+++ /dev/null
-/*
- * contrib/spi/timetravel.c
- *
- *
- * timetravel.c -- function to get time travel feature
- * using general triggers.
- *
- * Modified by BÖJTHE Zoltán, Hungary, mailto:urdesobt@axelero.hu
- */
-#include "postgres.h"
-
-#include <ctype.h>
-
-#include "access/htup_details.h"
-#include "catalog/pg_type.h"
-#include "commands/trigger.h"
-#include "executor/spi.h"
-#include "miscadmin.h"
-#include "utils/builtins.h"
-#include "utils/nabstime.h"
-#include "utils/rel.h"
-
-PG_MODULE_MAGIC;
-
-/* AbsoluteTime currabstime(void); */
-
-typedef struct
-{
- char *ident;
- SPIPlanPtr splan;
-} EPlan;
-
-static EPlan *Plans = NULL; /* for UPDATE/DELETE */
-static int nPlans = 0;
-
-typedef struct _TTOffList
-{
- struct _TTOffList *next;
- char name[FLEXIBLE_ARRAY_MEMBER];
-} TTOffList;
-
-static TTOffList *TTOff = NULL;
-
-static int findTTStatus(char *name);
-static EPlan *find_plan(char *ident, EPlan **eplan, int *nplans);
-
-/*
- * timetravel () --
- * 1. IF an update affects tuple with stop_date eq INFINITY
- * then form (and return) new tuple with start_date eq current date
- * and stop_date eq INFINITY [ and update_user eq current user ]
- * and all other column values as in new tuple, and insert tuple
- * with old data and stop_date eq current date
- * ELSE - skip updating of tuple.
- * 2. IF a delete affects tuple with stop_date eq INFINITY
- * then insert the same tuple with stop_date eq current date
- * [ and delete_user eq current user ]
- * ELSE - skip deletion of tuple.
- * 3. On INSERT, if start_date is NULL then current date will be
- * inserted, if stop_date is NULL then INFINITY will be inserted.
- * [ and insert_user eq current user, update_user and delete_user
- * eq NULL ]
- *
- * In CREATE TRIGGER you are to specify start_date and stop_date column
- * names:
- * EXECUTE PROCEDURE
- * timetravel ('date_on', 'date_off' [,'insert_user', 'update_user', 'delete_user' ] ).
- */
-
-#define MaxAttrNum 5
-#define MinAttrNum 2
-
-#define a_time_on 0
-#define a_time_off 1
-#define a_ins_user 2
-#define a_upd_user 3
-#define a_del_user 4
-
-PG_FUNCTION_INFO_V1(timetravel);
-
-Datum /* have to return HeapTuple to Executor */
-timetravel(PG_FUNCTION_ARGS)
-{
- TriggerData *trigdata = (TriggerData *) fcinfo->context;
- Trigger *trigger; /* to get trigger name */
- int argc;
- char **args; /* arguments */
- int attnum[MaxAttrNum]; /* fnumbers of start/stop columns */
- Datum oldtimeon,
- oldtimeoff;
- Datum newtimeon,
- newtimeoff,
- newuser,
- nulltext;
- Datum *cvals; /* column values */
- char *cnulls; /* column nulls */
- char *relname; /* triggered relation name */
- Relation rel; /* triggered relation */
- HeapTuple trigtuple;
- HeapTuple newtuple = NULL;
- HeapTuple rettuple;
- TupleDesc tupdesc; /* tuple description */
- int natts; /* # of attributes */
- EPlan *plan; /* prepared plan */
- char ident[2 * NAMEDATALEN];
- bool isnull; /* to know is some column NULL or not */
- bool isinsert = false;
- int ret;
- int i;
-
- /*
- * Some checks first...
- */
-
- /* Called by trigger manager ? */
- if (!CALLED_AS_TRIGGER(fcinfo))
- elog(ERROR, "timetravel: not fired by trigger manager");
-
- /* Should be called for ROW trigger */
- if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
- elog(ERROR, "timetravel: must be fired for row");
-
- /* Should be called BEFORE */
- if (!TRIGGER_FIRED_BEFORE(trigdata->tg_event))
- elog(ERROR, "timetravel: must be fired before event");
-
- /* INSERT ? */
- if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
- isinsert = true;
-
- if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
- newtuple = trigdata->tg_newtuple;
-
- trigtuple = trigdata->tg_trigtuple;
-
- rel = trigdata->tg_relation;
- relname = SPI_getrelname(rel);
-
- /* check if TT is OFF for this relation */
- if (0 == findTTStatus(relname))
- {
- /* OFF - nothing to do */
- pfree(relname);
- return PointerGetDatum((newtuple != NULL) ? newtuple : trigtuple);
- }
-
- trigger = trigdata->tg_trigger;
-
- argc = trigger->tgnargs;
- if (argc != MinAttrNum && argc != MaxAttrNum)
- elog(ERROR, "timetravel (%s): invalid (!= %d or %d) number of arguments %d",
- relname, MinAttrNum, MaxAttrNum, trigger->tgnargs);
-
- args = trigger->tgargs;
- tupdesc = rel->rd_att;
- natts = tupdesc->natts;
-
- for (i = 0; i < MinAttrNum; i++)
- {
- attnum[i] = SPI_fnumber(tupdesc, args[i]);
- if (attnum[i] <= 0)
- elog(ERROR, "timetravel (%s): there is no attribute %s", relname, args[i]);
- if (SPI_gettypeid(tupdesc, attnum[i]) != ABSTIMEOID)
- elog(ERROR, "timetravel (%s): attribute %s must be of abstime type",
- relname, args[i]);
- }
- for (; i < argc; i++)
- {
- attnum[i] = SPI_fnumber(tupdesc, args[i]);
- if (attnum[i] <= 0)
- elog(ERROR, "timetravel (%s): there is no attribute %s", relname, args[i]);
- if (SPI_gettypeid(tupdesc, attnum[i]) != TEXTOID)
- elog(ERROR, "timetravel (%s): attribute %s must be of text type",
- relname, args[i]);
- }
-
- /* create fields containing name */
- newuser = CStringGetTextDatum(GetUserNameFromId(GetUserId(), false));
-
- nulltext = (Datum) NULL;
-
- if (isinsert)
- { /* INSERT */
- int chnattrs = 0;
- int chattrs[MaxAttrNum];
- Datum newvals[MaxAttrNum];
- bool newnulls[MaxAttrNum];
-
- oldtimeon = SPI_getbinval(trigtuple, tupdesc, attnum[a_time_on], &isnull);
- if (isnull)
- {
- newvals[chnattrs] = GetCurrentAbsoluteTime();
- newnulls[chnattrs] = false;
- chattrs[chnattrs] = attnum[a_time_on];
- chnattrs++;
- }
-
- oldtimeoff = SPI_getbinval(trigtuple, tupdesc, attnum[a_time_off], &isnull);
- if (isnull)
- {
- if ((chnattrs == 0 && DatumGetInt32(oldtimeon) >= NOEND_ABSTIME) ||
- (chnattrs > 0 && DatumGetInt32(newvals[a_time_on]) >= NOEND_ABSTIME))
- elog(ERROR, "timetravel (%s): %s is infinity", relname, args[a_time_on]);
- newvals[chnattrs] = NOEND_ABSTIME;
- newnulls[chnattrs] = false;
- chattrs[chnattrs] = attnum[a_time_off];
- chnattrs++;
- }
- else
- {
- if ((chnattrs == 0 && DatumGetInt32(oldtimeon) > DatumGetInt32(oldtimeoff)) ||
- (chnattrs > 0 && DatumGetInt32(newvals[a_time_on]) > DatumGetInt32(oldtimeoff)))
- elog(ERROR, "timetravel (%s): %s gt %s", relname, args[a_time_on], args[a_time_off]);
- }
-
- pfree(relname);
- if (chnattrs <= 0)
- return PointerGetDatum(trigtuple);
-
- if (argc == MaxAttrNum)
- {
- /* clear update_user value */
- newvals[chnattrs] = nulltext;
- newnulls[chnattrs] = true;
- chattrs[chnattrs] = attnum[a_upd_user];
- chnattrs++;
- /* clear delete_user value */
- newvals[chnattrs] = nulltext;
- newnulls[chnattrs] = true;
- chattrs[chnattrs] = attnum[a_del_user];
- chnattrs++;
- /* set insert_user value */
- newvals[chnattrs] = newuser;
- newnulls[chnattrs] = false;
- chattrs[chnattrs] = attnum[a_ins_user];
- chnattrs++;
- }
- rettuple = heap_modify_tuple_by_cols(trigtuple, tupdesc,
- chnattrs, chattrs,
- newvals, newnulls);
- return PointerGetDatum(rettuple);
- /* end of INSERT */
- }
-
- /* UPDATE/DELETE: */
- oldtimeon = SPI_getbinval(trigtuple, tupdesc, attnum[a_time_on], &isnull);
- if (isnull)
- elog(ERROR, "timetravel (%s): %s must be NOT NULL", relname, args[a_time_on]);
-
- oldtimeoff = SPI_getbinval(trigtuple, tupdesc, attnum[a_time_off], &isnull);
- if (isnull)
- elog(ERROR, "timetravel (%s): %s must be NOT NULL", relname, args[a_time_off]);
-
- /*
- * If DELETE/UPDATE of tuple with stop_date neq INFINITY then say upper
- * Executor to skip operation for this tuple
- */
- if (newtuple != NULL)
- { /* UPDATE */
- newtimeon = SPI_getbinval(newtuple, tupdesc, attnum[a_time_on], &isnull);
- if (isnull)
- elog(ERROR, "timetravel (%s): %s must be NOT NULL", relname, args[a_time_on]);
-
- newtimeoff = SPI_getbinval(newtuple, tupdesc, attnum[a_time_off], &isnull);
- if (isnull)
- elog(ERROR, "timetravel (%s): %s must be NOT NULL", relname, args[a_time_off]);
-
- if (oldtimeon != newtimeon || oldtimeoff != newtimeoff)
- elog(ERROR, "timetravel (%s): you cannot change %s and/or %s columns (use set_timetravel)",
- relname, args[a_time_on], args[a_time_off]);
- }
- if (oldtimeoff != NOEND_ABSTIME)
- { /* current record is a deleted/updated record */
- pfree(relname);
- return PointerGetDatum(NULL);
- }
-
- newtimeoff = GetCurrentAbsoluteTime();
-
- /* Connect to SPI manager */
- if ((ret = SPI_connect()) < 0)
- elog(ERROR, "timetravel (%s): SPI_connect returned %d", relname, ret);
-
- /* Fetch tuple values and nulls */
- cvals = (Datum *) palloc(natts * sizeof(Datum));
- cnulls = (char *) palloc(natts * sizeof(char));
- for (i = 0; i < natts; i++)
- {
- cvals[i] = SPI_getbinval(trigtuple, tupdesc, i + 1, &isnull);
- cnulls[i] = (isnull) ? 'n' : ' ';
- }
-
- /* change date column(s) */
- cvals[attnum[a_time_off] - 1] = newtimeoff; /* stop_date eq current date */
- cnulls[attnum[a_time_off] - 1] = ' ';
-
- if (!newtuple)
- { /* DELETE */
- if (argc == MaxAttrNum)
- {
- cvals[attnum[a_del_user] - 1] = newuser; /* set delete user */
- cnulls[attnum[a_del_user] - 1] = ' ';
- }
- }
-
- /*
- * 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, &Plans, &nPlans);
-
- /* if there is no plan ... */
- if (plan->splan == NULL)
- {
- SPIPlanPtr pplan;
- Oid *ctypes;
- char sql[8192];
- char separ = ' ';
-
- /* allocate ctypes for preparation */
- ctypes = (Oid *) palloc(natts * sizeof(Oid));
-
- /*
- * Construct query: INSERT INTO _relation_ VALUES ($1, ...)
- */
- snprintf(sql, sizeof(sql), "INSERT INTO %s VALUES (", relname);
- for (i = 1; i <= natts; i++)
- {
- ctypes[i - 1] = SPI_gettypeid(tupdesc, i);
- if (!(TupleDescAttr(tupdesc, i - 1)->attisdropped)) /* skip dropped columns */
- {
- snprintf(sql + strlen(sql), sizeof(sql) - strlen(sql), "%c$%d", separ, i);
- separ = ',';
- }
- }
- snprintf(sql + strlen(sql), sizeof(sql) - strlen(sql), ")");
-
- elog(DEBUG4, "timetravel (%s) update: sql: %s", relname, sql);
-
- /* Prepare plan for query */
- pplan = SPI_prepare(sql, natts, ctypes);
- if (pplan == NULL)
- elog(ERROR, "timetravel (%s): SPI_prepare returned %s", relname, 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))
- elog(ERROR, "timetravel (%s): SPI_keepplan failed", relname);
-
- plan->splan = pplan;
- }
-
- /*
- * Ok, execute prepared plan.
- */
- ret = SPI_execp(plan->splan, cvals, cnulls, 0);
-
- if (ret < 0)
- elog(ERROR, "timetravel (%s): SPI_execp returned %d", relname, ret);
-
- /* Tuple to return to upper Executor ... */
- if (newtuple)
- { /* UPDATE */
- int chnattrs = 0;
- int chattrs[MaxAttrNum];
- Datum newvals[MaxAttrNum];
- char newnulls[MaxAttrNum];
-
- newvals[chnattrs] = newtimeoff;
- newnulls[chnattrs] = ' ';
- chattrs[chnattrs] = attnum[a_time_on];
- chnattrs++;
-
- newvals[chnattrs] = NOEND_ABSTIME;
- newnulls[chnattrs] = ' ';
- chattrs[chnattrs] = attnum[a_time_off];
- chnattrs++;
-
- if (argc == MaxAttrNum)
- {
- /* set update_user value */
- newvals[chnattrs] = newuser;
- newnulls[chnattrs] = ' ';
- chattrs[chnattrs] = attnum[a_upd_user];
- chnattrs++;
- /* clear delete_user value */
- newvals[chnattrs] = nulltext;
- newnulls[chnattrs] = 'n';
- chattrs[chnattrs] = attnum[a_del_user];
- chnattrs++;
- /* set insert_user value */
- newvals[chnattrs] = nulltext;
- newnulls[chnattrs] = 'n';
- chattrs[chnattrs] = attnum[a_ins_user];
- chnattrs++;
- }
-
- /*
- * Use SPI_modifytuple() here because we are inside SPI environment
- * but rettuple must be allocated in caller's context.
- */
- rettuple = SPI_modifytuple(rel, newtuple, chnattrs, chattrs, newvals, newnulls);
- }
- else
- /* DELETE case */
- rettuple = trigtuple;
-
- SPI_finish(); /* don't forget say Bye to SPI mgr */
-
- pfree(relname);
- return PointerGetDatum(rettuple);
-}
-
-/*
- * set_timetravel (relname, on) --
- * turn timetravel for specified relation ON/OFF
- */
-PG_FUNCTION_INFO_V1(set_timetravel);
-
-Datum
-set_timetravel(PG_FUNCTION_ARGS)
-{
- Name relname = PG_GETARG_NAME(0);
- int32 on = PG_GETARG_INT32(1);
- char *rname;
- char *d;
- char *s;
- int32 ret;
- TTOffList *prev,
- *pp;
-
- prev = NULL;
- for (pp = TTOff; pp; prev = pp, pp = pp->next)
- {
- if (namestrcmp(relname, pp->name) == 0)
- break;
- }
- if (pp)
- {
- /* OFF currently */
- if (on != 0)
- {
- /* turn ON */
- if (prev)
- prev->next = pp->next;
- else
- TTOff = pp->next;
- free(pp);
- }
- ret = 0;
- }
- else
- {
- /* ON currently */
- if (on == 0)
- {
- /* turn OFF */
- s = rname = DatumGetCString(DirectFunctionCall1(nameout, NameGetDatum(relname)));
- if (s)
- {
- pp = malloc(offsetof(TTOffList, name) + strlen(rname) + 1);
- if (pp)
- {
- pp->next = NULL;
- d = pp->name;
- while (*s)
- *d++ = tolower((unsigned char) *s++);
- *d = '\0';
- if (prev)
- prev->next = pp;
- else
- TTOff = pp;
- }
- pfree(rname);
- }
- }
- ret = 1;
- }
- PG_RETURN_INT32(ret);
-}
-
-/*
- * get_timetravel (relname) --
- * get timetravel status for specified relation (ON/OFF)
- */
-PG_FUNCTION_INFO_V1(get_timetravel);
-
-Datum
-get_timetravel(PG_FUNCTION_ARGS)
-{
- Name relname = PG_GETARG_NAME(0);
- TTOffList *pp;
-
- for (pp = TTOff; pp; pp = pp->next)
- {
- if (namestrcmp(relname, pp->name) == 0)
- PG_RETURN_INT32(0);
- }
- PG_RETURN_INT32(1);
-}
-
-static int
-findTTStatus(char *name)
-{
- TTOffList *pp;
-
- for (pp = TTOff; pp; pp = pp->next)
- if (pg_strcasecmp(name, pp->name) == 0)
- return 0;
- return 1;
-}
-
-/*
-AbsoluteTime
-currabstime()
-{
- return GetCurrentAbsoluteTime();
-}
-*/
-
-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 = strdup(ident);
- newp->splan = NULL;
- (*nplans)++;
-
- return newp;
-}
</para>
</sect2>
- <sect2>
- <title>timetravel — Functions for Implementing Time Travel</title>
-
- <para>
- Long ago, <productname>PostgreSQL</productname> had a built-in time travel feature
- that kept the insert and delete times for each tuple. This can be
- emulated using these functions. To use these functions,
- you must add to a table two columns of <type>abstime</type> type to store
- the date when a tuple was inserted (start_date) and changed/deleted
- (stop_date):
-
-<programlisting>
-CREATE TABLE mytab (
- ... ...
- start_date abstime,
- stop_date abstime
- ... ...
-);
-</programlisting>
-
- The columns can be named whatever you like, but in this discussion
- we'll call them start_date and stop_date.
- </para>
-
- <para>
- When a new row is inserted, start_date should normally be set to
- current time, and stop_date to <literal>infinity</literal>. The trigger
- will automatically substitute these values if the inserted data
- contains nulls in these columns. Generally, inserting explicit
- non-null data in these columns should only be done when re-loading
- dumped data.
- </para>
-
- <para>
- Tuples with stop_date equal to <literal>infinity</literal> are <quote>valid
- now</quote>, and can be modified. Tuples with a finite stop_date cannot
- be modified anymore — the trigger will prevent it. (If you need
- to do that, you can turn off time travel as shown below.)
- </para>
-
- <para>
- For a modifiable row, on update only the stop_date in the tuple being
- updated will be changed (to current time) and a new tuple with the modified
- data will be inserted. Start_date in this new tuple will be set to current
- time and stop_date to <literal>infinity</literal>.
- </para>
-
- <para>
- A delete does not actually remove the tuple but only sets its stop_date
- to current time.
- </para>
-
- <para>
- To query for tuples <quote>valid now</quote>, include
- <literal>stop_date = 'infinity'</literal> in the query's WHERE condition.
- (You might wish to incorporate that in a view.) Similarly, you can
- query for tuples valid at any past time with suitable conditions on
- start_date and stop_date.
- </para>
-
- <para>
- <function>timetravel()</function> is the general trigger function that supports
- this behavior. Create a <literal>BEFORE INSERT OR UPDATE OR DELETE</literal>
- trigger using this function on each time-traveled table. Specify two
- trigger arguments: the actual
- names of the start_date and stop_date columns.
- Optionally, you can specify one to three more arguments, which must refer
- to columns of type <type>text</type>. The trigger will store the name of
- the current user into the first of these columns during INSERT, the
- second column during UPDATE, and the third during DELETE.
- </para>
-
- <para>
- <function>set_timetravel()</function> allows you to turn time-travel on or off for
- a table.
- <literal>set_timetravel('mytab', 1)</literal> will turn TT ON for table <literal>mytab</literal>.
- <literal>set_timetravel('mytab', 0)</literal> will turn TT OFF for table <literal>mytab</literal>.
- In both cases the old status is reported. While TT is off, you can modify
- the start_date and stop_date columns freely. Note that the on/off status
- is local to the current database session — fresh sessions will
- always start out with TT ON for all tables.
- </para>
-
- <para>
- <function>get_timetravel()</function> returns the TT state for a table without
- changing it.
- </para>
-
- <para>
- There is an example in <filename>timetravel.example</filename>.
- </para>
- </sect2>
-
<sect2>
<title>autoinc — Functions for Autoincrementing Fields</title>
projects / users / rhaas / postgres.git / commitdiff