[receiver/googlecloudspanner] feat: table size stats (#18689)

* Add table stats to Google Cloud Spanner receiver

to track size/etc

* changelog message

* pr comment fixes

* spelling and ordering

* top actually

.chloggen/googlecloudpsanner-table-size-stats.yaml

@@ -0,0 +1,16 @@
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: 'enhancement'
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: googlecloudspannerreceiver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: "adding table size statistics as metrics"
+
+# One or more tracking issues related to the change
+issues: [18689]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:

receiver/googlecloudspannerreceiver/internal/metadataconfig/metadata.yaml

@@ -519,3 +519,22 @@ metadata:
         data:
           type: "gauge"
         unit: "second"
+#
+# -------------------------------------------- Table Size Stats ------------------------------------------------------
+#
+  - name: "hourly table size stats"
+    query: "SELECT * FROM SPANNER_SYS.TABLE_SIZES_STATS_1HOUR WHERE INTERVAL_END = @pullTimestamp ORDER BY INTERVAL_END DESC, USED_BYTES DESC"
+    metric_name_prefix: "database/spanner/table_sizes/top/"
+    timestamp_column_name: "INTERVAL_END"
+    high_cardinality: true
+    labels:
+      - name: "table_name"
+        column_name: "TABLE_NAME"
+        value_type: "string"
+    metrics:
+      - name: "used_bytes"
+        column_name: "USED_BYTES"
+        value_type: "int"
+        data:
+          type: "gauge"
+        unit: "byte"