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postgresql/contrib/spi/refint.c

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/*
* contrib/spi/refint.c
*
*
* refint.c -- set of functions to define referential integrity
* constraints using general triggers.
*/
#include "postgres.h"
#include <ctype.h>
#include "commands/trigger.h"
#include "executor/spi.h"
#include "utils/builtins.h"
#include "utils/memutils.h"
#include "utils/rel.h"
PG_MODULE_MAGIC;
typedef struct
{
char *ident;
int nplans;
SPIPlanPtr *splan;
} EPlan;
static EPlan *FPlans = NULL;
static int nFPlans = 0;
static EPlan *PPlans = NULL;
static int nPPlans = 0;
static EPlan *find_plan(char *ident, EPlan **eplan, int *nplans);
/*
* check_primary_key () -- check that key in tuple being inserted/updated
* references existing tuple in "primary" table.
* Though it's called without args You have to specify referenced
* table/keys while creating trigger: key field names in triggered table,
* referenced table name, referenced key field names:
* EXECUTE PROCEDURE
* check_primary_key ('Fkey1', 'Fkey2', 'Ptable', 'Pkey1', 'Pkey2').
*/
PG_FUNCTION_INFO_V1(check_primary_key);
Datum
check_primary_key(PG_FUNCTION_ARGS)
{
TriggerData *trigdata = (TriggerData *) fcinfo->context;
Trigger *trigger; /* to get trigger name */
int nargs; /* # of args specified in CREATE TRIGGER */
char **args; /* arguments: column names and table name */
int nkeys; /* # of key columns (= nargs / 2) */
Datum *kvals; /* key values */
char *relname; /* referenced relation name */
Relation rel; /* triggered relation */
HeapTuple tuple = NULL; /* tuple to return */
TupleDesc tupdesc; /* tuple description */
EPlan *plan; /* prepared plan */
Oid *argtypes = NULL; /* key types to prepare execution plan */
bool isnull; /* to know is some column NULL or not */
char ident[2 * NAMEDATALEN]; /* to identify myself */
int ret;
int i;
#ifdef DEBUG_QUERY
elog(DEBUG4, "check_primary_key: Enter Function");
#endif
/*
* Some checks first...
*/
/* Called by trigger manager ? */
if (!CALLED_AS_TRIGGER(fcinfo))
/* internal error */
elog(ERROR, "check_primary_key: not fired by trigger manager");
/* Should be called for ROW trigger */
if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
/* internal error */
elog(ERROR, "check_primary_key: must be fired for row");
/* If INSERTion then must check Tuple to being inserted */
if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
tuple = trigdata->tg_trigtuple;
/* Not should be called for DELETE */
else if (TRIGGER_FIRED_BY_DELETE(trigdata->tg_event))
/* internal error */
elog(ERROR, "check_primary_key: cannot process DELETE events");
/* If UPDATE, then must check new Tuple, not old one */
else
tuple = trigdata->tg_newtuple;
trigger = trigdata->tg_trigger;
nargs = trigger->tgnargs;
args = trigger->tgargs;
if (nargs % 2 != 1) /* odd number of arguments! */
/* internal error */
elog(ERROR, "check_primary_key: odd number of arguments should be specified");
nkeys = nargs / 2;
relname = args[nkeys];
rel = trigdata->tg_relation;
tupdesc = rel->rd_att;
/* Connect to SPI manager */
if ((ret = SPI_connect()) < 0)
/* internal error */
elog(ERROR, "check_primary_key: SPI_connect returned %d", ret);
/*
* We use SPI plan preparation feature, so allocate space to place key
* values.
*/
kvals = (Datum *) palloc(nkeys * sizeof(Datum));
/*
* Construct ident string as TriggerName $ TriggeredRelationId and try to
* find prepared execution plan.
*/
snprintf(ident, sizeof(ident), "%s$%u", trigger->tgname, rel->rd_id);
plan = find_plan(ident, &PPlans, &nPPlans);
/* if there is no plan then allocate argtypes for preparation */
if (plan->nplans <= 0)
argtypes = (Oid *) palloc(nkeys * sizeof(Oid));
/* For each column in key ... */
for (i = 0; i < nkeys; i++)
{
/* get index of column in tuple */
int fnumber = SPI_fnumber(tupdesc, args[i]);
/* Bad guys may give us un-existing column in CREATE TRIGGER */
if (fnumber <= 0)
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_COLUMN),
errmsg("there is no attribute \"%s\" in relation \"%s\"",
args[i], SPI_getrelname(rel))));
/* Well, get binary (in internal format) value of column */
kvals[i] = SPI_getbinval(tuple, tupdesc, fnumber, &isnull);
/*
* If it's NULL then nothing to do! DON'T FORGET call SPI_finish ()!
* DON'T FORGET return tuple! Executor inserts tuple you're returning!
* If you return NULL then nothing will be inserted!
*/
if (isnull)
{
SPI_finish();
return PointerGetDatum(tuple);
}
if (plan->nplans <= 0) /* Get typeId of column */
argtypes[i] = SPI_gettypeid(tupdesc, fnumber);
}
/*
* If we have to prepare plan ...
*/
if (plan->nplans <= 0)
{
SPIPlanPtr pplan;
char sql[8192];
/*
* Construct query: SELECT 1 FROM _referenced_relation_ WHERE Pkey1 =
* $1 [AND Pkey2 = $2 [...]]
*/
snprintf(sql, sizeof(sql), "select 1 from %s where ", relname);
for (i = 0; i < nkeys; i++)
{
snprintf(sql + strlen(sql), sizeof(sql) - strlen(sql), "%s = $%d %s",
args[i + nkeys + 1], i + 1, (i < nkeys - 1) ? "and " : "");
}
/* Prepare plan for query */
pplan = SPI_prepare(sql, nkeys, argtypes);
if (pplan == NULL)
/* internal error */
elog(ERROR, "check_primary_key: SPI_prepare returned %s", SPI_result_code_string(SPI_result));
/*
* Remember that SPI_prepare places plan in current memory context -
* so, we have to save plan in TopMemoryContext for later use.
*/
if (SPI_keepplan(pplan))
/* internal error */
elog(ERROR, "check_primary_key: SPI_keepplan failed");
plan->splan = (SPIPlanPtr *) MemoryContextAlloc(TopMemoryContext,
sizeof(SPIPlanPtr));
*(plan->splan) = pplan;
plan->nplans = 1;
}
/*
* Ok, execute prepared plan.
*/
ret = SPI_execp(*(plan->splan), kvals, NULL, 1);
/* we have no NULLs - so we pass ^^^^ here */
if (ret < 0)
/* internal error */
elog(ERROR, "check_primary_key: SPI_execp returned %d", ret);
/*
* If there are no tuples returned by SELECT then ...
*/
if (SPI_processed == 0)
ereport(ERROR,
(errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
errmsg("tuple references non-existent key"),
errdetail("Trigger \"%s\" found tuple referencing non-existent key in \"%s\".", trigger->tgname, relname)));
SPI_finish();
return PointerGetDatum(tuple);
}
/*
* check_foreign_key () -- check that key in tuple being deleted/updated
* is not referenced by tuples in "foreign" table(s).
* Though it's called without args You have to specify (while creating trigger):
* number of references, action to do if key referenced
* ('restrict' | 'setnull' | 'cascade'), key field names in triggered
* ("primary") table and referencing table(s)/keys:
* EXECUTE PROCEDURE
* check_foreign_key (2, 'restrict', 'Pkey1', 'Pkey2',
* 'Ftable1', 'Fkey11', 'Fkey12', 'Ftable2', 'Fkey21', 'Fkey22').
*/
PG_FUNCTION_INFO_V1(check_foreign_key);
Datum
check_foreign_key(PG_FUNCTION_ARGS)
{
TriggerData *trigdata = (TriggerData *) fcinfo->context;
Trigger *trigger; /* to get trigger name */
int nargs; /* # of args specified in CREATE TRIGGER */
char **args; /* arguments: as described above */
char **args_temp;
int nrefs; /* number of references (== # of plans) */
char action; /* 'R'estrict | 'S'etnull | 'C'ascade */
int nkeys; /* # of key columns */
Datum *kvals; /* key values */
char *relname; /* referencing relation name */
Relation rel; /* triggered relation */
HeapTuple trigtuple = NULL; /* tuple to being changed */
HeapTuple newtuple = NULL; /* tuple to return */
TupleDesc tupdesc; /* tuple description */
EPlan *plan; /* prepared plan(s) */
Oid *argtypes = NULL; /* key types to prepare execution plan */
bool isnull; /* to know is some column NULL or not */
bool isequal = true; /* are keys in both tuples equal (in UPDATE) */
char ident[2 * NAMEDATALEN]; /* to identify myself */
int is_update = 0;
int ret;
int i,
r;
#ifdef DEBUG_QUERY
elog(DEBUG4, "check_foreign_key: Enter Function");
#endif
/*
* Some checks first...
*/
/* Called by trigger manager ? */
if (!CALLED_AS_TRIGGER(fcinfo))
/* internal error */
elog(ERROR, "check_foreign_key: not fired by trigger manager");
/* Should be called for ROW trigger */
if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
/* internal error */
elog(ERROR, "check_foreign_key: must be fired for row");
/* Not should be called for INSERT */
if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
/* internal error */
elog(ERROR, "check_foreign_key: cannot process INSERT events");
/* Have to check tg_trigtuple - tuple being deleted */
trigtuple = trigdata->tg_trigtuple;
/*
* But if this is UPDATE then we have to return tg_newtuple. Also, if key
* in tg_newtuple is the same as in tg_trigtuple then nothing to do.
*/
is_update = 0;
if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
{
newtuple = trigdata->tg_newtuple;
is_update = 1;
}
trigger = trigdata->tg_trigger;
nargs = trigger->tgnargs;
args = trigger->tgargs;
if (nargs < 5) /* nrefs, action, key, Relation, key - at
* least */
/* internal error */
elog(ERROR, "check_foreign_key: too short %d (< 5) list of arguments", nargs);
nrefs = pg_strtoint32(args[0]);
if (nrefs < 1)
/* internal error */
elog(ERROR, "check_foreign_key: %d (< 1) number of references specified", nrefs);
action = tolower((unsigned char) *(args[1]));
if (action != 'r' && action != 'c' && action != 's')
/* internal error */
elog(ERROR, "check_foreign_key: invalid action %s", args[1]);
nargs -= 2;
args += 2;
nkeys = (nargs - nrefs) / (nrefs + 1);
if (nkeys <= 0 || nargs != (nrefs + nkeys * (nrefs + 1)))
/* internal error */
elog(ERROR, "check_foreign_key: invalid number of arguments %d for %d references",
nargs + 2, nrefs);
rel = trigdata->tg_relation;
tupdesc = rel->rd_att;
/* Connect to SPI manager */
if ((ret = SPI_connect()) < 0)
/* internal error */
elog(ERROR, "check_foreign_key: SPI_connect returned %d", ret);
/*
* We use SPI plan preparation feature, so allocate space to place key
* values.
*/
kvals = (Datum *) palloc(nkeys * sizeof(Datum));
/*
* Construct ident string as TriggerName $ TriggeredRelationId and try to
* find prepared execution plan(s).
*/
snprintf(ident, sizeof(ident), "%s$%u", trigger->tgname, rel->rd_id);
plan = find_plan(ident, &FPlans, &nFPlans);
/* if there is no plan(s) then allocate argtypes for preparation */
if (plan->nplans <= 0)
argtypes = (Oid *) palloc(nkeys * sizeof(Oid));
/*
* else - check that we have exactly nrefs plan(s) ready
*/
else if (plan->nplans != nrefs)
/* internal error */
elog(ERROR, "%s: check_foreign_key: # of plans changed in meantime",
trigger->tgname);
/* For each column in key ... */
for (i = 0; i < nkeys; i++)
{
/* get index of column in tuple */
int fnumber = SPI_fnumber(tupdesc, args[i]);
/* Bad guys may give us un-existing column in CREATE TRIGGER */
if (fnumber <= 0)
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_COLUMN),
errmsg("there is no attribute \"%s\" in relation \"%s\"",
args[i], SPI_getrelname(rel))));
/* Well, get binary (in internal format) value of column */
kvals[i] = SPI_getbinval(trigtuple, tupdesc, fnumber, &isnull);
/*
* If it's NULL then nothing to do! DON'T FORGET call SPI_finish ()!
* DON'T FORGET return tuple! Executor inserts tuple you're returning!
* If you return NULL then nothing will be inserted!
*/
if (isnull)
{
SPI_finish();
return PointerGetDatum((newtuple == NULL) ? trigtuple : newtuple);
}
/*
* If UPDATE then get column value from new tuple being inserted and
* compare is this the same as old one. For the moment we use string
* presentation of values...
*/
if (newtuple != NULL)
{
char *oldval = SPI_getvalue(trigtuple, tupdesc, fnumber);
char *newval;
/* this shouldn't happen! SPI_ERROR_NOOUTFUNC ? */
if (oldval == NULL)
/* internal error */
elog(ERROR, "check_foreign_key: SPI_getvalue returned %s", SPI_result_code_string(SPI_result));
newval = SPI_getvalue(newtuple, tupdesc, fnumber);
if (newval == NULL || strcmp(oldval, newval) != 0)
isequal = false;
}
if (plan->nplans <= 0) /* Get typeId of column */
argtypes[i] = SPI_gettypeid(tupdesc, fnumber);
}
args_temp = args;
nargs -= nkeys;
args += nkeys;
/*
* If we have to prepare plans ...
*/
if (plan->nplans <= 0)
{
SPIPlanPtr pplan;
char sql[8192];
char **args2 = args;
plan->splan = (SPIPlanPtr *) MemoryContextAlloc(TopMemoryContext,
nrefs * sizeof(SPIPlanPtr));
for (r = 0; r < nrefs; r++)
{
relname = args2[0];
/*---------
* For 'R'estrict action we construct SELECT query:
*
* SELECT 1
* FROM _referencing_relation_
* WHERE Fkey1 = $1 [AND Fkey2 = $2 [...]]
*
* to check is tuple referenced or not.
*---------
*/
if (action == 'r')
snprintf(sql, sizeof(sql), "select 1 from %s where ", relname);
/*---------
* For 'C'ascade action we construct DELETE query
*
* DELETE
* FROM _referencing_relation_
* WHERE Fkey1 = $1 [AND Fkey2 = $2 [...]]
*
* to delete all referencing tuples.
*---------
*/
/*
* Max : Cascade with UPDATE query i create update query that
* updates new key values in referenced tables
*/
else if (action == 'c')
{
if (is_update == 1)
{
int fn;
char *nv;
int k;
snprintf(sql, sizeof(sql), "update %s set ", relname);
for (k = 1; k <= nkeys; k++)
{
int is_char_type = 0;
char *type;
fn = SPI_fnumber(tupdesc, args_temp[k - 1]);
Assert(fn > 0); /* already checked above */
nv = SPI_getvalue(newtuple, tupdesc, fn);
type = SPI_gettype(tupdesc, fn);
if (strcmp(type, "text") == 0 ||
strcmp(type, "varchar") == 0 ||
strcmp(type, "char") == 0 ||
strcmp(type, "bpchar") == 0 ||
strcmp(type, "date") == 0 ||
strcmp(type, "timestamp") == 0)
is_char_type = 1;
#ifdef DEBUG_QUERY
elog(DEBUG4, "check_foreign_key Debug value %s type %s %d",
nv, type, is_char_type);
#endif
/*
* is_char_type =1 i set ' ' for define a new value
*/
snprintf(sql + strlen(sql), sizeof(sql) - strlen(sql),
" %s = %s%s%s %s ",
args2[k], (is_char_type > 0) ? "'" : "",
nv, (is_char_type > 0) ? "'" : "", (k < nkeys) ? ", " : "");
}
strcat(sql, " where ");
}
else
/* DELETE */
snprintf(sql, sizeof(sql), "delete from %s where ", relname);
}
/*
* For 'S'etnull action we construct UPDATE query - UPDATE
* _referencing_relation_ SET Fkey1 null [, Fkey2 null [...]]
* WHERE Fkey1 = $1 [AND Fkey2 = $2 [...]] - to set key columns in
* all referencing tuples to NULL.
*/
else if (action == 's')
{
snprintf(sql, sizeof(sql), "update %s set ", relname);
for (i = 1; i <= nkeys; i++)
{
snprintf(sql + strlen(sql), sizeof(sql) - strlen(sql),
"%s = null%s",
args2[i], (i < nkeys) ? ", " : "");
}
strcat(sql, " where ");
}
/* Construct WHERE qual */
for (i = 1; i <= nkeys; i++)
{
snprintf(sql + strlen(sql), sizeof(sql) - strlen(sql), "%s = $%d %s",
args2[i], i, (i < nkeys) ? "and " : "");
}
/* Prepare plan for query */
pplan = SPI_prepare(sql, nkeys, argtypes);
if (pplan == NULL)
/* internal error */
elog(ERROR, "check_foreign_key: SPI_prepare returned %s", SPI_result_code_string(SPI_result));
/*
* Remember that SPI_prepare places plan in current memory context
* - so, we have to save plan in Top memory context for later use.
*/
if (SPI_keepplan(pplan))
/* internal error */
elog(ERROR, "check_foreign_key: SPI_keepplan failed");
plan->splan[r] = pplan;
args2 += nkeys + 1; /* to the next relation */
}
plan->nplans = nrefs;
#ifdef DEBUG_QUERY
elog(DEBUG4, "check_foreign_key Debug Query is : %s ", sql);
#endif
}
/*
* If UPDATE and key is not changed ...
*/
if (newtuple != NULL && isequal)
{
SPI_finish();
return PointerGetDatum(newtuple);
}
/*
* Ok, execute prepared plan(s).
*/
for (r = 0; r < nrefs; r++)
{
/*
* For 'R'estrict we may to execute plan for one tuple only, for other
* actions - for all tuples.
*/
int tcount = (action == 'r') ? 1 : 0;
relname = args[0];
snprintf(ident, sizeof(ident), "%s$%u", trigger->tgname, rel->rd_id);
plan = find_plan(ident, &FPlans, &nFPlans);
ret = SPI_execp(plan->splan[r], kvals, NULL, tcount);
/* we have no NULLs - so we pass ^^^^ here */
if (ret < 0)
ereport(ERROR,
(errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
errmsg("SPI_execp returned %d", ret)));
/* If action is 'R'estrict ... */
if (action == 'r')
{
/* If there is tuple returned by SELECT then ... */
if (SPI_processed > 0)
ereport(ERROR,
(errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
errmsg("\"%s\": tuple is referenced in \"%s\"",
trigger->tgname, relname)));
}
else
{
#ifdef REFINT_VERBOSE
elog(NOTICE, "%s: " UINT64_FORMAT " tuple(s) of %s are %s",
trigger->tgname, SPI_processed, relname,
(action == 'c') ? "deleted" : "set to null");
#endif
}
args += nkeys + 1; /* to the next relation */
}
SPI_finish();
return PointerGetDatum((newtuple == NULL) ? trigtuple : newtuple);
}
static EPlan *
find_plan(char *ident, EPlan **eplan, int *nplans)
{
EPlan *newp;
int i;
MemoryContext oldcontext;
/*
* All allocations done for the plans need to happen in a session-safe
* context.
*/
oldcontext = MemoryContextSwitchTo(TopMemoryContext);
if (*nplans > 0)
{
for (i = 0; i < *nplans; i++)
{
if (strcmp((*eplan)[i].ident, ident) == 0)
break;
}
if (i != *nplans)
{
MemoryContextSwitchTo(oldcontext);
return (*eplan + i);
}
*eplan = (EPlan *) repalloc(*eplan, (i + 1) * sizeof(EPlan));
newp = *eplan + i;
}
else
{
newp = *eplan = (EPlan *) palloc(sizeof(EPlan));
(*nplans) = i = 0;
}
newp->ident = pstrdup(ident);
newp->nplans = 0;
newp->splan = NULL;
(*nplans)++;
MemoryContextSwitchTo(oldcontext);
return newp;
}
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