Re: speed up full table scan using psql

On 5/31/23 13:57, Lian Jiang wrote:
> The command is: psql $db_url -c "copy (select row_to_json(x_tmp_uniq)
> from public.mytable x_tmp_uniq) to stdout"
> postgres version:  14.7
> Does this mean COPY and java CopyManager may not help since my psql
> command already uses copy?

I don't think the issue is COPY itself but row_to_json(x_tmp_uniq).

This:

https://towardsdatascience.com/spark-essentials-how-to-read-and-write-data-with-pyspark-5c45e29227cd

indicates Spark can use CSV as an input source.

Given that I would just COPY the data out as CSV.

>
> Regarding pg_dump, it does not support json format which means extra
> work is needed to convert the supported format to jsonl (or parquet) so
> that they can be imported into snowflake. Still exploring but want to
> call it out early. Maybe 'custom' format can be parquet?
>
>
> Thanks
> Lian

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com