FrankChen021 commented on code in PR #19698:
URL: https://github.com/apache/druid/pull/19698#discussion_r3622006007
##########
server/src/main/java/org/apache/druid/metadata/SQLMetadataConnector.java:
##########
@@ -1038,6 +1045,73 @@ public void createAuditTable()
}
}
+ @Override
+ public void exportTable(
+ final String tableName,
+ final String outputPath
+ )
+ {
+ exportTableWithJdbc(tableName, outputPath);
+ }
+
+ /**
+ * Exports a table to a CSV file using generic JDBC.
+ * Binary columns are hex-encoded and booleans are written as true/false
strings.
+ * Subclasses may override {@link #exportTable} with a database-specific
implementation
+ * while this method remains available for testing or fallback.
+ */
+ protected void exportTableWithJdbc(
+ final String tableName,
+ final String outputPath
+ )
+ {
+ retryWithHandle(
+ (HandleCallback<Void>) handle -> {
+ try (Statement stmt = handle.getConnection().createStatement();
Review Comment:
Confirmed: `retryTransaction` gives PostgreSQL an auto-commit-disabled
connection, and `getStreamingFetchSize()` is applied before query execution,
enabling cursor-based fetching. Reviewed 8 of 8 changed files.
##########
services/src/main/java/org/apache/druid/cli/ExportMetadata.java:
##########
@@ -245,12 +245,18 @@ private void exportTable(
} else {
pathFormatString = "%s/%s.csv";
}
+ final String exportTableName = isDerby() ?
StringUtils.toUpperCase(tableName) : tableName;
dbConnector.exportTable(
- StringUtils.toUpperCase(tableName),
+ exportTableName,
Review Comment:
Thanks; the rewrite now preserves trailing values, but the documented
PostgreSQL `COPY druid_segments(...)` command still names only the original
nine columns. Current exports contain 12–14 fields, so `COPY` fails with extra
data; upgraded source tables can also have added columns in a different
physical order. Please export segments in an explicit stable column order and
update the import column lists accordingly. Reviewed 8 of 8 changed files.
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