Remove superfluous autoprewarm check

melanieplageman · melanieplageman · commit 7f848cb788ee · 2025-04-04T15:28:39.000-04:00
autoprewarm_database_main() prewarms blocks from the same database. It
is passed an array of sorted BlockInfoRecords and a start and stop index
into the array. The range represented should include only blocks
belonging to global objects or blocks from a single database. Remove an
unnecessary check that the current block is from the same database and
add an assert to ensure this invariant remains. Doing so removes a
special case that makes future refactoring to accommodate read
streamifying autoprewarm easier.

Noticed off-list by Andres Freund
diff --git a/contrib/pg_prewarm/autoprewarm.c b/contrib/pg_prewarm/autoprewarm.c
@@ -463,12 +463,10 @@ autoprewarm_database_main(Datum main_arg)
 		CHECK_FOR_INTERRUPTS();
 
 		/*
-		 * Quit if we've reached records for another database. If previous
-		 * blocks are of some global objects, then continue pre-warming.
+		 * All blocks between prewarm_start_idx and prewarm_stop_idx should
+		 * belong either to global objects or the same database.
 		 */
-		if (old_blk != NULL && old_blk->database != blk->database &&
-			old_blk->database != 0)
-			break;
+		Assert(blk->database == apw_state->database || blk->database == 0);
 
 		/*
 		 * As soon as we encounter a block of a new relation, close the old
