[pgpool-general: 8224] Re: Cache_unsafe_memqcache_table_list not working on reload
Tatsuo Ishii
ishii at sraoss.co.jp
Fri Jun 17 09:30:18 JST 2022
> Hi,
>
> I did the following:
>
> 1. Select * from city limit 1;
> 2. Add city to unsafe configuration.
> 3. Reload pgpool.
> 4. Select * from city limit 1; # return from the cache.
>
> I expected that pgpool after adding the table to the unsafe will not return
> the same query from the cache.
>
> I check the code and I saw that pgpool not check if the query is from table
> which included in the unsafe configuration. Means pgpool check only in
> store and not in fetch.
>
> Any thoughts? This is a bug?
It's intended. Fetching cache should be as fast as possible, because
slow query cache is meaningless (users want to use query cache to
speed up their queries). Checking cache_unsafeness is an expensive
operation: it requires parsing SQL and sending queries PostgreSQL's
system catalog.
Best reagards,
--
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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