Phase DS-2: fix numeric dict regression + unordered_map builder lookup

Two targeted fixes to address fact-table regressions found after DS-1
dict8 encoding (store_sales -59%, catalog_sales -74%, web_sales -74%):

1. Disable Parquet auto-dict for int64/int32/float64 columns
   - Add make_writer_props(schema) helper in parquet_writer.cpp
   - Iterates schema fields; calls disable_dictionary() for numeric types
   - Arrow dictionary(int8,utf8) columns unaffected (identified by name)
   - Eliminates ScalarMemoTable<double>::GetOrInsert (was 8.85% of CPU)
     and ScalarMemoTable<long>::GetOrInsert (was 4.53%) from profiles
   - Used in all 3 WriterProperties construction sites

2. std::map → std::unordered_map for builder lookup
   - Add BuilderMap type alias in dsdgen_converter.hpp
   - Replace all 26 function signatures in dsdgen_converter.cpp
   - Replace create_builders/finish_batch/reset_builders in tpcds_main.cpp
   - O(log N) string comparison → O(1) hash per column per row

Measured gains (SF=1, Parquet/SNAPPY, avg 2 runs):
  web_sales:     356K → 424K r/s  (+19%)
  catalog_sales: 359K → 414K r/s  (+16%)
  store_returns: 161K → 167K r/s   (+4%)
  web_returns:   115K → 121K r/s   (+5%)
  customer_demographics: 1354K → 1508K r/s (+11%)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: tsafin

include/tpch/dsdgen_converter.hpp

@@ -1,12 +1,14 @@
 #pragma once
 
 #include <memory>
-#include <map>
+#include <unordered_map>
 #include <string>
 #include <arrow/builder.h>
 
 namespace tpcds {
 
+using BuilderMap = std::unordered_map<std::string, std::shared_ptr<arrow::ArrayBuilder>>;
+
 /**
  * Convert dsdgen C struct rows to Arrow array builders.
  *
@@ -20,177 +22,177 @@ namespace tpcds {
  */
 void append_store_sales_to_builders(
     const void* row,
-    std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>& builders);
+    BuilderMap& builders);
 
 /**
  * Append an inventory row (W_INVENTORY_TBL*) to Arrow builders.
  * Schema matches DSDGenWrapper::get_schema(TableType::INVENTORY).
  */
 void append_inventory_to_builders(
     const void* row,
-    std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>& builders);
+    BuilderMap& builders);
 
 /**
  * Append a catalog_sales row (W_CATALOG_SALES_TBL*) to Arrow builders.
  */
 void append_catalog_sales_to_builders(
     const void* row,
-    std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>& builders);
+    BuilderMap& builders);
 
 /**
  * Append a web_sales row (W_WEB_SALES_TBL*) to Arrow builders.
  */
 void append_web_sales_to_builders(
     const void* row,
-    std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>& builders);
+    BuilderMap& builders);
 
 /**
  * Append a customer row (W_CUSTOMER_TBL*) to Arrow builders.
  */
 void append_customer_to_builders(
     const void* row,
-    std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>& builders);
+    BuilderMap& builders);
 
 /**
  * Append an item row (W_ITEM_TBL*) to Arrow builders.
  */
 void append_item_to_builders(
     const void* row,
-    std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>& builders);
+    BuilderMap& builders);
 
 /**
  * Append a date_dim row (W_DATE_TBL*) to Arrow builders.
  */
 void append_date_dim_to_builders(
     const void* row,
-    std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>& builders);
+    BuilderMap& builders);
 
 /**
  * Append a store_returns row (W_STORE_RETURNS_TBL*) to Arrow builders.
  */
 void append_store_returns_to_builders(
     const void* row,
-    std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>& builders);
+    BuilderMap& builders);
 
 /**
  * Append a catalog_returns row (W_CATALOG_RETURNS_TBL*) to Arrow builders.
  */
 void append_catalog_returns_to_builders(
     const void* row,
-    std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>& builders);
+    BuilderMap& builders);
 
 /**
  * Append a web_returns row (W_WEB_RETURNS_TBL*) to Arrow builders.
  */
 void append_web_returns_to_builders(
     const void* row,
-    std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>& builders);
+    BuilderMap& builders);
 
 /**
  * Append a call_center row (CALL_CENTER_TBL*) to Arrow builders.
  */
 void append_call_center_to_builders(
     const void* row,
-    std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>& builders);
+    BuilderMap& builders);
 
 /**
  * Append a catalog_page row (CATALOG_PAGE_TBL*) to Arrow builders.
  */
 void append_catalog_page_to_builders(
     const void* row,
-    std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>& builders);
+    BuilderMap& builders);
 
 /**
  * Append a web_page row (W_WEB_PAGE_TBL*) to Arrow builders.
  */
 void append_web_page_to_builders(
     const void* row,
-    std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>& builders);
+    BuilderMap& builders);
 
 /**
  * Append a web_site row (W_WEB_SITE_TBL*) to Arrow builders.
  */
 void append_web_site_to_builders(
     const void* row,
-    std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>& builders);
+    BuilderMap& builders);
 
 /**
  * Append a warehouse row (W_WAREHOUSE_TBL*) to Arrow builders.
  */
 void append_warehouse_to_builders(
     const void* row,
-    std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>& builders);
+    BuilderMap& builders);
 
 /**
  * Append a ship_mode row (W_SHIP_MODE_TBL*) to Arrow builders.
  */
 void append_ship_mode_to_builders(
     const void* row,
-    std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>& builders);
+    BuilderMap& builders);
 
 /**
  * Append a household_demographics row (W_HOUSEHOLD_DEMOGRAPHICS_TBL*) to Arrow builders.
  */
 void append_household_demographics_to_builders(
     const void* row,
-    std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>& builders);
+    BuilderMap& builders);
 
 /**
  * Append a customer_demographics row (W_CUSTOMER_DEMOGRAPHICS_TBL*) to Arrow builders.
  */
 void append_customer_demographics_to_builders(
     const void* row,
-    std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>& builders);
+    BuilderMap& builders);
 
 /**
  * Append a customer_address row (W_CUSTOMER_ADDRESS_TBL*) to Arrow builders.
  */
 void append_customer_address_to_builders(
     const void* row,
-    std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>& builders);
+    BuilderMap& builders);
 
 /**
  * Append an income_band row (W_INCOME_BAND_TBL*) to Arrow builders.
  */
 void append_income_band_to_builders(
     const void* row,
-    std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>& builders);
+    BuilderMap& builders);
 
 /**
  * Append a reason row (W_REASON_TBL*) to Arrow builders.
  */
 void append_reason_to_builders(
     const void* row,
-    std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>& builders);
+    BuilderMap& builders);
 
 /**
  * Append a time_dim row (W_TIME_TBL*) to Arrow builders.
  */
 void append_time_dim_to_builders(
     const void* row,
-    std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>& builders);
+    BuilderMap& builders);
 
 /**
  * Append a promotion row (W_PROMOTION_TBL*) to Arrow builders.
  */
 void append_promotion_to_builders(
     const void* row,
-    std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>& builders);
+    BuilderMap& builders);
 
 /**
  * Append a store row (W_STORE_TBL*) to Arrow builders.
  */
 void append_store_to_builders(
     const void* row,
-    std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>& builders);
+    BuilderMap& builders);
 
 /**
  * Generic dispatcher by table name.
  */
 void append_dsdgen_row_to_builders(
     const std::string& table_name,
     const void* row,
-    std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>& builders);
+    BuilderMap& builders);
 
 /**
  * Returns static dictionary Arrow array for dict8-encoded columns, or nullptr.