Re: [Maria-developers] a2520676ba1: MDEV-16249 CHECKSUM TABLE for a spider table is not parallel and saves all data in memory in the spider head by default

Hi, Kentoku! On Jun 05, Kentoku wrote:

revision-id: a2520676ba1 (mariadb-10.4.5-10-ga2520676ba1) parent(s): 31fe70290c5 author: Kentoku committer: Kentoku timestamp: 2019-05-23 14:36:18 +0900 message:

MDEV-16249 CHECKSUM TABLE for a spider table is not parallel and saves all data in memory in the spider head by default

please remember to add an empty line after the first line in the commit comment, see https://git-scm.com/docs/git-commit#_discussion

add checksum_null for setting null value of checksum

diff --git a/sql/ha_partition.cc b/sql/ha_partition.cc index 4e7fccca3af..e47da94ab20 100644 --- a/sql/ha_partition.cc +++ b/sql/ha_partition.cc @@ -8213,7 +8214,11 @@ int ha_partition::info(uint flag) stats.delete_length+= file->stats.delete_length; if (file->stats.check_time > stats.check_time) stats.check_time= file->stats.check_time; - stats.checksum+= file->stats.checksum; + if (!file->stats.checksum_null) + { + stats.checksum+= file->stats.checksum; + stats.checksum_null= FALSE; + }

I'm not sure about it. When a checksum can be NULL? I mean, normally, if you do A+B+C and one of the values is NULL, then the whole sum is NULL. But here you simply skip NULLs, like in aggregate SUM() function. To understand what semantics works better in this case, I need to understand when a checksum can be NULL in spider.

} if (stats.records && stats.records < 2 && !(m_file[0]->ha_table_flags() & HA_STATS_RECORDS_IS_EXACT))

All other server changes look good, thanks. Regards, Sergei Chief Architect MariaDB and security@mariadb.org