dengzhhu653 commented on PR #5929:
URL: https://github.com/apache/hive/pull/5929#issuecomment-3060469072
> > UPDATE TBS
> > SET last_updated = NOW()
> > WHERE TBL_ID = AND last_updated = ''; -- The exact timestamp you
originally read
>
> As far as I know in MySQL this will block others for the same row(the same
for update), if the 0 row returns, means we have acquired the X `tblId` row
lock, why do we need to retry again?
>
> But this inspires me we can alter the table during the updating the column
statistics, so we don't ask for the row lock explicitly, I will try and test
this approach. Thank you!
After some reach, I found it's hard to use DataNucleus without the pure
"UPDATE" query,
```java
mTable.setLastAccessTime((int) (System.currentTimeMillis()/1000));
pm.flush(); // here might flush the old MTable into data store
pm.refresh(mTable);
```
In `pm.flush()` the old state of the table can get overwritten the one in
data store, resulting to some columns missing in COLUMN_STATS_ACCURATE, for
example:
`{"COLUMN_STATS":{"col_0":"true","col_1":"true","col_2":"true","col_3":"true","col_5":"true","col_6":"true","col_7":"true","col_8":"true"}}`
`col_4` and `col_9` are missing.
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