/*
* mxid_age - compute age of a multi XID (relative to latest stable mxid)
*/
Datum
mxid_age(PG_FUNCTION_ARGS)
{
TransactionId xid = PG_GETARG_TRANSACTIONID(0);
MultiXactId now = ReadNextMultiXactId();
if (!MultiXactIdIsValid(xid))
PG_RETURN_INT32(INT_MAX);
PG_RETURN_INT32((int32) (now - xid));
}
/*
* ExecRefreshMatView -- execute a REFRESH MATERIALIZED VIEW command
*
* This refreshes the materialized view by creating a new table and swapping
* the relfilenodes of the new table and the old materialized view, so the OID
* of the original materialized view is preserved. Thus we do not lose GRANT
* nor references to this materialized view.
*
* If WITH NO DATA was specified, this is effectively like a TRUNCATE;
* otherwise it is like a TRUNCATE followed by an INSERT using the SELECT
* statement associated with the materialized view. The statement node's
* skipData field is used to indicate that the clause was used.
*
* Indexes are rebuilt too, via REINDEX. Since we are effectively bulk-loading
* the new heap, it's better to create the indexes afterwards than to fill them
* incrementally while we load.
*
* The scannable state is changed based on whether the contents reflect the
* result set of the materialized view's query.
*/
void
ExecRefreshMatView(RefreshMatViewStmt *stmt, const char *queryString,
ParamListInfo params, char *completionTag)
{
Oid matviewOid;
Relation matviewRel;
RewriteRule *rule;
List *actions;
Query *dataQuery;
Oid tableSpace;
Oid OIDNewHeap;
DestReceiver *dest;
/*
* Get a lock until end of transaction.
*/
matviewOid = RangeVarGetRelidExtended(stmt->relation,
AccessExclusiveLock, false, false,
RangeVarCallbackOwnsTable, NULL);
matviewRel = heap_open(matviewOid, NoLock);
/* Make sure it is a materialized view. */
if (matviewRel->rd_rel->relkind != RELKIND_MATVIEW)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("\"%s\" is not a materialized view",
RelationGetRelationName(matviewRel))));
/*
* We're not using materialized views in the system catalogs.
*/
Assert(!IsSystemRelation(matviewRel));
Assert(!matviewRel->rd_rel->relhasoids);
/*
* Check that everything is correct for a refresh. Problems at this point
* are internal errors, so elog is sufficient.
*/
if (matviewRel->rd_rel->relhasrules == false ||
matviewRel->rd_rules->numLocks < 1)
elog(ERROR,
"materialized view \"%s\" is missing rewrite information",
RelationGetRelationName(matviewRel));
if (matviewRel->rd_rules->numLocks > 1)
elog(ERROR,
"materialized view \"%s\" has too many rules",
RelationGetRelationName(matviewRel));
rule = matviewRel->rd_rules->rules[0];
if (rule->event != CMD_SELECT || !(rule->isInstead))
elog(ERROR,
"the rule for materialized view \"%s\" is not a SELECT INSTEAD OF rule",
RelationGetRelationName(matviewRel));
actions = rule->actions;
if (list_length(actions) != 1)
elog(ERROR,
"the rule for materialized view \"%s\" is not a single action",
RelationGetRelationName(matviewRel));
/*
* The stored query was rewritten at the time of the MV definition, but
* has not been scribbled on by the planner.
*/
dataQuery = (Query *) linitial(actions);
Assert(IsA(dataQuery, Query));
/*
* Check for active uses of the relation in the current transaction, such
* as open scans.
*
* NB: We count on this to protect us against problems with refreshing the
* data using HEAP_INSERT_FROZEN.
*/
CheckTableNotInUse(matviewRel, "REFRESH MATERIALIZED VIEW");
tableSpace = matviewRel->rd_rel->reltablespace;
heap_close(matviewRel, NoLock);
/* Create the transient table that will receive the regenerated data. */
OIDNewHeap = make_new_heap(matviewOid, tableSpace);
dest = CreateTransientRelDestReceiver(OIDNewHeap);
if (!stmt->skipData)
refresh_matview_datafill(dest, dataQuery, queryString);
/*
* Swap the physical files of the target and transient tables, then
* rebuild the target's indexes and throw away the transient table.
*/
finish_heap_swap(matviewOid, OIDNewHeap, false, false, true, true,
RecentXmin, ReadNextMultiXactId());
RelationCacheInvalidateEntry(matviewOid);
}
