alerts-server: Add currency_name to currencies table

alerts-server/conf/evolutions/default/7.sql

@@ -0,0 +1,34 @@
+-- In order to support coinmarketcap, we need to store the currency name
+-- to differentiate repeated currencies.
+--
+-- while the new column currency_name could be nullable, that have conflicts with
+-- the unique constraint because PostgreSQL doesn't consider null values as equal
+-- (at least when working with unique constraint), setting the empty string instead
+-- give us the expected effect.
+
+# --- !Ups
+
+-- add the new column
+ALTER TABLE currencies
+ADD COLUMN currency_name CITEXT NOT NULL DEFAULT '';
+
+-- update unique constraint to include the name
+ALTER TABLE currencies
+DROP CONSTRAINT currencies_unique;
+
+ALTER TABLE currencies
+ADD CONSTRAINT currencies_unique UNIQUE (exchange, market, currency, currency_name);
+
+# --- !Downs
+
+-- rollback unique constraint
+ALTER TABLE currencies
+DROP CONSTRAINT currencies_unique;
+
+ALTER TABLE currencies
+ADD CONSTRAINT currencies_unique UNIQUE (exchange, market, currency);
+
+
+-- drop the name column
+ALTER TABLE currencies
+DROP COLUMN currency_name;