*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.127 1999/11/28 02:10:01 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.128 1999/11/29 04:43:15 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "storage/sinval.h"
#include "storage/smgr.h"
#include "tcop/tcopprot.h"
+#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/inval.h"
#include "utils/portal.h"
}
/*
- * Open the class, get an exclusive lock on it, and vacuum it
+ * Open the class, get an exclusive lock on it, and check permissions.
+ *
+ * Note we choose to treat permissions failure as a NOTICE and keep
+ * trying to vacuum the rest of the DB --- is this appropriate?
*/
onerel = heap_open(relid, AccessExclusiveLock);
+#ifndef NO_SECURITY
+ if (!pg_ownercheck(GetPgUserName(), RelationGetRelationName(onerel),
+ RELNAME))
+ {
+ elog(NOTICE, "Skipping \"%s\" --- only table owner can VACUUM it",
+ RelationGetRelationName(onerel));
+ heap_close(onerel, AccessExclusiveLock);
+ CommitTransactionCommand();
+ return;
+ }
+#endif
+
+ /*
+ * Set up statistics-gathering machinery.
+ */
vacrelstats = (VRelStats *) palloc(sizeof(VRelStats));
vacrelstats->relid = relid;
vacrelstats->num_pages = vacrelstats->num_tuples = 0;
vacrelstats->hasindex = false;
- if (analyze && !IsSystemRelationName(RelationGetRelationName(onerel)))
+ /* we can VACUUM ANALYZE any table except pg_statistic; see vc_updstats */
+ if (analyze &&
+ strcmp(RelationGetRelationName(onerel), StatisticRelationName) != 0)
{
int attr_cnt,
*attnums = NULL;
stats->outfunc = InvalidOid;
}
vacrelstats->va_natts = attr_cnt;
- /* delete existing pg_statistics rows for relation */
+ /* delete existing pg_statistic rows for relation */
vc_delstats(relid, ((attnums) ? attr_cnt : 0), attnums);
if (attnums)
pfree(attnums);
}
/*
- * vc_updstats() -- update pg_class statistics for one relation
+ * vc_updstats() -- update statistics for one relation
+ *
+ * Statistics are stored in several places: the pg_class row for the
+ * relation has stats about the whole relation, the pg_attribute rows
+ * for each attribute store "disbursion", and there is a pg_statistic
+ * row for each (non-system) attribute. (Disbursion probably ought to
+ * be moved to pg_statistic, but it's not worth doing unless there's
+ * another reason to have to change pg_attribute.) Disbursion and
+ * pg_statistic values are only updated by VACUUM ANALYZE, but we
+ * always update the stats in pg_class.
*
* This routine works for both index and heap relation entries in
* pg_class. We violate no-overwrite semantics here by storing new
- * values for num_tuples, num_pages, and hasindex directly in the pg_class
+ * values for the statistics columns directly into the pg_class
* tuple that's already on the page. The reason for this is that if
- * we updated these tuples in the usual way, then every tuple in pg_class
- * would be replaced every day. This would make planning and executing
- * historical queries very expensive. Note that we also don't use
- * any locking while doing updation.
+ * we updated these tuples in the usual way, vacuuming pg_class itself
+ * wouldn't work very well --- by the time we got done with a vacuum
+ * cycle, most of the tuples in pg_class would've been obsoleted.
+ * Updating pg_class's own statistics would be especially tricky.
+ * Of course, this only works for fixed-size never-null columns, but
+ * these are.
+ *
+ * Updates of pg_attribute statistics are handled in the same way
+ * for the same reasons.
+ *
+ * To keep things simple, we punt for pg_statistic, and don't try
+ * to compute or store rows for pg_statistic itself in pg_statistic.
+ * This could possibly be made to work, but it's not worth the trouble.
*/
static void
-vc_updstats(Oid relid, int num_pages, int num_tuples, bool hasindex, VRelStats *vacrelstats)
+vc_updstats(Oid relid, int num_pages, int num_tuples, bool hasindex,
+ VRelStats *vacrelstats)
{
Relation rd,
ad,
pgcform->relpages = num_pages;
pgcform->relhasindex = hasindex;
+ /* invalidate the tuple in the cache and write the buffer */
+ RelationInvalidateHeapTuple(rd, &rtup);
+ WriteBuffer(buffer);
+
+ heap_close(rd, RowExclusiveLock);
+
if (vacrelstats != NULL && vacrelstats->va_natts > 0)
{
VacAttrStats *vacattrstats = vacrelstats->vacattrstats;
ad = heap_openr(AttributeRelationName, RowExclusiveLock);
sd = heap_openr(StatisticRelationName, RowExclusiveLock);
+
+ /* Find pg_attribute rows for this relation */
ScanKeyEntryInitialize(&askey, 0, Anum_pg_attribute_attrelid,
F_INT4EQ, relid);
while (HeapTupleIsValid(atup = heap_getnext(scan, 0)))
{
int i;
- float32data selratio; /* average ratio of rows selected
- * for a random constant */
VacAttrStats *stats;
- Datum values[Natts_pg_statistic];
- char nulls[Natts_pg_statistic];
attp = (Form_pg_attribute) GETSTRUCT(atup);
- if (attp->attnum <= 0) /* skip system attributes for now, */
- /* they are unique anyway */
+ if (attp->attnum <= 0) /* skip system attributes for now */
continue;
for (i = 0; i < natts; i++)
break;
}
if (i >= natts)
- continue;
+ continue; /* skip attr if no stats collected */
stats = &(vacattrstats[i]);
- /* overwrite the existing statistics in the tuple */
if (VacAttrStatsEqValid(stats))
{
+ float32data selratio; /* average ratio of rows selected
+ * for a random constant */
+
+ /* Compute disbursion */
if (stats->nonnull_cnt == 0 && stats->null_cnt == 0)
{
/* empty relation, so put a dummy value in attdisbursion */
else if (selratio > 1.0)
selratio = 1.0;
}
+
+ /* overwrite the existing statistics in the tuple */
attp->attdisbursion = selratio;
- /*
- * Invalidate the cache for the tuple and write the buffer
- */
+ /* invalidate the tuple in the cache and write the buffer */
RelationInvalidateHeapTuple(ad, atup);
WriteNoReleaseBuffer(scan->rs_cbuf);
- /* DO PG_STATISTIC INSERTS */
-
/*
- * doing system relations, especially pg_statistic is a
- * problem
+ * Create pg_statistic tuples for the relation, if we have
+ * gathered the right data. vc_delstats() previously
+ * deleted all the pg_statistic tuples for the rel, so we
+ * just have to insert new ones here.
+ *
+ * Note vc_vacone() has seen to it that we won't come here
+ * when vacuuming pg_statistic itself.
*/
- if (VacAttrStatsLtGtValid(stats) && stats->initialized
- /* && !IsSystemRelationName(NameData(pgcform->relname))
- */ )
+ if (VacAttrStatsLtGtValid(stats) && stats->initialized)
{
float32data nullratio;
float32data bestratio;
double best_cnt_d = stats->best_cnt,
null_cnt_d = stats->null_cnt,
nonnull_cnt_d = stats->nonnull_cnt; /* prevent overflow */
+ Datum values[Natts_pg_statistic];
+ char nulls[Natts_pg_statistic];
nullratio = null_cnt_d / (nonnull_cnt_d + null_cnt_d);
bestratio = best_cnt_d / (nonnull_cnt_d + null_cnt_d);
stup = heap_formtuple(sd->rd_att, values, nulls);
/* ----------------
- * insert the tuple in the relation.
+ * Watch out for oversize tuple, which can happen if
+ * all three of the saved data values are long.
+ * Our fallback strategy is just to not store the
+ * pg_statistic tuple at all in that case. (We could
+ * replace the values by NULLs and still store the
+ * numeric stats, but presently selfuncs.c couldn't
+ * do anything useful with that case anyway.)
+ *
+ * We could reduce the probability of overflow, but not
+ * prevent it, by storing the data values as compressed
+ * text; is that worth doing? The problem should go
+ * away whenever long tuples get implemented...
* ----------------
*/
- heap_insert(sd, stup);
-
+ if (MAXALIGN(stup->t_len) <= MaxTupleSize)
{
+ /* OK, store tuple and update indexes too */
Relation irelations[Num_pg_statistic_indices];
+
+ heap_insert(sd, stup);
CatalogOpenIndices(Num_pg_statistic_indices, Name_pg_statistic_indices, irelations);
CatalogIndexInsert(irelations, Num_pg_statistic_indices, sd, stup);
CatalogCloseIndices(Num_pg_statistic_indices, irelations);
}
}
heap_endscan(scan);
- heap_close(ad, RowExclusiveLock);
- heap_close(sd, RowExclusiveLock);
+ /* close rels, but hold locks till upcoming commit */
+ heap_close(ad, NoLock);
+ heap_close(sd, NoLock);
}
-
- /*
- * Invalidate the cached pg_class tuple and write the buffer
- */
- RelationInvalidateHeapTuple(rd, &rtup);
-
- WriteBuffer(buffer);
-
- heap_close(rd, RowExclusiveLock);
}
/*
- * vc_delstats() -- delete pg_statistics rows for a relation
+ * vc_delstats() -- delete pg_statistic rows for a relation
*
* If a list of attribute numbers is given, only zap stats for those attrs.
*/
}
heap_endscan(scan);
- heap_close(pgstatistic, RowExclusiveLock);
+ /*
+ * Close rel, but *keep* lock; we will need to reacquire it later,
+ * so there's a possibility of deadlock against another VACUUM process
+ * if we let go now. Keeping the lock shouldn't delay any common
+ * operation other than an attempted VACUUM of pg_statistic itself.
+ */
+ heap_close(pgstatistic, NoLock);
}
/*
projects / postgresql / commitdiff