diff options
Diffstat (limited to 'src/backend/commands/vacuum.c')
| -rw-r--r-- | src/backend/commands/vacuum.c | 14 |
1 files changed, 6 insertions, 8 deletions
diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c index 23eb605d4cb..308a51d95d7 100644 --- a/src/backend/commands/vacuum.c +++ b/src/backend/commands/vacuum.c @@ -1128,8 +1128,8 @@ vacuum_set_xid_limits(Relation rel, * live tuples seen; but if we did not, we should not blindly extrapolate * from that number, since VACUUM may have scanned a quite nonrandom * subset of the table. When we have only partial information, we take - * the old value of pg_class.reltuples as a measurement of the - * tuple density in the unscanned pages. + * the old value of pg_class.reltuples/pg_class.relpages as a measurement + * of the tuple density in the unscanned pages. * * Note: scanned_tuples should count only *live* tuples, since * pg_class.reltuples is defined that way. @@ -1152,18 +1152,16 @@ vac_estimate_reltuples(Relation relation, /* * If scanned_pages is zero but total_pages isn't, keep the existing value - * of reltuples. (Note: callers should avoid updating the pg_class - * statistics in this situation, since no new information has been - * provided.) + * of reltuples. (Note: we might be returning -1 in this case.) */ if (scanned_pages == 0) return old_rel_tuples; /* - * If old value of relpages is zero, old density is indeterminate; we - * can't do much except scale up scanned_tuples to match total_pages. + * If old density is unknown, we can't do much except scale up + * scanned_tuples to match total_pages. */ - if (old_rel_pages == 0) + if (old_rel_tuples < 0 || old_rel_pages == 0) return floor((scanned_tuples / scanned_pages) * total_pages + 0.5); /* |