exchange/src/exchangedb/0002-revolving_work_shards.sql

--
-- This file is part of TALER
-- Copyright (C) 2014--2022 Taler Systems SA
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-- TALER is free software; you can redistribute it and/or modify it under the
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CREATE UNLOGGED TABLE revolving_work_shards
  (shard_serial_id BIGINT GENERATED BY DEFAULT AS IDENTITY UNIQUE
  ,last_attempt INT8 NOT NULL
  ,start_row INT4 NOT NULL
  ,end_row INT4 NOT NULL
  ,active BOOLEAN NOT NULL DEFAULT FALSE
  ,job_name VARCHAR NOT NULL
  ,PRIMARY KEY (job_name, start_row)
  );
COMMENT ON TABLE revolving_work_shards
  IS 'coordinates work between multiple processes working on the same job with partitions that need to be repeatedly processed; unlogged because on system crashes the locks represented by this table will have to be cleared anyway, typically using "taler-exchange-dbinit -s"';
COMMENT ON COLUMN revolving_work_shards.shard_serial_id
  IS 'unique serial number identifying the shard';
COMMENT ON COLUMN revolving_work_shards.last_attempt
  IS 'last time a worker attempted to work on the shard';
COMMENT ON COLUMN revolving_work_shards.active
  IS 'set to TRUE when a worker is active on the shard';
COMMENT ON COLUMN revolving_work_shards.start_row
  IS 'row at which the shard scope starts, inclusive';
COMMENT ON COLUMN revolving_work_shards.end_row
  IS 'row at which the shard scope ends, exclusive';
COMMENT ON COLUMN revolving_work_shards.job_name
  IS 'unique name of the job the workers on this shard are performing';

CREATE INDEX revolving_work_shards_by_job_name_active_last_attempt_index
  ON revolving_work_shards
  (job_name
  ,active
  ,last_attempt
  );