RE: Number of buckets/partitions of dshash

From: "Ideriha, Takeshi" <ideriha(dot)takeshi(at)jp(dot)fujitsu(dot)com>
To: 'Kyotaro HORIGUCHI' <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>
Cc: "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: RE: Number of buckets/partitions of dshash
Date: 2018-11-06 23:55:06
Message-ID: 4E72940DA2BF16479384A86D54D0988A6F1EE1CD@G01JPEXMBKW04
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>From: Kyotaro HORIGUCHI [mailto:horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp]

>> This would cause some waste of memory on DSA because some partitions (buckets)
>is allocated but not used.
>>
>> So I'm thinking that current dshash design is still ok but flexible
>> size of partition is appropriate for some use cases like mine.
>>
>> Do you have any thoughts?
>
>We could do that easily, but shouldn't we find a way to reduce or eliminate the impact
>of locking first? dshash needs to hold partition lock while the caller is examining a
>returned entry.

Thanks for the comment.
I agreed.
It would take a long time to achieve it but as you've pointed out
finding way to minimize the locking time seems benefit for everyone and first priority.

Regards,
Takeshi Ideriha

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