Add min_issue to metadata

docs/api/covidcast_meta.md

@@ -38,6 +38,7 @@ None required.
 | `epidata[].max_value`     | maximum value                                                       | float            |
 | `epidata[].mean_value`    | mean of value                                                       | float            |
 | `epidata[].stdev_value`   | standard deviation of value                                         | float            |
+| `epidata[].min_issue`     | oldest date data was issued (e.g., 20200710)                        | integer          |
 | `epidata[].max_issue`     | most recent date data was issued (e.g., 20200710)                   | integer          |
 | `epidata[].min_lag`       | smallest lag from observation to issue, in `time_type` units        | integer          |
 | `epidata[].max_lag`       | largest lag from observation to issue, in `time_type` units         | integer          |
@@ -51,19 +52,23 @@ https://api.delphi.cmu.edu/epidata/covidcast_meta/
 {
   "result": 1,
   "epidata": [
-  {
+    {
       "data_source": "doctor-visits",
       "signal": "smoothed_adj_cli",
-      "last_update": 1592707979,
-      "stdev_value": 2.6647410028331,
-      "num_locations": 2500,
       "time_type": "day",
-      "max_value": 87.190476,
-      "mean_value": 1.4439366759191,
       "geo_type": "county",
-      "min_value": 0,
-      "max_time": 20200617,
-      "min_time": 20200201
+      "min_time": 20200201,
+      "max_time": 20240321,
+      "num_locations": 2586,
+      "min_value": 0.0,
+      "max_value": 87.670832,
+      "mean_value": 2.4972178,
+      "stdev_value": 3.6433783,
+      "last_update": 1711412545,
+      "min_issue": 20200507,
+      "max_issue": 20240325,
+      "min_lag": 2,
+      "max_lag": 129
     },
     ...
   ],

integrations/acquisition/covidcast/test_covidcast_meta_caching.py

@@ -137,6 +137,7 @@ def test_caching(self):
         'max_value': 1,
         'mean_value': 1,
         'stdev_value': 0,
+        'min_issue': 20200422,
         'max_issue': 20200423,
         'min_lag': 0,
         'max_lag': 1,

integrations/client/test_delphi_epidata.py

@@ -362,15 +362,19 @@ def test_covidcast_meta(self):
     # 1st issue: 0 10 20
     # 2nd issue: 1 11 21
     # 3rd issue: 2 12 22
-    rows = [
-      CovidcastTestRow.make_default_row(
-        time_value=DEFAULT_TIME_VALUE + t,
-        issue=DEFAULT_ISSUE + i,
-        value=t*10 + i
-      )
-      for i in range(3) for t in range(3)
-    ]
-    self._insert_rows(rows)
+    for i in range(3):
+      for t in range(3):
+        row = CovidcastTestRow.make_default_row(
+          time_value=DEFAULT_TIME_VALUE + t,
+          issue=DEFAULT_ISSUE + i,
+          value=t*10 + i
+        )
+        self._insert_rows([row])
+    self._insert_rows([CovidcastTestRow.make_default_row(
+      time_value=DEFAULT_TIME_VALUE-1,
+      issue=DEFAULT_ISSUE,
+      value=12
+    )])
 
     # cache it
     update_covidcast_meta_cache(args=None)
@@ -387,17 +391,18 @@ def test_covidcast_meta(self):
     del response['epidata'][0]['last_update']
 
     expected = dict(
-      data_source=rows[0].source,
-      signal=rows[0].signal,
-      time_type=rows[0].time_type,
-      geo_type=rows[0].geo_type,
-      min_time=DEFAULT_TIME_VALUE,
+      data_source=row.source,
+      signal=row.signal,
+      time_type=row.time_type,
+      geo_type=row.geo_type,
+      min_time=DEFAULT_TIME_VALUE - 1,
       max_time=DEFAULT_TIME_VALUE + 2,
       num_locations=1,
       min_value=2.,
       mean_value=12.,
       max_value=22.,
-      stdev_value=8.1649658, # population stdev, not sample, which is 10.
+      stdev_value=7.0710678, # population stdev, not sample, which is 10.
+      min_issue=DEFAULT_ISSUE,
       max_issue=DEFAULT_ISSUE + 2,
       min_lag=0,
       max_lag=0, # we didn't set lag when inputting data

integrations/server/test_covidcast_meta.py

@@ -129,6 +129,7 @@ def insert_placeholder_data(self):
               'mean_value': 15,
               'stdev_value': 5,
               'last_update': 123,
+              'min_issue': 1,
               'max_issue': 2,
               'min_lag': 0,
               'max_lag': 0,

src/acquisition/covidcast/database.py

@@ -473,6 +473,7 @@ def compute_covidcast_meta(self, table_name=None, n_threads=None):
         ROUND(AVG(`value`),7) AS `mean_value`,
         ROUND(STD(`value`),7) AS `stdev_value`,
         MAX(`value_updated_timestamp`) AS `last_update`,
+        MIN(`issue`) as `min_issue`,
         MAX(`issue`) as `max_issue`,
         MIN(`lag`) as `min_lag`,
         MAX(`lag`) as `max_lag`