+ curpages = RelationGetNumberOfBlocks(rel);
+
+ /*
+ * HACK: if the relation has never yet been vacuumed, use a
+ * minimum estimate of 10 pages. This emulates a desirable
+ * aspect of pre-8.0 behavior, which is that we wouldn't assume
+ * a newly created relation is really small, which saves us from
+ * making really bad plans during initial data loading. (The
+ * plans are not wrong when they are made, but if they are cached
+ * and used again after the table has grown a lot, they are bad.)
+ * It would be better to force replanning if the table size has
+ * changed a lot since the plan was made ... but we don't
+ * currently have any infrastructure for redoing cached plans at
+ * all, so we have to kluge things here instead.
+ *
+ * We approximate "never vacuumed" by "has relpages = 0", which
+ * means this will also fire on genuinely empty relations. Not
+ * great, but fortunately that's a seldom-seen case in the real
+ * world, and it shouldn't degrade the quality of the plan too
+ * much anyway to err in this direction.
+ */
+ if (curpages < 10 && rel->rd_rel->relpages == 0)
+ curpages = 10;
+
+ /* report estimated # pages */
+ *pages = curpages;