[source-mysql] No empty sample (#48545)

airbyte-integrations/connectors/source-mysql/metadata.yaml

@@ -9,7 +9,7 @@ data:
   connectorSubtype: database
   connectorType: source
   definitionId: 435bb9a5-7887-4809-aa58-28c27df0d7ad
-  dockerImageTag: 3.9.0-rc.14
+  dockerImageTag: 3.9.0-rc.15
   dockerRepository: airbyte/source-mysql
   documentationUrl: https://docs.airbyte.com/integrations/sources/mysql
   githubIssueLabel: source-mysql

airbyte-integrations/connectors/source-mysql/src/main/kotlin/io/airbyte/integrations/source/mysql/MysqlSourceOperations.kt

@@ -215,9 +215,12 @@ class MysqlSourceOperations :
                 // of table on very large tables ( > 100s million of rows)
                 val greatestRate: String = 0.00005.toString()
                 // Quick approximation to "select count(*) from table" which doesn't require
-                // full table scan.
+                // full table scan. However, note this could give delayed summary info about a table
+                // and thus a new table could be treated as empty despite we recently added rows.
+                // To prevent that from happening and resulted for skipping the table altogether,
+                // the minimum count is set to 10.
                 val quickCount =
-                    "SELECT table_rows FROM information_schema.tables WHERE table_schema = '$namespace' AND table_name = '$name'"
+                    "SELECT GREATEST(10, table_rows) FROM information_schema.tables WHERE table_schema = '$namespace' AND table_name = '$name'"
                 val greatest = "GREATEST($greatestRate, $sampleSize / ($quickCount))"
                 // Rand returns a value between 0 and 1
                 val where = "WHERE RAND() < $greatest "