[pgpool-hackers: 2338] Re: PostgreSQL 10 backward incompatibilities

Tatsuo Ishii ishii at sraoss.co.jp
Tue May 16 20:38:26 JST 2017

>> From the PostgreSQL 10 relelease note:
>> Rename SQL functions, tools, and options that reference “xlog” to “wal”
>> (Robert Haas)
>> This surely affects to Pgpool-II. I found these calls in Pgpool-II:
>>                 query = "SELECT pg_current_xlog_location()";
>>                 query = "SELECT pg_last_xlog_replay_location()";
>> We have to deal with this. Just changing these function names to new
>> ones will make Pgpool-II not work with pre-10 versions of
>> PostgreSQL. So will not be acceptable. Any idea?
> I think these calls are only made by pgpool-worker child process, So one
> way could be to get the server version of each attached backend at the
> child startup (SELECT current_setting('server_version_num'))  and store the
> version for each backend node in respective backend data structure.
> And latter before sending the query we can construct the appropriate query
> by looking at the version information for that backend.

server_version_num appeared in PostgreSQL 8.2. Since those functions
are only used in streaming replication, which first appeared in 9.6,
we can safely your method. Nice idea!

Best regards,
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php

More information about the pgpool-hackers mailing list