docs: document the -b bulk copy path (readme + CLAUDE)

Add the -b flag to the readme/CLAUDE flag lists and describe the bulk copy
migration sub-mode: SQLServerBulkCopy via the BulkSource adapter (SQL Server
dest only), why numeric/string-ish types route through NVARCHAR, the ~111min
-> ~4min win, and the 10k-row live progress counter.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

CLAUDE.md

@@ -58,9 +58,21 @@ The tool operates in two modes:
 
 **Migration Mode** (original functionality):
 - Activates when destination flags are provided
-- Reads from source, writes to destination with batched INSERTs
+- Reads from source, writes to destination with batched INSERTs (or bulk copy with `-b`)
 - Shows progress counters and timing information
 
+**Bulk Copy** (migration mode, `-b`, SQL Server dest only):
+- Streams the source ResultSet into SQL Server over the TDS bulk-load protocol
+  via `SQLServerBulkCopy` — no per-batch INSERT round trips. Far faster on
+  large/wide tables (a 1.27M-row, ~298-col load went ~111 min → ~4 min).
+- A `BulkSource` adapter (`ISQLServerBulkData`) maps source type names to JDBC
+  types we control. String-ish types (text/varchar/char/bpchar/json/jsonb/uuid
+  **and numeric**) are declared NVARCHAR and read via `getString` so SQL Server
+  converts losslessly — numeric goes this route because PG reports unconstrained
+  numeric as scale 0, which a typed DECIMAL path would round (123.45 → 123).
+- Emits a `\r`-counter every 10k rows for live progress, and prints the final
+  row count. Falls back to the INSERT path for non-SQL-Server dests.
+
 ### Data Flow
 
 **Query Mode:**
@@ -76,9 +88,10 @@ The tool operates in two modes:
 2. Read SQL query from file specified by -sq flag
 3. Connect to source and destination databases via JDBC
 4. Execute source query and fetch results (fetch size: 10,000 rows)
-5. Build batched INSERT statements (250 rows per batch)
-6. Execute batches against destination table specified by -dt flag
-7. Optionally clear target table before insert if -c flag is set
+5. Optionally clear target table before insert if -c flag is set
+6. With `-b` (SQL Server dest): bulk-copy the ResultSet via `SQLServerBulkCopy`.
+   Otherwise: build batched INSERT statements (250 rows per batch) and execute
+   them against the destination table specified by -dt
 
 ### Type Handling
 The tool includes explicit handling for different SQL data types in a switch statement (migration mode). Quoted string types: VARCHAR/NVARCHAR, TEXT/NTEXT, CHAR/NCHAR, CLOB/NCLOB, and the PostgreSQL string-ish types JSON, JSONB, BPCHAR (PG `char(n)`), and UUID. Date/time types (DATE, TIME, TIMESTAMP/DATETIME variants) are also quoted. String types get quote escaping (`'` → `''`) and optional trimming.
@@ -109,6 +122,7 @@ Command-line flags:
 - `-dt` - fully qualified destination table name (migration mode only)
 - `-t` - trim text fields (default: true)
 - `-c` - clear target table before insert (default: true, migration mode only)
+- `-b` - bulk copy into dest via SQLServerBulkCopy (migration mode, SQL Server dest only)
 - `-f` - output format: csv, tsv (query mode only, default: csv)
 
 ## Key Implementation Details

readme.md

@@ -187,4 +187,7 @@ jrunner -scu jdbc:postgresql://source:5432/sourcedb \
 **Options:**
 - `-t` - trim text fields (default: true)
 - `-c` - clear target table before insert (default: true)
+- `-b` - bulk copy into the destination (SQL Server dest only); streams via the
+  TDS bulk-load protocol instead of batched INSERTs — far faster on large/wide
+  tables. No-op for non-SQL-Server dests. (migration mode only)
 - `-f` - output format: csv, tsv (query mode only, default: csv)