Re: increase insert into local table from remote oracle tablepreformance

El 15 ago 2018, a las 10:43, Mariel Cherkassky <mariel.cherkassky@gmail.com> escribió:

Inserting directly into the partition didnt help, the performance are just the same. I tried to increase the prefetch value to 1000(alter foreign table hist_oracle options (add prefetch '1000') but still no change - 15 minutes for one partition(6GB).

On the oracle side the plan is full scan on the partition (I'm copying the entire partition into a postgresql partition..)

2018-08-15 1:28 GMT+03:00 legrand legrand <legrand_legrand@hotmail.com>:

main ideas are:

- inserting directly to the right partition:
  perform as many inserts as pg partitions found in main_table_hist, like
  INSERT INTO 14/08/2018_value1 select * from remote_oracle_hist where
day=to_date('14/08/2018','DD/MM/YYYY') and value='value1'

please check execution plan (in Oracle db) using EXPLAIN ANALYZE

- all those inserts should be executed in // (with 4 or 8 sql scripts)

- wal archiving should be disabled during hist data recovery only (not
during day to day operations)

- for prefetch see

https://github.com/laurenz/oracle_fdw

prefetch (optional, defaults to "200")

Sets the number of rows that will be fetched with a single round-trip
between PostgreSQL and Oracle during a foreign table scan. This is
implemented using Oracle row prefetching. The value must be between 0 and
10240, where a value of zero disables prefetching.

Higher values can speed up performance, but will use more memory on the
PostgreSQL server.

Regards
PAscal



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