[FLINK-39071] Select fields rather * to read snapshot data in case schema changes.

Author: loserwang1024

flink-cdc-connect/flink-cdc-source-connectors/flink-connector-postgres-cdc/src/main/java/org/apache/flink/cdc/connectors/postgres/source/fetch/PostgresScanFetchTask.java

@@ -287,12 +287,17 @@ private void createDataEventsForTable(
                             .filter(field -> table.columnWithName(field).typeName().equals("uuid"))
                             .collect(Collectors.toList());
 
+            List<String> columnNames =
+                    table.columns().stream()
+                            .map(column -> jdbcConnection.quotedColumnIdString(column.name()))
+                            .collect(Collectors.toList());
             final String selectSql =
                     PostgresQueryUtils.buildSplitScanQuery(
                             snapshotSplit.getTableId(),
                             snapshotSplit.getSplitKeyType(),
                             snapshotSplit.getSplitStart() == null,
                             snapshotSplit.getSplitEnd() == null,
+                            columnNames,
                             uuidFields);
             LOG.debug(
                     "For split '{}' of table {} using select statement: '{}'",

flink-cdc-connect/flink-cdc-source-connectors/flink-connector-postgres-cdc/src/main/java/org/apache/flink/cdc/connectors/postgres/source/utils/PostgresQueryUtils.java

@@ -31,7 +31,6 @@
 import java.util.Iterator;
 import java.util.List;
 import java.util.Optional;
-import java.util.stream.Collectors;
 
 import static org.apache.flink.cdc.connectors.base.utils.SourceRecordUtils.rowToArray;
 
@@ -156,29 +155,26 @@ public static String buildSplitScanQuery(
             boolean isFirstSplit,
             boolean isLastSplit,
             List<String> uuidFields) {
-        return buildSplitQuery(tableId, pkRowType, isFirstSplit, isLastSplit, uuidFields, -1, true);
+        return buildSplitScanQuery(tableId, pkRowType, isFirstSplit, isLastSplit, null, uuidFields);
     }
 
-    private static String buildSplitQuery(
+    public static String buildSplitScanQuery(
             TableId tableId,
             RowType pkRowType,
             boolean isFirstSplit,
             boolean isLastSplit,
-            List<String> uuidFields,
-            int limitSize,
-            boolean isScanningData) {
+            List<String> columnNames,
+            List<String> uuidFields) {
         final String condition;
 
         if (isFirstSplit && isLastSplit) {
             condition = null;
         } else if (isFirstSplit) {
             final StringBuilder sql = new StringBuilder();
             addPrimaryKeyColumnsToCondition(pkRowType, sql, " <= ", uuidFields);
-            if (isScanningData) {
-                sql.append(" AND NOT (");
-                addPrimaryKeyColumnsToCondition(pkRowType, sql, " = ", uuidFields);
-                sql.append(")");
-            }
+            sql.append(" AND NOT (");
+            addPrimaryKeyColumnsToCondition(pkRowType, sql, " = ", uuidFields);
+            sql.append(")");
             condition = sql.toString();
         } else if (isLastSplit) {
             final StringBuilder sql = new StringBuilder();
@@ -187,30 +183,19 @@ private static String buildSplitQuery(
         } else {
             final StringBuilder sql = new StringBuilder();
             addPrimaryKeyColumnsToCondition(pkRowType, sql, " >= ", uuidFields);
-            if (isScanningData) {
-                sql.append(" AND NOT (");
-                addPrimaryKeyColumnsToCondition(pkRowType, sql, " = ", uuidFields);
-                sql.append(")");
-            }
+            sql.append(" AND NOT (");
+            addPrimaryKeyColumnsToCondition(pkRowType, sql, " = ", uuidFields);
+            sql.append(")");
             sql.append(" AND ");
             addPrimaryKeyColumnsToCondition(pkRowType, sql, " <= ", uuidFields);
             condition = sql.toString();
         }
 
-        if (isScanningData) {
-            return buildSelectWithRowLimits(
-                    tableId, limitSize, "*", Optional.ofNullable(condition), Optional.empty());
-        } else {
-            final String orderBy =
-                    pkRowType.getFieldNames().stream().collect(Collectors.joining(", "));
-            return buildSelectWithBoundaryRowLimits(
-                    tableId,
-                    limitSize,
-                    getPrimaryKeyColumnsProjection(pkRowType),
-                    getMaxPrimaryKeyColumnsProjection(pkRowType),
-                    Optional.ofNullable(condition),
-                    orderBy);
-        }
+        return buildSelectWithRowLimits(
+                tableId,
+                columnNames == null ? "*" : String.join(",", columnNames),
+                Optional.ofNullable(condition),
+                Optional.empty());
     }
 
     public static PreparedStatement readTableSplitDataStatement(
@@ -330,7 +315,6 @@ private static String getMaxPrimaryKeyColumnsProjection(RowType pkRowType) {
 
     private static String buildSelectWithRowLimits(
             TableId tableId,
-            int limit,
             String projection,
             Optional<String> condition,
             Optional<String> orderBy) {
@@ -343,9 +327,6 @@ private static String buildSelectWithRowLimits(
         if (orderBy.isPresent()) {
             sql.append(" ORDER BY ").append(orderBy.get());
         }
-        if (limit > 0) {
-            sql.append(" LIMIT ").append(limit);
-        }
         return sql.toString();
     }