On 2021/07/25 7:50, Andres Freund wrote:
Hi, I've been repeatedly confused by the the number of WAL files supposedly added. Even when 100s of new WAL files are created the relevant portion of log_checkpoints will only ever list zero or one added WAL file. The reason for that is that CheckpointStats.ckpt_segs_added is only incremented in PreallocXlogFiles(). Which has the following comment: * XXX this is currently extremely conservative, since it forces only one * future log segment to exist, and even that only if we are 75% done with * the current one. This is only appropriate for very low-WAL-volume systems. Whereas in real workloads WAL files are almost exclusively created via XLogWrite()->XLogFileInit(). I think we should consider just removing that field. Or, even better, show something accurate instead.
+1 to show something accurate instead. It's also worth showing them in monitoring stats view like pg_stat_wal? Regards, -- Fujii Masao Advanced Computing Technology Center Research and Development Headquarters NTT DATA CORPORATION
