Re: Copying records from TABLE_A to TABLE_B (in the same database)

On 8/2/22 13:41, Adrian Klaver wrote:
> On 8/2/22 11:37 AM, Ron wrote:
>> AWS RDS Postgresql 12.10
>>
>> There are no indices or constraints (except for NOT NULL) on table_a.
>>
>> The two ways that I know are:
>>      INSERT INTO table_a SELECT * FROM table_b;

Argh, I got the tables backwards.  Should be:

INSERT INTO table_b SELECT * FROM table_a;

>> and
>>      \COPY table_a TO '/tmp/table_a.tsv' WITH (FORMAT BINARY);
>>      \COPY table_b FROM '/tmp/table_a.tsv' WITH (FORMAT BINARY);
>>
>> Is there a faster/better way?
>>
> Does table_a have existing records?

Yes.  Just before the copy, table_b was created using:
     CREATE TABLE table_b (LIKE table_a INCLUDING CONSTRAINTS INCLUDING 
DEFAULTS);

The only constraints on table_a are NOT NULL on various fields.

> If so do you care if there are duplicates?

TABLE_A (the source) has a UNIQUE index.  I'll be adding a similar PK on 
TABLE_B after the copy.

> How large a data set are you talking about?

It's varied.  The biggest have up to 20M rows with a bytea field, and others 
with 50M rather large (but no bytea) fields.

INSERT INTO is good enough for the small tables.

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