yzeng1618 commented on code in PR #9270:
URL: https://github.com/apache/seatunnel/pull/9270#discussion_r2076684475
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seatunnel-connectors-v2/connector-jdbc/src/main/java/org/apache/seatunnel/connectors/seatunnel/jdbc/internal/dialect/oracle/OracleTypeConverter.java:
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@@ -202,9 +213,17 @@ public Column convert(BasicTypeDefine typeDefine) {
builder.columnLength(BYTES_4GB - 1);
break;
case ORACLE_BLOB:
- builder.dataType(PrimitiveByteArrayType.INSTANCE);
- // The maximum length of the column is 4GB-1
- builder.columnLength(BYTES_4GB - 1);
+ if (handleBlobAsString) {
+ builder.dataType(BasicType.STRING_TYPE);
+ builder.columnLength(BYTES_4GB - 1);
+ log.info("Converted BLOB to STRING_TYPE with length: {}",
BYTES_4GB - 1);
+ } else {
+ builder.dataType(PrimitiveByteArrayType.INSTANCE);
+ builder.columnLength(BYTES_4GB - 1);
+ log.info(
+ "Converted BLOB to PrimitiveByteArrayType with
length: {}",
+ BYTES_4GB - 1);
+ }
Review Comment:
Thank you for your question.The design choice to handle BLOB data as strings
is based on real customer use cases. We've encountered numerous situations
where customers store XML files or other textual content in Oracle BLOB fields
rather than CLOB, particularly in legacy systems or specific application
scenarios.
When attempting to process these BLOB data directly in SQL queries using
type conversions (like TO_CLOB), users often face byte size limitations,
especially with large XML files. These limitations can result in data
truncation or conversion failures.
This is why we implemented the handleBlobAsString option, providing users
with flexibility during the ETL process:
1. When the data is actually textual content (like XML), it can be converted
to STRING_TYPE
2. When the data is genuinely binary, it maintains its original binary form
This approach circumvents Oracle's internal type conversion limitations,
offering more reliable processing capabilities for large textual data while
maintaining backward compatibility.
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