flink-cdc-connect/flink-cdc-source-connectors/flink-connector-db2-cdc/src/main/java/org/apache/flink/cdc/connectors/db2/source/utils/Db2Utils.java [253:302]:
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    private static String buildSplitQuery(
            TableId tableId,
            RowType pkRowType,
            boolean isFirstSplit,
            boolean isLastSplit,
            int limitSize,
            boolean isScanningData) {
        final String condition;

        if (isFirstSplit && isLastSplit) {
            condition = null;
        } else if (isFirstSplit) {
            final StringBuilder sql = new StringBuilder();
            addPrimaryKeyColumnsToCondition(pkRowType, sql, " <= ?");
            if (isScanningData) {
                sql.append(" AND NOT (");
                addPrimaryKeyColumnsToCondition(pkRowType, sql, " = ?");
                sql.append(")");
            }
            condition = sql.toString();
        } else if (isLastSplit) {
            final StringBuilder sql = new StringBuilder();
            addPrimaryKeyColumnsToCondition(pkRowType, sql, " >= ?");
            condition = sql.toString();
        } else {
            final StringBuilder sql = new StringBuilder();
            addPrimaryKeyColumnsToCondition(pkRowType, sql, " >= ?");
            if (isScanningData) {
                sql.append(" AND NOT (");
                addPrimaryKeyColumnsToCondition(pkRowType, sql, " = ?");
                sql.append(")");
            }
            sql.append(" AND ");
            addPrimaryKeyColumnsToCondition(pkRowType, sql, " <= ?");
            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);
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flink-cdc-connect/flink-cdc-source-connectors/flink-connector-oracle-cdc/src/main/java/org/apache/flink/cdc/connectors/oracle/source/utils/OracleUtils.java [111:160]:
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    private static String buildSplitQuery(
            TableId tableId,
            RowType pkRowType,
            boolean isFirstSplit,
            boolean isLastSplit,
            int limitSize,
            boolean isScanningData) {
        final String condition;

        if (isFirstSplit && isLastSplit) {
            condition = null;
        } else if (isFirstSplit) {
            final StringBuilder sql = new StringBuilder();
            addPrimaryKeyColumnsToCondition(pkRowType, sql, " <= ?");
            if (isScanningData) {
                sql.append(" AND NOT (");
                addPrimaryKeyColumnsToCondition(pkRowType, sql, " = ?");
                sql.append(")");
            }
            condition = sql.toString();
        } else if (isLastSplit) {
            final StringBuilder sql = new StringBuilder();
            addPrimaryKeyColumnsToCondition(pkRowType, sql, " >= ?");
            condition = sql.toString();
        } else {
            final StringBuilder sql = new StringBuilder();
            addPrimaryKeyColumnsToCondition(pkRowType, sql, " >= ?");
            if (isScanningData) {
                sql.append(" AND NOT (");
                addPrimaryKeyColumnsToCondition(pkRowType, sql, " = ?");
                sql.append(")");
            }
            sql.append(" AND ");
            addPrimaryKeyColumnsToCondition(pkRowType, sql, " <= ?");
            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);
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