Use Block Range index instead of b-tree to handle range operations

Signed-off-by: Kipchirchir Sigei <[email protected]>

onadata/apps/logger/migrations/0005_add_brindex_date_fields.py

@@ -0,0 +1,44 @@
+# Generated by Django 3.2.18 on 2023-03-13 15:34
+
+import django.contrib.postgres.indexes
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("logger", "0004_update_instance_geoms"),
+    ]
+
+    operations = [
+        migrations.SeparateDatabaseAndState(
+            database_operations=[
+                migrations.RunSQL(
+                    sql='CREATE INDEX "logger_inst_date_cr_079af3_brin" ON "logger_instance" USING brin ("date_created") WITH (autosummarize = on);',
+                    reverse_sql='DROP INDEX "logger_inst_date_cr_079af3_brin";',
+                ),
+                migrations.RunSQL(
+                    sql='CREATE INDEX "logger_inst_date_mo_270e0d_brin" ON "logger_instance" USING brin ("date_modified") WITH (autosummarize = on);',
+                    reverse_sql='DROP INDEX "logger_inst_date_mo_270e0d_brin";',
+                ),
+            ],
+            state_operations=[
+                migrations.AddIndex(
+                    model_name="instance",
+                    index=django.contrib.postgres.indexes.BrinIndex(
+                        autosummarize=True,
+                        fields=["date_created"],
+                        name="logger_inst_date_cr_079af3_brin",
+                    ),
+                ),
+                migrations.AddIndex(
+                    model_name="instance",
+                    index=django.contrib.postgres.indexes.BrinIndex(
+                        autosummarize=True,
+                        fields=["date_modified"],
+                        name="logger_inst_date_mo_270e0d_brin",
+                    ),
+                ),
+            ],
+        )
+    ]

onadata/apps/logger/models/instance.py

@@ -11,6 +11,7 @@
 from django.contrib.auth import get_user_model
 from django.contrib.gis.db import models
 from django.contrib.gis.geos import GeometryCollection, Point
+from django.contrib.postgres.indexes import BrinIndex
 from django.core.cache import cache
 from django.db import connection, transaction
 from django.db.models import Q
@@ -649,10 +650,10 @@ class Instance(models.Model, InstanceBaseClass):
     survey_type = models.ForeignKey("logger.SurveyType", on_delete=models.PROTECT)
 
     # shows when we first received this instance
-    date_created = models.DateTimeField(auto_now_add=True, db_index=True)
+    date_created = models.DateTimeField(auto_now_add=True)
 
     # this will end up representing "date last parsed"
-    date_modified = models.DateTimeField(auto_now=True, db_index=True)
+    date_modified = models.DateTimeField(auto_now=True)
 
     # this will end up representing "date instance was deleted"
     deleted_at = models.DateTimeField(null=True, default=None)
@@ -694,6 +695,10 @@ class Instance(models.Model, InstanceBaseClass):
     class Meta:
         app_label = "logger"
         unique_together = ("xform", "uuid")
+        indexes = [
+            BrinIndex(fields=['date_created'], autosummarize=True),
+            BrinIndex(fields=['date_modified'], autosummarize=True),
+        ]
 
     @classmethod
     def set_deleted_at(cls, instance_id, deleted_at=timezone.now(), user=None):