Re: Add Postgres module info - Mailing list pgsql-hackers
| From | Euler Taveira |
|---|---|
| Subject | Re: Add Postgres module info |
| Date | |
| Msg-id | f8608216-61d7-4885-b215-91e9d176386c@app.fastmail.com Whole thread Raw |
| In response to | Re: Add Postgres module info (Tom Lane <tgl@sss.pgh.pa.us>) |
| Responses |
Re: Add Postgres module info
|
| List | pgsql-hackers |
On Mon, Mar 24, 2025, at 12:54 PM, Tom Lane wrote:
Robert Haas <robertmhaas@gmail.com> writes:> It looks reasonable to me. I am a bit worried that using PG_VERSION as> the version string is going to feel like the wrong thing at some> stage, but I can't really say why, and I think it's better to do> something now and maybe have to revise it later than to do nothing now> and hope that we come up with a brilliant idea at some point in the> future.Agreed. I think something is clearly better than nothing here, andPG_VERSION has the huge advantage that we need no new mechanism tomaintain it. (A version identifier that isn't updated when it needsto be is worse than no identifier, IMO.)
Agreed. My only concern is that people can confuse this version with the one
available in pg_extension or pg_available_extension* functions.
If somebody thinks of a better idea and is willing to do the legworkto make it happen, we can surely change to something else later on.Or invent another field with different semantics, or whatever.
I think those modules without control file, it is natural to use PG_VERSION.
However, I'm concerned that users can confuse the version if we provide
PG_VERSION as version and the extension catalog says something different.
postgres=# select * from pg_available_extensions where name = 'plperl';
name | default_version | installed_version | comment
--------+-----------------+-------------------+-----------------------------
plperl | 1.0 | | PL/Perl procedural language
(1 row)
postgres=# load 'plperl';
LOAD
postgres=# select * from pg_get_loaded_modules();
module_name | version | file_name
-------------+---------+-----------
plperl | 18devel | plperl.so
(1 row)
Maybe a note into default_version [1] is sufficient to clarify or a mechanism
to grab the information from control file and expose it as a macro. (I attached
an idea to accomplish this goal although it lacks meson support.) Thoughts?
I played with it a bit and it seems good to go.
postgres=# select version();
version
----------------------------------------------------------------------------------------------
PostgreSQL 18devel on x86_64-pc-linux-gnu, compiled by gcc (Debian 12.2.0-14) 12.2.0, 64-bit
(1 row)
postgres=# select * from pg_get_loaded_modules();
module_name | version | file_name
-------------+---------+-----------
(0 rows)
postgres=# load 'wal2json';
LOAD
postgres=# select * from pg_get_loaded_modules();
module_name | version | file_name
-------------+---------+-------------
wal2json | 2.6 | wal2json.so
(1 row)
Code:
diff --git a/wal2json.c b/wal2json.c
index 0c6295d..1f439be 100644
--- a/wal2json.c
+++ b/wal2json.c
@@ -40,7 +40,14 @@
#define WAL2JSON_FORMAT_VERSION 2
#define WAL2JSON_FORMAT_MIN_VERSION 1
+#if PG_VERSION_NUM >= 180000
+PG_MODULE_MAGIC_EXT(
+ .name = "wal2json",
+ .version = WAL2JSON_VERSION
+);
+#else
PG_MODULE_MAGIC;
+#endif
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