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help / color / mirror / Atom feedFrom: Adrian Klaver <[email protected]>
To: Igor Korot <[email protected]>
To: pgsql-generallists.postgresql.org <[email protected]>
Subject: Re: Insert records in the tavke only if they are not exist
Date: Sat, 7 Dec 2024 10:32:23 -0800
Message-ID: <[email protected]> (raw)
In-Reply-To: <CA+FnnTy7w3jaZCOuMGMMNGySfiTjcHh5D06AUMc+w+i6yoKrMA@mail.gmail.com>
References: <CA+FnnTwcNNGsM_ck0ye1OsUN3Jjg94PzGMKRm--2ojJM_zVOMA@mail.gmail.com>
<[email protected]>
<CA+FnnTy7w3jaZCOuMGMMNGySfiTjcHh5D06AUMc+w+i6yoKrMA@mail.gmail.com>
On 12/7/24 09:59, Igor Korot wrote:
> Hi, Adrian,
>
> On Sat, Dec 7, 2024 at 11:18 AM Adrian Klaver <[email protected]> wrote:
>>
>> On 12/6/24 19:36, Igor Korot wrote:
>>> Hi, All,
>>>
>>> When my application starts up, ot creates some tables and insert records
>>> in them.
>>>
>>> When the app starts for the second time it should check if the tables
>>> and the records in them are exist and skip the process.
>>
>> Does this also apply to starts after the second time?
>
> Yes, it does.
>
> However, if the new table is created in the meantime - the new record
> should be created, because it is not there yet.
What determines that a new table needs to be created and populated?
>
>>
>> Is the data expected to change over time?
>
> Data change is possible.
>
> This is one of the tables:
>
> "CREATE TABLE IF NOT EXISTS \"sys.abcatfmt\"(\"abf_name\" char(30)
> NOT NULL, \"abf_frmt\" char(254), \"abf_type\" smallint, \"abf_cntr\"
> integer" ));";
> "CREATE UNIQUE INDEX IF NOT EXISTS pbcatf_x ON
> \"sys.abcatfmt\"(\"abf_name\" ASC);";
>
> My understanding is that "INSERT OR IGNORE" will check the unique
It is INSERT ... ON CONFLICT DO NOTHING | UPDATE.
> index and will not do anything if the recrd
> with such data on the index already exists.
So you have the option of either skipping the insert or updating
selected fields in the row.
>
>>
>>>
>>> Everything is good, except what if I have a connection from 2 different
>>> users?
>> Is it possible to have the app start up without external users connecting?
>
> Not sure what you mean here.
>
> Are you asking if the computer can run the app?
> Then the answer is NO. App is always started by the user.
> Please clarify.
This is going to need a more detailed explanation of what 'app' means.
Are you talking about the front end that the user launches or the
backend that runs the database or something else?
>
> Thank you.
>
>>
>>>
>>> I can run this inside transaction, but will this be enough? Will stating
>>> transaction lock the DB and the second user will wait for transaction to
>>> complete?
>>>
>>> Thank you.
>>>
>>
>> --
>> Adrian Klaver
>> [email protected]
>>
--
Adrian Klaver
[email protected]
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