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postgresql/src/backend/utils/adt/ri_triggers.c

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/*-------------------------------------------------------------------------
*
* 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) 1996-2019, PostgreSQL Global Development Group
*
* src/backend/utils/adt/ri_triggers.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.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/executor.h"
#include "executor/spi.h"
#include "lib/ilist.h"
#include "parser/parse_coerce.h"
#include "parser/parse_relation.h"
#include "miscadmin.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/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 */
/* these queries are executed against the PK (referenced) table: */
#define RI_PLAN_CHECK_LOOKUPPK 1
#define RI_PLAN_CHECK_LOOKUPPK_FROM_PK 2
#define RI_PLAN_LAST_ON_PK RI_PLAN_CHECK_LOOKUPPK_FROM_PK
/* these queries are executed against the FK (referencing) table: */
#define RI_PLAN_CASCADE_DEL_DODELETE 3
#define RI_PLAN_CASCADE_UPD_DOUPDATE 4
#define RI_PLAN_RESTRICT_CHECKREF 5
#define RI_PLAN_SETNULL_DOUPDATE 6
#define RI_PLAN_SETDEFAULT_DOUPDATE 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? */
uint32 oidHashValue; /* hash value of pg_constraint OID */
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 */
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);
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 SPIPlanPtr ri_PlanCheck(const char *querystr, int nargs, Oid *argtypes,
RI_QueryKey *qkey, Relation fk_rel, Relation pk_rel,
bool cache_plan);
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 *violator, TupleDesc tupdesc,
int queryno) pg_attribute_noreturn();
/*
* 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;
RI_QueryKey qkey;
SPIPlanPtr qplan;
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 the query below
* to only include non-null columns, or by writing a
* special version here)
*/
break;
#endif
}
case RI_KEYS_NONE_NULL:
/*
* Have a full qualified key - continue below for all three kinds
* of MATCH.
*/
break;
}
if (SPI_connect() != SPI_OK_CONNECT)
elog(ERROR, "SPI_connect failed");
/* Fetch or prepare a saved plan for the real check */
ri_BuildQueryKey(&qkey, riinfo, RI_PLAN_CHECK_LOOKUPPK);
if ((qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
{
StringInfoData querybuf;
char pkrelname[MAX_QUOTED_REL_NAME_LEN];
char attname[MAX_QUOTED_NAME_LEN];
char paramname[16];
const char *querysep;
Oid queryoids[RI_MAX_NUMKEYS];
/* ----------
* The query string built is
* SELECT 1 FROM ONLY <pktable> x WHERE pkatt1 = $1 [AND ...]
* FOR KEY SHARE OF x
* The type id's for the $ parameters are those of the
* corresponding FK attributes.
* ----------
*/
initStringInfo(&querybuf);
quoteRelationName(pkrelname, pk_rel);
appendStringInfo(&querybuf, "SELECT 1 FROM ONLY %s x", pkrelname);
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]);
quoteOneName(attname,
RIAttName(pk_rel, riinfo->pk_attnums[i]));
sprintf(paramname, "$%d", i + 1);
ri_GenerateQual(&querybuf, querysep,
attname, pk_type,
riinfo->pf_eq_oprs[i],
paramname, fk_type);
querysep = "AND";
queryoids[i] = fk_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, true);
}
/*
* Now check that foreign key exists in PK table
*/
ri_PerformCheck(riinfo, &qkey, qplan,
fk_rel, pk_rel,
NULL, newslot,
false,
SPI_OK_SELECT);
if (SPI_finish() != SPI_OK_FINISH)
elog(ERROR, "SPI_finish failed");
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)
{
SPIPlanPtr qplan;
RI_QueryKey qkey;
bool result;
/* Only called for non-null rows */
Assert(ri_NullCheck(RelationGetDescr(pk_rel), oldslot, riinfo, true) == RI_KEYS_NONE_NULL);
if (SPI_connect() != SPI_OK_CONNECT)
elog(ERROR, "SPI_connect failed");
/*
* Fetch or prepare a saved plan for checking PK table with values coming
* from a PK row
*/
ri_BuildQueryKey(&qkey, riinfo, RI_PLAN_CHECK_LOOKUPPK_FROM_PK);
if ((qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
{
StringInfoData querybuf;
char pkrelname[MAX_QUOTED_REL_NAME_LEN];
char attname[MAX_QUOTED_NAME_LEN];
char paramname[16];
const char *querysep;
Oid queryoids[RI_MAX_NUMKEYS];
/* ----------
* The query string built is
* SELECT 1 FROM ONLY <pktable> x WHERE pkatt1 = $1 [AND ...]
* FOR KEY SHARE OF x
* The type id's for the $ parameters are those of the
* PK attributes themselves.
* ----------
*/
initStringInfo(&querybuf);
quoteRelationName(pkrelname, pk_rel);
appendStringInfo(&querybuf, "SELECT 1 FROM ONLY %s x", pkrelname);
querysep = "WHERE";
for (int i = 0; i < riinfo->nkeys; i++)
{
Oid pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
quoteOneName(attname,
RIAttName(pk_rel, riinfo->pk_attnums[i]));
sprintf(paramname, "$%d", i + 1);
ri_GenerateQual(&querybuf, querysep,
attname, pk_type,
riinfo->pp_eq_oprs[i],
paramname, pk_type);
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, true);
}
/*
* We have a plan now. Run it.
*/
result = ri_PerformCheck(riinfo, &qkey, qplan,
fk_rel, pk_rel,
oldslot, NULL,
true, /* treat like update */
SPI_OK_SELECT);
if (SPI_finish() != SPI_OK_FINISH)
elog(ERROR, "SPI_finish failed");
return result;
}
/*
* 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_CHECKREF);
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, true);
}
/*
* 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_DEL_DODELETE);
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, true);
}
/*
* 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_UPD_DOUPDATE);
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;
}
appendStringInfoString(&querybuf, qualbuf.data);
/* Prepare and save the plan */
qplan = ri_PlanCheck(querybuf.data, riinfo->nkeys * 2, queryoids,
&qkey, fk_rel, pk_rel, true);
}
/*
* 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_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_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_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_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)
{
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 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 set null/default operation (it's
* the same query for delete and update cases)
*/
ri_BuildQueryKey(&qkey, riinfo,
(is_set_null
? RI_PLAN_SETNULL_DOUPDATE
: RI_PLAN_SETDEFAULT_DOUPDATE));
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];
const char *fk_only;
/* ----------
* 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);
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; 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]));
appendStringInfo(&querybuf,
"%s %s = %s",
querysep, attname,
is_set_null ? "NULL" : "DEFAULT");
sprintf(paramname, "$%d", i + 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;
}
appendStringInfoString(&querybuf, qualbuf.data);
/* Prepare and save the plan */
qplan = ri_PlanCheck(querybuf.data, riinfo->nkeys, queryoids,
&qkey, fk_rel, pk_rel, true);
}
/*
* 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;
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;
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 ";
appendStringInfo(&querybuf,
" FROM %s%s fk LEFT OUTER JOIN ONLY %s pk ON",
fk_only, fkrelname, 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.
*
* 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);
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))));
/*
* We tell ri_ReportViolation we were doing the RI_PLAN_CHECK_LOOKUPPK
* query, which isn't true, but will cause it to use
* fake_riinfo.fk_attnums as we need.
*/
ri_ReportViolation(&fake_riinfo,
pk_rel, fk_rel,
slot, tupdesc,
RI_PLAN_CHECK_LOOKUPPK);
ExecDropSingleTupleTableSlot(slot);
}
if (SPI_finish() != SPI_OK_FINISH)
elog(ERROR, "SPI_finish failed");
/*
* Restore work_mem.
*/
AtEOXact_GUC(true, save_nestlevel);
return true;
}
/* ----------
* 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 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)
{
/*
* We assume struct RI_QueryKey contains no padding bytes, else we'd need
* to use memset to clear them.
*/
key->constr_id = riinfo->constraint_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);
riinfo->oidHashValue = GetSysCacheHashValue1(CONSTROID,
ObjectIdGetDatum(constraintOid));
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);
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;
}
/*
* 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);
if (hashvalue == 0 || riinfo->oidHashValue == 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
*
* If cache_plan is true, the plan is saved into our plan hashtable
* so that we don't need to plan it again.
*/
static SPIPlanPtr
ri_PlanCheck(const char *querystr, int nargs, Oid *argtypes,
RI_QueryKey *qkey, Relation fk_rel, Relation pk_rel,
bool cache_plan)
{
SPIPlanPtr qplan;
Relation query_rel;
Oid save_userid;
int save_sec_context;
/*
* Use the query type code to determine whether the query is run against
* the PK or FK table; we'll do the check as that table's owner
*/
if (qkey->constr_queryno <= RI_PLAN_LAST_ON_PK)
query_rel = pk_rel;
else
query_rel = fk_rel;
/* 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 if requested */
if (cache_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)
{
Relation query_rel,
source_rel;
bool source_is_pk;
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];
/*
* Use the query type code to determine whether the query is run against
* the PK or FK table; we'll do the check as that table's owner
*/
if (qkey->constr_queryno <= RI_PLAN_LAST_ON_PK)
query_rel = pk_rel;
else
query_rel = fk_rel;
/*
* The values for the query are taken from the table on which the trigger
* is called - it is normally the other one with respect to query_rel. An
* exception is ri_Check_Pk_Match(), which uses the PK table for both (and
* sets queryno to RI_PLAN_CHECK_LOOKUPPK_FROM_PK). We might eventually
* need some less klugy way to determine this.
*/
if (qkey->constr_queryno == RI_PLAN_CHECK_LOOKUPPK)
{
source_rel = fk_rel;
source_is_pk = false;
}
else
{
source_rel = pk_rel;
source_is_pk = true;
}
/* Extract the parameters to be passed into the query */
if (newslot)
{
ri_ExtractValues(source_rel, newslot, riinfo, source_is_pk,
vals, nulls);
if (oldslot)
ri_ExtractValues(source_rel, oldslot, riinfo, source_is_pk,
vals + riinfo->nkeys, nulls + riinfo->nkeys);
}
else
{
ri_ExtractValues(source_rel, oldslot, riinfo, source_is_pk,
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 (qkey->constr_queryno != RI_PLAN_CHECK_LOOKUPPK_FROM_PK &&
expect_OK == SPI_OK_SELECT &&
(SPI_processed == 0) == (qkey->constr_queryno == RI_PLAN_CHECK_LOOKUPPK))
ri_ReportViolation(riinfo,
pk_rel, fk_rel,
newslot ? newslot : oldslot,
NULL,
qkey->constr_queryno);
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,
* 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,
int queryno)
{
StringInfoData key_names;
StringInfoData key_values;
bool onfk;
const int16 *attnums;
Oid rel_oid;
AclResult aclresult;
bool has_perm = true;
/*
* Determine which relation to complain about. If tupdesc wasn't passed
* by caller, assume the violator tuple came from there.
*/
onfk = (queryno == RI_PLAN_CHECK_LOOKUPPK);
if (onfk)
{
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.
*/
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 (onfk)
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;
memset(&ctl, 0, sizeof(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);
memset(&ctl, 0, sizeof(ctl));
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);
memset(&ctl, 0, sizeof(ctl));
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.
*/
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);
Assert(lefttype == righttype);
if (typeid == lefttype)
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;
}
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