From: | Melanie Plageman <melanieplageman(at)gmail(dot)com> |
---|---|
To: | Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
Cc: | Peter Geoghegan <pg(at)bowt(dot)ie>, "bharath(dot)rupireddyforpostgres(at)gmail(dot)com" <bharath(dot)rupireddyforpostgres(at)gmail(dot)com> |
Subject: | Add pg_walinspect function with block info columns |
Date: | 2023-03-01 17:51:16 |
Message-ID: | CAAKRu_bORebdZmcV8V4cZBzU8M_C6tDDdbiPhCZ6i-iuSXW9TA@mail.gmail.com |
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Lists: | pgsql-hackers |
Hi,
When using pg_walinspect, and calling functions like
pg_get_wal_records_info(), I often wish that the various information in
the block_ref column was separated out into columns so that I could
easily access them and pass them to various other functions to add
information -- like getting the relname from pg_class like this:
SELECT n.nspname, c.relname, wal_info.*
FROM pg_get_wal_records_extended_info(:start_lsn, :end_lsn) wal_info
JOIN pg_class c
ON wal_info.relfilenode = pg_relation_filenode(c.oid) AND
wal_info.reldatabase IN (0, (SELECT oid FROM pg_database
WHERE datname = current_database()))
JOIN pg_namespace n ON n.oid = c.relnamespace;
This has been mentioned in [1] amongst other places.
So, attached is a patch with pg_get_wal_records_extended_info(). I
suspect the name is not very good. Also, it is nearly a direct copy of
pg_get_wal_fpi_infos() except for the helper called to fill in the
tuplestore, so it might be worth doing something about that.
However, I am mainly looking for feedback about whether or not others
would find this useful, and, if so, what columns they would like to see
in the returned tuplestore.
Note that I didn't include the cumulative fpi_len for all the pages
since pg_get_wal_fpi_info() now exists. I noticed that
pg_get_wal_fpi_info() doesn't list compression information (which is in
the block_ref column of pg_get_wal_records_info()). I don't know if this
is worth including in my proposed function
pg_get_wal_records_extended_info().
- Melanie
Attachment | Content-Type | Size |
---|---|---|
v1-0001-Add-extended-block-info-function-to-pg_walinspect.patch | text/x-patch | 5.8 KB |
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