[pgpool-hackers: 2337] Re: PostgreSQL 10 backward incompatibilities

Muhammad Usama m.usama at gmail.com
Tue May 16 19:13:07 JST 2017

On Tue, May 16, 2017 at 6:07 AM, Tatsuo Ishii <ishii at sraoss.co.jp> wrote:

> 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.

Best Regards
Muhammad Usama

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