Patrick TJ McPhee wrote:

How about something along the lines of

BEGIN;
ALTER TABLE log RENAME to log_old;
CREATE TABLE log(...);
COMMIT;

BEGIN;
LOCK table log_old;
COPY log_old TO 'filename-path';
DROP TABLE log_old;
COMMIT;

I believe this will keep the writers writing while keeping the efficiency
of truncating.

It's almost a pity that there's no

TRUNCATE TABLE log MOVE DATA TO log_copy;

or similar; ie with two identical table definitions `log' and `log_copy' swap the backing file from `log' to `log_copy' before truncating `log'.

`log_copy' could be a new temp table created with CREATE TEMPORARY TABLE ... LIKE.

This sort of thing doesn't seem to come up all that much, though.

--
Craig Ringer

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