Re: [GENERAL] Foreign Keys: check_primary_function - Mailing list pgsql-hackers

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);
> }


--
  Bruce Momjian                        |  http://www.op.net/~candle
  maillist@candle.pha.pa.us            |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026