Re: BUG #19687: ALTER SEQUENCE provokes error XX001 could not read blocks

On Wed, Sep 23, 2026, 19:00 Alexander Lakhin <exclusion(at)gmail(dot)com> wrote:

> Hello Ayush and Alexandre,
>
> 14.09.2026 22:07, Ayush Tiwari wrote:
>
> On Mon, 14 Sept 2026 at 20:23, PG Bug reporting form<noreply(at)postgresql(dot)org> <noreply(at)postgresql(dot)org> wrote:
>
> The following bug has been logged on the website:
>
> Bug reference: 19687
> ...
> The following script:
> ...
>
> triggers:
> iteration 3
> ERROR: could not read blocks 0..0 in file "base/16384/16597": read only 0
> of 8192 bytes
> 2026-09-14 07:53:16.554 EEST [2078499:4] psql XX001 ERROR: could not read
> blocks 0..0 in file "base/16384/16597": read only 0 of 8192 bytes
> 2026-09-14 07:53:16.554 EEST [2078499:5] psql XX001 STATEMENT: SELECT *
> FROM s;
>
>
> Thank you for working on the fix!
>
> Just for the record: with these parameters:
> cpu_tuple_cost = 10000
> min_parallel_table_scan_size = 1
>
> set, the same script triggers also:
> TRAP: failed Assert("RelFileLocatorEquals(relation->rd_locator,
> pscan->phs_locator)"), File: "tableam.c", Line: 173, PID: 4140896
> ExceptionalCondition at assert.c:51:13
> table_beginscan_parallel at tableam.c:178:14
> ExecSeqScanInitializeWorker at nodeSeqscan.c:450:30
> ExecParallelInitializeWorker at execParallel.c:1406:5
> ParallelQueryMain at execParallel.c:1566:2
> ParallelWorkerMain at parallel.c:1571:2
> BackgroundWorkerMain at bgworker.c:868:2
> postmaster_child_launch at launch_backend.c:269:3
> StartBackgroundWorker at postmaster.c:4222:5
> (inlined by) maybe_start_bgworkers at postmaster.c:4385:9
> ServerLoop at postmaster.c:1745:6
> CreateOptsFile at postmaster.c:4166:3
> (inlined by) PostmasterMain at postmaster.c:1301:7
> check_root at main.c:448:3
> (inlined by) main at main.c:195:3
>

With the patch or without it?

Regards,
Alexandre