/*-------------------------------------------------------------------------
*
* execIndexing.c
* routines for inserting index tuples and enforcing unique and
* exclusive constraints.
*
* ExecInsertIndexTuples() is the main entry point. It's called after
* inserting a tuple to the heap, and it inserts corresponding index tuples
* into all indexes. At the same time, it enforces any unique and
* exclusion constraints:
*
* Unique Indexes
* --------------
*
* Enforcing a unique constraint is straightforward. When the index AM
* inserts the tuple to the index, it also checks that there are no
* conflicting tuples in the index already. It does so atomically, so that
* even if two backends try to insert the same key concurrently, only one
* of them will succeed. All the logic to ensure atomicity, and to wait
* for in-progress transactions to finish, is handled by the index AM.
*
* If a unique constraint is deferred, we request the index AM to not
* throw an error if a conflict is found. Instead, we make note that there
* was a conflict and return the list of indexes with conflicts to the
* caller. The caller must re-check them later, by calling index_insert()
* with the UNIQUE_CHECK_EXISTING option.
*
* Exclusion Constraints
* ---------------------
*
* Exclusion constraints are different from unique indexes in that when the
* tuple is inserted to the index, the index AM does not check for
* duplicate keys at the same time. After the insertion, we perform a
* separate scan on the index to check for conflicting tuples, and if one
* is found, we throw an error and the transaction is aborted. If the
* conflicting tuple's inserter or deleter is in-progress, we wait for it
* to finish first.
*
* There is a chance of deadlock, if two backends insert a tuple at the
* same time, and then perform the scan to check for conflicts. They will
* find each other's tuple, and both try to wait for each other. The
* deadlock detector will detect that, and abort one of the transactions.
* That's fairly harmless, as one of them was bound to abort with a
* "duplicate key error" anyway, although you get a different error
* message.
*
* If an exclusion constraint is deferred, we still perform the conflict
* checking scan immediately after inserting the index tuple. But instead
* of throwing an error if a conflict is found, we return that information
* to the caller. The caller must re-check them later by calling
* check_exclusion_constraint().
*
* Speculative insertion
* ---------------------
*
* Speculative insertion is a two-phase mechanism used to implement
* INSERT ... ON CONFLICT DO UPDATE/NOTHING. The tuple is first inserted
* to the heap and update the indexes as usual, but if a constraint is
* violated, we can still back out the insertion without aborting the whole
* transaction. In an INSERT ... ON CONFLICT statement, if a conflict is
* detected, the inserted tuple is backed out and the ON CONFLICT action is
* executed instead.
*
* Insertion to a unique index works as usual: the index AM checks for
* duplicate keys atomically with the insertion. But instead of throwing
* an error on a conflict, the speculatively inserted heap tuple is backed
* out.
*
* Exclusion constraints are slightly more complicated. As mentioned
* earlier, there is a risk of deadlock when two backends insert the same
* key concurrently. That was not a problem for regular insertions, when
* one of the transactions has to be aborted anyway, but with a speculative
* insertion we cannot let a deadlock happen, because we only want to back
* out the speculatively inserted tuple on conflict, not abort the whole
* transaction.
*
* When a backend detects that the speculative insertion conflicts with
* another in-progress tuple, it has two options:
*
* 1. back out the speculatively inserted tuple, then wait for the other
* transaction, and retry. Or,
* 2. wait for the other transaction, with the speculatively inserted tuple
* still in place.
*
* If two backends insert at the same time, and both try to wait for each
* other, they will deadlock. So option 2 is not acceptable. Option 1
* avoids the deadlock, but it is prone to a livelock instead. Both
* transactions will wake up immediately as the other transaction backs
* out. Then they both retry, and conflict with each other again, lather,
* rinse, repeat.
*
* To avoid the livelock, one of the backends must back out first, and then
* wait, while the other one waits without backing out. It doesn't matter
* which one backs out, so we employ an arbitrary rule that the transaction
* with the higher XID backs out.
*
*
* Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/executor/execIndexing.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/relscan.h"
#include "access/xact.h"
#include "catalog/index.h"
#include "executor/executor.h"
#include "nodes/nodeFuncs.h"
#include "storage/lmgr.h"
#include "utils/tqual.h"
/* waitMode argument to check_exclusion_or_unique_constraint() */
typedef enum
{
CEOUC_WAIT,
CEOUC_NOWAIT,
CEOUC_LIVELOCK_PREVENTING_WAIT
} CEOUC_WAIT_MODE;
static bool check_exclusion_or_unique_constraint(Relation heap, Relation index,
IndexInfo *indexInfo,
ItemPointer tupleid,
Datum *values, bool *isnull,
EState *estate, bool newIndex,
CEOUC_WAIT_MODE waitMode,
bool errorOK,
ItemPointer conflictTid);
static bool index_recheck_constraint(Relation index, Oid *constr_procs,
Datum *existing_values, bool *existing_isnull,
Datum *new_values);
/* ----------------------------------------------------------------
* ExecOpenIndices
*
* Find the indices associated with a result relation, open them,
* and save information about them in the result ResultRelInfo.
*
* At entry, caller has already opened and locked
* resultRelInfo->ri_RelationDesc.
* ----------------------------------------------------------------
*/
void
ExecOpenIndices(ResultRelInfo *resultRelInfo, bool speculative)
{
Relation resultRelation = resultRelInfo->ri_RelationDesc;
List *indexoidlist;
ListCell *l;
int len,
i;
RelationPtr relationDescs;
IndexInfo **indexInfoArray;
resultRelInfo->ri_NumIndices = 0;
/* fast path if no indexes */
if (!RelationGetForm(resultRelation)->relhasindex)
return;
/*
* Get cached list of index OIDs
*/
indexoidlist = RelationGetIndexList(resultRelation);
len = list_length(indexoidlist);
if (len == 0)
return;
/*
* allocate space for result arrays
*/
relationDescs = (RelationPtr) palloc(len * sizeof(Relation));
indexInfoArray = (IndexInfo **) palloc(len * sizeof(IndexInfo *));
resultRelInfo->ri_NumIndices = len;
resultRelInfo->ri_IndexRelationDescs = relationDescs;
resultRelInfo->ri_IndexRelationInfo = indexInfoArray;
/*
* For each index, open the index relation and save pg_index info. We
* acquire RowExclusiveLock, signifying we will update the index.
*
* Note: we do this even if the index is not IndexIsReady; it's not worth
* the trouble to optimize for the case where it isn't.
*/
i = 0;
foreach(l, indexoidlist)
{
Oid indexOid = lfirst_oid(l);
Relation indexDesc;
IndexInfo *ii;
indexDesc = index_open(indexOid, RowExclusiveLock);
/* extract index key information from the index's pg_index info */
ii = BuildIndexInfo(indexDesc);
/*
* If the indexes are to be used for speculative insertion, add extra
* information required by unique index entries.
*/
if (speculative && ii->ii_Unique)
BuildSpeculativeIndexInfo(indexDesc, ii);
relationDescs[i] = indexDesc;
indexInfoArray[i] = ii;
i++;
}
list_free(indexoidlist);
}
/* ----------------------------------------------------------------
* ExecCloseIndices
*
* Close the index relations stored in resultRelInfo
* ----------------------------------------------------------------
*/
void
ExecCloseIndices(ResultRelInfo *resultRelInfo)
{
int i;
int numIndices;
RelationPtr indexDescs;
numIndices = resultRelInfo->ri_NumIndices;
indexDescs = resultRelInfo->ri_IndexRelationDescs;
for (i = 0; i < numIndices; i++)
{
if (indexDescs[i] == NULL)
continue; /* shouldn't happen? */
/* Drop lock acquired by ExecOpenIndices */
index_close(indexDescs[i], RowExclusiveLock);
}
/*
* XXX should free indexInfo array here too? Currently we assume that
* such stuff will be cleaned up automatically in FreeExecutorState.
*/
}
/* ----------------------------------------------------------------
* ExecInsertIndexTuples
*
* This routine takes care of inserting index tuples
* into all the relations indexing the result relation
* when a heap tuple is inserted into the result relation.
*
* Unique and exclusion constraints are enforced at the same
* time. This returns a list of index OIDs for any unique or
* exclusion constraints that are deferred and that had
* potential (unconfirmed) conflicts. (if noDupErr == true,
* the same is done for non-deferred constraints, but report
* if conflict was speculative or deferred conflict to caller)
*
* If 'arbiterIndexes' is nonempty, noDupErr applies only to
* those indexes. NIL means noDupErr applies to all indexes.
*
* CAUTION: this must not be called for a HOT update.
* We can't defend against that here for lack of info.
* Should we change the API to make it safer?
* ----------------------------------------------------------------
*/
List *
ExecInsertIndexTuples(TupleTableSlot *slot,
ItemPointer tupleid,
EState *estate,
bool noDupErr,
bool *specConflict,
List *arbiterIndexes)
{
List *result = NIL;
ResultRelInfo *resultRelInfo;
int i;
int numIndices;
RelationPtr relationDescs;
Relation heapRelation;
IndexInfo **indexInfoArray;
ExprContext *econtext;
Datum values[INDEX_MAX_KEYS];
bool isnull[INDEX_MAX_KEYS];
/*
* Get information from the result relation info structure.
*/
resultRelInfo = estate->es_result_relation_info;
numIndices = resultRelInfo->ri_NumIndices;
relationDescs = resultRelInfo->ri_IndexRelationDescs;
indexInfoArray = resultRelInfo->ri_IndexRelationInfo;
heapRelation = resultRelInfo->ri_RelationDesc;
/*
* We will use the EState's per-tuple context for evaluating predicates
* and index expressions (creating it if it's not already there).
*/
econtext = GetPerTupleExprContext(estate);
/* Arrange for econtext's scan tuple to be the tuple under test */
econtext->ecxt_scantuple = slot;
/*
* for each index, form and insert the index tuple
*/
for (i = 0; i < numIndices; i++)
{
Relation indexRelation = relationDescs[i];
IndexInfo *indexInfo;
bool applyNoDupErr;
IndexUniqueCheck checkUnique;
bool satisfiesConstraint;
if (indexRelation == NULL)
continue;
indexInfo = indexInfoArray[i];
/* If the index is marked as read-only, ignore it */
if (!indexInfo->ii_ReadyForInserts)
continue;
/* Check for partial index */
if (indexInfo->ii_Predicate != NIL)
{
List *predicate;
/*
* If predicate state not set up yet, create it (in the estate's
* per-query context)
*/
predicate = indexInfo->ii_PredicateState;
if (predicate == NIL)
{
predicate = (List *)
ExecPrepareExpr((Expr *) indexInfo->ii_Predicate,
estate);
indexInfo->ii_PredicateState = predicate;
}
/* Skip this index-update if the predicate isn't satisfied */
if (!ExecQual(predicate, econtext, false))
continue;
}
/*
* FormIndexDatum fills in its values and isnull parameters with the
* appropriate values for the column(s) of the index.
*/
FormIndexDatum(indexInfo,
slot,
estate,
values,
isnull);
/* Check whether to apply noDupErr to this index */
applyNoDupErr = noDupErr &&
(arbiterIndexes == NIL ||
list_member_oid(arbiterIndexes,
indexRelation->rd_index->indexrelid));
/*
* The index AM does the actual insertion, plus uniqueness checking.
*
* For an immediate-mode unique index, we just tell the index AM to
* throw error if not unique.
*
* For a deferrable unique index, we tell the index AM to just detect
* possible non-uniqueness, and we add the index OID to the result
* list if further checking is needed.
*
* For a speculative insertion (used by INSERT ... ON CONFLICT), do
* the same as for a deferrable unique index.
*/
if (!indexRelation->rd_index->indisunique)
checkUnique = UNIQUE_CHECK_NO;
else if (applyNoDupErr)
checkUnique = UNIQUE_CHECK_PARTIAL;
else if (indexRelation->rd_index->indimmediate)
checkUnique = UNIQUE_CHECK_YES;
else
checkUnique = UNIQUE_CHECK_PARTIAL;
satisfiesConstraint =
index_insert(indexRelation, /* index relation */
values, /* array of index Datums */
isnull, /* null flags */
tupleid, /* tid of heap tuple */
heapRelation, /* heap relation */
checkUnique); /* type of uniqueness check to do */
/*
* If the index has an associated exclusion constraint, check that.
* This is simpler than the process for uniqueness checks since we
* always insert first and then check. If the constraint is deferred,
* we check now anyway, but don't throw error on violation or wait for
* a conclusive outcome from a concurrent insertion; instead we'll
* queue a recheck event. Similarly, noDupErr callers (speculative
* inserters) will recheck later, and wait for a conclusive outcome
* then.
*
* An index for an exclusion constraint can't also be UNIQUE (not an
* essential property, we just don't allow it in the grammar), so no
* need to preserve the prior state of satisfiesConstraint.
*/
if (indexInfo->ii_ExclusionOps != NULL)
{
bool violationOK;
CEOUC_WAIT_MODE waitMode;
if (applyNoDupErr)
{
violationOK = true;
waitMode = CEOUC_LIVELOCK_PREVENTING_WAIT;
}
else if (!indexRelation->rd_index->indimmediate)
{
violationOK = true;
waitMode = CEOUC_NOWAIT;
}
else
{
violationOK = false;
waitMode = CEOUC_WAIT;
}
satisfiesConstraint =
check_exclusion_or_unique_constraint(heapRelation,
indexRelation, indexInfo,
tupleid, values, isnull,
estate, false,
waitMode, violationOK, NULL);
}
if ((checkUnique == UNIQUE_CHECK_PARTIAL ||
indexInfo->ii_ExclusionOps != NULL) &&
!satisfiesConstraint)
{
/*
* The tuple potentially violates the uniqueness or exclusion
* constraint, so make a note of the index so that we can re-check
* it later. Speculative inserters are told if there was a
* speculative conflict, since that always requires a restart.
*/
result = lappend_oid(result, RelationGetRelid(indexRelation));
if (indexRelation->rd_index->indimmediate && specConflict)
*specConflict = true;
}
}
return result;
}
/* ----------------------------------------------------------------
* ExecCheckIndexConstraints
*
* This routine checks if a tuple violates any unique or
* exclusion constraints. Returns true if there is no conflict.
* Otherwise returns false, and the TID of the conflicting
* tuple is returned in *conflictTid.
*
* If 'arbiterIndexes' is given, only those indexes are checked.
* NIL means all indexes.
*
* Note that this doesn't lock the values in any way, so it's
* possible that a conflicting tuple is inserted immediately
* after this returns. But this can be used for a pre-check
* before insertion.
* ----------------------------------------------------------------
*/
bool
ExecCheckIndexConstraints(TupleTableSlot *slot,
EState *estate, ItemPointer conflictTid,
List *arbiterIndexes)
{
ResultRelInfo *resultRelInfo;
int i;
int numIndices;
RelationPtr relationDescs;
Relation heapRelation;
IndexInfo **indexInfoArray;
ExprContext *econtext;
Datum values[INDEX_MAX_KEYS];
bool isnull[INDEX_MAX_KEYS];
ItemPointerData invalidItemPtr;
bool checkedIndex = false;
ItemPointerSetInvalid(conflictTid);
ItemPointerSetInvalid(&invalidItemPtr);
/*
* Get information from the result relation info structure.
*/
resultRelInfo = estate->es_result_relation_info;
numIndices = resultRelInfo->ri_NumIndices;
relationDescs = resultRelInfo->ri_IndexRelationDescs;
indexInfoArray = resultRelInfo->ri_IndexRelationInfo;
heapRelation = resultRelInfo->ri_RelationDesc;
/*
* We will use the EState's per-tuple context for evaluating predicates
* and index expressions (creating it if it's not already there).
*/
econtext = GetPerTupleExprContext(estate);
/* Arrange for econtext's scan tuple to be the tuple under test */
econtext->ecxt_scantuple = slot;
/*
* For each index, form index tuple and check if it satisfies the
* constraint.
*/
for (i = 0; i < numIndices; i++)
{
Relation indexRelation = relationDescs[i];
IndexInfo *indexInfo;
bool satisfiesConstraint;
if (indexRelation == NULL)
continue;
indexInfo = indexInfoArray[i];
if (!indexInfo->ii_Unique && !indexInfo->ii_ExclusionOps)
continue;
/* If the index is marked as read-only, ignore it */
if (!indexInfo->ii_ReadyForInserts)
continue;
/* When specific arbiter indexes requested, only examine them */
if (arbiterIndexes != NIL &&
!list_member_oid(arbiterIndexes,
indexRelation->rd_index->indexrelid))
continue;
if (!indexRelation->rd_index->indimmediate)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("ON CONFLICT does not support deferrable unique constraints/exclusion constraints as arbiters"),
errtableconstraint(heapRelation,
RelationGetRelationName(indexRelation))));
checkedIndex = true;
/* Check for partial index */
if (indexInfo->ii_Predicate != NIL)
{
List *predicate;
/*
* If predicate state not set up yet, create it (in the estate's
* per-query context)
*/
predicate = indexInfo->ii_PredicateState;
if (predicate == NIL)
{
predicate = (List *)
ExecPrepareExpr((Expr *) indexInfo->ii_Predicate,
estate);
indexInfo->ii_PredicateState = predicate;
}
/* Skip this index-update if the predicate isn't satisfied */
if (!ExecQual(predicate, econtext, false))
continue;
}
/*
* FormIndexDatum fills in its values and isnull parameters with the
* appropriate values for the column(s) of the index.
*/
FormIndexDatum(indexInfo,
slot,
estate,
values,
isnull);
satisfiesConstraint =
check_exclusion_or_unique_constraint(heapRelation, indexRelation,
indexInfo, &invalidItemPtr,
values, isnull, estate, false,
CEOUC_WAIT, true,
conflictTid);
if (!satisfiesConstraint)
return false;
}
if (arbiterIndexes != NIL && !checkedIndex)
elog(ERROR, "unexpected failure to find arbiter index");
return true;
}
/*
* Check for violation of an exclusion or unique constraint
*
* heap: the table containing the new tuple
* index: the index supporting the constraint
* indexInfo: info about the index, including the exclusion properties
* tupleid: heap TID of the new tuple we have just inserted (invalid if we
* haven't inserted a new tuple yet)
* values, isnull: the *index* column values computed for the new tuple
* estate: an EState we can do evaluation in
* newIndex: if true, we are trying to build a new index (this affects
* only the wording of error messages)
* waitMode: whether to wait for concurrent inserters/deleters
* violationOK: if true, don't throw error for violation
* conflictTid: if not-NULL, the TID of the conflicting tuple is returned here
*
* Returns true if OK, false if actual or potential violation
*
* 'waitMode' determines what happens if a conflict is detected with a tuple
* that was inserted or deleted by a transaction that's still running.
* CEOUC_WAIT means that we wait for the transaction to commit, before
* throwing an error or returning. CEOUC_NOWAIT means that we report the
* violation immediately; so the violation is only potential, and the caller
* must recheck sometime later. This behavior is convenient for deferred
* exclusion checks; we need not bother queuing a deferred event if there is
* definitely no conflict at insertion time.
*
* CEOUC_LIVELOCK_PREVENTING_WAIT is like CEOUC_NOWAIT, but we will sometimes
* wait anyway, to prevent livelocking if two transactions try inserting at
* the same time. This is used with speculative insertions, for INSERT ON
* CONFLICT statements. (See notes in file header)
*
* If violationOK is true, we just report the potential or actual violation to
* the caller by returning 'false'. Otherwise we throw a descriptive error
* message here. When violationOK is false, a false result is impossible.
*
* Note: The indexam is normally responsible for checking unique constraints,
* so this normally only needs to be used for exclusion constraints. But this
* function is also called when doing a "pre-check" for conflicts on a unique
* constraint, when doing speculative insertion. Caller may use the returned
* conflict TID to take further steps.
*/
static bool
check_exclusion_or_unique_constraint(Relation heap, Relation index,
IndexInfo *indexInfo,
ItemPointer tupleid,
Datum *values, bool *isnull,
EState *estate, bool newIndex,
CEOUC_WAIT_MODE waitMode,
bool violationOK,
ItemPointer conflictTid)
{
Oid *constr_procs;
uint16 *constr_strats;
Oid *index_collations = index->rd_indcollation;
int index_natts = index->rd_index->indnatts;
IndexScanDesc index_scan;
HeapTuple tup;
ScanKeyData scankeys[INDEX_MAX_KEYS];
SnapshotData DirtySnapshot;
int i;
bool conflict;
bool found_self;
ExprContext *econtext;
TupleTableSlot *existing_slot;
TupleTableSlot *save_scantuple;
if (indexInfo->ii_ExclusionOps)
{
constr_procs = indexInfo->ii_ExclusionProcs;
constr_strats = indexInfo->ii_ExclusionStrats;
}
else
{
constr_procs = indexInfo->ii_UniqueProcs;
constr_strats = indexInfo->ii_UniqueStrats;
}
/*
* If any of the input values are NULL, the constraint check is assumed to
* pass (i.e., we assume the operators are strict).
*/
for (i = 0; i < index_natts; i++)
{
if (isnull[i])
return true;
}
/*
* Search the tuples that are in the index for any violations, including
* tuples that aren't visible yet.
*/
InitDirtySnapshot(DirtySnapshot);
for (i = 0; i < index_natts; i++)
{
ScanKeyEntryInitialize(&scankeys[i],
0,
i + 1,
constr_strats[i],
InvalidOid,
index_collations[i],
constr_procs[i],
values[i]);
}
/*
* Need a TupleTableSlot to put existing tuples in.
*
* To use FormIndexDatum, we have to make the econtext's scantuple point
* to this slot. Be sure to save and restore caller's value for
* scantuple.
*/
existing_slot = MakeSingleTupleTableSlot(RelationGetDescr(heap));
econtext = GetPerTupleExprContext(estate);
save_scantuple = econtext->ecxt_scantuple;
econtext->ecxt_scantuple = existing_slot;
/*
* May have to restart scan from this point if a potential conflict is
* found.
*/
retry:
conflict = false;
found_self = false;
index_scan = index_beginscan(heap, index, &DirtySnapshot, index_natts, 0);
index_rescan(index_scan, scankeys, index_natts, NULL, 0);
while ((tup = index_getnext(index_scan,
ForwardScanDirection)) != NULL)
{
TransactionId xwait;
ItemPointerData ctid_wait;
XLTW_Oper reason_wait;
Datum existing_values[INDEX_MAX_KEYS];
bool existing_isnull[INDEX_MAX_KEYS];
char *error_new;
char *error_existing;
/*
* Ignore the entry for the tuple we're trying to check.
*/
if (ItemPointerIsValid(tupleid) &&
ItemPointerEquals(tupleid, &tup->t_self))
{
if (found_self) /* should not happen */
elog(ERROR, "found self tuple multiple times in index \"%s\"",
RelationGetRelationName(index));
found_self = true;
continue;
}
/*
* Extract the index column values and isnull flags from the existing
* tuple.
*/
ExecStoreTuple(tup, existing_slot, InvalidBuffer, false);
FormIndexDatum(indexInfo, existing_slot, estate,
existing_values, existing_isnull);
/* If lossy indexscan, must recheck the condition */
if (index_scan->xs_recheck)
{
if (!index_recheck_constraint(index,
constr_procs,
existing_values,
existing_isnull,
values))
continue; /* tuple doesn't actually match, so no
* conflict */
}
/*
* At this point we have either a conflict or a potential conflict.
*
* If an in-progress transaction is affecting the visibility of this
* tuple, we need to wait for it to complete and then recheck (unless
* the caller requested not to). For simplicity we do rechecking by
* just restarting the whole scan --- this case probably doesn't
* happen often enough to be worth trying harder, and anyway we don't
* want to hold any index internal locks while waiting.
*/
xwait = TransactionIdIsValid(DirtySnapshot.xmin) ?
DirtySnapshot.xmin : DirtySnapshot.xmax;
if (TransactionIdIsValid(xwait) &&
(waitMode == CEOUC_WAIT ||
(waitMode == CEOUC_LIVELOCK_PREVENTING_WAIT &&
DirtySnapshot.speculativeToken &&
TransactionIdPrecedes(GetCurrentTransactionId(), xwait))))
{
ctid_wait = tup->t_data->t_ctid;
reason_wait = indexInfo->ii_ExclusionOps ?
XLTW_RecheckExclusionConstr : XLTW_InsertIndex;
index_endscan(index_scan);
if (DirtySnapshot.speculativeToken)
SpeculativeInsertionWait(DirtySnapshot.xmin,
DirtySnapshot.speculativeToken);
else
XactLockTableWait(xwait, heap, &ctid_wait, reason_wait);
goto retry;
}
/*
* We have a definite conflict (or a potential one, but the caller
* didn't want to wait). Return it to caller, or report it.
*/
if (violationOK)
{
conflict = true;
if (conflictTid)
*conflictTid = tup->t_self;
break;
}
error_new = BuildIndexValueDescription(index, values, isnull);
error_existing = BuildIndexValueDescription(index, existing_values,
existing_isnull);
if (newIndex)
ereport(ERROR,
(errcode(ERRCODE_EXCLUSION_VIOLATION),
errmsg("could not create exclusion constraint \"%s\"",
RelationGetRelationName(index)),
error_new && error_existing ?
errdetail("Key %s conflicts with key %s.",
error_new, error_existing) :
errdetail("Key conflicts exist."),
errtableconstraint(heap,
RelationGetRelationName(index))));
else
ereport(ERROR,
(errcode(ERRCODE_EXCLUSION_VIOLATION),
errmsg("conflicting key value violates exclusion constraint \"%s\"",
RelationGetRelationName(index)),
error_new && error_existing ?
errdetail("Key %s conflicts with existing key %s.",
error_new, error_existing) :
errdetail("Key conflicts with existing key."),
errtableconstraint(heap,
RelationGetRelationName(index))));
}
index_endscan(index_scan);
/*
* Ordinarily, at this point the search should have found the originally
* inserted tuple (if any), unless we exited the loop early because of
* conflict. However, it is possible to define exclusion constraints for
* which that wouldn't be true --- for instance, if the operator is <>. So
* we no longer complain if found_self is still false.
*/
econtext->ecxt_scantuple = save_scantuple;
ExecDropSingleTupleTableSlot(existing_slot);
return !conflict;
}
/*
* Check for violation of an exclusion constraint
*
* This is a dumbed down version of check_exclusion_or_unique_constraint
* for external callers. They don't need all the special modes.
*/
void
check_exclusion_constraint(Relation heap, Relation index,
IndexInfo *indexInfo,
ItemPointer tupleid,
Datum *values, bool *isnull,
EState *estate, bool newIndex)
{
(void) check_exclusion_or_unique_constraint(heap, index, indexInfo, tupleid,
values, isnull,
estate, newIndex,
CEOUC_WAIT, false, NULL);
}
/*
* Check existing tuple's index values to see if it really matches the
* exclusion condition against the new_values. Returns true if conflict.
*/
static bool
index_recheck_constraint(Relation index, Oid *constr_procs,
Datum *existing_values, bool *existing_isnull,
Datum *new_values)
{
int index_natts = index->rd_index->indnatts;
int i;
for (i = 0; i < index_natts; i++)
{
/* Assume the exclusion operators are strict */
if (existing_isnull[i])
return false;
if (!DatumGetBool(OidFunctionCall2Coll(constr_procs[i],
index->rd_indcollation[i],
existing_values[i],
new_values[i])))
return false;
}
return true;
}