OLMIS-7858: Add four indexes on requisition schema (#94)

src/main/resources/db/migration/20240314174732705__add_requisition_indexes.sql

@@ -0,0 +1,51 @@
+-- This script allows to add indexes to core database without possibility to add duplicated one, with two different names but on the same columns.
+CREATE FUNCTION addindexesifnotexist(schema_parameter VARCHAR, table_parameter VARCHAR, indexed_parameter VARCHAR)
+RETURNS void AS
+$$
+DECLARE index_exists BOOLEAN;
+DECLARE new_index_name VARCHAR;
+DECLARE comma_replaced_indexed_parameter VARCHAR;
+
+BEGIN
+	SELECT EXISTS (
+        SELECT 1
+        FROM (
+            SELECT
+                n.nspname AS schema_name,
+                t.relname AS table_name,
+                i.relname AS index_name,
+                array_to_string(array_agg(a.attname ORDER BY a.attname), ',') AS indexed_columns
+            FROM pg_class t
+            JOIN pg_index ix ON t.oid = ix.indrelid
+            JOIN pg_class i ON i.oid = ix.indexrelid
+            JOIN pg_attribute a ON a.attrelid = t.oid AND a.attnum = ANY(ix.indkey)
+            JOIN pg_namespace n ON n.oid = t.relnamespace
+            WHERE t.relkind = 'r'  -- regular tables (relations)
+            GROUP BY
+                n.nspname,
+                t.relname,
+                i.relname
+        ) AS existing_indexes_info
+        WHERE schema_name = schema_parameter
+	    AND table_name = table_parameter
+	    AND indexed_columns = indexed_parameter
+    ) INTO index_exists;
+
+   SELECT REPLACE(indexed_parameter, ',', '_') INTO comma_replaced_indexed_parameter;
+   SELECT CONCAT(table_parameter, '_', comma_replaced_indexed_parameter, '_idx') INTO new_index_name;
+
+   IF NOT index_exists THEN
+    EXECUTE format('CREATE INDEX %I ON %I.%I (%s)', new_index_name, schema_parameter, table_parameter, indexed_parameter);
+   END IF;
+
+END; $$ LANGUAGE plpgsql;
+
+
+-- do not insert whitespaces in parameters, variables in the third argument must be sorted alfabetically
+SELECT * FROM addindexesifnotexist('requisition', 'status_messages', 'requisitionid');
+SELECT * FROM addindexesifnotexist('requisition', 'requisitions_previous_requisitions', 'previousrequisitionid');
+SELECT * FROM addindexesifnotexist('requisition', 'stock_adjustments', 'requisitionlineitemid');
+SELECT * FROM addindexesifnotexist('requisition', 'stock_adjustment_reasons', 'requisitionid');
+
+
+DROP FUNCTION addindexesifnotexist(varchar, varchar, varchar);