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Generated columns

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This is an SQL-standard feature that allows creating columns that are
computed from expressions rather than assigned, similar to a view or
materialized view but on a column basis.

This implements one kind of generated column: stored (computed on
write).  Another kind, virtual (computed on read), is planned for the
future, and some room is left for it.

Reviewed-by: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Pavel Stehule <pavel.stehule@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/b151f851-4019-bdb1-699e-ebab07d2f40a@2ndquadrant.com
This commit is contained in:
Peter Eisentraut
2019-03-30 08:13:09 +01:00
parent 6b8b5364dd
commit fc22b6623b
84 changed files with 3067 additions and 157 deletions
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31
src/backend/commands/trigger.c
View File

@@ -75,8 +75,9 @@ static int MyTriggerDepth = 0;
* they use, so we let them be duplicated. Be sure to update all if one needs
* to be changed, however.
*/
#define GetUpdatedColumns(relinfo, estate) \
(exec_rt_fetch((relinfo)->ri_RangeTableIndex, estate)->updatedCols)
#define GetAllUpdatedColumns(relinfo, estate) \
(bms_union(exec_rt_fetch((relinfo)->ri_RangeTableIndex, estate)->updatedCols, \
exec_rt_fetch((relinfo)->ri_RangeTableIndex, estate)->extraUpdatedCols))
/* Local function prototypes */
static void ConvertTriggerToFK(CreateTrigStmt *stmt, Oid funcoid);
@@ -640,6 +641,24 @@ CreateTrigger(CreateTrigStmt *stmt, const char *queryString,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("BEFORE trigger's WHEN condition cannot reference NEW system columns"),
parser_errposition(pstate, var->location)));
if (TRIGGER_FOR_BEFORE(tgtype) &&
var->varattno == 0 &&
RelationGetDescr(rel)->constr &&
RelationGetDescr(rel)->constr->has_generated_stored)
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("BEFORE trigger's WHEN condition cannot reference NEW generated columns"),
errdetail("A whole-row reference is used and the table contains generated columns."),
parser_errposition(pstate, var->location)));
if (TRIGGER_FOR_BEFORE(tgtype) &&
var->varattno > 0 &&
TupleDescAttr(RelationGetDescr(rel), var->varattno - 1)->attgenerated)
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("BEFORE trigger's WHEN condition cannot reference NEW generated columns"),
errdetail("Column \"%s\" is a generated column.",
NameStr(TupleDescAttr(RelationGetDescr(rel), var->varattno - 1)->attname)),
parser_errposition(pstate, var->location)));
break;
default:
/* can't happen without add_missing_from, so just elog */
@@ -2931,7 +2950,7 @@ ExecBSUpdateTriggers(EState *estate, ResultRelInfo *relinfo)
CMD_UPDATE))
return;
updatedCols = GetUpdatedColumns(relinfo, estate);
updatedCols = GetAllUpdatedColumns(relinfo, estate);
LocTriggerData.type = T_TriggerData;
LocTriggerData.tg_event = TRIGGER_EVENT_UPDATE |
@@ -2980,7 +2999,7 @@ ExecASUpdateTriggers(EState *estate, ResultRelInfo *relinfo,
if (trigdesc && trigdesc->trig_update_after_statement)
AfterTriggerSaveEvent(estate, relinfo, TRIGGER_EVENT_UPDATE,
false, NULL, NULL, NIL,
GetUpdatedColumns(relinfo, estate),
GetAllUpdatedColumns(relinfo, estate),
transition_capture);
}
@@ -3049,7 +3068,7 @@ ExecBRUpdateTriggers(EState *estate, EPQState *epqstate,
LocTriggerData.tg_relation = relinfo->ri_RelationDesc;
LocTriggerData.tg_oldtable = NULL;
LocTriggerData.tg_newtable = NULL;
updatedCols = GetUpdatedColumns(relinfo, estate);
updatedCols = GetAllUpdatedColumns(relinfo, estate);
for (i = 0; i < trigdesc->numtriggers; i++)
{
Trigger *trigger = &trigdesc->triggers[i];
@@ -3140,7 +3159,7 @@ ExecARUpdateTriggers(EState *estate, ResultRelInfo *relinfo,
AfterTriggerSaveEvent(estate, relinfo, TRIGGER_EVENT_UPDATE,
true, oldslot, newslot, recheckIndexes,
GetUpdatedColumns(relinfo, estate),
GetAllUpdatedColumns(relinfo, estate),
transition_capture);
}
}