I think you are right after reading code in compute_parallel_vacuum_workers() :)
发件人: Tom Lane <tgl@sss.pgh.pa.us> 发送时间: 2020年12月1日 2:54 收件人: Yulin PEI <ypeiae@connect.ust.hk> 抄送: Masahiko Sawada <sawada.mshk@gmail.com>; pgsql-hackers@lists.postgresql.org <pgsql-hackers@lists.postgresql.org> 主题: Re: 回复: [PATCH] BUG FIX: Core dump could happen when VACUUM FULL in standalone mode
Yulin PEI <ypeiae@connect.ust.hk> writes: > Yes, I agree because (IsNormalProcessingMode() ) means that current process is not in bootstrap mode and postmaster process will not build index. > So my new modified patch is attached.
This is a good catch, but the proposed fix still seems pretty random and unlike how it's done elsewhere. It seems to me that since index_build() is relying on plan_create_index_workers() to assess parallel safety, that's where to check IsUnderPostmaster. Moreover, the existing code in compute_parallel_vacuum_workers (which gets this right) associates the IsUnderPostmaster check with the initial check on max_parallel_maintenance_workers. So I think that the right fix is to adopt the compute_parallel_vacuum_workers coding in plan_create_index_workers, and thereby create a model for future uses of max_parallel_maintenance_workers to follow.
