docs: -b now covers Postgres (COPY) as well as SQL Server

Update readme + CLAUDE: -b is no longer SQL-Server-only. Describe the Postgres
COPY FROM STDIN path (CopyManager, text-based, CSV-quoted, empty vs NULL) next
to the existing SQL Server SQLServerBulkCopy path; DB2 still falls back to INSERT.

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

CLAUDE.md

@@ -61,17 +61,26 @@ The tool operates in two modes:
 - 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.
+**Bulk Copy** (migration mode, `-b`) — uses the dest's native bulk path; falls
+back to the INSERT path for any other dest (e.g. DB2):
+
+*SQL Server dest* — streams the source ResultSet over the TDS bulk-load
+protocol via `SQLServerBulkCopy` (no per-batch INSERT round trips; 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).
+
+*Postgres dest* — streams via `COPY <table> FROM STDIN WITH (FORMAT csv)` using
+the JDBC `CopyManager`. COPY is text-based, so the server parses each field into
+the column type — no per-type handling. Every non-null value is CSV-quoted
+(empty string stays distinct from NULL, which is an empty unquoted field); rows
+flush in 1000-row buffers.
+
+Both emit a `\r`-counter every 10k rows for live progress and print the final
+row count.
 
 ### Data Flow
 
@@ -89,9 +98,9 @@ The tool operates in two modes:
 3. Connect to source and destination databases via JDBC
 4. Execute source query and fetch results (fetch size: 10,000 rows)
 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
+6. With `-b`: bulk-load via the dest's native path (SQL Server → `SQLServerBulkCopy`,
+   Postgres → `COPY FROM STDIN`). Otherwise: build batched INSERT statements
+   (250 rows per batch) and execute them against the destination table (-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.
@@ -122,7 +131,7 @@ 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)
+- `-b` - bulk load into dest (migration mode): SQL Server via SQLServerBulkCopy, Postgres via COPY
 - `-f` - output format: csv, tsv (query mode only, default: csv)
 
 ## Key Implementation Details

readme.md

@@ -187,7 +187,8 @@ 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)
+- `-b` - bulk load into the destination instead of batched INSERTs — far faster
+  on large/wide tables. SQL Server: TDS bulk-load via SQLServerBulkCopy.
+  Postgres: COPY FROM STDIN. Other dests (e.g. DB2) fall back to INSERT.
+  (migration mode only)
 - `-f` - output format: csv, tsv (query mode only, default: csv)