From: | Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp> |
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To: | Atri Sharma <atri(dot)jiit(at)gmail(dot)com> |
Cc: | Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Accessing non catalog table in backend |
Date: | 2016-01-05 06:13:23 |
Message-ID: | 568B5F03.5070408@lab.ntt.co.jp |
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Lists: | pgsql-hackers |
On 2016/01/05 14:30, Atri Sharma wrote:
> On Tue, Jan 5, 2016 at 9:54 AM, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>
>> On 2016/01/05 3:53, Atri Sharma wrote:
>>> I was wary to use SPI inside the executor for node evaluation functions.
>>> Does it seem safe?
>>
>> What is "node evaluation functions"? Is it "Plan" nodes or "Expr" nodes
>> that you are talking about? I guess you'd know to use ExecProcNode() or
>> ExecEvalExpr() for them, respectively.
>>
> I fail to see the relevance of which node is getting evaluated (its a Plan
> node BTW) for this question. The concern I had was around using SPI inside
> executor and its fail safety.
Sorry, I may have misunderstood your question(s). Seeing your first
question in the thread, I see that you're looking to query non-system
tables within the executor. AFAIU, most of the processing within executor
takes the form of some node in some execution pipeline of a plan tree.
Perhaps, you're imagining some kind of node, subnode or some such. By the
way, some places like ATRewriteTable(), validateCheckConstraint() scan
user tables directly using low-level utilities within a dummy executor
context. I think Jim suggested something like that upthread.
Thanks,
Amit
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