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feat: -b bulk copy into Postgres dest via COPY FROM STDIN

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Extends -b to Postgres destinations: stream the source ResultSet into PG with
COPY <dt> FROM STDIN (FORMAT csv) via the JDBC CopyManager, instead of batched
INSERTs. COPY is text-based so the server parses each field into the column
type — no per-type quoting needed. Every non-null value is CSV-quoted (so
empty string stays distinct from NULL, which is an empty unquoted field);
rows are flushed in 1000-row buffers with a 10k-row progress counter.

Validated DB2->PG: numeric precision (123.4567), jsonb, unicode, embedded
quotes, NULL vs empty-string all correct.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This commit is contained in:
Paul Trowbridge 2026-06-18 23:04:59 -04:00
parent a61e018932
commit 6fe2bea089
1 changed files with 45 additions and 0 deletions
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45
jrunner/src/main/java/jrunner/jrunner.java
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@ -10,6 +10,9 @@ import com.microsoft.sqlserver.jdbc.SQLServerBulkCopy;
import com.microsoft.sqlserver.jdbc.SQLServerBulkCopyOptions;
import com.microsoft.sqlserver.jdbc.ISQLServerBulkData;
import com.microsoft.sqlserver.jdbc.SQLServerException;
import org.postgresql.PGConnection;
import org.postgresql.copy.CopyManager;
import org.postgresql.copy.CopyIn;
public class jrunner {
//static final String QUERY = "SELECT * from rlarp.osm LIMIT 100";
@ -333,6 +336,48 @@ public class jrunner {
e.printStackTrace();
System.exit(0);
}
} else if (bulk && dcu.toLowerCase().startsWith("jdbc:postgresql:")) {
//-------------------------------bulk copy (COPY, Postgres dest)--------------------------------------------
// Stream the source ResultSet into Postgres via COPY ... FROM STDIN.
// COPY is text-based: each field is sent as CSV text and the server
// parses it into the column type, so there's no per-type quoting.
// Non-null values are always CSV-quoted; NULL is an empty unquoted
// field; column order must match the dest (positional, as always).
System.out.println("------------bulk copy (COPY)------------------------------");
try {
CopyManager cm = ((PGConnection) dcon).getCopyAPI();
CopyIn cin = cm.copyIn("COPY " + dt + " FROM STDIN WITH (FORMAT csv)");
StringBuilder buf = new StringBuilder();
long rows = 0;
while (rs.next()) {
for (int i = 1; i <= cols; i++) {
if (i > 1) { buf.append(','); }
String val = rs.getString(i);
if (!rs.wasNull() && val != null) {
if (trim) { val = val.trim(); }
buf.append('"').append(val.replace("\"", "\"\"")).append('"');
}
// else: empty field -> NULL
}
buf.append('\n');
rows++;
if (rows % 1000 == 0) {
byte[] b = buf.toString().getBytes(java.nio.charset.StandardCharsets.UTF_8);
cin.writeToCopy(b, 0, b.length);
buf.setLength(0);
if (rows % 10000 == 0) { System.out.print("\r" + rows); System.out.flush(); }
}
}
if (buf.length() > 0) {
byte[] b = buf.toString().getBytes(java.nio.charset.StandardCharsets.UTF_8);
cin.writeToCopy(b, 0, b.length);
}
cin.endCopy();
System.out.print("\r" + rows);
} catch (Exception e) {
e.printStackTrace();
System.exit(0);
}
} else {
System.out.println("------------row count-------------------------------------");
//-------------------------------build & execute sql-------------------------------------------------------------