preliminary work on supporting sharding/parallel aggregation (undertested, but tests pass again)

1 files changed, 75 insertions, 0 deletions

diff --git a/src/exchangedb/exchange-0003.sql b/src/exchangedb/exchange-0003.sql
new file mode 100644
index 00000000..e1c9273f
--- /dev/null
+++ b/src/exchangedb/exchange-0003.sql
@@ -0,0 +1,75 @@
+--
+-- This file is part of TALER
+-- Copyright (C) 2021 Taler Systems SA
+--
+-- TALER is free software; you can redistribute it and/or modify it under the
+-- terms of the GNU General Public License as published by the Free Software
+-- Foundation; either version 3, or (at your option) any later version.
+--
+-- TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+-- WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+-- A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+--
+-- You should have received a copy of the GNU General Public License along with
+-- TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+--
+
+-- Everything in one big transaction
+BEGIN;
+
+-- Check patch versioning is in place.
+SELECT _v.register_patch('exchange-0003', NULL, NULL);
+
+
+
+ALTER TABLE deposits
+  ADD COLUMN shard INT4 NOT NULL DEFAULT 0;
+COMMENT ON COLUMN deposits.shard
+  IS 'Used for load sharding. Should be set based on h_wire, merchant_pub and a service salt. Default of 0 onlyapplies for colums migrated from a previous version without sharding support. 64-bit value because we need an *unsigned* 32-bit value.';
+
+DROP INDEX deposits_get_ready_index;
+CREATE INDEX deposits_get_ready_index
+  ON deposits
+  (shard
+  ,tiny
+  ,done
+  ,wire_deadline
+  ,refund_deadline
+  );
+COMMENT ON INDEX deposits_get_ready_index
+  IS 'for deposits_get_ready';
+
+
+
+CREATE UNLOGGED TABLE IF NOT EXISTS revolving_work_shards
+  (shard_serial_id BIGSERIAL 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)
+  );
+CREATE INDEX IF NOT EXISTS revolving_work_shards_index
+  ON revolving_work_shards
+  (job_name
+  ,active
+  ,last_attempt
+  );
+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';
+
+-- Complete transaction
+COMMIT;