SK_BT_MAXVAL |
SK_BT_NEXT | SK_BT_PRIOR))
{
Assert(key->sk_flags & SK_SEARCHARRAY);
Assert(key->sk_flags & SK_BT_SKIP);
Assert(requiredSameDir || forcenonrequired);
/*
* Cannot fall back on _bt_tuple_before_array_skeys when we're
* treating the scan's keys as nonrequired, though. Just handle
* this like any other non-required equality-type array key.
*/
if (forcenonrequired)
return _bt_advance_array_keys(scan, NULL, tuple, tupnatts,
tupdesc, *ikey, false);
*continuescan = false;
return false;
}
/* row-comparison keys need special processing */
if (key->sk_flags & SK_ROW_HEADER)
{
if (_bt_check_rowcompare(key, tuple, tupnatts, tupdesc, dir,
forcenonrequired, continuescan))
continue;
return false;
}
datum = index_getattr(tuple,
key->sk_attno,
tupdesc,
&isNull);
if (key->sk_flags & SK_ISNULL)
{
/* Handle IS NULL/NOT NULL tests */
if (key->sk_flags & SK_SEARCHNULL)
{
if (isNull)
continue; /* tuple satisfies this qual */
}
else
{
Assert(key->sk_flags & SK_SEARCHNOTNULL);
Assert(!(key->sk_flags & SK_BT_SKIP));
if (!isNull)
continue; /* tuple satisfies this qual */
}
/*
* Tuple fails this qual. If it's a required qual for the current
* scan direction, then we can conclude no further tuples will
* pass, either.
*/
if (requiredSameDir)
*continuescan = false;
else if (unlikely(key->sk_flags & SK_BT_SKIP))
{
/*
* If we're treating scan keys as nonrequired, and encounter a
* skip array scan key whose current element is NULL, then it
* must be a non-range skip array. It must be satisfied, so
* there's no need to call _bt_advance_array_keys to check.
*/
Assert(forcenonrequired && *ikey > 0);
continue;
}
/*
* This indextuple doesn't match the qual.
*/
return false;
}
if (isNull)
{
/*
* Scalar scan key isn't satisfied by NULL tuple value.
*
* If we're treating scan keys as nonrequired, and key is for a
* skip array, then we must attempt to advance the array to NULL
* (if we're successful then the tuple might match the qual).
*/
if (unlikely(forcenonrequired && key->sk_flags & SK_BT_SKIP))
return _bt_advance_array_keys(scan, NULL, tuple, tupnatts,
tupdesc, *ikey, false);
if (key->sk_flags & SK_BT_NULLS_FIRST)
{
/*
* Since NULLs are sorted before non-NULLs, we know we have
* reached the lower limit of the range of values for this
* index attr. On a backward scan, we can stop if this qual
* is one of the "must match" subset. We can stop regardless
* of whether the qual is > or <, so long as it's required,
* because it's not possible for any future tuples to pass. On
* a forward scan, however, we must keep going, because we may
* have initially positioned to the start of the index.
* (_bt_advance_array_keys also relies on this behavior during
* forward scans.)
*/
if ((requiredSameDir || requiredOppositeDirOnly) &&
ScanDirectionIsBackward(dir))
*continuescan = false;
}
else
{
/*
* Since NULLs are sorted after non-NULLs, we know we have
* reached the upper limit of the range of values for this
* index attr. On a forward scan, we can stop if this qual is
* one of the "must match" subset. We can stop regardless of
* whether the qual is > or <, so long as it's required,
* because it's not possible for any future tuples to pass. On
* a backward scan, however, we must keep going, because we
* may have initially positioned to the end of the index.
* (_bt_advance_array_keys also relies on this behavior during
* backward scans.)
*/
if ((requiredSameDir || requiredOppositeDirOnly) &&
ScanDirectionIsForward(dir))
*continuescan = false;
}
/*
* This indextuple doesn't match the qual.
*/
return false;
}
if (!DatumGetBool(FunctionCall2Coll(&key->sk_func, key->sk_collation,
datum, key->sk_argument)))
{
/*
* Tuple fails this qual. If it's a required qual for the current
* scan direction, then we can conclude no further tuples will
* pass, either.
*/
if (requiredSameDir)
*continuescan = false;
/*
* If this is a non-required equality-type array key, the tuple
* needs to be checked against every possible array key. Handle
* this by "advancing" the scan key's array to a matching value
* (if we're successful then the tuple might match the qual).
*/
else if (advancenonrequired &&
key->sk_strategy == BTEqualStrategyNumber &&
(key->sk_flags & SK_SEARCHARRAY))
return _bt_advance_array_keys(scan, NULL, tuple, tupnatts,
tupdesc, *ikey, false);
/*
* This indextuple doesn't match the qual.
*/
return false;
}
}
/* If we get here, the tuple passes all index quals. */
return true;
}
/*
* Test whether an indextuple satisfies a row-comparison scan condition.
*
* Return true if so, false if not. If not, also clear *continuescan if
* it's not possible for any future tuples in the current scan direction
* to pass the qual.
*
* This is a subroutine for _bt_checkkeys/_bt_check_compare. Caller passes us
* a row compare header key taken from so->keyData[].
*
* Row value comparisons can be described in terms of logical expansions that
* use only scalar operators. Consider the following example row comparison:
*
* "(a, b, c) > (7, 'bar', 62)"
*
* This can be evaluated as:
*
* "(a = 7 AND b = 'bar' AND c > 62) OR (a = 7 AND b > 'bar') OR (a > 7)".
*
* Notice that this condition is satisfied by _all_ rows that satisfy "a > 7",
* and by a subset of all rows that satisfy "a >= 7" (possibly all such rows).
* It _can't_ be satisfied by other rows (where "a < 7" or where "a IS NULL").
* A row comparison header key can therefore often be treated as if it was a
* simple scalar inequality on the row compare's most significant column.
* (For example, _bt_advance_array_keys and most preprocessing routines treat
* row compares like any other same-strategy inequality on the same column.)
*
* Things get more complicated for our row compare given a row where "a = 7".
* Note that a row compare isn't necessarily satisfied by _every_ tuple that
* appears between the first and last satisfied tuple returned by the scan,
* due to the way that its lower-order subkeys are only conditionally applied.
* A forwards scan that uses our example qual might initially return a tuple
* "(a, b, c) = (7, 'zebra', 54)". But it won't subsequently return a tuple
* "(a, b, c) = (7, NULL, 1)" located to the right of the first matching tuple
* (assume that "b" was declared NULLS LAST here). The scan will only return
* additional matches upon reaching tuples where "a > 7". If you rereview our
* example row comparison's logical expansion, you'll understand why this is.
* (Here we assume that all subkeys could be marked required, guaranteeing
* that row comparison order matches index order. This is the common case.)
*
* Note that a row comparison header key behaves _exactly_ the same as a
* similar scalar inequality key on the row's most significant column once the
* scan reaches the point where it no longer needs to evaluate lower-order
* subkeys (or before the point where it starts needing to evaluate them).
* For example, once a forwards scan that uses our example qual reaches the
* first tuple "a > 7", we'll behave in just the same way as our caller would
* behave with a similar scalar inequality "a > 7" for the remainder of the
* scan (assuming that the scan never changes direction/never goes backwards).
* We'll even set continuescan=false according to exactly the same rules as
* the ones our caller applies with simple scalar inequalities, including the
* rules it applies when NULL tuple values don't satisfy an inequality qual.
*/
static bool
_bt_check_rowcompare(ScanKey header, IndexTuple tuple, int tupnatts,
TupleDesc tupdesc, ScanDirection dir,
bool forcenonrequired, bool *continuescan)
{
ScanKey subkey = (ScanKey) DatumGetPointer(header->sk_argument);
int32 cmpresult = 0;
bool result;
/* First subkey should be same as the header says */
Assert(header->sk_flags & SK_ROW_HEADER);
Assert(subkey->sk_attno == header->sk_attno);
Assert(subkey->sk_strategy == header->sk_strategy);
/* Loop over columns of the row condition */
for (;;)
{
Datum datum;
bool isNull;
Assert(subkey->sk_flags & SK_ROW_MEMBER);
/* When a NULL row member is compared, the row never matches */
if (subkey->sk_flags & SK_ISNULL)
{
/*
* Unlike the simple-scankey case, this isn't a disallowed case
* (except when it's the first row element that has the NULL arg).
* But it can never match. If all the earlier row comparison
* columns are required for the scan direction, we can stop the
* scan, because there can't be another tuple that will succeed.
*/
Assert(subkey != (ScanKey) DatumGetPointer(header->sk_argument));
subkey--;
if (forcenonrequired)
{
/* treating scan's keys as non-required */
}
else if ((subkey->sk_flags & SK_BT_REQFWD) &&
ScanDirectionIsForward(dir))
*continuescan = false;
else if ((subkey->sk_flags & SK_BT_REQBKWD) &&
ScanDirectionIsBackward(dir))
*continuescan = false;
return false;
}
if (subkey->sk_attno > tupnatts)
{
/*
* This attribute is truncated (must be high key). The value for
* this attribute in the first non-pivot tuple on the page to the
* right could be any possible value. Assume that truncated
* attribute passes the qual.
*/
Assert(BTreeTupleIsPivot(tuple));
return true;
}
datum = index_getattr(tuple,
subkey->sk_attno,
tupdesc,
&isNull);
if (isNull)
{
int reqflags;
if (forcenonrequired)
{
/* treating scan's keys as non-required */
}
else if (subkey->sk_flags & SK_BT_NULLS_FIRST)
{
/*
* Since NULLs are sorted before non-NULLs, we know we have
* reached the lower limit of the range of values for this
* index attr. On a backward scan, we can stop if this qual
* is one of the "must match" subset. However, on a forwards
* scan, we must keep going, because we may have initially
* positioned to the start of the index.
*
* All required NULLS FIRST > row members can use NULL tuple
* values to end backwards scans, just like with other values.
* A qual "WHERE (a, b, c) > (9, 42, 'foo')" can terminate a
* backwards scan upon reaching the index's rightmost "a = 9"
* tuple whose "b" column contains a NULL (if not sooner).
* Since "b" is NULLS FIRST, we can treat its NULLs as "<" 42.
*/
reqflags = SK_BT_REQBKWD;
/*
* When a most significant required NULLS FIRST < row compare
* member sees NULL tuple values during a backwards scan, it
* signals the end of matches for the whole row compare/scan.
* A qual "WHERE (a, b, c) < (9, 42, 'foo')" will terminate a
* backwards scan upon reaching the rightmost tuple whose "a"
* column has a NULL. The "a" NULL value is "<" 9, and yet
* our < row compare will still end the scan. (This isn't
* safe with later/lower-order row members. Notice that it
* can only happen with an "a" NULL some time after the scan
* completely stops needing to use its "b" and "c" members.)
*/
if (subkey == (ScanKey) DatumGetPointer(header->sk_argument))
reqflags |= SK_BT_REQFWD; /* safe, first row member */
if ((subkey->sk_flags & reqflags) &&
ScanDirectionIsBackward(dir))
*continuescan = false;
}
else
{
/*
* Since NULLs are sorted after non-NULLs, we know we have
* reached the upper limit of the range of values for this
* index attr. On a forward scan, we can stop if this qual is
* one of the "must match" subset. However, on a backward
* scan, we must keep going, because we may have initially
* positioned to the end of the index.
*
* All required NULLS LAST < row members can use NULL tuple
* values to end forwards scans, just like with other values.
* A qual "WHERE (a, b, c) < (9, 42, 'foo')" can terminate a
* forwards scan upon reaching the index's leftmost "a = 9"
* tuple whose "b" column contains a NULL (if not sooner).
* Since "b" is NULLS LAST, we can treat its NULLs as ">" 42.
*/
reqflags = SK_BT_REQFWD;
/*
* When a most significant required NULLS LAST > row compare
* member sees NULL tuple values during a forwards scan, it
* signals the end of matches for the whole row compare/scan.
* A qual "WHERE (a, b, c) > (9, 42, 'foo')" will terminate a
* forwards scan upon reaching the leftmost tuple whose "a"
* column has a NULL. The "a" NULL value is ">" 9, and yet
* our > row compare will end the scan. (This isn't safe with
* later/lower-order row members. Notice that it can only
* happen with an "a" NULL some time after the scan completely
* stops needing to use its "b" and "c" members.)
*/
if (subkey == (ScanKey) DatumGetPointer(header->sk_argument))
reqflags |= SK_BT_REQBKWD; /* safe, first row member */
if ((subkey->sk_flags & reqflags) &&
ScanDirectionIsForward(dir))
*continuescan = false;
}
/*
* In any case, this indextuple doesn't match the qual.
*/
return false;
}
/* Perform the test --- three-way comparison not bool operator */
cmpresult = DatumGetInt32(FunctionCall2Coll(&subkey->sk_func,
subkey->sk_collation,
datum,
subkey->sk_argument));
if (subkey->sk_flags & SK_BT_DESC)
INVERT_COMPARE_RESULT(cmpresult);
/* Done comparing if unequal, else advance to next column */
if (cmpresult != 0)
break;
if (subkey->sk_flags & SK_ROW_END)
break;
subkey++;
}
/*
* At this point cmpresult indicates the overall result of the row
* comparison, and subkey points to the deciding column (or the last
* column if the result is "=").
*/
switch (subkey->sk_strategy)
{
/* EQ and NE cases aren't allowed here */
case BTLessStrategyNumber:
result = (cmpresult < 0);
break;
case BTLessEqualStrategyNumber:
result = (cmpresult <= 0);
break;
case BTGreaterEqualStrategyNumber:
result = (cmpresult >= 0);
break;
case BTGreaterStrategyNumber:
result = (cmpresult > 0);
break;
default:
elog(ERROR, "unexpected strategy number %d", subkey->sk_strategy);
result = 0; /* keep compiler quiet */
break;
}
if (!result && !forcenonrequired)
{
/*
* Tuple fails this qual. If it's a required qual for the current
* scan direction, then we can conclude no further tuples will pass,
* either. Note we have to look at the deciding column, not
* necessarily the first or last column of the row condition.
*/
if ((subkey->sk_flags & SK_BT_REQFWD) &&
ScanDirectionIsForward(dir))
*continuescan = false;
else if ((subkey->sk_flags & SK_BT_REQBKWD) &&
ScanDirectionIsBackward(dir))
*continuescan = false;
}
return result;
}
/*
* Determine if a scan with array keys should skip over uninteresting tuples.
*
* This is a subroutine for _bt_checkkeys. Called when _bt_readpage's linear
* search process (started after it finishes reading an initial group of
* matching tuples, used to locate the start of the next group of tuples
* matching the next set of required array keys) has already scanned an
* excessive number of tuples whose key space is "between arrays".
*
* When we perform look ahead successfully, we'll sets pstate.skip, which
* instructs _bt_readpage to skip ahead to that tuple next (could be past the
* end of the scan's leaf page). Pages where the optimization is effective
* will generally still need to skip several times. Each call here performs
* only a single "look ahead" comparison of a later tuple, whose distance from
* the current tuple's offset number is determined by applying heuristics.
*/
static void
_bt_checkkeys_look_ahead(IndexScanDesc scan, BTReadPageState *pstate,
int tupnatts, TupleDesc tupdesc)
{
BTScanOpaque so = (BTScanOpaque) scan->opaque;
ScanDirection dir = so->currPos.dir;
OffsetNumber aheadoffnum;
IndexTuple ahead;
Assert(!pstate->forcenonrequired);
/* Avoid looking ahead when comparing the page high key */
if (pstate->offnum < pstate->minoff)
return;
/*
* Don't look ahead when there aren't enough tuples remaining on the page
* (in the current scan direction) for it to be worth our while
*/
if (ScanDirectionIsForward(dir) &&
pstate->offnum >= pstate->maxoff - LOOK_AHEAD_DEFAULT_DISTANCE)
return;
else if (ScanDirectionIsBackward(dir) &&
pstate->offnum <= pstate->minoff + LOOK_AHEAD_DEFAULT_DISTANCE)
return;
/*
* The look ahead distance starts small, and ramps up as each call here
* allows _bt_readpage to skip over more tuples
*/
if (!pstate->targetdistance)
pstate->targetdistance = LOOK_AHEAD_DEFAULT_DISTANCE;
else if (pstate->targetdistance < MaxIndexTuplesPerPage / 2)
pstate->targetdistance *= 2;
/* Don't read past the end (or before the start) of the page, though */
if (ScanDirectionIsForward(dir))
aheadoffnum = Min((int) pstate->maxoff,
(int) pstate->offnum + pstate->targetdistance);
else
aheadoffnum = Max((int) pstate->minoff,
(int) pstate->offnum - pstate->targetdistance);
ahead = (IndexTuple) PageGetItem(pstate->page,
PageGetItemId(pstate->page, aheadoffnum));
if (_bt_tuple_before_array_skeys(scan, dir, ahead, tupdesc, tupnatts,
false, 0, NULL))
{
/*
* Success -- instruct _bt_readpage to skip ahead to very next tuple
* after the one we determined was still before the current array keys
*/
if (ScanDirectionIsForward(dir))
pstate->skip = aheadoffnum + 1;
else
pstate->skip = aheadoffnum - 1;
}
else
{
/*
* Failure -- "ahead" tuple is too far ahead (we were too aggressive).
*
* Reset the number of rechecks, and aggressively reduce the target
* distance (we're much more aggressive here than we were when the
* distance was initially ramped up).
*/
pstate->rechecks = 0;
pstate->targetdistance = Max(pstate->targetdistance / 8, 1);
}
}
/*
* _bt_killitems - set LP_DEAD state for items an indexscan caller has
* told us were killed
*
* scan->opaque, referenced locally through so, contains information about the
* current page and killed tuples thereon (generally, this should only be
* called if so->numKilled > 0).
*
* Caller should not have a lock on the so->currPos page, but must hold a
* buffer pin when !so->dropPin. When we return, it still won't be locked.
* It'll continue to hold whatever pins were held before calling here.
*
* We match items by heap TID before assuming they are the right ones to set
* LP_DEAD. If the scan is one that holds a buffer pin on the target page
* continuously from initially reading the items until applying this function
* (if it is a !so->dropPin scan), VACUUM cannot have deleted any items on the
* page, so the page's TIDs can't have been recycled by now. There's no risk
* that we'll confuse a new index tuple that happens to use a recycled TID
* with a now-removed tuple with the same TID (that used to be on this same
* page). We can't rely on that during scans that drop buffer pins eagerly
* (so->dropPin scans), though, so we must condition setting LP_DEAD bits on
* the page LSN having not changed since back when _bt_readpage saw the page.
* We totally give up on setting LP_DEAD bits when the page LSN changed.
*
* We give up much less often during !so->dropPin scans, but it still happens.
* We cope with cases where items have moved right due to insertions. If an
* item has moved off the current page due to a split, we'll fail to find it
* and just give up on it.
*/
void
_bt_killitems(IndexScanDesc scan)
{
Relation rel = scan->indexRelation;
BTScanOpaque so = (BTScanOpaque) scan->opaque;
Page page;
BTPageOpaque opaque;
OffsetNumber minoff;
OffsetNumber maxoff;
int numKilled = so->numKilled;
bool killedsomething = false;
Buffer buf;
Assert(numKilled > 0);
Assert(BTScanPosIsValid(so->currPos));
Assert(scan->heapRelation != NULL); /* can't be a bitmap index scan */
if (!so->dropPin)
{
/*
* We have held the pin on this page since we read the index tuples,
* so all we need to do is lock it. The pin will have prevented
* concurrent VACUUMs from recycling any of the TIDs on the page.
*/
Assert(BTScanPosIsPinned(so->currPos));
buf = so->currPos.buf;
_bt_lockbuf(rel, buf, BT_READ);
}
else
{
XLogRecPtr latestlsn;
if (BTreeTupleIsPosting(ituple))
{
int pi = i + 1;
int nposting = BTreeTupleGetNPosting(ituple);
int j;
/*
* We rely on the convention that heap TIDs in the scanpos
* items array are stored in ascending heap TID order for a
* group of TIDs that originally came from a posting list
* tuple. This convention even applies during backwards
* scans, where returning the TIDs in descending order might
* seem more natural. This is about effectiveness, not
* correctness.
*
* Note that the page may have been modified in almost any way
* since we first read it (in the !so->dropPin case), so it's
* possible that this posting list tuple wasn't a posting list
* tuple when we first encountered its heap TIDs.
*/
for (j = 0; j < nposting; j++)
{
ItemPointer item = BTreeTupleGetPostingN(ituple, j);
if (!ItemPointerEquals(item, &kitem->heapTid))
break; /* out of posting list loop */
/*
* kitem must have matching offnum when heap TIDs match,
* though only in the common case where the page can't
* have been concurrently modified
*/
Assert(kitem->indexOffset == offnum || !so->dropPin);
/*
* Read-ahead to later kitems here.
*
* We rely on the assumption that not advancing kitem here
* will prevent us from considering the posting list tuple
* fully dead by not matching its next heap TID in next
* loop iteration.
*
* If, on the other hand, this is the final heap TID in
* the posting list tuple, then tuple gets killed
* regardless (i.e. we handle the case where the last
* kitem is also the last heap TID in the last index tuple
* correctly -- posting tuple still gets killed).
*/
if (pi < numKilled)
kitem = &so->currPos.items[so->killedItems[pi++]];
}
/*
* Don't bother advancing the outermost loop's int iterator to
* avoid processing killed items that relate to the same
* offnum/posting list tuple. This micro-optimization hardly
* seems worth it. (Further iterations of the outermost loop
* will fail to match on this same posting list's first heap
* TID instead, so we'll advance to the next offnum/index
* tuple pretty quickly.)
*/
if (j == nposting)
killtuple = true;
}
else if (ItemPointerEquals(&ituple->t_tid, &kitem->heapTid))
killtuple = true;
/*
* Mark index item as dead, if it isn't already. Since this
* happens while holding a buffer lock possibly in shared mode,
* it's possible that multiple processes attempt to do this
* simultaneously, leading to multiple full-page images being sent
* to WAL (if wal_log_hints or data checksums are enabled), which
* is undesirable.
*/
if (killtuple && !ItemIdIsDead(iid))
{
/* found the item/all posting list items */
ItemIdMarkDead(iid);
killedsomething = true;
break; /* out of inner search loop */
}
offnum = OffsetNumberNext(offnum);
}
}
/*
* Since this can be redone later if needed, mark as dirty hint.
*
* Whenever we mark anything LP_DEAD, we also set the page's
* BTP_HAS_GARBAGE flag, which is likewise just a hint. (Note that we
* only rely on the page-level flag in !heapkeyspace indexes.)
*/
if (killedsomething)
{
opaque->btpo_flags |= BTP_HAS_GARBAGE;
MarkBufferDirtyHint(buf, true);
}
if (!so->dropPin)
_bt_unlockbuf(rel, buf);
else
_bt_relbuf(rel, buf);
}
/*
* The following routines manage a shared-memory area in which we track
* assignment of "vacuum cycle IDs" to currently-active btree vacuuming
* operations. There is a single counter which increments each time we
* start a vacuum to assign it a cycle ID. Since multiple vacuums could
* be active concurrently, we have to track the cycle ID for each active
* vacuum; this requires at most MaxBackends entries (usually far fewer).
* We assume at most one vacuum can be active for a given index.
*
* Access to the shared memory area is controlled by BtreeVacuumLock.
* In principle we could use a separate lmgr locktag for each index,
* but a single LWLock is much cheaper, and given the short time that
* the lock is ever held, the concurrency hit should be minimal.
*/
typedef struct BTOneVacInfo
{
LockRelId relid; /* global identifier of an index */
BTCycleId cycleid; /* cycle ID for its active VACUUM */
} BTOneVacInfo;
typedef struct BTVacInfo
{
BTCycleId cycle_ctr; /* cycle ID most recently assigned */
int num_vacuums; /* number of currently active VACUUMs */
int max_vacuums; /* allocated length of vacuums[] array */
BTOneVacInfo vacuums[FLEXIBLE_ARRAY_MEMBER];
} BTVacInfo;
static BTVacInfo *btvacinfo;
/*
* _bt_vacuum_cycleid --- get the active vacuum cycle ID for an index,
* or zero if there is no active VACUUM
*
* Note: for correct interlocking, the caller must already hold pin and
* exclusive lock on each buffer it will store the cycle ID into. This
* ensures that even if a VACUUM starts immediately afterwards, it cannot
* process those pages until the page split is complete.
*/
BTCycleId
_bt_vacuum_cycleid(Relation rel)
{
BTCycleId result = 0;
int i;
/* Share lock is enough since this is a read-only operation */
LWLockAcquire(BtreeVacuumLock, LW_SHARED);
for (i = 0; i < btvacinfo->num_vacuums; i++)
{
BTOneVacInfo *vac = &btvacinfo->vacuums[i];
if (vac->relid.relId == rel->rd_lockInfo.lockRelId.relId &&
vac->relid.dbId == rel->rd_lockInfo.lockRelId.dbId)
{
result = vac->cycleid;
break;
}
}
LWLockRelease(BtreeVacuumLock);
return result;
}
/*
* _bt_start_vacuum --- assign a cycle ID to a just-starting VACUUM operation
*
* Note: the caller must guarantee that it will eventually call
* _bt_end_vacuum, else we'll permanently leak an array slot. To ensure
* that this happens even in elog(FATAL) scenarios, the appropriate coding
* is not just a PG_TRY, but
* PG_ENSURE_ERROR_CLEANUP(_bt_end_vacuum_callback, PointerGetDatum(rel))
*/
BTCycleId
_bt_start_vacuum(Relation rel)
{
BTCycleId result;
int i;
BTOneVacInfo *vac;
LWLockAcquire(BtreeVacuumLock, LW_EXCLUSIVE);
/*
* Assign the next cycle ID, being careful to avoid zero as well as the
* reserved high values.
*/
result = ++(btvacinfo->cycle_ctr);
if (result == 0 || result > MAX_BT_CYCLE_ID)
result = btvacinfo->cycle_ctr = 1;
/* Let's just make sure there's no entry already for this index */
for (i = 0; i < btvacinfo->num_vacuums; i++)
{
vac = &btvacinfo->vacuums[i];
if (vac->relid.relId == rel->rd_lockInfo.lockRelId.relId &&
vac->relid.dbId == rel->rd_lockInfo.lockRelId.dbId)
{
/*
* Unlike most places in the backend, we have to explicitly
* release our LWLock before throwing an error. This is because
* we expect _bt_end_vacuum() to be called before transaction
* abort cleanup can run to release LWLocks.
*/
LWLockRelease(BtreeVacuumLock);
elog(ERROR, "multiple active vacuums for index \"%s\"",
RelationGetRelationName(rel));
}
}
/* OK, add an entry */
if (btvacinfo->num_vacuums >= btvacinfo->max_vacuums)
{
LWLockRelease(BtreeVacuumLock);
elog(ERROR, "out of btvacinfo slots");
}
vac = &btvacinfo->vacuums[btvacinfo->num_vacuums];
vac->relid = rel->rd_lockInfo.lockRelId;
vac->cycleid = result;
btvacinfo->num_vacuums++;
LWLockRelease(BtreeVacuumLock);
return result;
}
/*
* _bt_end_vacuum --- mark a btree VACUUM operation as done
*
* Note: this is deliberately coded not to complain if no entry is found;
* this allows the caller to put PG_TRY around the start_vacuum operation.
*/
void
_bt_end_vacuum(Relation rel)
{ int i;
LWLockAcquire(BtreeVacuumLock, LW_EXCLUSIVE);
/* Find the array entry */ for (i = 0; i < btvacinfo->num_vacuums; i++)
{
BTOneVacInfo *vac = &btvacinfo->vacuums[i];
if (vac->relid.relId == rel->rd_lockInfo.lockRelId.relId &&
vac->relid.dbId == rel->rd_lockInfo.lockRelId.dbId)
{ /* Remove it by shifting down the last entry */
*vac = btvacinfo->vacuums[btvacinfo->num_vacuums - 1];
btvacinfo->num_vacuums--; break;
}
}
/* *btproperty()--Checkbooleanpropertiesofindexes. * *Thisisoptional,buthandlingAMPROP_RETURNABLEheresavesopeningtherel *tocallbtcanreturn.
*/
bool
btproperty(Oid index_oid, int attno,
IndexAMProperty prop, constchar *propname,
bool *res, bool *isnull)
{ switch (prop)
{ case AMPROP_RETURNABLE: /* answer only for columns, not AM or whole index */ if (attno == 0) returnfalse; /* otherwise, btree can always return data */
*res = true; returntrue;
default: returnfalse; /* punt to generic code */
}
}
/* *btbuildphasename()--Returnnameofindexbuildphase.
*/ char *
btbuildphasename(int64 phasenum)
{ switch (phasenum)
{ case PROGRESS_CREATEIDX_SUBPHASE_INITIALIZE: return"initializing"; case PROGRESS_BTREE_PHASE_INDEXBUILD_TABLESCAN: return"scanning table"; case PROGRESS_BTREE_PHASE_PERFORMSORT_1: return"sorting live tuples"; case PROGRESS_BTREE_PHASE_PERFORMSORT_2: return"sorting dead tuples"; case PROGRESS_BTREE_PHASE_LEAF_LOAD: return"loading tuples in tree"; default: returnNULL;
}
}
/* !heapkeyspace indexes do not support deduplication */ if (!heapkeyspace && BTreeTupleIsPosting(itup)) returnfalse;
/* Posting list tuples should never have "pivot heap TID" bit set */ if (BTreeTupleIsPosting(itup) &&
(ItemPointerGetOffsetNumberNoCheck(&itup->t_tid) &
BT_PIVOT_HEAP_TID_ATTR) != 0) returnfalse;
/* INCLUDE indexes do not support deduplication */ if (natts != nkeyatts && BTreeTupleIsPosting(itup)) returnfalse;
if (P_ISLEAF(opaque))
{ if (offnum >= P_FIRSTDATAKEY(opaque))
{ /* *Non-pivottupleshouldneverbeexplicitlymarkedasapivot *tuple
*/ if (BTreeTupleIsPivot(itup)) returnfalse;
/* *Internalpageinsertionscannotfailhere,becausethatwouldmeanthat *anearlierleaflevelinsertionthatshouldhavefaileddidn't
*/
opaque = BTPageGetOpaque(page); ifP_ISLEAF
(,"cannot insert oversized tuple %u internal page index "s"java.lang.StringIndexOutOfBoundsException: Index 91 out of bounds for length 91
itemsz, RelationGetRelationName(rel));
ERRORjava.lang.StringIndexOutOfBoundsException: Index 15 out of bounds for length 15
(errcode( const valueSpan = property"-";
errmsg("index row size %zu exceeds btree version %u maximum %zu for index \"*
itemsz,
:BTREE_NOVAC_VERSION,
propertyViews( = . = ;
RelationGetRelationName(rel)),
errdetail("Index row references tuple (%u,%u) in relation \"%s\".",
ItemPointerGetBlockNumber(BTreeTupleGetHeapTID(newtup)),
ItemPointerGetOffsetNumber(BTreeTupleGetHeapTID(newtup)),
RelationGetRelationName(heap)),
errhint("Values larger than 1/3 of a buffer java.lang.StringIndexOutOfBoundsException: Index 51 out of bounds for length 23 "Consider a function index of an MD5 hash of the value, " "or use full text expander;
errtableconstraint(heap, if (nameSpan.firstChild.textContent === name)
}
/* *Areallattributesin*Theofthejava.lang.StringIndexOutOfBoundsException: Range [35, 34) out of bounds for length 46 * *Weuseeachattribute'sBTEQUALIMAGE_PROCopclassprocedure.Ifany *opclasseitherBTEQUALIMAGE_PROCprocedureorreturnsfalse,we *returnfalse;otherwisewejava.lang.StringIndexOutOfBoundsException: Range [20, 19) out of bounds for length 50 * *Returnedbooleanvalue("xpanding"+index+the"java.lang.StringIndexOutOfBoundsException: Index 64 out of bounds for length 64 *Deduplicationcanonlybeusedwhenwereturntrue.
*/
bool
_bt_allequalimage(Relation rel, bool debugmessage)
java.lang.StringIndexOutOfBoundsException: Range [8, 7) out of bounds for length 50
bool allequalimage = true;
" the "; if ( Selectallthe text, it checkthe in theclipboard.
IndexRelationGetNumberOfKeyAttributes(rel)java.lang.StringIndexOutOfBoundsException: Index 45 out of bounds for length 45 returnfalse;
for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes*java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
{
{:10, p , }}
Oid opcintype = rel->rd_opcintype[i];
Oid collation = rel->rd_indcollation[i];
Oid equalimageproc
/* *IfthereisnoBTEQUALIMAGE_PROCthendeduplicationisassumedto tryjava.lang.StringIndexOutOfBoundsException: Index 7 out of bounds for length 7
*/ if (!OidIsValid(equalimageproc) ||
!DatumGetBool(OidFunctionCall1Coll(equalimageproc,
ObjectIdGetDatum(opcintype))))
{
allequalimage = false;
expectedPattern =expectedPattern.replace(/\[\\r\\n\][+*]/g, terminator);
}
}
if (debugmessage)
{ if (allequalimage)
elog(DEBUG1, "index \"%s\" can safely expectedPattern = expectedPattern.trimRight();
RelationGetRelationName( else
elog(DEBUG1, "index \"%s\" cannot use deduplication",
RelationGetRelationName(rel));
}
}
Messung V0.5 in Prozent
¤ Die Informationen auf dieser Webseite wurden
nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit,
noch Qualität der bereit gestellten Informationen zugesichert.0.157Bemerkung:
(vorverarbeitet am 2026-10-11)
¤
Die Informationen auf dieser Webseite wurden
nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit,
noch Qualität der bereit gestellten Informationen zugesichert.
Bemerkung:
Die farbliche Syntaxdarstellung und die Messung sind noch experimentell.
