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Select fileds rathert * to read snapshot data in case schema changes. #4273

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Merged
lvyanquan merged 1 commit into from
Feb 27, 2026
Merged

Select fileds rathert * to read snapshot data in case schema changes. #4273

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5 changes: 5 additions & 0 deletions ...ain/java/org/apache/flink/cdc/connectors/postgres/source/fetch/PostgresScanFetchTask.java
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Original file line number Diff line number Diff line change
Expand Up @@ -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);
Comment thread
loserwang1024 marked this conversation as resolved.
LOG.debug(
"For split '{}' of table {} using select statement: '{}'",
Expand Down
49 changes: 15 additions & 34 deletions ...c/main/java/org/apache/flink/cdc/connectors/postgres/source/utils/PostgresQueryUtils.java
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Original file line number Diff line number Diff line change
Expand Up @@ -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;

Expand Down Expand Up @@ -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();
Expand All @@ -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(
Expand Down Expand Up @@ -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) {
Expand All @@ -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();
}

Expand Down
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