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Re: alter table xxx set unlogged take long time - Mailing list pgsql-performance

From Jim Mlodgenski
Subject Re: alter table xxx set unlogged take long time
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Msg-id CAB_5SRf6JmebYvcVXmzRtpDB1e9+KsGHLJGznjmWzpg2LxcPAQ@mail.gmail.com
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In response to RE: alter table xxx set unlogged take long time  ("James Pang (chaolpan)" <chaolpan@cisco.com>)
Responses RE: alter table xxx set unlogged take long time  ("James Pang (chaolpan)" <chaolpan@cisco.com>)
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On Tue, Jul 26, 2022 at 8:45 AM James Pang (chaolpan) <chaolpan@cisco.com> wrote:
Without step 3 ,  copy data take long time.   Use wal_level=minimal can help make COPY load data without logging ?


I assume that you're most concerned with the total time of moving the data from the source database into the final table so you might get a big win by not moving the data twice and directly load the table through a Foregin Data Wrapper and avoid the csv export/import. Something like the oracle_fdw might help here:

-----Original Message-----
From: Tom Lane <tgl@sss.pgh.pa.us>
Sent: Tuesday, July 26, 2022 8:43 PM
To: James Pang (chaolpan) <chaolpan@cisco.com>
Cc: Jim Mlodgenski <jimmy76@gmail.com>; pgsql-performance@lists.postgresql.org
Subject: Re: alter table xxx set unlogged take long time

"James Pang (chaolpan)" <chaolpan@cisco.com> writes:
> How to make it fast ?  These are our steps about copy large data from Oracle to Postgres
>   1.  Create table in Postgres  2. Extract data from Oracle to CSV  3. Alter table set xxx unlogged,   4. Run copy command into Postgres db  5. Alter table set xxx logged  6. Create index …

The easy answer is to skip steps 3 and 5.

                        regards, tom lane

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