Refactor some database functions (#540)

Signed-off-by: Sergio Castaño Arteaga <tegioz@icloud.com>

Author: tegioz

database/migrations/functions/001_load_functions.sql

@@ -23,6 +23,10 @@
 {{ template "common/list_event_ticket_types.sql" }} -- Dependency for get_event_full and payments
 {{ template "common/get_group_summary.sql" }} -- Do not sort alphabetically, has dependency
 {{ template "common/questionnaire_answers_exist_for_event.sql" }} -- Do not sort alphabetically, dependency for get_event_full and update_event
+{{ template "common/stats_label_count_series.sql" }}
+{{ template "common/stats_label_count_series_by_name.sql" }}
+{{ template "common/stats_running_total_series.sql" }}
+{{ template "common/stats_running_total_series_by_name.sql" }}
 {{ template "common/validate_questionnaire_questions_payload.sql" }} -- Do not sort alphabetically, dependency for add/update_event and validate_questionnaire_answers_payload
 {{ template "common/validate_questionnaire_answers_payload.sql" }} -- Do not sort alphabetically, dependency for attend_event, submit_event_registration_answers and prepare_event_checkout_purchase
 {{ template "common/get_event_full.sql" }}

database/migrations/functions/common/stats_label_count_series.sql

@@ -0,0 +1,17 @@
+-- Builds an ordered label count series from labeled count rows.
+create or replace function stats_label_count_series(p_counts jsonb)
+returns json as $$
+select coalesce(
+    json_agg(json_build_array(label, count) order by label),
+    '[]'::json
+)
+from (
+    select
+        count_row.label,
+        count_row.count
+    from jsonb_to_recordset(coalesce(p_counts, '[]'::jsonb)) as count_row(
+        label text,
+        count int
+    )
+) counts;
+$$ language sql immutable;

database/migrations/functions/common/stats_label_count_series_by_name.sql

@@ -0,0 +1,24 @@
+-- Builds ordered label count series grouped by name.
+create or replace function stats_label_count_series_by_name(p_counts jsonb)
+returns json as $$
+with named_counts as (
+    select
+        count_row.series_name,
+        jsonb_agg(to_jsonb(count_row)) as counts
+    from jsonb_to_recordset(coalesce(p_counts, '[]'::jsonb)) as count_row(
+        series_name text,
+        label text,
+        count int
+    )
+    group by count_row.series_name
+)
+select coalesce(
+    json_object_agg(
+        series_name,
+        stats_label_count_series(counts)
+        order by series_name
+    ),
+    '{}'::json
+)
+from named_counts;
+$$ language sql immutable;

database/migrations/functions/common/stats_running_total_series.sql

@@ -0,0 +1,17 @@
+-- Builds an ordered cumulative count series from timestamp bucket count rows.
+create or replace function stats_running_total_series(p_counts jsonb)
+returns json as $$
+select coalesce(
+    json_agg(json_build_array(ts, cumulative_total) order by ts),
+    '[]'::json
+)
+from (
+    select
+        floor(extract(epoch from bucket_start) * 1000)::bigint as ts,
+        sum(count) over (order by bucket_start)::int as cumulative_total
+    from jsonb_to_recordset(coalesce(p_counts, '[]'::jsonb)) as count_row(
+        bucket_start timestamptz,
+        count int
+    )
+) totals;
+$$ language sql immutable;

database/migrations/functions/common/stats_running_total_series_by_name.sql

@@ -0,0 +1,24 @@
+-- Builds ordered cumulative count series grouped by name.
+create or replace function stats_running_total_series_by_name(p_counts jsonb)
+returns json as $$
+with named_counts as (
+    select
+        series_name,
+        jsonb_agg(to_jsonb(count_row)) as counts
+    from jsonb_to_recordset(coalesce(p_counts, '[]'::jsonb)) as count_row(
+        series_name text,
+        bucket_start timestamptz,
+        count int
+    )
+    group by series_name
+)
+select coalesce(
+    json_object_agg(
+        series_name,
+        stats_running_total_series(counts)
+        order by series_name
+    ),
+    '{}'::json
+)
+from named_counts;
+$$ language sql immutable;