0013-work_shards.sql (1640B)
1 -- 2 -- This file is part of TALER 3 -- Copyright (C) 2026 Taler Systems SA 4 -- 5 -- TALER is free software; you can redistribute it and/or modify it under the 6 -- terms of the GNU General Public License as published by the Free Software 7 -- Foundation; either version 3, or (at your option) any later version. 8 -- 9 -- TALER is distributed in the hope that it will be useful, but WITHOUT ANY 10 -- WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR 11 -- A PARTICULAR PURPOSE. See the GNU General Public License for more details. 12 -- 13 -- You should have received a copy of the GNU General Public License along with 14 -- TALER; see the file COPYING. If not, see <http://www.gnu.org/licenses/> 15 -- 16 17 -- Track how far a worker has come *within* a shard, so that the work it 18 -- committed can be recorded long before the shard as a whole is finished, and 19 -- so that a worker picking the shard up later resumes instead of restarting. 20 ALTER TABLE work_shards 21 ADD COLUMN progress_row INT8; 22 23 -- Existing rows have no recorded progress. Starting them over is always safe 24 -- (every job using this table is idempotent, it just costs extra work), so 25 -- point them at the beginning of their shard. 26 UPDATE work_shards 27 SET progress_row=start_row; 28 29 ALTER TABLE work_shards 30 ALTER COLUMN progress_row SET NOT NULL; 31 32 COMMENT ON COLUMN work_shards.progress_row 33 IS 'rows in [start_row,progress_row) of this shard have been processed and committed; equal to start_row while nothing has been done yet and to end_row once the shard is complete. Only ever moves forward, so a second worker that concurrently grabbed the same shard cannot rewind it.';