Question about HEAP_XMIN_COMMITTED

Hi

I did the following steps on PG.

1. Building a synchronous streaming replication environment.
2. Executing the following SQL statements on primary
  (1) postgres=# CREATE EXTENSION pageinspect;
  (2) postgres=# begin;
  (3) postgres=# select txid_current();
  (4) postgres=# create table mytest6(i int);
  (6) postgres=# insert into mytest6 values(1);
  (7) postgres=# commit;
3. Executing the following SQL statements on standby
  (8) postgres=# select * from mytest6;
             i 
            ---
             1
          (1 row)
  (9) postgres=# SELECT t_infomask FROM heap_page_items(get_raw_page('pg_class', 0)) where t_xmin=502※;
　       　t_infomask 
           ------------
            2049
          (1 row)
      ※502 is the transaction ID returned by step (3) above.

In the result of step (9),the value of the t_infomask field is 2049(0x801) which means that HEAP_XMAX_INVALID 
and HEAP_HASNULL flags were setted, but HEAP_XMIN_COMMITTED flag was not setted.

According to source , when step (8) was executed,SetHintBits function were called to set HEAP_XMIN_COMMITTED.
however, the minRecoveryPoint value was not updated. So HEAP_XMIN_COMMITTED flag was not setted successfully.

After CheckPoint, select from mytest6 again in another session, we can see HEAP_XMIN_COMMITTED flag was setted.

So my question is that before checkpoint, HEAP_XMIN_COMMITTED flag was not setted correctly, right?

Or we need to move minRecoveryPoint forword to make HEAP_XMIN_COMMITTED flag setted correctly when first select
from mytest6.


Best Regards, LiuHuailing
-- 
以上
Liu Huailing
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Liu Huailing
Development Department III
Software Division II
Nanjing Fujitsu Nanda Software Tech. Co., Ltd.(FNST)
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