Remove timetravel extension.

The extension depended on old types which are about to be removed. As
the code additionally was pretty crufty and didn't provide much in the
way of functionality, removing the extension seems to be the best way
forward.  It's fairly trivial to write functionality in plpgsql that
more than covers what timetravel did.

Author: Andres Freund
Discussion:
    https://postgr.es/m/20171213080506.cwjkpcz3bkk6yz2u@alap3.anarazel.de
    https://postgr.es/m/25615.1513115237@sss.pgh.pa.us

6 files changed, 3 insertions, 670 deletions

diff --git a/contrib/spi/Makefile b/contrib/spi/Makefile
index 42aa3740c4..6bc2318e0a 100644
--- a/contrib/spi/Makefile
+++ b/contrib/spi/Makefile
@@ -1,14 +1,13 @@
 # contrib/spi/Makefile
 
-MODULES = autoinc insert_username moddatetime refint timetravel
+MODULES = autoinc insert_username moddatetime refint
 
-EXTENSION = autoinc insert_username moddatetime refint timetravel
+EXTENSION = autoinc insert_username moddatetime refint
 
 DATA = autoinc--1.0.sql autoinc--unpackaged--1.0.sql \
        insert_username--1.0.sql insert_username--unpackaged--1.0.sql \
        moddatetime--1.0.sql moddatetime--unpackaged--1.0.sql \
-       refint--1.0.sql refint--unpackaged--1.0.sql \
-       timetravel--1.0.sql timetravel--unpackaged--1.0.sql
+       refint--1.0.sql refint--unpackaged--1.0.sql
 PGFILEDESC = "spi - examples of using SPI and triggers"
 
 DOCS = $(addsuffix .example, $(MODULES))
diff --git a/contrib/spi/timetravel--1.0.sql b/contrib/spi/timetravel--1.0.sql
deleted file mode 100644
index c34ca09965..0000000000
--- a/contrib/spi/timetravel--1.0.sql
+++ /dev/null
@@ -1,19 +0,0 @@
-/* contrib/spi/timetravel--1.0.sql */
-
--- complain if script is sourced in psql, rather than via CREATE EXTENSION
-\echo Use "CREATE EXTENSION timetravel" to load this file. \quit
-
-CREATE FUNCTION timetravel()
-RETURNS trigger
-AS 'MODULE_PATHNAME'
-LANGUAGE C;
-
-CREATE FUNCTION set_timetravel(name, int4)
-RETURNS int4
-AS 'MODULE_PATHNAME'
-LANGUAGE C RETURNS NULL ON NULL INPUT;
-
-CREATE FUNCTION get_timetravel(name)
-RETURNS int4
-AS 'MODULE_PATHNAME'
-LANGUAGE C RETURNS NULL ON NULL INPUT;
diff --git a/contrib/spi/timetravel--unpackaged--1.0.sql b/contrib/spi/timetravel--unpackaged--1.0.sql
deleted file mode 100644
index 121bceba9b..0000000000
--- a/contrib/spi/timetravel--unpackaged--1.0.sql
+++ /dev/null
@@ -1,8 +0,0 @@
-/* contrib/spi/timetravel--unpackaged--1.0.sql */
-
--- complain if script is sourced in psql, rather than via CREATE EXTENSION
-\echo Use "CREATE EXTENSION timetravel FROM unpackaged" to load this file. \quit
-
-ALTER EXTENSION timetravel ADD function timetravel();
-ALTER EXTENSION timetravel ADD function set_timetravel(name,integer);
-ALTER EXTENSION timetravel ADD function get_timetravel(name);
diff --git a/contrib/spi/timetravel.c b/contrib/spi/timetravel.c
deleted file mode 100644
index 00f661e6b6..0000000000
--- a/contrib/spi/timetravel.c
+++ /dev/null
@@ -1,553 +0,0 @@
-/*
- * 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;
-}
diff --git a/contrib/spi/timetravel.control b/contrib/spi/timetravel.control
deleted file mode 100644
index 9b4bb6ba04..0000000000
--- a/contrib/spi/timetravel.control
+++ /dev/null
@@ -1,5 +0,0 @@
-# timetravel extension
-comment = 'functions for implementing time travel'
-default_version = '1.0'
-module_pathname = '$libdir/timetravel'
-relocatable = true
diff --git a/contrib/spi/timetravel.example b/contrib/spi/timetravel.example
deleted file mode 100644
index 35a7f65408..0000000000
--- a/contrib/spi/timetravel.example
+++ /dev/null
@@ -1,81 +0,0 @@
-drop table tttest;
-
-create table tttest (
-	price_id	int4,
-	price_val	int4,
-	price_on	abstime,
-	price_off	abstime
-);
-
-create unique index tttest_idx on tttest (price_id,price_off);
-alter table tttest add column q1 text;
-alter table tttest add column q2 int;
-alter table tttest drop column q1;
-
-create trigger timetravel
-	before insert or delete or update on tttest
-	for each row
-	execute procedure
-	timetravel (price_on, price_off);
-
-insert into tttest values (1, 1, null, null);
-insert into tttest(price_id, price_val) values (2, 2);
-insert into tttest(price_id, price_val,price_off) values (3, 3, 'infinity');
-
-insert into tttest(price_id, price_val,price_off) values (4, 4,
-	abstime('now'::timestamp - '100 days'::interval));
-insert into tttest(price_id, price_val,price_on) values (3, 3, 'infinity'); -- duplicate key
-
-select * from tttest;
-delete from tttest where price_id = 2;
-select * from tttest;
--- what do we see ?
-
--- get current prices
-select * from tttest where price_off = 'infinity';
-
--- change price for price_id == 3
-update tttest set price_val = 30 where price_id = 3;
-select * from tttest;
-
--- now we want to change price_id from 3 to 5 in ALL tuples
--- but this gets us not what we need
-update tttest set price_id = 5 where price_id = 3;
-select * from tttest;
-
--- restore data as before last update:
-select set_timetravel('tttest', 0);	-- turn TT OFF!
-
-select get_timetravel('tttest');	-- check status
-
-delete from tttest where price_id = 5;
-update tttest set price_off = 'infinity' where price_val = 30;
-select * from tttest;
-
--- and try change price_id now!
-update tttest set price_id = 5 where price_id = 3;
-select * from tttest;
--- isn't it what we need ?
-
-select set_timetravel('tttest', 1);	-- turn TT ON!
-
-select get_timetravel('tttest');	-- check status
-
--- we want to correct some date
-update tttest set price_on = 'Jan-01-1990 00:00:01' where price_id = 5 and
-	price_off <> 'infinity';
--- but this doesn't work
-
--- try in this way
-select set_timetravel('tttest', 0);	-- turn TT OFF!
-
-select get_timetravel('tttest');	-- check status
-
-update tttest set price_on = '01-Jan-1990 00:00:01' where price_id = 5 and
-	price_off <> 'infinity';
-select * from tttest;
--- isn't it what we need ?
-
--- get price for price_id == 5 as it was '10-Jan-1990'
-select * from tttest where price_id = 5 and
-	price_on <= '10-Jan-1990' and price_off > '10-Jan-1990';