Re: [GENERAL] Foreign Keys: check_primary_function

Applied.

> Hi All,
> I've changed the check_primary_key() function code to allow for either
> the "automatic insert key rule" or "dependent insert key rule".
> Previously it restricted the addtion of a child entry if the
> corresponding parent entry was not there. Now if the option is
> "automatic" it will add an entry in the parent too ( it will be
> successful if there are no no-null fields in the parent apart from the
> primary key).
> The way to use it now is:
> /*
> * 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,type of action
> [automatic|dependent]:
> * EXECUTE PROCEDURE
> * check_primary_key ('Fkey1', 'Fkey2', 'Ptable', 'Pkey1', 'Pkey2',
> '[automatic|dependent]').
> */
> I am attaching the new ../contrib/spi/refint.c file which will do this.
> I will be glad to help in case of any problems.
>
> - Anand.
>
>

> /*
> * refint.c -- set of functions to define referential integrity
> * constraints using general triggers.
> */
>
> #include "executor/spi.h" /* this is what you need to work with SPI */
> #include "commands/trigger.h" /* -"- and triggers */
> #include <ctype.h> /* tolower () */
>
> HeapTuple check_primary_key(void);
> HeapTuple check_foreign_key(void);
>
>
> typedef struct
> {
> char *ident;
> int nplans;
> void **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,type of action [automatic|dependent]:
> * EXECUTE PROCEDURE
> * check_primary_key ('Fkey1', 'Fkey2', 'Ptable', 'Pkey1', 'Pkey2','[automatic|dependent]').
> */
>
> HeapTuple /* have to return HeapTuple to Executor */
> check_primary_key()
> {
> 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-1) / 2) */
> Datum *kvals; /* key values */
> char *relname; /* referenced relation name */
> char *action; /* action on insert or update*/
> 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;
>
> /*
> * Some checks first...
> */
>
> /* Called by trigger manager ? */
> if (!CurrentTriggerData)
> elog(ERROR, "check_primary_key: triggers are not initialized");
>
> /* Should be called for ROW trigger */
> if (TRIGGER_FIRED_FOR_STATEMENT(CurrentTriggerData->tg_event))
> elog(ERROR, "check_primary_key: can't process STATEMENT events");
>
> /* If INSERTion then must check Tuple to being inserted */
> if (TRIGGER_FIRED_BY_INSERT(CurrentTriggerData->tg_event))
>
> tuple = CurrentTriggerData->tg_trigtuple;
>
> /* Not should be called for DELETE */
> else if (TRIGGER_FIRED_BY_DELETE(CurrentTriggerData->tg_event))
>
> elog(ERROR, "check_primary_key: can't process DELETE events");
>
> /* If UPDATion the must check new Tuple, not old one */
> else
> tuple = CurrentTriggerData->tg_newtuple;
>
> trigger = CurrentTriggerData->tg_trigger;
> nargs = trigger->tgnargs;
> args = trigger->tgargs;
>
> if ((nargs-1) % 2 != 1) /* odd number of arguments! */
> elog(ERROR, "check_primary_key: even number of arguments should be specified");
>
> nkeys = (nargs-1) / 2;
> action=args[nargs -1];
> if (strcmp(action,"automatic") && strcmp(action,"dependent"))
> elog(ERROR,"check_primary_key: unknown action");
> nargs=nargs-1;
> relname = args[nkeys];
> rel = CurrentTriggerData->tg_relation;
> tupdesc = rel->rd_att;
>
> /*
> * Setting CurrentTriggerData to NULL prevents direct calls to trigger
> * functions in queries. Normally, trigger functions have to be called
> * by trigger manager code only.
> */
> CurrentTriggerData = NULL;
>
> /* Connect to SPI manager */
> if ((ret = SPI_connect()) < 0)
> 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.
> */
> sprintf(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)
> elog(ERROR, "check_primary_key: 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 (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)
> {
> void *pplan;
> char sql[8192];
>
> /*
> * Construct query: SELECT 1 FROM _referenced_relation_ WHERE
> * Pkey1 = $1 [AND Pkey2 = $2 [...]]
> */
> sprintf(sql, "select 1 from %s where ", relname);
> for (i = 0; i < nkeys; i++)
> {
> sprintf(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)
> elog(ERROR, "check_primary_key: SPI_prepare returned %d", SPI_result);
>
> /*
> * Remember that SPI_prepare places plan in current memory context
> * - so, we have to save plan in Top memory context for latter
> * use.
> */
> pplan = SPI_saveplan(pplan);
> if (pplan == NULL)
> elog(ERROR, "check_primary_key: SPI_saveplan returned %d", SPI_result);
> plan->splan = (void **) malloc(sizeof(void *));
> *(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)
> elog(ERROR, "check_primary_key: SPI_execp returned %d", ret);
>
> /*
> * If there are no tuples returned by SELECT then ...
> */
> if (SPI_processed == 0 && strcmp(action,"dependent")==0)
> elog(ERROR, "%s: tuple references non-existing key in %s",
> trigger->tgname, relname);
> else if (strcmp(action,"automatic")==0)
> {
> /* insert tuple in parent with only primary keys */
> /* prepare plan */
> void *pplan;
> char sql[8192];
>
> /*
> * Construct query:INSERT INTO relname (Pkey1[,Pkey2]*) values ($1,$2..);
> */
> sprintf(sql, "insert into %s ( ", relname);
> for (i = 0; i < nkeys; i++)
> {
> sprintf(sql + strlen(sql), "%s%s ", args[i + nkeys + 1],(i<nkeys-1) ? ",":"");
> }
> sprintf(sql+strlen(sql),") values (");
> for (i=0;i<nkeys; i++)
> {
> sprintf(sql+strlen(sql),"$%d%s ",i+1,(i<nkeys-1) ? ",":"");
> }
> sprintf(sql+strlen(sql),")");
>
> /* Prepare plan for query */
> pplan = SPI_prepare(sql, nkeys, argtypes);
> if (pplan == NULL)
> elog(ERROR, "check_primary_key: SPI_prepare returned %d", SPI_result);
>
> /*
> * Remember that SPI_prepare places plan in current memory context
> * - so, we have to save plan in Top memory context for latter
> * use.
> */
> pplan = SPI_saveplan(pplan);
> if (pplan == NULL)
> elog(ERROR, "check_primary_key: SPI_saveplan returned %d", SPI_result);
> plan->splan = (void **) malloc(sizeof(void *));
> *(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)
> elog(ERROR, "check_primary_key: SPI_execp returned %d", ret);
>
> /*
> * If there are no tuples returned by INSERT then ...
> */
> if (SPI_processed == 0)
> elog(ERROR, "error: can't enter automatically in %s",relname);
> }
>
> SPI_finish();
>
> return (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').
> */
>
> HeapTuple /* have to return HeapTuple to Executor */
> check_foreign_key()
> {
> Trigger *trigger; /* to get trigger name */
> int nargs; /* # of args specified in CREATE TRIGGER */
> char **args; /* arguments: as described above */
> 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 ret;
> int i,
> r;
>
> /*
> * Some checks first...
> */
>
> /* Called by trigger manager ? */
> if (!CurrentTriggerData)
> elog(ERROR, "check_foreign_key: triggers are not initialized");
>
> /* Should be called for ROW trigger */
> if (TRIGGER_FIRED_FOR_STATEMENT(CurrentTriggerData->tg_event))
> elog(ERROR, "check_foreign_key: can't process STATEMENT events");
>
> /* Not should be called for INSERT */
> if (TRIGGER_FIRED_BY_INSERT(CurrentTriggerData->tg_event))
>
> elog(ERROR, "check_foreign_key: can't process INSERT events");
>
> /* Have to check tg_trigtuple - tuple being deleted */
> trigtuple = CurrentTriggerData->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.
> */
> if (TRIGGER_FIRED_BY_UPDATE(CurrentTriggerData->tg_event))
> newtuple = CurrentTriggerData->tg_newtuple;
>
> trigger = CurrentTriggerData->tg_trigger;
> nargs = trigger->tgnargs;
> args = trigger->tgargs;
>
> if (nargs < 5) /* nrefs, action, key, Relation, key - at
> * least */
> elog(ERROR, "check_foreign_key: too short %d (< 5) list of arguments", nargs);
> nrefs = pg_atoi(args[0], sizeof(int), 0);
> if (nrefs < 1)
> elog(ERROR, "check_foreign_key: %d (< 1) number of references specified", nrefs);
> action = tolower(*(args[1]));
> if (action != 'r' && action != 'c' && action != 's')
> 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)))
> elog(ERROR, "check_foreign_key: invalid number of arguments %d for %d references",
> nargs + 2, nrefs);
>
> rel = CurrentTriggerData->tg_relation;
> tupdesc = rel->rd_att;
>
> /*
> * Setting CurrentTriggerData to NULL prevents direct calls to trigger
> * functions in queries. Normally, trigger functions have to be called
> * by trigger manager code only.
> */
> CurrentTriggerData = NULL;
>
> /* Connect to SPI manager */
> if ((ret = SPI_connect()) < 0)
> 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).
> */
> sprintf(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)
> 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)
> elog(ERROR, "check_foreign_key: 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 ((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)
> elog(ERROR, "check_foreign_key: SPI_getvalue returned %d", 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);
> }
> nargs -= nkeys;
> args += nkeys;
>
> /*
> * If we have to prepare plans ...
> */
> if (plan->nplans <= 0)
> {
> void *pplan;
> char sql[8192];
> char **args2 = args;
>
> plan->splan = (void **) malloc(nrefs * sizeof(void *));
>
> 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')
>
> sprintf(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.
> */
> else if (action == 'c')
>
> sprintf(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')
> {
> sprintf(sql, "update %s set ", relname);
> for (i = 1; i <= nkeys; i++)
> {
> sprintf(sql + strlen(sql), "%s = null%s",
> args2[i], (i < nkeys) ? ", " : "");
> }
> strcat(sql, " where ");
> }
>
> /* Construct WHERE qual */
> for (i = 1; i <= nkeys; i++)
> {
> sprintf(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)
> elog(ERROR, "check_foreign_key: SPI_prepare returned %d", SPI_result);
>
> /*
> * Remember that SPI_prepare places plan in current memory
> * context - so, we have to save plan in Top memory context
> * for latter use.
> */
> pplan = SPI_saveplan(pplan);
> if (pplan == NULL)
> elog(ERROR, "check_foreign_key: SPI_saveplan returned %d", SPI_result);
>
> plan->splan[r] = pplan;
>
> args2 += nkeys + 1; /* to the next relation */
> }
> plan->nplans = nrefs;
> }
>
> /*
> * If UPDATE and key is not changed ...
> */
> if (newtuple != NULL && isequal)
> {
> SPI_finish();
> return (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];
>
> ret = SPI_execp(plan->splan[r], kvals, NULL, tcount);
> /* we have no NULLs - so we pass ^^^^ here */
>
> if (ret < 0)
> elog(ERROR, "check_foreign_key: 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)
> elog(ERROR, "%s: tuple referenced in %s",
> trigger->tgname, relname);
> }
> #ifdef REFINT_VERBOSE
> else
> elog(NOTICE, "%s: %d tuple(s) of %s are %s",
> trigger->tgname, SPI_processed, relname,
> (action == 'c') ? "deleted" : "setted to null");
> #endif
> args += nkeys + 1; /* to the next relation */
> }
>
> SPI_finish();
>
> return ((newtuple == NULL) ? trigtuple : newtuple);
> }
>
> static EPlan *
> find_plan(char *ident, EPlan ** eplan, int *nplans)
> {
> EPlan *newp;
> int i;
>
> if (*nplans > 0)
> {
> for (i = 0; i < *nplans; i++)
> {
> if (strcmp((*eplan)[i].ident, ident) == 0)
> break;
> }
> if (i != *nplans)
> return (*eplan + i);
> *eplan = (EPlan *) realloc(*eplan, (i + 1) * sizeof(EPlan));
> newp = *eplan + i;
> }
> else
> {
> newp = *eplan = (EPlan *) malloc(sizeof(EPlan));
> (*nplans) = i = 0;
> }
>
> newp->ident = (char *) malloc(strlen(ident) + 1);
> strcpy(newp->ident, ident);
> newp->nplans = 0;
> newp->splan = NULL;
> (*nplans)++;
>
> return (newp);
> }

--
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