Re: [HACKERS] Clock with Adaptive Replacement - Mailing list pgsql-hackers

From Vladimir Sitnikov
Subject Re: [HACKERS] Clock with Adaptive Replacement
Date
Msg-id CAB=Je-HC6veTnAOWjV5-xKLykx14RSJshcJ_Ov1fGu5bzNhnfw@mail.gmail.com
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In response to Re: [HACKERS] Clock with Adaptive Replacement  (Peter Geoghegan <pg@bowt.ie>)
List pgsql-hackers
>I don't have time to check this out just now, but it seems like an
excellent idea

There are a couple of sad things:
1) DTrace probes seem to be disabled by default. At least, I had to build PostgreSQL with --enable-dtrace in my macOS.
Does that (the requirement to enable dtrace within PostgreSQL) block from capturing trace files from real-life applications?

There's an option to use system-level IO trace points (e.g. https://github.com/omniti-labs/pgtreats/blob/master/tools/pg_file_stress ), however it would be harder to get DB/relation kind of ids.

2) (database, tablespace, relation) oids cannot be easily mapped from within a DTrace script. One can workaround that by using a SQL connection to the database, however it gets a bit complicated if there are multiple DB instances. What I mean is it is hard to tell which connection URL to use in order to resolve the oids in question.

Vladimir

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