feat: generate reversed-name data for sort pushdown benchmark

Use tpchgen --parts=3 to create 3 sorted non-overlapping parquet files,
then rename so alphabetical order is reversed vs key order:
  a_part3.parquet (highest keys, sorts first alphabetically)
  b_part2.parquet
  c_part1.parquet (lowest keys, sorts last alphabetically)

This is much simpler than the previous approach (no datafusion-cli needed).

Release benchmark results (6M rows, single partition):
  Q1 ORDER BY ASC:      main 259ms → PR 122ms (53% faster)
  Q3 SELECT * ORDER BY: main 700ms → PR 353ms (50% faster)

Author: zhuqi-lucas

benchmarks/bench.sh

@@ -314,8 +314,7 @@ main() {
                     data_tpch "1" "parquet"
                     ;;
                 sort_pushdown|sort_pushdown_sorted)
-                    # same data as for tpch
-                    data_tpch "1" "parquet"
+                    data_sort_pushdown
                     ;;
                 sort_tpch)
                     # same data as for tpch
@@ -1085,19 +1084,57 @@ run_external_aggr() {
 }
 
 # Runs the sort pushdown benchmark (without WITH ORDER)
+# Generates sort pushdown benchmark data: TPC-H lineitem with 3 parts,
+# renamed so alphabetical order does NOT match sort key order.
+# This forces the sort pushdown optimizer to reorder files by statistics.
+#
+# tpchgen produces 3 sorted, non-overlapping parquet files:
+#   lineitem.1.parquet: l_orderkey 1 ~ 2M        (lowest keys)
+#   lineitem.2.parquet: l_orderkey 2M ~ 4M
+#   lineitem.3.parquet: l_orderkey 4M ~ 6M       (highest keys)
+#
+# We rename them so alphabetical order is reversed:
+#   a_part3.parquet (highest keys, sorts first alphabetically)
+#   b_part2.parquet
+#   c_part1.parquet (lowest keys, sorts last alphabetically)
+data_sort_pushdown() {
+    SORT_PUSHDOWN_DIR="${DATA_DIR}/sort_pushdown/lineitem"
+    if [ -d "${SORT_PUSHDOWN_DIR}" ] && [ "$(ls -A ${SORT_PUSHDOWN_DIR}/*.parquet 2>/dev/null)" ]; then
+        echo "Sort pushdown data already exists at ${SORT_PUSHDOWN_DIR}"
+        return
+    fi
+
+    echo "Generating sort pushdown benchmark data (3 parts with reversed naming)..."
+
+    TEMP_DIR="${DATA_DIR}/sort_pushdown_temp"
+    mkdir -p "${TEMP_DIR}" "${SORT_PUSHDOWN_DIR}"
+
+    tpchgen-cli --scale-factor 1 --format parquet --parquet-compression='ZSTD(1)' --parts=3 --output-dir "${TEMP_DIR}"
+
+    # Rename: reverse alphabetical order vs key order
+    mv "${TEMP_DIR}/lineitem/lineitem.3.parquet" "${SORT_PUSHDOWN_DIR}/a_part3.parquet"
+    mv "${TEMP_DIR}/lineitem/lineitem.2.parquet" "${SORT_PUSHDOWN_DIR}/b_part2.parquet"
+    mv "${TEMP_DIR}/lineitem/lineitem.1.parquet" "${SORT_PUSHDOWN_DIR}/c_part1.parquet"
+
+    rm -rf "${TEMP_DIR}"
+
+    echo "Sort pushdown data generated at ${SORT_PUSHDOWN_DIR}"
+    ls -la "${SORT_PUSHDOWN_DIR}"
+}
+
 run_sort_pushdown() {
-    TPCH_DIR="${DATA_DIR}/tpch_sf1"
+    SORT_PUSHDOWN_DIR="${DATA_DIR}/sort_pushdown"
     RESULTS_FILE="${RESULTS_DIR}/sort_pushdown.json"
     echo "Running sort pushdown benchmark (no WITH ORDER)..."
-    debug_run $CARGO_COMMAND --bin dfbench -- sort-pushdown --iterations 5 --path "${TPCH_DIR}" -o "${RESULTS_FILE}" ${QUERY_ARG} ${LATENCY_ARG}
+    debug_run $CARGO_COMMAND --bin dfbench -- sort-pushdown --iterations 5 --path "${SORT_PUSHDOWN_DIR}" --queries-path "${SCRIPT_DIR}/queries/sort_pushdown" -o "${RESULTS_FILE}" ${QUERY_ARG} ${LATENCY_ARG}
 }
 
 # Runs the sort pushdown benchmark with WITH ORDER (enables sort elimination)
 run_sort_pushdown_sorted() {
-    TPCH_DIR="${DATA_DIR}/tpch_sf1"
+    SORT_PUSHDOWN_DIR="${DATA_DIR}/sort_pushdown"
     RESULTS_FILE="${RESULTS_DIR}/sort_pushdown_sorted.json"
     echo "Running sort pushdown benchmark (with WITH ORDER)..."
-    debug_run $CARGO_COMMAND --bin dfbench -- sort-pushdown --sorted --iterations 5 --path "${TPCH_DIR}" -o "${RESULTS_FILE}" ${QUERY_ARG} ${LATENCY_ARG}
+    debug_run $CARGO_COMMAND --bin dfbench -- sort-pushdown --sorted --iterations 5 --path "${SORT_PUSHDOWN_DIR}" --queries-path "${SCRIPT_DIR}/queries/sort_pushdown" -o "${RESULTS_FILE}" ${QUERY_ARG} ${LATENCY_ARG}
 }
 
 # Runs the sort integration benchmark