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Hi, Aleksey! just one comment below, no comments on all your other replies. The issue is in review, shall I take another look or it's on you now? On Sep 01, Aleksey Midenkov wrote:
@@ -836,22 +842,26 @@ void partition_info::vers_set_hist_part(THD *thd) { if (next == vers_info->now_part) { - my_error(WARN_VERS_PART_FULL, MYF(ME_WARNING|ME_ERROR_LOG), - table->s->db.str, table->s->table_name.str, - vers_info->hist_part->partition_name, "LIMIT"); + if (auto_inc) + create_count= 1; + else + my_error(WARN_VERS_PART_FULL, MYF(ME_WARNING|ME_ERROR_LOG), + table->s->db.str, table->s->table_name.str, + vers_info->hist_part->partition_name, "LIMIT"); } else vers_info->hist_part= next; } - return; + // reserve at least one history partition + if (auto_inc && create_count == 0 && + vers_info->hist_part->id + 1 == vers_info->now_part->id) + create_count= 1;
Questionable. What does it solve?
This is for the LOCK TABLES when the history partition is almost full:
-- source include/have_partition.inc
create or replace table t1 (x int) with system versioning partition by system_time limit 10 auto;
insert into t1 values (1), (2), (3), (4), (5), (6), (7), (8), (9); update t1 set x= x + 10;
lock tables t1 write; update t1 set x= 1 where x = 11; update t1 set x= 2 where x = 12; update t1 set x= 3 where x = 13; unlock tables;
select count(x) from t1 partition (p0); show create table t1; drop tables t1;
Imagine 1000000 instead of 10. Locked commands operate on a small subset of records. Nevertheless they are condemned to end in the wrong partition if we didn't reserve one at the LOCK TABLES (we cannot add new partitions while the table is locked). That of course works only if LOCK TABLES is short enough to not fill the whole partition (which is expected to be a normal scenario). We will not need this when we auto-add under LOCK TABLES.
I think you could just say that "new partitions aren't added under LOCK TABLES" and that's all. A documented limitation for now, lifted later. I don't think there will be a lot of users using LOCK TABLES with system versioned tables and auto-adding of partitions. Probably the main (if not the only) use case would be loading the dump created by mysqldump. And it loads the _whole table_ under LOCK TABLES, so your trick won't help anyway. Regards, Sergei VP of MariaDB Server Engineering and security@mariadb.org