Re: [HACKERS] Binary search in fmgr_isbuiltin() is a bottleneck.

On Wed, Sep 27, 2017 at 1:00 PM, Andres Freund <andres@anarazel.de> wrote:
> We could relatively easily move it to be once-per-postmaster start for
> !EXEC_BACKEND builds. Constantly doing expensive binary searches is also
> pretty brute force ;)

I think one useful way to look at it might be -

How many fmgr searches does a backend need to do in order to make up
for the time spent building the hash table?

How many fmgr searches, if any, do we do during backend startup as a
matter of course?

If we're going to make up the time that it takes to build the hash
table by the time the user runs a handful of queries, there's really
no point in stressing about this.  The use case where somebody
repeatedly connects and disconnects without running any significant
number of real queries is not an important one.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company


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