On Thu, Sep 14, 2017 at 12:30 PM, Michael Paquier <michael.paqu...@gmail.com> wrote: > On Wed, Sep 13, 2017 at 4:43 PM, Amit Langote > <langote_amit...@lab.ntt.co.jp> wrote: >> Sure, no problem. >
> > + * > + * This won't be of any help unless we use option like REGBUF_STANDARD > + * while registering the buffer for metapage as otherwise, it won't try to > + * remove the hole while logging the full page image. > */ > This comment is in the btree code. But you actually add > REGBUF_STANDARD. So I think that this could be just removed. > > * Set pd_lower just past the end of the metadata. This is not essential > - * but it makes the page look compressible to xlog.c. > + * but it makes the page look compressible to xlog.c. See > + * _bt_initmetapage. > This reference could be removed as well as _bt_initmetapage does not > provide any information, the existing comment is wrong without your > patch, and then becomes right with this patch. > I have added this comment just to add some explanation as to why we are setting pd_lower and what makes it useful. We can change it or remove it, but I am not sure what is the right thing to do here, may be we can defer this to the committer. > > It seems to me that an update of pd_lower is missing in _bt_getroot(), > just before marking the buffer as dirty I think. And there is a second > in _bt_unlink_halfdead_page(), a third in _bt_insertonpg() and finally > one in _bt_newroot(). > > > For hash, hashbulkdelete(), _hash_vacuum_one_page(), > _hash_addovflpage(), _hash_freeovflpage() and _hash_doinsert() are > missing the shot, no? We could have a meta page of a hash index > upgraded from PG10. > Why do we need to change metapage at every place for btree or hash? Any index that is upgraded should have pd_lower set, do you have any case in mind where it won't be set? For hash, if someone upgrades from a version lower than 9.6, it might not have set, but we already give warning to reindex the hash indexes upgraded from a version lower than 10. -- With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
