On 3/31/26 20:12, Andres Freund wrote: > Hi, > > On 2026-03-31 20:03:02 +0200, Tomas Vondra wrote: >> On 3/31/26 19:41, Andres Freund wrote: >>> Hi, >>> >>> On 2026-03-30 20:21:29 +0200, Tomas Vondra wrote: >>>>>> From 410eaaebe7b814ac9f44c080e153f4ec1d6d6b86 Mon Sep 17 00:00:00 2001 >>>>>> From: Tomas Vondra <[email protected]> >>>>>> Date: Thu, 19 Mar 2026 22:25:09 +0100 >>>>>> Subject: [PATCH v5 3/6] explain: show prefetch stats in EXPLAIN (ANALYZE) >>>>>> >>>>>> This adds details about AIO / prefetch for executor nodes using a >>>>>> ReadStream. Right now this applies only to BitmapHeapScan, because >>>>>> that's the only scan node using a ReadStream and collecting >>>>>> instrumentation from workers. >>>>> >>>>> I don't understand why that means it should be done as part of this >>>>> commit, >>>>> whereas seqscans shouldn't? >>>>> >>>> >>>> Are you suggesting the commit adds support for all those scans (BHS, >>>> SeqScan and TidRangeScan) or none of them? >>> >>> I guess I mostly just didn't quite understand what differentiates bitmap >>> scans >>> from the other scans, based on this explanation. >>> >>> >>>> To me it seems better to have at least some scan because of testing. But >>>> SeqScan/TidRangeScan don't have the instrumentation infrastructure for >>>> parallel queries, and I don't want to do that in the main patch - it seems >>>> rather unrelated. And I also don't want to add it before the main patch. >>> >>> I'd probably do the latter, i.e. add it before the main patch. Or at least >>> separately from the change to show read stream instrumentation. >>> >> >> Sorry, I'm confused. Which "latter" option you mean? > > Adding the instrumentation infrastructure for seqscan, tidscan as a separate > patch before the main commit. >
I don't like that, because then we're adding instrumentation that doesn't actually contain anything. How would you even know it does the right thing? I think it's better to add that after the main commit. regards -- Tomas Vondra
