I would like to understand if increasing work_mem does help improving the speed of the COPY command.

Does COPY use work_mem or maint_work_mem extensively?

  • Are you using COPY for a table, or for the results of a query? If the latter, then optimizing the query will be the way to speed things up.
    – jmelesky
    Aug 21 '19 at 14:17
  • It's COPY for a table which is 250 GB and I am importing it from S3 to RDS Postgres
    – Ramya
    Aug 21 '19 at 14:26

No, COPY does not need a lot of memory.

There are two things to speed up COPY:

  • Remove any indexes and constraints on the table before you COPY into it.

  • Increase max_wal_size so that you don't get more checkpoints than necessary.

    Of course, if you COPY into an UNLOGGED table, it will be even faster.

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