MagicStack / MagicStack/asyncpg

Cockroachdb copy_records_to_table support?

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Description

  • asyncpg version: v0.21.0
  • PostgreSQL version: CCL v20.1.8 @ 2020/10/21 15:46:38 (go1.13.9)
  • Python version: 3.8
  • Platform: macos
  • Do you use pgbouncer?: no
  • Did you install asyncpg with pip?: yes

EDIT:
Confirmed cockroachdb does not support the COPY ... FROM STDIN syntax. (https://github.com/cockroachdb/cockroach/issues/16392)

Reasoning is:
"because it's 1) complicated and 2) slow. All the data goes through a single connection. CockroachDB provides an IMPORT PGDUMP statement which is much faster and can operate in parallel."

Hopefully one of the maintainers can comment on this.


Hello, I'm not sure if this has been asked before, but I'm having issues running copy_records_to_table into a cockroachdb table/temp table. Here's a code snippet which will reproduce the issue when running a local cockroachdb.

Exception:

PostgresSyntaxError at or near "(": syntax error
DETAIL:  source SQL:
COPY "cool_table" FROM STDIN (FORMAT binary)
                             ^
import asyncio
import asyncpg


async def bwrite():
    dsn = "postgres://root@localhost:26257/postgres"
    conn: asyncpg.Connection = await asyncpg.connect(dsn)
    await conn.execute("SET experimental_enable_temp_tables = on")
    await conn.execute(
        """CREATE TEMP TABLE cool_table(
                objectid int8,
                CONSTRAINT "primary" PRIMARY KEY (objectid ASC)
            );"""
    )
    try:
        this_res = await conn.fetch("SHOW TABLES from pg_temp")
        print(this_res)
        await conn.copy_records_to_table(
            "cool_table", records=[(12345,), (67890,)]
        )
    except Exception as e:
        print(e)


if __name__ == "__main__":
    # build: CCL v20.1.8 @ 2020/10/21 15:46:38 (go1.13.9)
    loop = asyncio.get_event_loop()
    res = loop.run_until_complete(bwrite())



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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with asyncpg.Connection.copy_records_to_table and the generated COPY "cool_table" FROM STDIN (FORMAT binary) statement shown in the issue. Use the provided reproduction with CockroachDB and a temporary table as the acceptance case; done means the requested support works or the incompatibility and supported alternative are clearly established.

Written by the indexing model from the issue text.

Assessment

Tech stack
postgresql, python
Domain
database
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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