Fix briefly showing old progress stats for ANALYZE on inherited tables.

hlinnaka · hlinnaka · commit 992d2ca81d2b · 2023-09-30T17:07:24.000+03:00
ANALYZE on a table with inheritance children analyzes all the child tables in a loop. When stepping to next child table, it updated the child rel ID value in the command progress stats, but did not reset the 'sample_blks_total' and 'sample_blks_scanned' counters. acquire_sample_rows() updates 'sample_blks_total' as soon as the scan starts and 'sample_blks_scanned' after processing the first block, but until then, pg_stat_progress_analyze would display a bogus combination of the new child table relid with old counter values from the previously processed child table. Fix by resetting 'sample_blks_total' and 'sample_blks_scanned' to zero at the same time that 'current_child_table_relid' is updated. Backpatch to v13, where pg_stat_progress_analyze view was introduced. Reported-by: Justin Pryzby Discussion: https://www.postgresql.org/message-id/20230122162345.GP13860%40telsasoft.com
diff --git a/src/backend/commands/analyze.c b/src/backend/commands/analyze.c
@@ -1534,8 +1534,25 @@ acquire_inherited_sample_rows(Relation onerel, int elevel,
 		AcquireSampleRowsFunc acquirefunc = acquirefuncs[i];
 		double		childblocks = relblocks[i];
 
-		pgstat_progress_update_param(PROGRESS_ANALYZE_CURRENT_CHILD_TABLE_RELID,
-									 RelationGetRelid(childrel));
+		/*
+		 * Report progress.  The sampling function will normally report blocks
+		 * done/total, but we need to reset them to 0 here, so that they don't
+		 * show an old value until that.
+		 */
+		{
+			const int	progress_index[] = {
+				PROGRESS_ANALYZE_CURRENT_CHILD_TABLE_RELID,
+				PROGRESS_ANALYZE_BLOCKS_DONE,
+				PROGRESS_ANALYZE_BLOCKS_TOTAL
+			};
+			const int64 progress_vals[] = {
+				RelationGetRelid(childrel),
+				0,
+				0,
+			};
+
+			pgstat_progress_update_multi_param(3, progress_index, progress_vals);
+		}
 
 		if (childblocks > 0)
 		{
