fix: do not rotate timestamptz to UTC

In order to be timezone-agnostic, we submit partition bounds without
timezone offsets, like:
 VALUES FROM ('YYYY-MM-DD 00:00:00') TO ('YYYY-MM-DD 00:00:00')
The time zone of the session is automatically applied by Postgres.

When reading back these values, we get for instance
 YYYY-MM-DD 00:00:00+02
if the current time zone offset is +02.

If we rotate this timestamp locally to UTC and resubmit it without the
offset, it is now incorrect (unless the server happens to be
configured in UTC).

The fix consists of ignoring the offset when reading the current
bounds, to be consistently timezone-agnostic. The offset always
corresponds implicitly to the time zone of the SQL session, and
must not be forced in the value of the timestamp.

The SQL time zone can be changed dynamically with the PGTZ environment
variable if desired.

Signed-off-by: Daniel Vérité <dverite@gmail.com>

Author: dverite

pkg/ppm/bounds.go

@@ -114,7 +114,8 @@ func parseBoundAsUUIDv7(partition postgresql.PartitionResult) (lowerBound, upper
 }
 
 func convertToDateTimeWithoutTimezone(bound time.Time) time.Time {
-	parsedTime, err := time.Parse("2006-01-02 15:04:05", bound.UTC().Format("2006-01-02 15:04:05"))
+	/* Remove the time zone offset without rotating the timestamp to UTC */
+	parsedTime, err := time.Parse("2006-01-02 15:04:05", bound.Format("2006-01-02 15:04:05"))
 	if err != nil {
 		return time.Time{}
 	}

pkg/ppm/bounds_internal_test.go

@@ -45,8 +45,8 @@ func TestParseBounds(t *testing.T) {
 				LowerBound: "2024-01-01 23:30:00-01",
 				UpperBound: "2025-02-03 00:30:00+01",
 			},
-			"2024-01-02T00:30:00Z",
-			"2025-02-02T23:30:00Z",
+			"2024-01-01T23:30:00Z",
+			"2025-02-03T00:30:00Z",
 		},
 		{
 			"UUIDv7 bounds",

scripts/bats/30_provisioning.bats

@@ -364,3 +364,55 @@ EOF
   run list_existing_partitions "unittest" "public" "${TABLE}"
   assert_output "$expected2"
 }
+
+@test "Test a timestamptz key with provisioning crossing a DST transition " {
+  local TABLE="test_tz1"
+  local INTERVAL=weekly
+  local RETENTION=3
+  local PREPROVISIONED=2
+
+  declare -x PGTZ="Europe/Paris"
+
+  create_table_timestamptz_range ${TABLE}
+
+  local CONFIGURATION=$(basic_configuration ${TABLE} weekly created_at $RETENTION $PREPROVISIONED)
+  local CONFIGURATION_FILE=$(generate_configuration_file "${CONFIGURATION}")
+
+  PPM_WORK_DATE="2025-03-06" run "$PPM_PROG" run provisioning -c ${CONFIGURATION_FILE}
+  assert_success
+  assert_output --partial "All partitions are correctly provisioned"
+
+  local expected_1=$(cat <<EOF
+public|${TABLE}_2025_w07|2025-02-10 00:00:00+01|2025-02-17 00:00:00+01
+public|${TABLE}_2025_w08|2025-02-17 00:00:00+01|2025-02-24 00:00:00+01
+public|${TABLE}_2025_w09|2025-02-24 00:00:00+01|2025-03-03 00:00:00+01
+public|${TABLE}_2025_w10|2025-03-03 00:00:00+01|2025-03-10 00:00:00+01
+public|${TABLE}_2025_w11|2025-03-10 00:00:00+01|2025-03-17 00:00:00+01
+public|${TABLE}_2025_w12|2025-03-17 00:00:00+01|2025-03-24 00:00:00+01
+EOF
+  )
+
+  run list_existing_partitions "unittest" "public" ${TABLE}
+  assert_output "$expected_1"
+
+  # Now advance one week up to the end of March 2025
+  # The transition to summer time (GMT+1 => GMT+2) occurs at 2025-05-30 02:00 => 03:00
+
+  PPM_WORK_DATE="2025-03-13" run "$PPM_PROG" run provisioning -c ${CONFIGURATION_FILE}
+  assert_success
+  assert_output --partial "All partitions are correctly provisioned"
+
+  local expected_2=$(cat <<EOF
+public|${TABLE}_2025_w07|2025-02-10 00:00:00+01|2025-02-17 00:00:00+01
+public|${TABLE}_2025_w08|2025-02-17 00:00:00+01|2025-02-24 00:00:00+01
+public|${TABLE}_2025_w09|2025-02-24 00:00:00+01|2025-03-03 00:00:00+01
+public|${TABLE}_2025_w10|2025-03-03 00:00:00+01|2025-03-10 00:00:00+01
+public|${TABLE}_2025_w11|2025-03-10 00:00:00+01|2025-03-17 00:00:00+01
+public|${TABLE}_2025_w12|2025-03-17 00:00:00+01|2025-03-24 00:00:00+01
+public|${TABLE}_2025_w13|2025-03-24 00:00:00+01|2025-03-31 00:00:00+02
+EOF
+)
+  run list_existing_partitions "unittest" "public" ${TABLE}
+  assert_output "$expected_2"
+
+}

scripts/bats/test/libs/seeds.bash

@@ -39,6 +39,19 @@ EOQ
   execute_sql "${QUERY}"
 }
 
+create_table_timestamptz_range() {
+  local TABLE="$1"
+
+  read -r -d '' QUERY <<EOQ ||
+  CREATE TABLE ${TABLE} (
+    id              BIGSERIAL,
+    value	    INT,
+    created_at      TIMESTAMPTZ NOT NULL
+  ) PARTITION BY RANGE (created_at);
+EOQ
+  execute_sql "${QUERY}"
+}
+
 generate_configuration_file() {
   local PARTITION_CONFIGURATION=$1
   local CONFIGURATION_TEMPLATE_FILE=configuration/template.yaml
@@ -51,3 +64,19 @@ generate_configuration_file() {
 
   echo $FILENAME
 }
+
+# Return a common configuration
+# Arguments: table interval partition-key retention preprovisioned
+basic_configuration() {
+cat << EOF_conf
+partitions:
+  unittest:
+    schema: public
+    table: $1
+    interval: $2
+    partitionKey: $3
+    cleanupPolicy: drop
+    retention: $4
+    preProvisioned: $5
+EOF_conf
+}