| From: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> |
|---|---|
| To: | Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com> |
| Cc: | Petr Jelinek <petr(at)2ndquadrant(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, hlinnaka(at)iki(dot)fi, Robert Haas <robertmhaas(at)gmail(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us>, Sawada Masahiko <sawada(dot)mshk(at)gmail(dot)com>, Greg Stark <stark(at)mit(dot)edu>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> |
| Subject: | Re: Reducing tuple overhead |
| Date: | 2015-04-30 04:31:31 |
| Message-ID: | CAA4eK1Khu958CUGhOstF5gYCy7Tywj6e3Xokv67b-DkihxNgYw@mail.gmail.com |
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On Tue, Apr 28, 2015 at 2:31 AM, Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com> wrote:
>
> On 4/25/15 12:12 AM, Amit Kapila wrote:
>>
>> > ... which isn't possible. You can not go from a heap tuple to an
>> index tuple.
>>
>> We will have the access to index value during delete, so why do you
>> think that we need linkage between heap and index tuple to perform
>> Delete operation? I think we need to think more to design Delete
>> .. by CTID, but that should be doable.
>
>
> The problem with just having the value is that if *anything* changes
between how you evaluated the value when you created the index tuple and
when you evaluate it a second time you'll corrupt your index.
>
I think I am missing something here, but when this second
evaluation is needed. Basically what I understand from index
insertion is that it evaluates the value to be inserted in index
before calling nbtree module and then nbtree just inserts the
value/tuple passed to it.
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com
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