database/postgres
database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-04-25 21:42:33 +03:00
Code
postgres/src/backend/utils/adt/ri_triggers.c
Alvaro Herrera 99392cdd78
Rewrite some RI code to avoid using SPI 
Modify the subroutines called by RI trigger functions that want to check
if a given referenced value exists in the referenced relation to simply
scan the foreign key constraint's unique index, instead of using SPI to
execute
  SELECT 1 FROM referenced_relation WHERE ref_key = $1
This saves a lot of work, especially when inserting into or updating a
referencing relation.

This rewrite allows to fix a PK row visibility bug caused by a partition
descriptor hack which requires ActiveSnapshot to be set to come up with
the correct set of partitions for the RI query running under REPEATABLE
READ isolation.  We now set that snapshot indepedently of the snapshot
to be used by the PK index scan, so the two no longer interfere.  The
buggy output in src/test/isolation/expected/fk-snapshot.out of the
relevant test case added by commit 00cb86e75d6d has been corrected.
(The bug still exists in branch 14, however, but this fix is too
invasive to backpatch.)

Author: Amit Langote <amitlangote09@gmail.com>
Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Reviewed-by: Corey Huinker <corey.huinker@gmail.com>
Reviewed-by: Li Japin <japinli@hotmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Zhihong Yu <zyu@yugabyte.com>
Discussion: https://postgr.es/m/CA+HiwqGkfJfYdeq5vHPh6eqPKjSbfpDDY+j-kXYFePQedtSLeg@mail.gmail.com
2022-04-07 21:10:03 +02:00

3110 lines
92 KiB
C
Raw Blame History

/*-------------------------------------------------------------------------
*
* ri_triggers.c
*
* Generic trigger procedures for referential integrity constraint
* checks.
*
* Note about memory management: the private hashtables kept here live
* across query and transaction boundaries, in fact they live as long as
* the backend does. This works because the hashtable structures
* themselves are allocated by dynahash.c in its permanent DynaHashCxt,
* and the SPI plans they point to are saved using SPI_keepplan().
* There is not currently any provision for throwing away a no-longer-needed
* plan --- consider improving this someday.
*
*
* Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
*
* src/backend/utils/adt/ri_triggers.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/genam.h"
#include "access/htup_details.h"
#include "access/sysattr.h"
#include "access/table.h"
#include "access/tableam.h"
#include "access/xact.h"
#include "catalog/pg_collation.h"
#include "catalog/pg_constraint.h"
#include "catalog/pg_operator.h"
#include "catalog/pg_type.h"
#include "commands/trigger.h"
#include "executor/execPartition.h"
#include "executor/executor.h"
#include "executor/spi.h"
#include "lib/ilist.h"
#include "miscadmin.h"
#include "parser/parse_coerce.h"
#include "parser/parse_relation.h"
#include "storage/bufmgr.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/datum.h"
#include "utils/fmgroids.h"
#include "utils/guc.h"
#include "utils/inval.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/rel.h"
#include "utils/rls.h"
#include "utils/ruleutils.h"
#include "utils/snapmgr.h"
#include "utils/syscache.h"
/*
* Local definitions
*/
#define RI_MAX_NUMKEYS INDEX_MAX_KEYS
#define RI_INIT_CONSTRAINTHASHSIZE 64
#define RI_INIT_QUERYHASHSIZE (RI_INIT_CONSTRAINTHASHSIZE * 4)
#define RI_KEYS_ALL_NULL 0
#define RI_KEYS_SOME_NULL 1
#define RI_KEYS_NONE_NULL 2
/* RI query type codes */
#define RI_PLAN_CASCADE_ONDELETE 1
#define RI_PLAN_CASCADE_ONUPDATE 2
/* For RESTRICT, the same plan can be used for both ON DELETE and ON UPDATE triggers. */
#define RI_PLAN_RESTRICT 3
#define RI_PLAN_SETNULL_ONDELETE 4
#define RI_PLAN_SETNULL_ONUPDATE 5
#define RI_PLAN_SETDEFAULT_ONDELETE 6
#define RI_PLAN_SETDEFAULT_ONUPDATE 7
#define MAX_QUOTED_NAME_LEN (NAMEDATALEN*2+3)
#define MAX_QUOTED_REL_NAME_LEN (MAX_QUOTED_NAME_LEN*2)
#define RIAttName(rel, attnum) NameStr(*attnumAttName(rel, attnum))
#define RIAttType(rel, attnum) attnumTypeId(rel, attnum)
#define RIAttCollation(rel, attnum) attnumCollationId(rel, attnum)
#define RI_TRIGTYPE_INSERT 1
#define RI_TRIGTYPE_UPDATE 2
#define RI_TRIGTYPE_DELETE 3
/*
* RI_ConstraintInfo
*
* Information extracted from an FK pg_constraint entry. This is cached in
* ri_constraint_cache.
*/
typedef struct RI_ConstraintInfo
{
Oid constraint_id; /* OID of pg_constraint entry (hash key) */
bool valid; /* successfully initialized? */
Oid constraint_root_id; /* OID of topmost ancestor constraint;
* same as constraint_id if not inherited */
uint32 oidHashValue; /* hash value of constraint_id */
uint32 rootHashValue; /* hash value of constraint_root_id */
NameData conname; /* name of the FK constraint */
Oid pk_relid; /* referenced relation */
Oid fk_relid; /* referencing relation */
char confupdtype; /* foreign key's ON UPDATE action */
char confdeltype; /* foreign key's ON DELETE action */
int ndelsetcols; /* number of columns referenced in ON DELETE SET clause */
int16 confdelsetcols[RI_MAX_NUMKEYS]; /* attnums of cols to set on delete */
char confmatchtype; /* foreign key's match type */
int nkeys; /* number of key columns */
int16 pk_attnums[RI_MAX_NUMKEYS]; /* attnums of referenced cols */
int16 fk_attnums[RI_MAX_NUMKEYS]; /* attnums of referencing cols */
Oid pf_eq_oprs[RI_MAX_NUMKEYS]; /* equality operators (PK = FK) */
Oid pp_eq_oprs[RI_MAX_NUMKEYS]; /* equality operators (PK = PK) */
Oid ff_eq_oprs[RI_MAX_NUMKEYS]; /* equality operators (FK = FK) */
dlist_node valid_link; /* Link in list of valid entries */
} RI_ConstraintInfo;
/*
* RI_QueryKey
*
* The key identifying a prepared SPI plan in our query hashtable
*/
typedef struct RI_QueryKey
{
Oid constr_id; /* OID of pg_constraint entry */
int32 constr_queryno; /* query type ID, see RI_PLAN_XXX above */
} RI_QueryKey;
/*
* RI_QueryHashEntry
*/
typedef struct RI_QueryHashEntry
{
RI_QueryKey key;
SPIPlanPtr plan;
} RI_QueryHashEntry;
/*
* RI_CompareKey
*
* The key identifying an entry showing how to compare two values
*/
typedef struct RI_CompareKey
{
Oid eq_opr; /* the equality operator to apply */
Oid typeid; /* the data type to apply it to */
} RI_CompareKey;
/*
* RI_CompareHashEntry
*/
typedef struct RI_CompareHashEntry
{
RI_CompareKey key;
bool valid; /* successfully initialized? */
FmgrInfo eq_opr_finfo; /* call info for equality fn */
FmgrInfo cast_func_finfo; /* in case we must coerce input */
} RI_CompareHashEntry;
/*
* Local data
*/
static HTAB *ri_constraint_cache = NULL;
static HTAB *ri_query_cache = NULL;
static HTAB *ri_compare_cache = NULL;
static dlist_head ri_constraint_cache_valid_list;
static int ri_constraint_cache_valid_count = 0;
/*
* Local function prototypes
*/
static bool ri_Check_Pk_Match(Relation pk_rel, Relation fk_rel,
TupleTableSlot *oldslot,
const RI_ConstraintInfo *riinfo);
static Datum ri_restrict(TriggerData *trigdata, bool is_no_action);
static Datum ri_set(TriggerData *trigdata, bool is_set_null, int tgkind);
static void quoteOneName(char *buffer, const char *name);
static void quoteRelationName(char *buffer, Relation rel);
static void ri_GenerateQual(StringInfo buf,
const char *sep,
const char *leftop, Oid leftoptype,
Oid opoid,
const char *rightop, Oid rightoptype);
static void ri_GenerateQualCollation(StringInfo buf, Oid collation);
static int ri_NullCheck(TupleDesc tupdesc, TupleTableSlot *slot,
const RI_ConstraintInfo *riinfo, bool rel_is_pk);
static void ri_BuildQueryKey(RI_QueryKey *key,
const RI_ConstraintInfo *riinfo,
int32 constr_queryno);
static bool ri_KeysEqual(Relation rel, TupleTableSlot *oldslot, TupleTableSlot *newslot,
const RI_ConstraintInfo *riinfo, bool rel_is_pk);
static bool ri_AttributesEqual(Oid eq_opr, Oid typeid,
Datum oldvalue, Datum newvalue);
static void ri_InitHashTables(void);
static void InvalidateConstraintCacheCallBack(Datum arg, int cacheid, uint32 hashvalue);
static SPIPlanPtr ri_FetchPreparedPlan(RI_QueryKey *key);
static void ri_HashPreparedPlan(RI_QueryKey *key, SPIPlanPtr plan);
static RI_CompareHashEntry *ri_HashCompareOp(Oid eq_opr, Oid typeid);
static void ri_CheckTrigger(FunctionCallInfo fcinfo, const char *funcname,
int tgkind);
static const RI_ConstraintInfo *ri_FetchConstraintInfo(Trigger *trigger,
Relation trig_rel, bool rel_is_pk);
static const RI_ConstraintInfo *ri_LoadConstraintInfo(Oid constraintOid);
static Oid get_ri_constraint_root(Oid constrOid);
static SPIPlanPtr ri_PlanCheck(const char *querystr, int nargs, Oid *argtypes,
RI_QueryKey *qkey, Relation fk_rel, Relation pk_rel);
static bool ri_PerformCheck(const RI_ConstraintInfo *riinfo,
RI_QueryKey *qkey, SPIPlanPtr qplan,
Relation fk_rel, Relation pk_rel,
TupleTableSlot *oldslot, TupleTableSlot *newslot,
bool detectNewRows, int expect_OK);
static void ri_ExtractValues(Relation rel, TupleTableSlot *slot,
const RI_ConstraintInfo *riinfo, bool rel_is_pk,
Datum *vals, char *nulls);
static void ri_ReportViolation(const RI_ConstraintInfo *riinfo,
Relation pk_rel, Relation fk_rel,
TupleTableSlot *violatorslot, TupleDesc tupdesc,
bool on_fk, bool partgone) pg_attribute_noreturn();
static Oid get_fkey_unique_index(Oid conoid);
/*
* Checks whether a tuple containing the unique key as extracted from the
* tuple provided in 'slot' exists in 'pk_rel'. The key is extracted using the
* constraint's index given in 'riinfo', which is also scanned to check the
* existence of the key.
*
* If 'pk_rel' is a partitioned table, the check is performed on its leaf
* partition that would contain the key.
*
* The provided tuple is either the one being inserted into the referencing
* relation ('fk_rel' is non-NULL), or the one being deleted from the
* referenced relation, that is, 'pk_rel' ('fk_rel' is NULL).
*/
static bool
ri_ReferencedKeyExists(Relation pk_rel, Relation fk_rel,
TupleTableSlot *slot, const RI_ConstraintInfo *riinfo)
{
Oid constr_id = riinfo->constraint_id;
Oid idxoid;
Relation idxrel;
Relation leaf_pk_rel = NULL;
int num_pk;
int i;
bool found = false;
const Oid *eq_oprs;
Datum pk_vals[INDEX_MAX_KEYS];
char pk_nulls[INDEX_MAX_KEYS];
ScanKeyData skey[INDEX_MAX_KEYS];
Snapshot snap = InvalidSnapshot;
bool pushed_latest_snapshot = false;
IndexScanDesc scan;
TupleTableSlot *outslot;
Oid saved_userid;
int saved_sec_context;
AclResult aclresult;
/*
* Extract the unique key from the provided slot and choose the equality
* operators to use when scanning the index below.
*/
if (fk_rel)
{
ri_ExtractValues(fk_rel, slot, riinfo, false, pk_vals, pk_nulls);
/* Use PK = FK equality operator. */
eq_oprs = riinfo->pf_eq_oprs;
/*
* May need to cast each of the individual values of the foreign key
* to the corresponding PK column's type if the equality operator
* demands it.
*/
for (i = 0; i < riinfo->nkeys; i++)
{
if (pk_nulls[i] != 'n')
{
Oid eq_opr = eq_oprs[i];
Oid typeid = RIAttType(fk_rel, riinfo->fk_attnums[i]);
RI_CompareHashEntry *entry = ri_HashCompareOp(eq_opr, typeid);
if (OidIsValid(entry->cast_func_finfo.fn_oid))
pk_vals[i] = FunctionCall3(&entry->cast_func_finfo,
pk_vals[i],
Int32GetDatum(-1), /* typmod */
BoolGetDatum(false)); /* implicit coercion */
}
}
}
else
{
ri_ExtractValues(pk_rel, slot, riinfo, true, pk_vals, pk_nulls);
/* Use PK = PK equality operator. */
eq_oprs = riinfo->pp_eq_oprs;
}
/*
* Switch to referenced table's owner to perform the below operations as.
* This matches what ri_PerformCheck() does.
*
* Note that as with queries done by ri_PerformCheck(), the way we select
* the referenced row below effectively bypasses any RLS policies that may
* be present on the referenced table.
*/
GetUserIdAndSecContext(&saved_userid, &saved_sec_context);
SetUserIdAndSecContext(RelationGetForm(pk_rel)->relowner,
saved_sec_context | SECURITY_LOCAL_USERID_CHANGE);
/*
* Also check that the new user has permissions to look into the schema of
* and SELECT from the referenced table.
*/
aclresult = pg_namespace_aclcheck(RelationGetNamespace(pk_rel),
GetUserId(), ACL_USAGE);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, OBJECT_SCHEMA,
get_namespace_name(RelationGetNamespace(pk_rel)));
aclresult = pg_class_aclcheck(RelationGetRelid(pk_rel), GetUserId(),
ACL_SELECT);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, OBJECT_TABLE,
RelationGetRelationName(pk_rel));
/* Make the changes of the current command visible in all cases. */
CommandCounterIncrement();
/*
* In the case of scanning the PK index for ri_Check_Pk_Match(), we'd like
* to see all rows that could be interesting, even those that would not be
* visible to the transaction snapshot. To do so, force-push the latest
* snapshot.
*/
if (fk_rel == NULL)
{
snap = GetLatestSnapshot();
PushActiveSnapshot(snap);
pushed_latest_snapshot = true;
}
else
{
snap = GetTransactionSnapshot();
PushActiveSnapshot(snap);
}
/*
* Open the constraint index to be scanned.
*
* If the target table is partitioned, we must look up the leaf partition
* and its corresponding unique index to search the keys in.
*/
idxoid = get_fkey_unique_index(constr_id);
if (pk_rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
{
Oid leaf_idxoid;
Snapshot mysnap = InvalidSnapshot;
/*
* XXX the partition descriptor machinery has a hack that assumes that
* the queries originating in this module push the latest snapshot in
* the transaction-snapshot mode. If we haven't pushed one already,
* do so now.
*/
if (!pushed_latest_snapshot)
{
mysnap = GetLatestSnapshot();
PushActiveSnapshot(mysnap);
}
leaf_pk_rel = ExecGetLeafPartitionForKey(pk_rel, riinfo->nkeys,
riinfo->pk_attnums,
pk_vals, pk_nulls,
idxoid, RowShareLock,
&leaf_idxoid);
/*
* XXX done fiddling with the partition descriptor machinery so unset
* the active snapshot if we must.
*/
if (mysnap != InvalidSnapshot)
PopActiveSnapshot();
/*
* If no suitable leaf partition exists, neither can the key we're
* looking for.
*/
if (leaf_pk_rel == NULL)
{
SetUserIdAndSecContext(saved_userid, saved_sec_context);
PopActiveSnapshot();
return false;
}
pk_rel = leaf_pk_rel;
idxoid = leaf_idxoid;
}
idxrel = index_open(idxoid, RowShareLock);
/* Set up ScanKeys for the index scan. */
num_pk = IndexRelationGetNumberOfKeyAttributes(idxrel);
for (i = 0; i < num_pk; i++)
{
int pkattno = i + 1;
Oid operator = eq_oprs[i];
Oid opfamily = idxrel->rd_opfamily[i];
StrategyNumber strat = get_op_opfamily_strategy(operator, opfamily);
RegProcedure regop = get_opcode(operator);
/* Initialize the scankey. */
ScanKeyInit(&skey[i],
pkattno,
strat,
regop,
pk_vals[i]);
skey[i].sk_collation = idxrel->rd_indcollation[i];
/*
* Check for null value. Should not occur, because callers currently
* take care of the cases in which they do occur.
*/
if (pk_nulls[i] == 'n')
skey[i].sk_flags |= SK_ISNULL;
}
scan = index_beginscan(pk_rel, idxrel, snap, num_pk, 0);
index_rescan(scan, skey, num_pk, NULL, 0);
/* Look for the tuple, and if found, try to lock it in key share mode. */
outslot = table_slot_create(pk_rel, NULL);
if (index_getnext_slot(scan, ForwardScanDirection, outslot))
{
/*
* If we fail to lock the tuple for whatever reason, assume it doesn't
* exist.
*/
found = ExecLockTableTuple(pk_rel, &(outslot->tts_tid), outslot,
snap,
GetCurrentCommandId(false),
LockTupleKeyShare,
LockWaitBlock, NULL);
}
index_endscan(scan);
ExecDropSingleTupleTableSlot(outslot);
/* Don't release lock until commit. */
index_close(idxrel, NoLock);
/* Close leaf partition relation if any. */
if (leaf_pk_rel)
table_close(leaf_pk_rel, NoLock);
/* Restore UID and security context */
SetUserIdAndSecContext(saved_userid, saved_sec_context);
PopActiveSnapshot();
return found;
}
/*
* get_fkey_unique_index
* Returns the unique index used by a supposedly foreign key constraint
*
* XXX This is very similar to get_constraint_index; probably they should be
* unified.
*/
static Oid
get_fkey_unique_index(Oid conoid)
{
Oid result = InvalidOid;
HeapTuple tp;
tp = SearchSysCache1(CONSTROID, ObjectIdGetDatum(conoid));
if (HeapTupleIsValid(tp))
{
Form_pg_constraint contup = (Form_pg_constraint) GETSTRUCT(tp);
if (contup->contype == CONSTRAINT_FOREIGN)
result = contup->conindid;
ReleaseSysCache(tp);
}
if (!OidIsValid(result))
elog(ERROR, "unique index not found for foreign key constraint %u",
conoid);
return result;
}
/*
* RI_FKey_check -
*
* Check foreign key existence (combined for INSERT and UPDATE).
*/
static Datum
RI_FKey_check(TriggerData *trigdata)
{
const RI_ConstraintInfo *riinfo;
Relation fk_rel;
Relation pk_rel;
TupleTableSlot *newslot;
riinfo = ri_FetchConstraintInfo(trigdata->tg_trigger,
trigdata->tg_relation, false);
if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
newslot = trigdata->tg_newslot;
else
newslot = trigdata->tg_trigslot;
/*
* We should not even consider checking the row if it is no longer valid,
* since it was either deleted (so the deferred check should be skipped)
* or updated (in which case only the latest version of the row should be
* checked). Test its liveness according to SnapshotSelf. We need pin
* and lock on the buffer to call HeapTupleSatisfiesVisibility. Caller
* should be holding pin, but not lock.
*/
if (!table_tuple_satisfies_snapshot(trigdata->tg_relation, newslot, SnapshotSelf))
return PointerGetDatum(NULL);
/*
* Get the relation descriptors of the FK and PK tables.
*
* pk_rel is opened in RowShareLock mode since that's what our eventual
* SELECT FOR KEY SHARE will get on it.
*/
fk_rel = trigdata->tg_relation;
pk_rel = table_open(riinfo->pk_relid, RowShareLock);
switch (ri_NullCheck(RelationGetDescr(fk_rel), newslot, riinfo, false))
{
case RI_KEYS_ALL_NULL:
/*
* No further check needed - an all-NULL key passes every type of
* foreign key constraint.
*/
table_close(pk_rel, RowShareLock);
return PointerGetDatum(NULL);
case RI_KEYS_SOME_NULL:
/*
* This is the only case that differs between the three kinds of
* MATCH.
*/
switch (riinfo->confmatchtype)
{
case FKCONSTR_MATCH_FULL:
/*
* Not allowed - MATCH FULL says either all or none of the
* attributes can be NULLs
*/
ereport(ERROR,
(errcode(ERRCODE_FOREIGN_KEY_VIOLATION),
errmsg("insert or update on table \"%s\" violates foreign key constraint \"%s\"",
RelationGetRelationName(fk_rel),
NameStr(riinfo->conname)),
errdetail("MATCH FULL does not allow mixing of null and nonnull key values."),
errtableconstraint(fk_rel,
NameStr(riinfo->conname))));
table_close(pk_rel, RowShareLock);
return PointerGetDatum(NULL);
case FKCONSTR_MATCH_SIMPLE:
/*
* MATCH SIMPLE - if ANY column is null, the key passes
* the constraint.
*/
table_close(pk_rel, RowShareLock);
return PointerGetDatum(NULL);
#ifdef NOT_USED
case FKCONSTR_MATCH_PARTIAL:
/*
* MATCH PARTIAL - all non-null columns must match. (not
* implemented, can be done by modifying
* ri_ReferencedKeyExists() to only include non-null
* columns.
*/
break;
#endif
}
case RI_KEYS_NONE_NULL:
/*
* Have a full qualified key - continue below for all three kinds
* of MATCH.
*/
break;
}
if (!ri_ReferencedKeyExists(pk_rel, fk_rel, newslot, riinfo))
ri_ReportViolation(riinfo,
pk_rel, fk_rel,
newslot,
NULL,
true, false);
table_close(pk_rel, RowShareLock);
return PointerGetDatum(NULL);
}
/*
* RI_FKey_check_ins -
*
* Check foreign key existence at insert event on FK table.
*/
Datum
RI_FKey_check_ins(PG_FUNCTION_ARGS)
{
/* Check that this is a valid trigger call on the right time and event. */
ri_CheckTrigger(fcinfo, "RI_FKey_check_ins", RI_TRIGTYPE_INSERT);
/* Share code with UPDATE case. */
return RI_FKey_check((TriggerData *) fcinfo->context);
}
/*
* RI_FKey_check_upd -
*
* Check foreign key existence at update event on FK table.
*/
Datum
RI_FKey_check_upd(PG_FUNCTION_ARGS)
{
/* Check that this is a valid trigger call on the right time and event. */
ri_CheckTrigger(fcinfo, "RI_FKey_check_upd", RI_TRIGTYPE_UPDATE);
/* Share code with INSERT case. */
return RI_FKey_check((TriggerData *) fcinfo->context);
}
/*
* ri_Check_Pk_Match
*
* Check to see if another PK row has been created that provides the same
* key values as the "oldslot" that's been modified or deleted in our trigger
* event. Returns true if a match is found in the PK table.
*
* We assume the caller checked that the oldslot contains no NULL key values,
* since otherwise a match is impossible.
*/
static bool
ri_Check_Pk_Match(Relation pk_rel, Relation fk_rel,
TupleTableSlot *oldslot,
const RI_ConstraintInfo *riinfo)
{
/* Only called for non-null rows */
Assert(ri_NullCheck(RelationGetDescr(pk_rel), oldslot, riinfo, true) == RI_KEYS_NONE_NULL);
return ri_ReferencedKeyExists(pk_rel, NULL, oldslot, riinfo);
}
/*
* RI_FKey_noaction_del -
*
* Give an error and roll back the current transaction if the
* delete has resulted in a violation of the given referential
* integrity constraint.
*/
Datum
RI_FKey_noaction_del(PG_FUNCTION_ARGS)
{
/* Check that this is a valid trigger call on the right time and event. */
ri_CheckTrigger(fcinfo, "RI_FKey_noaction_del", RI_TRIGTYPE_DELETE);
/* Share code with RESTRICT/UPDATE cases. */
return ri_restrict((TriggerData *) fcinfo->context, true);
}
/*
* RI_FKey_restrict_del -
*
* Restrict delete from PK table to rows unreferenced by foreign key.
*
* The SQL standard intends that this referential action occur exactly when
* the delete is performed, rather than after. This appears to be
* the only difference between "NO ACTION" and "RESTRICT". In Postgres
* we still implement this as an AFTER trigger, but it's non-deferrable.
*/
Datum
RI_FKey_restrict_del(PG_FUNCTION_ARGS)
{
/* Check that this is a valid trigger call on the right time and event. */
ri_CheckTrigger(fcinfo, "RI_FKey_restrict_del", RI_TRIGTYPE_DELETE);
/* Share code with NO ACTION/UPDATE cases. */
return ri_restrict((TriggerData *) fcinfo->context, false);
}
/*
* RI_FKey_noaction_upd -
*
* Give an error and roll back the current transaction if the
* update has resulted in a violation of the given referential
* integrity constraint.
*/
Datum
RI_FKey_noaction_upd(PG_FUNCTION_ARGS)
{
/* Check that this is a valid trigger call on the right time and event. */
ri_CheckTrigger(fcinfo, "RI_FKey_noaction_upd", RI_TRIGTYPE_UPDATE);
/* Share code with RESTRICT/DELETE cases. */
return ri_restrict((TriggerData *) fcinfo->context, true);
}
/*
* RI_FKey_restrict_upd -
*
* Restrict update of PK to rows unreferenced by foreign key.
*
* The SQL standard intends that this referential action occur exactly when
* the update is performed, rather than after. This appears to be
* the only difference between "NO ACTION" and "RESTRICT". In Postgres
* we still implement this as an AFTER trigger, but it's non-deferrable.
*/
Datum
RI_FKey_restrict_upd(PG_FUNCTION_ARGS)
{
/* Check that this is a valid trigger call on the right time and event. */
ri_CheckTrigger(fcinfo, "RI_FKey_restrict_upd", RI_TRIGTYPE_UPDATE);
/* Share code with NO ACTION/DELETE cases. */
return ri_restrict((TriggerData *) fcinfo->context, false);
}
/*
* ri_restrict -
*
* Common code for ON DELETE RESTRICT, ON DELETE NO ACTION,
* ON UPDATE RESTRICT, and ON UPDATE NO ACTION.
*/
static Datum
ri_restrict(TriggerData *trigdata, bool is_no_action)
{
const RI_ConstraintInfo *riinfo;
Relation fk_rel;
Relation pk_rel;
TupleTableSlot *oldslot;
RI_QueryKey qkey;
SPIPlanPtr qplan;
riinfo = ri_FetchConstraintInfo(trigdata->tg_trigger,
trigdata->tg_relation, true);
/*
* Get the relation descriptors of the FK and PK tables and the old tuple.
*
* fk_rel is opened in RowShareLock mode since that's what our eventual
* SELECT FOR KEY SHARE will get on it.
*/
fk_rel = table_open(riinfo->fk_relid, RowShareLock);
pk_rel = trigdata->tg_relation;
oldslot = trigdata->tg_trigslot;
/*
* If another PK row now exists providing the old key values, we should
* not do anything. However, this check should only be made in the NO
* ACTION case; in RESTRICT cases we don't wish to allow another row to be
* substituted.
*/
if (is_no_action &&
ri_Check_Pk_Match(pk_rel, fk_rel, oldslot, riinfo))
{
table_close(fk_rel, RowShareLock);
return PointerGetDatum(NULL);
}
if (SPI_connect() != SPI_OK_CONNECT)
elog(ERROR, "SPI_connect failed");
/*
* Fetch or prepare a saved plan for the restrict lookup (it's the same
* query for delete and update cases)
*/
ri_BuildQueryKey(&qkey, riinfo, RI_PLAN_RESTRICT);
if ((qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
{
StringInfoData querybuf;
char fkrelname[MAX_QUOTED_REL_NAME_LEN];
char attname[MAX_QUOTED_NAME_LEN];
char paramname[16];
const char *querysep;
Oid queryoids[RI_MAX_NUMKEYS];
const char *fk_only;
/* ----------
* The query string built is
* SELECT 1 FROM [ONLY] <fktable> x WHERE $1 = fkatt1 [AND ...]
* FOR KEY SHARE OF x
* The type id's for the $ parameters are those of the
* corresponding PK attributes.
* ----------
*/
initStringInfo(&querybuf);
fk_only = fk_rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE ?
"" : "ONLY ";
quoteRelationName(fkrelname, fk_rel);
appendStringInfo(&querybuf, "SELECT 1 FROM %s%s x",
fk_only, fkrelname);
querysep = "WHERE";
for (int i = 0; i < riinfo->nkeys; i++)
{
Oid pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
Oid fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
Oid pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
Oid fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
quoteOneName(attname,
RIAttName(fk_rel, riinfo->fk_attnums[i]));
sprintf(paramname, "$%d", i + 1);
ri_GenerateQual(&querybuf, querysep,
paramname, pk_type,
riinfo->pf_eq_oprs[i],
attname, fk_type);
if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
ri_GenerateQualCollation(&querybuf, pk_coll);
querysep = "AND";
queryoids[i] = pk_type;
}
appendStringInfoString(&querybuf, " FOR KEY SHARE OF x");
/* Prepare and save the plan */
qplan = ri_PlanCheck(querybuf.data, riinfo->nkeys, queryoids,
&qkey, fk_rel, pk_rel);
}
/*
* We have a plan now. Run it to check for existing references.
*/
ri_PerformCheck(riinfo, &qkey, qplan,
fk_rel, pk_rel,
oldslot, NULL,
true, /* must detect new rows */
SPI_OK_SELECT);
if (SPI_finish() != SPI_OK_FINISH)
elog(ERROR, "SPI_finish failed");
table_close(fk_rel, RowShareLock);
return PointerGetDatum(NULL);
}
/*
* RI_FKey_cascade_del -
*
* Cascaded delete foreign key references at delete event on PK table.
*/
Datum
RI_FKey_cascade_del(PG_FUNCTION_ARGS)
{
TriggerData *trigdata = (TriggerData *) fcinfo->context;
const RI_ConstraintInfo *riinfo;
Relation fk_rel;
Relation pk_rel;
TupleTableSlot *oldslot;
RI_QueryKey qkey;
SPIPlanPtr qplan;
/* Check that this is a valid trigger call on the right time and event. */
ri_CheckTrigger(fcinfo, "RI_FKey_cascade_del", RI_TRIGTYPE_DELETE);
riinfo = ri_FetchConstraintInfo(trigdata->tg_trigger,
trigdata->tg_relation, true);
/*
* Get the relation descriptors of the FK and PK tables and the old tuple.
*
* fk_rel is opened in RowExclusiveLock mode since that's what our
* eventual DELETE will get on it.
*/
fk_rel = table_open(riinfo->fk_relid, RowExclusiveLock);
pk_rel = trigdata->tg_relation;
oldslot = trigdata->tg_trigslot;
if (SPI_connect() != SPI_OK_CONNECT)
elog(ERROR, "SPI_connect failed");
/* Fetch or prepare a saved plan for the cascaded delete */
ri_BuildQueryKey(&qkey, riinfo, RI_PLAN_CASCADE_ONDELETE);
if ((qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
{
StringInfoData querybuf;
char fkrelname[MAX_QUOTED_REL_NAME_LEN];
char attname[MAX_QUOTED_NAME_LEN];
char paramname[16];
const char *querysep;
Oid queryoids[RI_MAX_NUMKEYS];
const char *fk_only;
/* ----------
* The query string built is
* DELETE FROM [ONLY] <fktable> WHERE $1 = fkatt1 [AND ...]
* The type id's for the $ parameters are those of the
* corresponding PK attributes.
* ----------
*/
initStringInfo(&querybuf);
fk_only = fk_rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE ?
"" : "ONLY ";
quoteRelationName(fkrelname, fk_rel);
appendStringInfo(&querybuf, "DELETE FROM %s%s",
fk_only, fkrelname);
querysep = "WHERE";
for (int i = 0; i < riinfo->nkeys; i++)
{
Oid pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
Oid fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
Oid pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
Oid fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
quoteOneName(attname,
RIAttName(fk_rel, riinfo->fk_attnums[i]));
sprintf(paramname, "$%d", i + 1);
ri_GenerateQual(&querybuf, querysep,
paramname, pk_type,
riinfo->pf_eq_oprs[i],
attname, fk_type);
if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
ri_GenerateQualCollation(&querybuf, pk_coll);
querysep = "AND";
queryoids[i] = pk_type;
}
/* Prepare and save the plan */
qplan = ri_PlanCheck(querybuf.data, riinfo->nkeys, queryoids,
&qkey, fk_rel, pk_rel);
}
/*
* We have a plan now. Build up the arguments from the key values in the
* deleted PK tuple and delete the referencing rows
*/
ri_PerformCheck(riinfo, &qkey, qplan,
fk_rel, pk_rel,
oldslot, NULL,
true, /* must detect new rows */
SPI_OK_DELETE);
if (SPI_finish() != SPI_OK_FINISH)
elog(ERROR, "SPI_finish failed");
table_close(fk_rel, RowExclusiveLock);
return PointerGetDatum(NULL);
}
/*
* RI_FKey_cascade_upd -
*
* Cascaded update foreign key references at update event on PK table.
*/
Datum
RI_FKey_cascade_upd(PG_FUNCTION_ARGS)
{
TriggerData *trigdata = (TriggerData *) fcinfo->context;
const RI_ConstraintInfo *riinfo;
Relation fk_rel;
Relation pk_rel;
TupleTableSlot *newslot;
TupleTableSlot *oldslot;
RI_QueryKey qkey;
SPIPlanPtr qplan;
/* Check that this is a valid trigger call on the right time and event. */
ri_CheckTrigger(fcinfo, "RI_FKey_cascade_upd", RI_TRIGTYPE_UPDATE);
riinfo = ri_FetchConstraintInfo(trigdata->tg_trigger,
trigdata->tg_relation, true);
/*
* Get the relation descriptors of the FK and PK tables and the new and
* old tuple.
*
* fk_rel is opened in RowExclusiveLock mode since that's what our
* eventual UPDATE will get on it.
*/
fk_rel = table_open(riinfo->fk_relid, RowExclusiveLock);
pk_rel = trigdata->tg_relation;
newslot = trigdata->tg_newslot;
oldslot = trigdata->tg_trigslot;
if (SPI_connect() != SPI_OK_CONNECT)
elog(ERROR, "SPI_connect failed");
/* Fetch or prepare a saved plan for the cascaded update */
ri_BuildQueryKey(&qkey, riinfo, RI_PLAN_CASCADE_ONUPDATE);
if ((qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
{
StringInfoData querybuf;
StringInfoData qualbuf;
char fkrelname[MAX_QUOTED_REL_NAME_LEN];
char attname[MAX_QUOTED_NAME_LEN];
char paramname[16];
const char *querysep;
const char *qualsep;
Oid queryoids[RI_MAX_NUMKEYS * 2];
const char *fk_only;
/* ----------
* The query string built is
* UPDATE [ONLY] <fktable> SET fkatt1 = $1 [, ...]
* WHERE $n = fkatt1 [AND ...]
* The type id's for the $ parameters are those of the
* corresponding PK attributes. Note that we are assuming
* there is an assignment cast from the PK to the FK type;
* else the parser will fail.
* ----------
*/
initStringInfo(&querybuf);
initStringInfo(&qualbuf);
fk_only = fk_rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE ?
"" : "ONLY ";
quoteRelationName(fkrelname, fk_rel);
appendStringInfo(&querybuf, "UPDATE %s%s SET",
fk_only, fkrelname);
querysep = "";
qualsep = "WHERE";
for (int i = 0, j = riinfo->nkeys; i < riinfo->nkeys; i++, j++)
{
Oid pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
Oid fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
Oid pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
Oid fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
quoteOneName(attname,
RIAttName(fk_rel, riinfo->fk_attnums[i]));
appendStringInfo(&querybuf,
"%s %s = $%d",
querysep, attname, i + 1);
sprintf(paramname, "$%d", j + 1);
ri_GenerateQual(&qualbuf, qualsep,
paramname, pk_type,
riinfo->pf_eq_oprs[i],
attname, fk_type);
if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
ri_GenerateQualCollation(&querybuf, pk_coll);
querysep = ",";
qualsep = "AND";
queryoids[i] = pk_type;
queryoids[j] = pk_type;
}
appendBinaryStringInfo(&querybuf, qualbuf.data, qualbuf.len);
/* Prepare and save the plan */
qplan = ri_PlanCheck(querybuf.data, riinfo->nkeys * 2, queryoids,
&qkey, fk_rel, pk_rel);
}
/*
* We have a plan now. Run it to update the existing references.
*/
ri_PerformCheck(riinfo, &qkey, qplan,
fk_rel, pk_rel,
oldslot, newslot,
true, /* must detect new rows */
SPI_OK_UPDATE);
if (SPI_finish() != SPI_OK_FINISH)
elog(ERROR, "SPI_finish failed");
table_close(fk_rel, RowExclusiveLock);
return PointerGetDatum(NULL);
}
/*
* RI_FKey_setnull_del -
*
* Set foreign key references to NULL values at delete event on PK table.
*/
Datum
RI_FKey_setnull_del(PG_FUNCTION_ARGS)
{
/* Check that this is a valid trigger call on the right time and event. */
ri_CheckTrigger(fcinfo, "RI_FKey_setnull_del", RI_TRIGTYPE_DELETE);
/* Share code with UPDATE case */
return ri_set((TriggerData *) fcinfo->context, true, RI_TRIGTYPE_DELETE);
}
/*
* RI_FKey_setnull_upd -
*
* Set foreign key references to NULL at update event on PK table.
*/
Datum
RI_FKey_setnull_upd(PG_FUNCTION_ARGS)
{
/* Check that this is a valid trigger call on the right time and event. */
ri_CheckTrigger(fcinfo, "RI_FKey_setnull_upd", RI_TRIGTYPE_UPDATE);
/* Share code with DELETE case */
return ri_set((TriggerData *) fcinfo->context, true, RI_TRIGTYPE_UPDATE);
}
/*
* RI_FKey_setdefault_del -
*
* Set foreign key references to defaults at delete event on PK table.
*/
Datum
RI_FKey_setdefault_del(PG_FUNCTION_ARGS)
{
/* Check that this is a valid trigger call on the right time and event. */
ri_CheckTrigger(fcinfo, "RI_FKey_setdefault_del", RI_TRIGTYPE_DELETE);
/* Share code with UPDATE case */
return ri_set((TriggerData *) fcinfo->context, false, RI_TRIGTYPE_DELETE);
}
/*
* RI_FKey_setdefault_upd -
*
* Set foreign key references to defaults at update event on PK table.
*/
Datum
RI_FKey_setdefault_upd(PG_FUNCTION_ARGS)
{
/* Check that this is a valid trigger call on the right time and event. */
ri_CheckTrigger(fcinfo, "RI_FKey_setdefault_upd", RI_TRIGTYPE_UPDATE);
/* Share code with DELETE case */
return ri_set((TriggerData *) fcinfo->context, false, RI_TRIGTYPE_UPDATE);
}
/*
* ri_set -
*
* Common code for ON DELETE SET NULL, ON DELETE SET DEFAULT, ON UPDATE SET
* NULL, and ON UPDATE SET DEFAULT.
*/
static Datum
ri_set(TriggerData *trigdata, bool is_set_null, int tgkind)
{
const RI_ConstraintInfo *riinfo;
Relation fk_rel;
Relation pk_rel;
TupleTableSlot *oldslot;
RI_QueryKey qkey;
SPIPlanPtr qplan;
int32 queryno;
riinfo = ri_FetchConstraintInfo(trigdata->tg_trigger,
trigdata->tg_relation, true);
/*
* Get the relation descriptors of the FK and PK tables and the old tuple.
*
* fk_rel is opened in RowExclusiveLock mode since that's what our
* eventual UPDATE will get on it.
*/
fk_rel = table_open(riinfo->fk_relid, RowExclusiveLock);
pk_rel = trigdata->tg_relation;
oldslot = trigdata->tg_trigslot;
if (SPI_connect() != SPI_OK_CONNECT)
elog(ERROR, "SPI_connect failed");
/*
* Fetch or prepare a saved plan for the trigger.
*/
switch (tgkind) {
case RI_TRIGTYPE_UPDATE:
queryno = is_set_null
? RI_PLAN_SETNULL_ONUPDATE
: RI_PLAN_SETDEFAULT_ONUPDATE;
break;
case RI_TRIGTYPE_DELETE:
queryno = is_set_null
? RI_PLAN_SETNULL_ONDELETE
: RI_PLAN_SETDEFAULT_ONDELETE;
break;
default:
elog(ERROR, "invalid tgkind passed to ri_set");
}
ri_BuildQueryKey(&qkey, riinfo, queryno);
if ((qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
{
StringInfoData querybuf;
char fkrelname[MAX_QUOTED_REL_NAME_LEN];
char attname[MAX_QUOTED_NAME_LEN];
char paramname[16];
const char *querysep;
const char *qualsep;
Oid queryoids[RI_MAX_NUMKEYS];
const char *fk_only;
int num_cols_to_set;
const int16 *set_cols;
switch (tgkind) {
case RI_TRIGTYPE_UPDATE:
num_cols_to_set = riinfo->nkeys;
set_cols = riinfo->fk_attnums;
break;
case RI_TRIGTYPE_DELETE:
/*
* If confdelsetcols are present, then we only update
* the columns specified in that array, otherwise we
* update all the referencing columns.
*/
if (riinfo->ndelsetcols != 0) {
num_cols_to_set = riinfo->ndelsetcols;
set_cols = riinfo->confdelsetcols;
}
else {
num_cols_to_set = riinfo->nkeys;
set_cols = riinfo->fk_attnums;
}
break;
default:
elog(ERROR, "invalid tgkind passed to ri_set");
}
/* ----------
* The query string built is
* UPDATE [ONLY] <fktable> SET fkatt1 = {NULL|DEFAULT} [, ...]
* WHERE $1 = fkatt1 [AND ...]
* The type id's for the $ parameters are those of the
* corresponding PK attributes.
* ----------
*/
initStringInfo(&querybuf);
fk_only = fk_rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE ?
"" : "ONLY ";
quoteRelationName(fkrelname, fk_rel);
appendStringInfo(&querybuf, "UPDATE %s%s SET",
fk_only, fkrelname);
/*
* Add assignment clauses
*/
querysep = "";
for (int i = 0; i < num_cols_to_set; i++)
{
quoteOneName(attname, RIAttName(fk_rel, set_cols[i]));
appendStringInfo(&querybuf,
"%s %s = %s",
querysep, attname,
is_set_null ? "NULL" : "DEFAULT");
querysep = ",";
}
/*
* Add WHERE clause
*/
qualsep = "WHERE";
for (int i = 0; i < riinfo->nkeys; i++)
{
Oid pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
Oid fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
Oid pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
Oid fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
quoteOneName(attname,
RIAttName(fk_rel, riinfo->fk_attnums[i]));
sprintf(paramname, "$%d", i + 1);
ri_GenerateQual(&querybuf, qualsep,
paramname, pk_type,
riinfo->pf_eq_oprs[i],
attname, fk_type);
if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
ri_GenerateQualCollation(&querybuf, pk_coll);
qualsep = "AND";
queryoids[i] = pk_type;
}
/* Prepare and save the plan */
qplan = ri_PlanCheck(querybuf.data, riinfo->nkeys, queryoids,
&qkey, fk_rel, pk_rel);
}
/*
* We have a plan now. Run it to update the existing references.
*/
ri_PerformCheck(riinfo, &qkey, qplan,
fk_rel, pk_rel,
oldslot, NULL,
true, /* must detect new rows */
SPI_OK_UPDATE);
if (SPI_finish() != SPI_OK_FINISH)
elog(ERROR, "SPI_finish failed");
table_close(fk_rel, RowExclusiveLock);
if (is_set_null)
return PointerGetDatum(NULL);
else
{
/*
* If we just deleted or updated the PK row whose key was equal to the
* FK columns' default values, and a referencing row exists in the FK
* table, we would have updated that row to the same values it already
* had --- and RI_FKey_fk_upd_check_required would hence believe no
* check is necessary. So we need to do another lookup now and in
* case a reference still exists, abort the operation. That is
* already implemented in the NO ACTION trigger, so just run it. (This
* recheck is only needed in the SET DEFAULT case, since CASCADE would
* remove such rows in case of a DELETE operation or would change the
* FK key values in case of an UPDATE, while SET NULL is certain to
* result in rows that satisfy the FK constraint.)
*/
return ri_restrict(trigdata, true);
}
}
/*
* RI_FKey_pk_upd_check_required -
*
* Check if we really need to fire the RI trigger for an update or delete to a PK
* relation. This is called by the AFTER trigger queue manager to see if
* it can skip queuing an instance of an RI trigger. Returns true if the
* trigger must be fired, false if we can prove the constraint will still
* be satisfied.
*
* newslot will be NULL if this is called for a delete.
*/
bool
RI_FKey_pk_upd_check_required(Trigger *trigger, Relation pk_rel,
TupleTableSlot *oldslot, TupleTableSlot *newslot)
{
const RI_ConstraintInfo *riinfo;
riinfo = ri_FetchConstraintInfo(trigger, pk_rel, true);
/*
* If any old key value is NULL, the row could not have been referenced by
* an FK row, so no check is needed.
*/
if (ri_NullCheck(RelationGetDescr(pk_rel), oldslot, riinfo, true) != RI_KEYS_NONE_NULL)
return false;
/* If all old and new key values are equal, no check is needed */
if (newslot && ri_KeysEqual(pk_rel, oldslot, newslot, riinfo, true))
return false;
/* Else we need to fire the trigger. */
return true;
}
/*
* RI_FKey_fk_upd_check_required -
*
* Check if we really need to fire the RI trigger for an update to an FK
* relation. This is called by the AFTER trigger queue manager to see if
* it can skip queuing an instance of an RI trigger. Returns true if the
* trigger must be fired, false if we can prove the constraint will still
* be satisfied.
*/
bool
RI_FKey_fk_upd_check_required(Trigger *trigger, Relation fk_rel,
TupleTableSlot *oldslot, TupleTableSlot *newslot)
{
const RI_ConstraintInfo *riinfo;
int ri_nullcheck;
Datum xminDatum;
TransactionId xmin;
bool isnull;
/*
* AfterTriggerSaveEvent() handles things such that this function is never
* called for partitioned tables.
*/
Assert(fk_rel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE);
riinfo = ri_FetchConstraintInfo(trigger, fk_rel, false);
ri_nullcheck = ri_NullCheck(RelationGetDescr(fk_rel), newslot, riinfo, false);
/*
* If all new key values are NULL, the row satisfies the constraint, so no
* check is needed.
*/
if (ri_nullcheck == RI_KEYS_ALL_NULL)
return false;
/*
* If some new key values are NULL, the behavior depends on the match
* type.
*/
else if (ri_nullcheck == RI_KEYS_SOME_NULL)
{
switch (riinfo->confmatchtype)
{
case FKCONSTR_MATCH_SIMPLE:
/*
* If any new key value is NULL, the row must satisfy the
* constraint, so no check is needed.
*/
return false;
case FKCONSTR_MATCH_PARTIAL:
/*
* Don't know, must run full check.
*/
break;
case FKCONSTR_MATCH_FULL:
/*
* If some new key values are NULL, the row fails the
* constraint. We must not throw error here, because the row
* might get invalidated before the constraint is to be
* checked, but we should queue the event to apply the check
* later.
*/
return true;
}
}
/*
* Continues here for no new key values are NULL, or we couldn't decide
* yet.
*/
/*
* If the original row was inserted by our own transaction, we must fire
* the trigger whether or not the keys are equal. This is because our
* UPDATE will invalidate the INSERT so that the INSERT RI trigger will
* not do anything; so we had better do the UPDATE check. (We could skip
* this if we knew the INSERT trigger already fired, but there is no easy
* way to know that.)
*/
xminDatum = slot_getsysattr(oldslot, MinTransactionIdAttributeNumber, &isnull);
Assert(!isnull);
xmin = DatumGetTransactionId(xminDatum);
if (TransactionIdIsCurrentTransactionId(xmin))
return true;
/* If all old and new key values are equal, no check is needed */
if (ri_KeysEqual(fk_rel, oldslot, newslot, riinfo, false))
return false;
/* Else we need to fire the trigger. */
return true;
}
/*
* RI_Initial_Check -
*
* Check an entire table for non-matching values using a single query.
* This is not a trigger procedure, but is called during ALTER TABLE
* ADD FOREIGN KEY to validate the initial table contents.
*
* We expect that the caller has made provision to prevent any problems
* caused by concurrent actions. This could be either by locking rel and
* pkrel at ShareRowExclusiveLock or higher, or by otherwise ensuring
* that triggers implementing the checks are already active.
* Hence, we do not need to lock individual rows for the check.
*
* If the check fails because the current user doesn't have permissions
* to read both tables, return false to let our caller know that they will
* need to do something else to check the constraint.
*/
bool
RI_Initial_Check(Trigger *trigger, Relation fk_rel, Relation pk_rel)
{
const RI_ConstraintInfo *riinfo;
StringInfoData querybuf;
char pkrelname[MAX_QUOTED_REL_NAME_LEN];
char fkrelname[MAX_QUOTED_REL_NAME_LEN];
char pkattname[MAX_QUOTED_NAME_LEN + 3];
char fkattname[MAX_QUOTED_NAME_LEN + 3];
RangeTblEntry *pkrte;
RangeTblEntry *fkrte;
const char *sep;
const char *fk_only;
const char *pk_only;
int save_nestlevel;
char workmembuf[32];
int spi_result;
SPIPlanPtr qplan;
riinfo = ri_FetchConstraintInfo(trigger, fk_rel, false);
/*
* Check to make sure current user has enough permissions to do the test
* query. (If not, caller can fall back to the trigger method, which
* works because it changes user IDs on the fly.)
*
* XXX are there any other show-stopper conditions to check?
*/
pkrte = makeNode(RangeTblEntry);
pkrte->rtekind = RTE_RELATION;
pkrte->relid = RelationGetRelid(pk_rel);
pkrte->relkind = pk_rel->rd_rel->relkind;
pkrte->rellockmode = AccessShareLock;
pkrte->requiredPerms = ACL_SELECT;
fkrte = makeNode(RangeTblEntry);
fkrte->rtekind = RTE_RELATION;
fkrte->relid = RelationGetRelid(fk_rel);
fkrte->relkind = fk_rel->rd_rel->relkind;
fkrte->rellockmode = AccessShareLock;
fkrte->requiredPerms = ACL_SELECT;
for (int i = 0; i < riinfo->nkeys; i++)
{
int attno;
attno = riinfo->pk_attnums[i] - FirstLowInvalidHeapAttributeNumber;
pkrte->selectedCols = bms_add_member(pkrte->selectedCols, attno);
attno = riinfo->fk_attnums[i] - FirstLowInvalidHeapAttributeNumber;
fkrte->selectedCols = bms_add_member(fkrte->selectedCols, attno);
}
if (!ExecCheckRTPerms(list_make2(fkrte, pkrte), false))
return false;
/*
* Also punt if RLS is enabled on either table unless this role has the
* bypassrls right or is the table owner of the table(s) involved which
* have RLS enabled.
*/
if (!has_bypassrls_privilege(GetUserId()) &&
((pk_rel->rd_rel->relrowsecurity &&
!pg_class_ownercheck(pkrte->relid, GetUserId())) ||
(fk_rel->rd_rel->relrowsecurity &&
!pg_class_ownercheck(fkrte->relid, GetUserId()))))
return false;
/*----------
* The query string built is:
* SELECT fk.keycols FROM [ONLY] relname fk
* LEFT OUTER JOIN [ONLY] pkrelname pk
* ON (pk.pkkeycol1=fk.keycol1 [AND ...])
* WHERE pk.pkkeycol1 IS NULL AND
* For MATCH SIMPLE:
* (fk.keycol1 IS NOT NULL [AND ...])
* For MATCH FULL:
* (fk.keycol1 IS NOT NULL [OR ...])
*
* We attach COLLATE clauses to the operators when comparing columns
* that have different collations.
*----------
*/
initStringInfo(&querybuf);
appendStringInfoString(&querybuf, "SELECT ");
sep = "";
for (int i = 0; i < riinfo->nkeys; i++)
{
quoteOneName(fkattname,
RIAttName(fk_rel, riinfo->fk_attnums[i]));
appendStringInfo(&querybuf, "%sfk.%s", sep, fkattname);
sep = ", ";
}
quoteRelationName(pkrelname, pk_rel);
quoteRelationName(fkrelname, fk_rel);
fk_only = fk_rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE ?
"" : "ONLY ";
pk_only = pk_rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE ?
"" : "ONLY ";
appendStringInfo(&querybuf,
" FROM %s%s fk LEFT OUTER JOIN %s%s pk ON",
fk_only, fkrelname, pk_only, pkrelname);
strcpy(pkattname, "pk.");
strcpy(fkattname, "fk.");
sep = "(";
for (int i = 0; i < riinfo->nkeys; i++)
{
Oid pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
Oid fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
Oid pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
Oid fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
quoteOneName(pkattname + 3,
RIAttName(pk_rel, riinfo->pk_attnums[i]));
quoteOneName(fkattname + 3,
RIAttName(fk_rel, riinfo->fk_attnums[i]));
ri_GenerateQual(&querybuf, sep,
pkattname, pk_type,
riinfo->pf_eq_oprs[i],
fkattname, fk_type);
if (pk_coll != fk_coll)
ri_GenerateQualCollation(&querybuf, pk_coll);
sep = "AND";
}
/*
* It's sufficient to test any one pk attribute for null to detect a join
* failure.
*/
quoteOneName(pkattname, RIAttName(pk_rel, riinfo->pk_attnums[0]));
appendStringInfo(&querybuf, ") WHERE pk.%s IS NULL AND (", pkattname);
sep = "";
for (int i = 0; i < riinfo->nkeys; i++)
{
quoteOneName(fkattname, RIAttName(fk_rel, riinfo->fk_attnums[i]));
appendStringInfo(&querybuf,
"%sfk.%s IS NOT NULL",
sep, fkattname);
switch (riinfo->confmatchtype)
{
case FKCONSTR_MATCH_SIMPLE:
sep = " AND ";
break;
case FKCONSTR_MATCH_FULL:
sep = " OR ";
break;
}
}
appendStringInfoChar(&querybuf, ')');
/*
* Temporarily increase work_mem so that the check query can be executed
* more efficiently. It seems okay to do this because the query is simple
* enough to not use a multiple of work_mem, and one typically would not
* have many large foreign-key validations happening concurrently. So
* this seems to meet the criteria for being considered a "maintenance"
* operation, and accordingly we use maintenance_work_mem. However, we
* must also set hash_mem_multiplier to 1, since it is surely not okay to
* let that get applied to the maintenance_work_mem value.
*
* We use the equivalent of a function SET option to allow the setting to
* persist for exactly the duration of the check query. guc.c also takes
* care of undoing the setting on error.
*/
save_nestlevel = NewGUCNestLevel();
snprintf(workmembuf, sizeof(workmembuf), "%d", maintenance_work_mem);
(void) set_config_option("work_mem", workmembuf,
PGC_USERSET, PGC_S_SESSION,
GUC_ACTION_SAVE, true, 0, false);
(void) set_config_option("hash_mem_multiplier", "1",
PGC_USERSET, PGC_S_SESSION,
GUC_ACTION_SAVE, true, 0, false);
if (SPI_connect() != SPI_OK_CONNECT)
elog(ERROR, "SPI_connect failed");
/*
* Generate the plan. We don't need to cache it, and there are no
* arguments to the plan.
*/
qplan = SPI_prepare(querybuf.data, 0, NULL);
if (qplan == NULL)
elog(ERROR, "SPI_prepare returned %s for %s",
SPI_result_code_string(SPI_result), querybuf.data);
/*
* Run the plan. For safety we force a current snapshot to be used. (In
* transaction-snapshot mode, this arguably violates transaction isolation
* rules, but we really haven't got much choice.) We don't need to
* register the snapshot, because SPI_execute_snapshot will see to it. We
* need at most one tuple returned, so pass limit = 1.
*/
spi_result = SPI_execute_snapshot(qplan,
NULL, NULL,
GetLatestSnapshot(),
InvalidSnapshot,
true, false, 1);
/* Check result */
if (spi_result != SPI_OK_SELECT)
elog(ERROR, "SPI_execute_snapshot returned %s", SPI_result_code_string(spi_result));
/* Did we find a tuple violating the constraint? */
if (SPI_processed > 0)
{
TupleTableSlot *slot;
HeapTuple tuple = SPI_tuptable->vals[0];
TupleDesc tupdesc = SPI_tuptable->tupdesc;
RI_ConstraintInfo fake_riinfo;
slot = MakeSingleTupleTableSlot(tupdesc, &TTSOpsVirtual);
heap_deform_tuple(tuple, tupdesc,
slot->tts_values, slot->tts_isnull);
ExecStoreVirtualTuple(slot);
/*
* The columns to look at in the result tuple are 1..N, not whatever
* they are in the fk_rel. Hack up riinfo so that the subroutines
* called here will behave properly.
*
* In addition to this, we have to pass the correct tupdesc to
* ri_ReportViolation, overriding its normal habit of using the pk_rel
* or fk_rel's tupdesc.
*/
memcpy(&fake_riinfo, riinfo, sizeof(RI_ConstraintInfo));
for (int i = 0; i < fake_riinfo.nkeys; i++)
fake_riinfo.fk_attnums[i] = i + 1;
/*
* If it's MATCH FULL, and there are any nulls in the FK keys,
* complain about that rather than the lack of a match. MATCH FULL
* disallows partially-null FK rows.
*/
if (fake_riinfo.confmatchtype == FKCONSTR_MATCH_FULL &&
ri_NullCheck(tupdesc, slot, &fake_riinfo, false) != RI_KEYS_NONE_NULL)
ereport(ERROR,
(errcode(ERRCODE_FOREIGN_KEY_VIOLATION),
errmsg("insert or update on table \"%s\" violates foreign key constraint \"%s\"",
RelationGetRelationName(fk_rel),
NameStr(fake_riinfo.conname)),
errdetail("MATCH FULL does not allow mixing of null and nonnull key values."),
errtableconstraint(fk_rel,
NameStr(fake_riinfo.conname))));
ri_ReportViolation(&fake_riinfo,
pk_rel, fk_rel,
slot, tupdesc,
true, false);
ExecDropSingleTupleTableSlot(slot);
}
if (SPI_finish() != SPI_OK_FINISH)
elog(ERROR, "SPI_finish failed");
/*
* Restore work_mem and hash_mem_multiplier.
*/
AtEOXact_GUC(true, save_nestlevel);
return true;
}
/*
* RI_PartitionRemove_Check -
*
* Verify no referencing values exist, when a partition is detached on
* the referenced side of a foreign key constraint.
*/
void
RI_PartitionRemove_Check(Trigger *trigger, Relation fk_rel, Relation pk_rel)
{
const RI_ConstraintInfo *riinfo;
StringInfoData querybuf;
char *constraintDef;
char pkrelname[MAX_QUOTED_REL_NAME_LEN];
char fkrelname[MAX_QUOTED_REL_NAME_LEN];
char pkattname[MAX_QUOTED_NAME_LEN + 3];
char fkattname[MAX_QUOTED_NAME_LEN + 3];
const char *sep;
const char *fk_only;
int save_nestlevel;
char workmembuf[32];
int spi_result;
SPIPlanPtr qplan;
int i;
riinfo = ri_FetchConstraintInfo(trigger, fk_rel, false);
/*
* We don't check permissions before displaying the error message, on the
* assumption that the user detaching the partition must have enough
* privileges to examine the table contents anyhow.
*/
/*----------
* The query string built is:
* SELECT fk.keycols FROM [ONLY] relname fk
* JOIN pkrelname pk
* ON (pk.pkkeycol1=fk.keycol1 [AND ...])
* WHERE (<partition constraint>) AND
* For MATCH SIMPLE:
* (fk.keycol1 IS NOT NULL [AND ...])
* For MATCH FULL:
* (fk.keycol1 IS NOT NULL [OR ...])
*
* We attach COLLATE clauses to the operators when comparing columns
* that have different collations.
*----------
*/
initStringInfo(&querybuf);
appendStringInfoString(&querybuf, "SELECT ");
sep = "";
for (i = 0; i < riinfo->nkeys; i++)
{
quoteOneName(fkattname,
RIAttName(fk_rel, riinfo->fk_attnums[i]));
appendStringInfo(&querybuf, "%sfk.%s", sep, fkattname);
sep = ", ";
}
quoteRelationName(pkrelname, pk_rel);
quoteRelationName(fkrelname, fk_rel);
fk_only = fk_rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE ?
"" : "ONLY ";
appendStringInfo(&querybuf,
" FROM %s%s fk JOIN %s pk ON",
fk_only, fkrelname, pkrelname);
strcpy(pkattname, "pk.");
strcpy(fkattname, "fk.");
sep = "(";
for (i = 0; i < riinfo->nkeys; i++)
{
Oid pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
Oid fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
Oid pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
Oid fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
quoteOneName(pkattname + 3,
RIAttName(pk_rel, riinfo->pk_attnums[i]));
quoteOneName(fkattname + 3,
RIAttName(fk_rel, riinfo->fk_attnums[i]));
ri_GenerateQual(&querybuf, sep,
pkattname, pk_type,
riinfo->pf_eq_oprs[i],
fkattname, fk_type);
if (pk_coll != fk_coll)
ri_GenerateQualCollation(&querybuf, pk_coll);
sep = "AND";
}
/*
* Start the WHERE clause with the partition constraint (except if this is
* the default partition and there's no other partition, because the
* partition constraint is the empty string in that case.)
*/
constraintDef = pg_get_partconstrdef_string(RelationGetRelid(pk_rel), "pk");
if (constraintDef && constraintDef[0] != '\0')
appendStringInfo(&querybuf, ") WHERE %s AND (",
constraintDef);
else
appendStringInfoString(&querybuf, ") WHERE (");
sep = "";
for (i = 0; i < riinfo->nkeys; i++)
{
quoteOneName(fkattname, RIAttName(fk_rel, riinfo->fk_attnums[i]));
appendStringInfo(&querybuf,
"%sfk.%s IS NOT NULL",
sep, fkattname);
switch (riinfo->confmatchtype)
{
case FKCONSTR_MATCH_SIMPLE:
sep = " AND ";
break;
case FKCONSTR_MATCH_FULL:
sep = " OR ";
break;
}
}
appendStringInfoChar(&querybuf, ')');
/*
* Temporarily increase work_mem so that the check query can be executed
* more efficiently. It seems okay to do this because the query is simple
* enough to not use a multiple of work_mem, and one typically would not
* have many large foreign-key validations happening concurrently. So
* this seems to meet the criteria for being considered a "maintenance"
* operation, and accordingly we use maintenance_work_mem. However, we
* must also set hash_mem_multiplier to 1, since it is surely not okay to
* let that get applied to the maintenance_work_mem value.
*
* We use the equivalent of a function SET option to allow the setting to
* persist for exactly the duration of the check query. guc.c also takes
* care of undoing the setting on error.
*/
save_nestlevel = NewGUCNestLevel();
snprintf(workmembuf, sizeof(workmembuf), "%d", maintenance_work_mem);
(void) set_config_option("work_mem", workmembuf,
PGC_USERSET, PGC_S_SESSION,
GUC_ACTION_SAVE, true, 0, false);
(void) set_config_option("hash_mem_multiplier", "1",
PGC_USERSET, PGC_S_SESSION,
GUC_ACTION_SAVE, true, 0, false);
if (SPI_connect() != SPI_OK_CONNECT)
elog(ERROR, "SPI_connect failed");
/*
* Generate the plan. We don't need to cache it, and there are no
* arguments to the plan.
*/
qplan = SPI_prepare(querybuf.data, 0, NULL);
if (qplan == NULL)
elog(ERROR, "SPI_prepare returned %s for %s",
SPI_result_code_string(SPI_result), querybuf.data);
/*
* Run the plan. For safety we force a current snapshot to be used. (In
* transaction-snapshot mode, this arguably violates transaction isolation
* rules, but we really haven't got much choice.) We don't need to
* register the snapshot, because SPI_execute_snapshot will see to it. We
* need at most one tuple returned, so pass limit = 1.
*/
spi_result = SPI_execute_snapshot(qplan,
NULL, NULL,
GetLatestSnapshot(),
InvalidSnapshot,
true, false, 1);
/* Check result */
if (spi_result != SPI_OK_SELECT)
elog(ERROR, "SPI_execute_snapshot returned %s", SPI_result_code_string(spi_result));
/* Did we find a tuple that would violate the constraint? */
if (SPI_processed > 0)
{
TupleTableSlot *slot;
HeapTuple tuple = SPI_tuptable->vals[0];
TupleDesc tupdesc = SPI_tuptable->tupdesc;
RI_ConstraintInfo fake_riinfo;
slot = MakeSingleTupleTableSlot(tupdesc, &TTSOpsVirtual);
heap_deform_tuple(tuple, tupdesc,
slot->tts_values, slot->tts_isnull);
ExecStoreVirtualTuple(slot);
/*
* The columns to look at in the result tuple are 1..N, not whatever
* they are in the fk_rel. Hack up riinfo so that ri_ReportViolation
* will behave properly.
*
* In addition to this, we have to pass the correct tupdesc to
* ri_ReportViolation, overriding its normal habit of using the pk_rel
* or fk_rel's tupdesc.
*/
memcpy(&fake_riinfo, riinfo, sizeof(RI_ConstraintInfo));
for (i = 0; i < fake_riinfo.nkeys; i++)
fake_riinfo.pk_attnums[i] = i + 1;
ri_ReportViolation(&fake_riinfo, pk_rel, fk_rel,
slot, tupdesc, true, true);
}
if (SPI_finish() != SPI_OK_FINISH)
elog(ERROR, "SPI_finish failed");
/*
* Restore work_mem and hash_mem_multiplier.
*/
AtEOXact_GUC(true, save_nestlevel);
}
/* ----------
* Local functions below
* ----------
*/
/*
* quoteOneName --- safely quote a single SQL name
*
* buffer must be MAX_QUOTED_NAME_LEN long (includes room for \0)
*/
static void
quoteOneName(char *buffer, const char *name)
{
/* Rather than trying to be smart, just always quote it. */
*buffer++ = '"';
while (*name)
{
if (*name == '"')
*buffer++ = '"';
*buffer++ = *name++;
}
*buffer++ = '"';
*buffer = '\0';
}
/*
* quoteRelationName --- safely quote a fully qualified relation name
*
* buffer must be MAX_QUOTED_REL_NAME_LEN long (includes room for \0)
*/
static void
quoteRelationName(char *buffer, Relation rel)
{
quoteOneName(buffer, get_namespace_name(RelationGetNamespace(rel)));
buffer += strlen(buffer);
*buffer++ = '.';
quoteOneName(buffer, RelationGetRelationName(rel));
}
/*
* ri_GenerateQual --- generate a WHERE clause equating two variables
*
* This basically appends " sep leftop op rightop" to buf, adding casts
* and schema qualification as needed to ensure that the parser will select
* the operator we specify. leftop and rightop should be parenthesized
* if they aren't variables or parameters.
*/
static void
ri_GenerateQual(StringInfo buf,
const char *sep,
const char *leftop, Oid leftoptype,
Oid opoid,
const char *rightop, Oid rightoptype)
{
appendStringInfo(buf, " %s ", sep);
generate_operator_clause(buf, leftop, leftoptype, opoid,
rightop, rightoptype);
}
/*
* ri_GenerateQualCollation --- add a COLLATE spec to a WHERE clause
*
* At present, we intentionally do not use this function for RI queries that
* compare a variable to a $n parameter. Since parameter symbols always have
* default collation, the effect will be to use the variable's collation.
* Now that is only strictly correct when testing the referenced column, since
* the SQL standard specifies that RI comparisons should use the referenced
* column's collation. However, so long as all collations have the same
* notion of equality (which they do, because texteq reduces to bitwise
* equality), there's no visible semantic impact from using the referencing
* column's collation when testing it, and this is a good thing to do because
* it lets us use a normal index on the referencing column. However, we do
* have to use this function when directly comparing the referencing and
* referenced columns, if they are of different collations; else the parser
* will fail to resolve the collation to use.
*/
static void
ri_GenerateQualCollation(StringInfo buf, Oid collation)
{
HeapTuple tp;
Form_pg_collation colltup;
char *collname;
char onename[MAX_QUOTED_NAME_LEN];
/* Nothing to do if it's a noncollatable data type */
if (!OidIsValid(collation))
return;
tp = SearchSysCache1(COLLOID, ObjectIdGetDatum(collation));
if (!HeapTupleIsValid(tp))
elog(ERROR, "cache lookup failed for collation %u", collation);
colltup = (Form_pg_collation) GETSTRUCT(tp);
collname = NameStr(colltup->collname);
/*
* We qualify the name always, for simplicity and to ensure the query is
* not search-path-dependent.
*/
quoteOneName(onename, get_namespace_name(colltup->collnamespace));
appendStringInfo(buf, " COLLATE %s", onename);
quoteOneName(onename, collname);
appendStringInfo(buf, ".%s", onename);
ReleaseSysCache(tp);
}
/* ----------
* ri_BuildQueryKey -
*
* Construct a hashtable key for a prepared SPI plan of an FK constraint.
*
* key: output argument, *key is filled in based on the other arguments
* riinfo: info derived from pg_constraint entry
* constr_queryno: an internal number identifying the query type
* (see RI_PLAN_XXX constants at head of file)
* ----------
*/
static void
ri_BuildQueryKey(RI_QueryKey *key, const RI_ConstraintInfo *riinfo,
int32 constr_queryno)
{
/*
* Inherited constraints with a common ancestor can share ri_query_cache
* entries, because each query processes the other table involved in the
* FK constraint (i.e., not the table on which the trigger has been
* fired), and so it will be the same for all members of the inheritance
* tree. So we may use the root constraint's OID in the hash key, rather
* than the constraint's own OID. This avoids creating duplicate SPI
* plans, saving lots of work and memory when there are many partitions
* with similar FK constraints.
*
* (Note that we must still have a separate RI_ConstraintInfo for each
* constraint, because partitions can have different column orders,
* resulting in different pk_attnums[] or fk_attnums[] array contents.)
*
* (Note also that for a standalone or non-inherited constraint,
* constraint_root_id is same as constraint_id.)
*
* We assume struct RI_QueryKey contains no padding bytes, else we'd need
* to use memset to clear them.
*/
key->constr_id = riinfo->constraint_root_id;
key->constr_queryno = constr_queryno;
}
/*
* Check that RI trigger function was called in expected context
*/
static void
ri_CheckTrigger(FunctionCallInfo fcinfo, const char *funcname, int tgkind)
{
TriggerData *trigdata = (TriggerData *) fcinfo->context;
if (!CALLED_AS_TRIGGER(fcinfo))
ereport(ERROR,
(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
errmsg("function \"%s\" was not called by trigger manager", funcname)));
/*
* Check proper event
*/
if (!TRIGGER_FIRED_AFTER(trigdata->tg_event) ||
!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
ereport(ERROR,
(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
errmsg("function \"%s\" must be fired AFTER ROW", funcname)));
switch (tgkind)
{
case RI_TRIGTYPE_INSERT:
if (!TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
ereport(ERROR,
(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
errmsg("function \"%s\" must be fired for INSERT", funcname)));
break;
case RI_TRIGTYPE_UPDATE:
if (!TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
ereport(ERROR,
(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
errmsg("function \"%s\" must be fired for UPDATE", funcname)));
break;
case RI_TRIGTYPE_DELETE:
if (!TRIGGER_FIRED_BY_DELETE(trigdata->tg_event))
ereport(ERROR,
(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
errmsg("function \"%s\" must be fired for DELETE", funcname)));
break;
}
}
/*
* Fetch the RI_ConstraintInfo struct for the trigger's FK constraint.
*/
static const RI_ConstraintInfo *
ri_FetchConstraintInfo(Trigger *trigger, Relation trig_rel, bool rel_is_pk)
{
Oid constraintOid = trigger->tgconstraint;
const RI_ConstraintInfo *riinfo;
/*
* Check that the FK constraint's OID is available; it might not be if
* we've been invoked via an ordinary trigger or an old-style "constraint
* trigger".
*/
if (!OidIsValid(constraintOid))
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("no pg_constraint entry for trigger \"%s\" on table \"%s\"",
trigger->tgname, RelationGetRelationName(trig_rel)),
errhint("Remove this referential integrity trigger and its mates, then do ALTER TABLE ADD CONSTRAINT.")));
/* Find or create a hashtable entry for the constraint */
riinfo = ri_LoadConstraintInfo(constraintOid);
/* Do some easy cross-checks against the trigger call data */
if (rel_is_pk)
{
if (riinfo->fk_relid != trigger->tgconstrrelid ||
riinfo->pk_relid != RelationGetRelid(trig_rel))
elog(ERROR, "wrong pg_constraint entry for trigger \"%s\" on table \"%s\"",
trigger->tgname, RelationGetRelationName(trig_rel));
}
else
{
if (riinfo->fk_relid != RelationGetRelid(trig_rel) ||
riinfo->pk_relid != trigger->tgconstrrelid)
elog(ERROR, "wrong pg_constraint entry for trigger \"%s\" on table \"%s\"",
trigger->tgname, RelationGetRelationName(trig_rel));
}
if (riinfo->confmatchtype != FKCONSTR_MATCH_FULL &&
riinfo->confmatchtype != FKCONSTR_MATCH_PARTIAL &&
riinfo->confmatchtype != FKCONSTR_MATCH_SIMPLE)
elog(ERROR, "unrecognized confmatchtype: %d",
riinfo->confmatchtype);
if (riinfo->confmatchtype == FKCONSTR_MATCH_PARTIAL)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("MATCH PARTIAL not yet implemented")));
return riinfo;
}
/*
* Fetch or create the RI_ConstraintInfo struct for an FK constraint.
*/
static const RI_ConstraintInfo *
ri_LoadConstraintInfo(Oid constraintOid)
{
RI_ConstraintInfo *riinfo;
bool found;
HeapTuple tup;
Form_pg_constraint conForm;
/*
* On the first call initialize the hashtable
*/
if (!ri_constraint_cache)
ri_InitHashTables();
/*
* Find or create a hash entry. If we find a valid one, just return it.
*/
riinfo = (RI_ConstraintInfo *) hash_search(ri_constraint_cache,
(void *) &constraintOid,
HASH_ENTER, &found);
if (!found)
riinfo->valid = false;
else if (riinfo->valid)
return riinfo;
/*
* Fetch the pg_constraint row so we can fill in the entry.
*/
tup = SearchSysCache1(CONSTROID, ObjectIdGetDatum(constraintOid));
if (!HeapTupleIsValid(tup)) /* should not happen */
elog(ERROR, "cache lookup failed for constraint %u", constraintOid);
conForm = (Form_pg_constraint) GETSTRUCT(tup);
if (conForm->contype != CONSTRAINT_FOREIGN) /* should not happen */
elog(ERROR, "constraint %u is not a foreign key constraint",
constraintOid);
/* And extract data */
Assert(riinfo->constraint_id == constraintOid);
if (OidIsValid(conForm->conparentid))
riinfo->constraint_root_id =
get_ri_constraint_root(conForm->conparentid);
else
riinfo->constraint_root_id = constraintOid;
riinfo->oidHashValue = GetSysCacheHashValue1(CONSTROID,
ObjectIdGetDatum(constraintOid));
riinfo->rootHashValue = GetSysCacheHashValue1(CONSTROID,
ObjectIdGetDatum(riinfo->constraint_root_id));
memcpy(&riinfo->conname, &conForm->conname, sizeof(NameData));
riinfo->pk_relid = conForm->confrelid;
riinfo->fk_relid = conForm->conrelid;
riinfo->confupdtype = conForm->confupdtype;
riinfo->confdeltype = conForm->confdeltype;
riinfo->confmatchtype = conForm->confmatchtype;
DeconstructFkConstraintRow(tup,
&riinfo->nkeys,
riinfo->fk_attnums,
riinfo->pk_attnums,
riinfo->pf_eq_oprs,
riinfo->pp_eq_oprs,
riinfo->ff_eq_oprs,
&riinfo->ndelsetcols,
riinfo->confdelsetcols);
ReleaseSysCache(tup);
/*
* For efficient processing of invalidation messages below, we keep a
* doubly-linked list, and a count, of all currently valid entries.
*/
dlist_push_tail(&ri_constraint_cache_valid_list, &riinfo->valid_link);
ri_constraint_cache_valid_count++;
riinfo->valid = true;
return riinfo;
}
/*
* get_ri_constraint_root
* Returns the OID of the constraint's root parent
*/
static Oid
get_ri_constraint_root(Oid constrOid)
{
for (;;)
{
HeapTuple tuple;
Oid constrParentOid;
tuple = SearchSysCache1(CONSTROID, ObjectIdGetDatum(constrOid));
if (!HeapTupleIsValid(tuple))
elog(ERROR, "cache lookup failed for constraint %u", constrOid);
constrParentOid = ((Form_pg_constraint) GETSTRUCT(tuple))->conparentid;
ReleaseSysCache(tuple);
if (!OidIsValid(constrParentOid))
break; /* we reached the root constraint */
constrOid = constrParentOid;
}
return constrOid;
}
/*
* Callback for pg_constraint inval events
*
* While most syscache callbacks just flush all their entries, pg_constraint
* gets enough update traffic that it's probably worth being smarter.
* Invalidate any ri_constraint_cache entry associated with the syscache
* entry with the specified hash value, or all entries if hashvalue == 0.
*
* Note: at the time a cache invalidation message is processed there may be
* active references to the cache. Because of this we never remove entries
* from the cache, but only mark them invalid, which is harmless to active
* uses. (Any query using an entry should hold a lock sufficient to keep that
* data from changing under it --- but we may get cache flushes anyway.)
*/
static void
InvalidateConstraintCacheCallBack(Datum arg, int cacheid, uint32 hashvalue)
{
dlist_mutable_iter iter;
Assert(ri_constraint_cache != NULL);
/*
* If the list of currently valid entries gets excessively large, we mark
* them all invalid so we can empty the list. This arrangement avoids
* O(N^2) behavior in situations where a session touches many foreign keys
* and also does many ALTER TABLEs, such as a restore from pg_dump.
*/
if (ri_constraint_cache_valid_count > 1000)
hashvalue = 0; /* pretend it's a cache reset */
dlist_foreach_modify(iter, &ri_constraint_cache_valid_list)
{
RI_ConstraintInfo *riinfo = dlist_container(RI_ConstraintInfo,
valid_link, iter.cur);
/*
* We must invalidate not only entries directly matching the given
* hash value, but also child entries, in case the invalidation
* affects a root constraint.
*/
if (hashvalue == 0 ||
riinfo->oidHashValue == hashvalue ||
riinfo->rootHashValue == hashvalue)
{
riinfo->valid = false;
/* Remove invalidated entries from the list, too */
dlist_delete(iter.cur);
ri_constraint_cache_valid_count--;
}
}
}
/*
* Prepare execution plan for a query to enforce an RI restriction
*/
static SPIPlanPtr
ri_PlanCheck(const char *querystr, int nargs, Oid *argtypes,
RI_QueryKey *qkey, Relation fk_rel, Relation pk_rel)
{
SPIPlanPtr qplan;
/* There are currently no queries that run on PK table. */
Relation query_rel = fk_rel;
Oid save_userid;
int save_sec_context;
/* Switch to proper UID to perform check as */
GetUserIdAndSecContext(&save_userid, &save_sec_context);
SetUserIdAndSecContext(RelationGetForm(query_rel)->relowner,
save_sec_context | SECURITY_LOCAL_USERID_CHANGE |
SECURITY_NOFORCE_RLS);
/* Create the plan */
qplan = SPI_prepare(querystr, nargs, argtypes);
if (qplan == NULL)
elog(ERROR, "SPI_prepare returned %s for %s", SPI_result_code_string(SPI_result), querystr);
/* Restore UID and security context */
SetUserIdAndSecContext(save_userid, save_sec_context);
/* Save the plan */
SPI_keepplan(qplan);
ri_HashPreparedPlan(qkey, qplan);
return qplan;
}
/*
* Perform a query to enforce an RI restriction
*/
static bool
ri_PerformCheck(const RI_ConstraintInfo *riinfo,
RI_QueryKey *qkey, SPIPlanPtr qplan,
Relation fk_rel, Relation pk_rel,
TupleTableSlot *oldslot, TupleTableSlot *newslot,
bool detectNewRows, int expect_OK)
{
/* There are currently no queries that run on PK table. */
Relation query_rel = fk_rel,
source_rel = pk_rel;
Snapshot test_snapshot;
Snapshot crosscheck_snapshot;
int limit;
int spi_result;
Oid save_userid;
int save_sec_context;
Datum vals[RI_MAX_NUMKEYS * 2];
char nulls[RI_MAX_NUMKEYS * 2];
/* Extract the parameters to be passed into the query */
if (newslot)
{
ri_ExtractValues(source_rel, newslot, riinfo, true, vals, nulls);
if (oldslot)
ri_ExtractValues(source_rel, oldslot, riinfo, true,
vals + riinfo->nkeys, nulls + riinfo->nkeys);
}
else
{
ri_ExtractValues(source_rel, oldslot, riinfo, true, vals, nulls);
}
/*
* In READ COMMITTED mode, we just need to use an up-to-date regular
* snapshot, and we will see all rows that could be interesting. But in
* transaction-snapshot mode, we can't change the transaction snapshot. If
* the caller passes detectNewRows == false then it's okay to do the query
* with the transaction snapshot; otherwise we use a current snapshot, and
* tell the executor to error out if it finds any rows under the current
* snapshot that wouldn't be visible per the transaction snapshot. Note
* that SPI_execute_snapshot will register the snapshots, so we don't need
* to bother here.
*/
if (IsolationUsesXactSnapshot() && detectNewRows)
{
CommandCounterIncrement(); /* be sure all my own work is visible */
test_snapshot = GetLatestSnapshot();
crosscheck_snapshot = GetTransactionSnapshot();
}
else
{
/* the default SPI behavior is okay */
test_snapshot = InvalidSnapshot;
crosscheck_snapshot = InvalidSnapshot;
}
/*
* If this is a select query (e.g., for a 'no action' or 'restrict'
* trigger), we only need to see if there is a single row in the table,
* matching the key. Otherwise, limit = 0 - because we want the query to
* affect ALL the matching rows.
*/
limit = (expect_OK == SPI_OK_SELECT) ? 1 : 0;
/* Switch to proper UID to perform check as */
GetUserIdAndSecContext(&save_userid, &save_sec_context);
SetUserIdAndSecContext(RelationGetForm(query_rel)->relowner,
save_sec_context | SECURITY_LOCAL_USERID_CHANGE |
SECURITY_NOFORCE_RLS);
/* Finally we can run the query. */
spi_result = SPI_execute_snapshot(qplan,
vals, nulls,
test_snapshot, crosscheck_snapshot,
false, false, limit);
/* Restore UID and security context */
SetUserIdAndSecContext(save_userid, save_sec_context);
/* Check result */
if (spi_result < 0)
elog(ERROR, "SPI_execute_snapshot returned %s", SPI_result_code_string(spi_result));
if (expect_OK >= 0 && spi_result != expect_OK)
ereport(ERROR,
(errcode(ERRCODE_INTERNAL_ERROR),
errmsg("referential integrity query on \"%s\" from constraint \"%s\" on \"%s\" gave unexpected result",
RelationGetRelationName(pk_rel),
NameStr(riinfo->conname),
RelationGetRelationName(fk_rel)),
errhint("This is most likely due to a rule having rewritten the query.")));
/* XXX wouldn't it be clearer to do this part at the caller? */
if (expect_OK == SPI_OK_SELECT && SPI_processed != 0)
ri_ReportViolation(riinfo,
pk_rel, fk_rel,
newslot ? newslot : oldslot,
NULL,
false, false);
return SPI_processed != 0;
}
/*
* Extract fields from a tuple into Datum/nulls arrays
*/
static void
ri_ExtractValues(Relation rel, TupleTableSlot *slot,
const RI_ConstraintInfo *riinfo, bool rel_is_pk,
Datum *vals, char *nulls)
{
const int16 *attnums;
bool isnull;
if (rel_is_pk)
attnums = riinfo->pk_attnums;
else
attnums = riinfo->fk_attnums;
for (int i = 0; i < riinfo->nkeys; i++)
{
vals[i] = slot_getattr(slot, attnums[i], &isnull);
nulls[i] = isnull ? 'n' : ' ';
}
}
/*
* Produce an error report
*
* If the failed constraint was on insert/update to the FK table (on_fk is
* true), we want the key names and values extracted from there, and the
* error message to look like 'key blah is not present in PK'.
* Otherwise, the attr names and values come from the PK table and the
* message looks like 'key blah is still referenced from FK'.
*/
static void
ri_ReportViolation(const RI_ConstraintInfo *riinfo,
Relation pk_rel, Relation fk_rel,
TupleTableSlot *violatorslot, TupleDesc tupdesc,
bool on_fk, bool partgone)
{
StringInfoData key_names;
StringInfoData key_values;
const int16 *attnums;
Oid rel_oid;
AclResult aclresult;
bool has_perm = true;
/*
* If tupdesc wasn't passed by caller, assume the violator tuple came from
* there.
*/
if (on_fk)
{
attnums = riinfo->fk_attnums;
rel_oid = fk_rel->rd_id;
if (tupdesc == NULL)
tupdesc = fk_rel->rd_att;
}
else
{
attnums = riinfo->pk_attnums;
rel_oid = pk_rel->rd_id;
if (tupdesc == NULL)
tupdesc = pk_rel->rd_att;
}
/*
* Check permissions- if the user does not have access to view the data in
* any of the key columns then we don't include the errdetail() below.
*
* Check if RLS is enabled on the relation first. If so, we don't return
* any specifics to avoid leaking data.
*
* Check table-level permissions next and, failing that, column-level
* privileges.
*
* When a partition at the referenced side is being detached/dropped, we
* needn't check, since the user must be the table owner anyway.
*/
if (partgone)
has_perm = true;
else if (check_enable_rls(rel_oid, InvalidOid, true) != RLS_ENABLED)
{
aclresult = pg_class_aclcheck(rel_oid, GetUserId(), ACL_SELECT);
if (aclresult != ACLCHECK_OK)
{
/* Try for column-level permissions */
for (int idx = 0; idx < riinfo->nkeys; idx++)
{
aclresult = pg_attribute_aclcheck(rel_oid, attnums[idx],
GetUserId(),
ACL_SELECT);
/* No access to the key */
if (aclresult != ACLCHECK_OK)
{
has_perm = false;
break;
}
}
}
}
else
has_perm = false;
if (has_perm)
{
/* Get printable versions of the keys involved */
initStringInfo(&key_names);
initStringInfo(&key_values);
for (int idx = 0; idx < riinfo->nkeys; idx++)
{
int fnum = attnums[idx];
Form_pg_attribute att = TupleDescAttr(tupdesc, fnum - 1);
char *name,
*val;
Datum datum;
bool isnull;
name = NameStr(att->attname);
datum = slot_getattr(violatorslot, fnum, &isnull);
if (!isnull)
{
Oid foutoid;
bool typisvarlena;
getTypeOutputInfo(att->atttypid, &foutoid, &typisvarlena);
val = OidOutputFunctionCall(foutoid, datum);
}
else
val = "null";
if (idx > 0)
{
appendStringInfoString(&key_names, ", ");
appendStringInfoString(&key_values, ", ");
}
appendStringInfoString(&key_names, name);
appendStringInfoString(&key_values, val);
}
}
if (partgone)
ereport(ERROR,
(errcode(ERRCODE_FOREIGN_KEY_VIOLATION),
errmsg("removing partition \"%s\" violates foreign key constraint \"%s\"",
RelationGetRelationName(pk_rel),
NameStr(riinfo->conname)),
errdetail("Key (%s)=(%s) is still referenced from table \"%s\".",
key_names.data, key_values.data,
RelationGetRelationName(fk_rel)),
errtableconstraint(fk_rel, NameStr(riinfo->conname))));
else if (on_fk)
ereport(ERROR,
(errcode(ERRCODE_FOREIGN_KEY_VIOLATION),
errmsg("insert or update on table \"%s\" violates foreign key constraint \"%s\"",
RelationGetRelationName(fk_rel),
NameStr(riinfo->conname)),
has_perm ?
errdetail("Key (%s)=(%s) is not present in table \"%s\".",
key_names.data, key_values.data,
RelationGetRelationName(pk_rel)) :
errdetail("Key is not present in table \"%s\".",
RelationGetRelationName(pk_rel)),
errtableconstraint(fk_rel, NameStr(riinfo->conname))));
else
ereport(ERROR,
(errcode(ERRCODE_FOREIGN_KEY_VIOLATION),
errmsg("update or delete on table \"%s\" violates foreign key constraint \"%s\" on table \"%s\"",
RelationGetRelationName(pk_rel),
NameStr(riinfo->conname),
RelationGetRelationName(fk_rel)),
has_perm ?
errdetail("Key (%s)=(%s) is still referenced from table \"%s\".",
key_names.data, key_values.data,
RelationGetRelationName(fk_rel)) :
errdetail("Key is still referenced from table \"%s\".",
RelationGetRelationName(fk_rel)),
errtableconstraint(fk_rel, NameStr(riinfo->conname))));
}
/*
* ri_NullCheck -
*
* Determine the NULL state of all key values in a tuple
*
* Returns one of RI_KEYS_ALL_NULL, RI_KEYS_NONE_NULL or RI_KEYS_SOME_NULL.
*/
static int
ri_NullCheck(TupleDesc tupDesc,
TupleTableSlot *slot,
const RI_ConstraintInfo *riinfo, bool rel_is_pk)
{
const int16 *attnums;
bool allnull = true;
bool nonenull = true;
if (rel_is_pk)
attnums = riinfo->pk_attnums;
else
attnums = riinfo->fk_attnums;
for (int i = 0; i < riinfo->nkeys; i++)
{
if (slot_attisnull(slot, attnums[i]))
nonenull = false;
else
allnull = false;
}
if (allnull)
return RI_KEYS_ALL_NULL;
if (nonenull)
return RI_KEYS_NONE_NULL;
return RI_KEYS_SOME_NULL;
}
/*
* ri_InitHashTables -
*
* Initialize our internal hash tables.
*/
static void
ri_InitHashTables(void)
{
HASHCTL ctl;
ctl.keysize = sizeof(Oid);
ctl.entrysize = sizeof(RI_ConstraintInfo);
ri_constraint_cache = hash_create("RI constraint cache",
RI_INIT_CONSTRAINTHASHSIZE,
&ctl, HASH_ELEM | HASH_BLOBS);
/* Arrange to flush cache on pg_constraint changes */
CacheRegisterSyscacheCallback(CONSTROID,
InvalidateConstraintCacheCallBack,
(Datum) 0);
ctl.keysize = sizeof(RI_QueryKey);
ctl.entrysize = sizeof(RI_QueryHashEntry);
ri_query_cache = hash_create("RI query cache",
RI_INIT_QUERYHASHSIZE,
&ctl, HASH_ELEM | HASH_BLOBS);
ctl.keysize = sizeof(RI_CompareKey);
ctl.entrysize = sizeof(RI_CompareHashEntry);
ri_compare_cache = hash_create("RI compare cache",
RI_INIT_QUERYHASHSIZE,
&ctl, HASH_ELEM | HASH_BLOBS);
}
/*
* ri_FetchPreparedPlan -
*
* Lookup for a query key in our private hash table of prepared
* and saved SPI execution plans. Return the plan if found or NULL.
*/
static SPIPlanPtr
ri_FetchPreparedPlan(RI_QueryKey *key)
{
RI_QueryHashEntry *entry;
SPIPlanPtr plan;
/*
* On the first call initialize the hashtable
*/
if (!ri_query_cache)
ri_InitHashTables();
/*
* Lookup for the key
*/
entry = (RI_QueryHashEntry *) hash_search(ri_query_cache,
(void *) key,
HASH_FIND, NULL);
if (entry == NULL)
return NULL;
/*
* Check whether the plan is still valid. If it isn't, we don't want to
* simply rely on plancache.c to regenerate it; rather we should start
* from scratch and rebuild the query text too. This is to cover cases
* such as table/column renames. We depend on the plancache machinery to
* detect possible invalidations, though.
*
* CAUTION: this check is only trustworthy if the caller has already
* locked both FK and PK rels.
*/
plan = entry->plan;
if (plan && SPI_plan_is_valid(plan))
return plan;
/*
* Otherwise we might as well flush the cached plan now, to free a little
* memory space before we make a new one.
*/
entry->plan = NULL;
if (plan)
SPI_freeplan(plan);
return NULL;
}
/*
* ri_HashPreparedPlan -
*
* Add another plan to our private SPI query plan hashtable.
*/
static void
ri_HashPreparedPlan(RI_QueryKey *key, SPIPlanPtr plan)
{
RI_QueryHashEntry *entry;
bool found;
/*
* On the first call initialize the hashtable
*/
if (!ri_query_cache)
ri_InitHashTables();
/*
* Add the new plan. We might be overwriting an entry previously found
* invalid by ri_FetchPreparedPlan.
*/
entry = (RI_QueryHashEntry *) hash_search(ri_query_cache,
(void *) key,
HASH_ENTER, &found);
Assert(!found || entry->plan == NULL);
entry->plan = plan;
}
/*
* ri_KeysEqual -
*
* Check if all key values in OLD and NEW are equal.
*
* Note: at some point we might wish to redefine this as checking for
* "IS NOT DISTINCT" rather than "=", that is, allow two nulls to be
* considered equal. Currently there is no need since all callers have
* previously found at least one of the rows to contain no nulls.
*/
static bool
ri_KeysEqual(Relation rel, TupleTableSlot *oldslot, TupleTableSlot *newslot,
const RI_ConstraintInfo *riinfo, bool rel_is_pk)
{
const int16 *attnums;
if (rel_is_pk)
attnums = riinfo->pk_attnums;
else
attnums = riinfo->fk_attnums;
/* XXX: could be worthwhile to fetch all necessary attrs at once */
for (int i = 0; i < riinfo->nkeys; i++)
{
Datum oldvalue;
Datum newvalue;
bool isnull;
/*
* Get one attribute's oldvalue. If it is NULL - they're not equal.
*/
oldvalue = slot_getattr(oldslot, attnums[i], &isnull);
if (isnull)
return false;
/*
* Get one attribute's newvalue. If it is NULL - they're not equal.
*/
newvalue = slot_getattr(newslot, attnums[i], &isnull);
if (isnull)
return false;
if (rel_is_pk)
{
/*
* If we are looking at the PK table, then do a bytewise
* comparison. We must propagate PK changes if the value is
* changed to one that "looks" different but would compare as
* equal using the equality operator. This only makes a
* difference for ON UPDATE CASCADE, but for consistency we treat
* all changes to the PK the same.
*/
Form_pg_attribute att = TupleDescAttr(oldslot->tts_tupleDescriptor, attnums[i] - 1);
if (!datum_image_eq(oldvalue, newvalue, att->attbyval, att->attlen))
return false;
}
else
{
/*
* For the FK table, compare with the appropriate equality
* operator. Changes that compare equal will still satisfy the
* constraint after the update.
*/
if (!ri_AttributesEqual(riinfo->ff_eq_oprs[i], RIAttType(rel, attnums[i]),
oldvalue, newvalue))
return false;
}
}
return true;
}
/*
* ri_AttributesEqual -
*
* Call the appropriate equality comparison operator for two values.
*
* NB: we have already checked that neither value is null.
*/
static bool
ri_AttributesEqual(Oid eq_opr, Oid typeid,
Datum oldvalue, Datum newvalue)
{
RI_CompareHashEntry *entry = ri_HashCompareOp(eq_opr, typeid);
/* Do we need to cast the values? */
if (OidIsValid(entry->cast_func_finfo.fn_oid))
{
oldvalue = FunctionCall3(&entry->cast_func_finfo,
oldvalue,
Int32GetDatum(-1), /* typmod */
BoolGetDatum(false)); /* implicit coercion */
newvalue = FunctionCall3(&entry->cast_func_finfo,
newvalue,
Int32GetDatum(-1), /* typmod */
BoolGetDatum(false)); /* implicit coercion */
}
/*
* Apply the comparison operator.
*
* Note: This function is part of a call stack that determines whether an
* update to a row is significant enough that it needs checking or action
* on the other side of a foreign-key constraint. Therefore, the
* comparison here would need to be done with the collation of the *other*
* table. For simplicity (e.g., we might not even have the other table
* open), we'll just use the default collation here, which could lead to
* some false negatives. All this would break if we ever allow
* database-wide collations to be nondeterministic.
*/
return DatumGetBool(FunctionCall2Coll(&entry->eq_opr_finfo,
DEFAULT_COLLATION_OID,
oldvalue, newvalue));
}
/*
* ri_HashCompareOp -
*
* See if we know how to compare two values, and create a new hash entry
* if not. The entry contains the FmgrInfo of the equality operator function
* and that of the cast function, if one is needed to convert the right
* operand (whose type OID has been passed) before passing it to the equality
* function.
*/
static RI_CompareHashEntry *
ri_HashCompareOp(Oid eq_opr, Oid typeid)
{
RI_CompareKey key;
RI_CompareHashEntry *entry;
bool found;
/*
* On the first call initialize the hashtable
*/
if (!ri_compare_cache)
ri_InitHashTables();
/*
* Find or create a hash entry. Note we're assuming RI_CompareKey
* contains no struct padding.
*/
key.eq_opr = eq_opr;
key.typeid = typeid;
entry = (RI_CompareHashEntry *) hash_search(ri_compare_cache,
(void *) &key,
HASH_ENTER, &found);
if (!found)
entry->valid = false;
/*
* If not already initialized, do so. Since we'll keep this hash entry
* for the life of the backend, put any subsidiary info for the function
* cache structs into TopMemoryContext.
*/
if (!entry->valid)
{
Oid lefttype,
righttype,
castfunc;
CoercionPathType pathtype;
/* We always need to know how to call the equality operator */
fmgr_info_cxt(get_opcode(eq_opr), &entry->eq_opr_finfo,
TopMemoryContext);
/*
* If we chose to use a cast from FK to PK type, we may have to apply
* the cast function to get to the operator's input type.
*
* XXX eventually it would be good to support array-coercion cases
* here and in ri_AttributesEqual(). At the moment there is no point
* because cases involving nonidentical array types will be rejected
* at constraint creation time.
*
* XXX perhaps also consider supporting CoerceViaIO? No need at the
* moment since that will never be generated for implicit coercions.
*/
op_input_types(eq_opr, &lefttype, &righttype);
/*
* Don't need to cast if the values that will be passed to the
* operator will be of expected operand type(s). The operator can be
* cross-type (such as when called by ri_ReferencedKeyExists()), in
* which case, we only need the cast if the right operand value
* doesn't match the type expected by the operator.
*/
if ((lefttype == righttype && typeid == lefttype) ||
(lefttype != righttype && typeid == righttype))
castfunc = InvalidOid; /* simplest case */
else
{
pathtype = find_coercion_pathway(lefttype, typeid,
COERCION_IMPLICIT,
&castfunc);
if (pathtype != COERCION_PATH_FUNC &&
pathtype != COERCION_PATH_RELABELTYPE)
{
/*
* The declared input type of the eq_opr might be a
* polymorphic type such as ANYARRAY or ANYENUM, or other
* special cases such as RECORD; find_coercion_pathway
* currently doesn't subsume these special cases.
*/
if (!IsBinaryCoercible(typeid, lefttype))
elog(ERROR, "no conversion function from %s to %s",
format_type_be(typeid),
format_type_be(lefttype));
}
}
if (OidIsValid(castfunc))
fmgr_info_cxt(castfunc, &entry->cast_func_finfo,
TopMemoryContext);
else
entry->cast_func_finfo.fn_oid = InvalidOid;
entry->valid = true;
}
return entry;
}
/*
* Given a trigger function OID, determine whether it is an RI trigger,
* and if so whether it is attached to PK or FK relation.
*/
int
RI_FKey_trigger_type(Oid tgfoid)
{
switch (tgfoid)
{
case F_RI_FKEY_CASCADE_DEL:
case F_RI_FKEY_CASCADE_UPD:
case F_RI_FKEY_RESTRICT_DEL:
case F_RI_FKEY_RESTRICT_UPD:
case F_RI_FKEY_SETNULL_DEL:
case F_RI_FKEY_SETNULL_UPD:
case F_RI_FKEY_SETDEFAULT_DEL:
case F_RI_FKEY_SETDEFAULT_UPD:
case F_RI_FKEY_NOACTION_DEL:
case F_RI_FKEY_NOACTION_UPD:
return RI_TRIGGER_PK;
case F_RI_FKEY_CHECK_INS:
case F_RI_FKEY_CHECK_UPD:
return RI_TRIGGER_FK;
}
return RI_TRIGGER_NONE;
}
View Git Blame Copy Permalink