feat: add spread merged cells

src/extension/analyze_sheet.rs

@@ -11,6 +11,7 @@ use crate::extension::Param;
 use crate::extension::Range;
 use crate::extension::RangeParam;
 use crate::extension::SheetParam;
+use crate::extension::SpreadMergedCellsParam;
 use crate::spreadsheet::criteria::Criteria;
 use crate::spreadsheet::open_spreadsheet;
 use duckdb::core::DataChunkHandle;
@@ -42,6 +43,8 @@ struct AnalyzeSheetParameters {
     nulls: Option<HashSet<String>>,
     /// Whether to convert errors to null values (default: false)
     error_as_null: Option<bool>,
+    /// Whether to spread merged cells across merged ranges (default: false)
+    spread_merged_cells: Option<bool>,
 }
 
 impl TryFrom<&BindInfo> for AnalyzeSheetParameters {
@@ -57,6 +60,7 @@ impl TryFrom<&BindInfo> for AnalyzeSheetParameters {
             analyze_rows: AnalyzeRowsParam::read(bind)?,
             nulls: NullsParam::read(bind)?,
             error_as_null: ErrorAsNullParam::read(bind)?,
+            spread_merged_cells: SpreadMergedCellsParam::read(bind)?
         })
     }
 }
@@ -89,6 +93,7 @@ impl TryFrom<&AnalyzeSheetParameters> for AnalyzeSheetBindData {
             error_as_null: parameters.error_as_null.unwrap_or(false),
             skip_empty_rows: false,
             end_at_empty_row: false,
+            spread_merged_cells: parameters.spread_merged_cells.unwrap_or(false),
         }, &Vec::new())? {
             for column in &table.columns {
                 columns.push((

src/extension/analyze_sheets.rs

@@ -10,6 +10,7 @@ use crate::extension::Param;
 use crate::extension::Range;
 use crate::extension::RangeParam;
 use crate::extension::SheetsParam;
+use crate::extension::SpreadMergedCellsParam;
 use crate::spreadsheet::criteria::Criteria;
 use crate::spreadsheet::open_spreadsheet;
 use duckdb::core::DataChunkHandle;
@@ -42,6 +43,8 @@ struct AnalyzeSheetsParameters {
     nulls: Option<HashSet<String>>,
     /// Whether to convert errors to null values (default: false)
     error_as_null: Option<bool>,
+    /// Whether to spread merged cells across merged ranges (default: false)
+    spread_merged_cells: Option<bool>,
 }
 
 impl TryFrom<&BindInfo> for AnalyzeSheetsParameters {
@@ -63,6 +66,7 @@ impl TryFrom<&BindInfo> for AnalyzeSheetsParameters {
             analyze_rows: AnalyzeRowsParam::read(bind)?,
             nulls: NullsParam::read(bind)?,
             error_as_null: ErrorAsNullParam::read(bind)?,
+            spread_merged_cells: SpreadMergedCellsParam::read(bind)?
         })
     }
 }
@@ -114,6 +118,7 @@ impl TryFrom<&AnalyzeSheetsParameters> for AnalyzeSheetsBindData {
                 error_as_null: parameters.error_as_null.unwrap_or(false),
                 skip_empty_rows: false,
                 end_at_empty_row: false,
+                spread_merged_cells: parameters.spread_merged_cells.unwrap_or(false),
             }, &Vec::new()).with_prefix(spreadsheet.name().as_str())? {
                 for column in &table.columns {
                     columns.push((

src/extension/mod.rs

@@ -86,6 +86,7 @@ struct NullsParam;
 struct ErrorAsNullParam;
 struct SkipEmptyRowsParam;
 struct EndAtEmptyRowParam;
+struct SpreadMergedCellsParam;
 struct FileNameColumnParam;
 struct SheetNameColumnParam;
 
@@ -316,6 +317,21 @@ impl NamedParam<bool> for EndAtEmptyRowParam {
     }
 }
 
+/// Parameter handler for spreading data from merged cells across merged ranges.
+impl NamedParam<bool> for SpreadMergedCellsParam {
+    fn name() -> &'static str {
+        "spread_merged_cells"
+    }
+
+    fn kind() -> LogicalTypeHandle {
+        LogicalTypeHandle::from(LogicalTypeId::Boolean)
+    }
+
+    fn cast(value: Value) -> Result<bool, RustySheetError> {
+        Ok(value.to_bool())
+    }
+}
+
 impl NamedParam<String> for FileNameColumnParam {
     fn name() -> &'static str {
         "file_name_column"

src/extension/read_sheet.rs

@@ -3,6 +3,7 @@ use crate::database::column::Column;
 use crate::database::column::ColumnType;
 use crate::error::ResultMessage;
 use crate::error::RustySheetError;
+use crate::extension::SpreadMergedCellsParam;
 use crate::extension::writer::write_to_vector;
 use crate::extension::AnalyzeRowsParam;
 use crate::extension::ColumnsParam;
@@ -62,6 +63,8 @@ struct ReadSheetParameters {
     file_name_column: Option<String>,
     /// column name for sheet name of record
     sheet_name_column: Option<String>,
+    /// Whether to spread merged cells across merged ranges (default: false)
+    spread_merged_cells: Option<bool>,
 }
 
 impl TryFrom<&BindInfo> for ReadSheetParameters {
@@ -83,6 +86,7 @@ impl TryFrom<&BindInfo> for ReadSheetParameters {
             end_at_empty_row: EndAtEmptyRowParam::read(bind)?,
             file_name_column: FileNameColumnParam::read(bind)?,
             sheet_name_column: SheetNameColumnParam::read(bind)?,
+            spread_merged_cells: SpreadMergedCellsParam::read(bind)?,
         })
     }
 }
@@ -101,6 +105,8 @@ pub(crate) struct ReadSheetBindData {
     sheets: Vec<Sheet>,
     /// Shared string table for efficient string storage (XLSX/XLSB format)
     shared_strings: Vec<Option<String>>,
+    /// Whether to spread merged cells across merged ranges (default: false)
+    spread_merged_cells: bool,
 }
 
 impl TryFrom<&ReadSheetParameters> for ReadSheetBindData {
@@ -122,7 +128,7 @@ impl TryFrom<&ReadSheetParameters> for ReadSheetBindData {
         let error_as_null = parameters.error_as_null.unwrap_or(false);
         let skip_empty_rows = parameters.skip_empty_rows.unwrap_or(false);
         let end_at_empty_row = parameters.end_at_empty_row.unwrap_or(false);
-
+        let spread_merged_cells = parameters.spread_merged_cells.unwrap_or(false);
         // Analyze the sheet structure to determine column types and bounds
         let tables = spreadsheet.analyze_sheets(header, &Criteria {
             sheet_name_patterns: sheet_name_pattern.to_owned(),
@@ -133,6 +139,7 @@ impl TryFrom<&ReadSheetParameters> for ReadSheetBindData {
             error_as_null,
             skip_empty_rows,
             end_at_empty_row,
+            spread_merged_cells,
         }, parameters.columns.as_ref().unwrap_or(&vec![]))?;
 
         // Extract the first matching sheet or return error if no match found
@@ -171,6 +178,7 @@ impl TryFrom<&ReadSheetParameters> for ReadSheetBindData {
             error_as_null,
             skip_empty_rows,
             end_at_empty_row,
+            spread_merged_cells,
         })?;
 
         let shared_strings = shared_strings
@@ -189,6 +197,7 @@ impl TryFrom<&ReadSheetParameters> for ReadSheetBindData {
             sheet_name_column,
             sheets,
             shared_strings,
+            spread_merged_cells,
         })
     }
 }
@@ -303,6 +312,7 @@ impl VTab for ReadSheetTableFunction {
             ErrorAsNullParam::definition(),
             SkipEmptyRowsParam::definition(),
             EndAtEmptyRowParam::definition(),
+            SpreadMergedCellsParam::definition(),
             FileNameColumnParam::definition(),
             SheetNameColumnParam::definition(),
         ])

src/extension/read_sheets.rs

@@ -3,6 +3,7 @@ use crate::database::column::ColumnType;
 use crate::database::table::Table;
 use crate::error::ResultMessage;
 use crate::error::RustySheetError;
+use crate::extension::SpreadMergedCellsParam;
 use crate::extension::writer::write_to_vector;
 use crate::extension::AnalyzeRowsParam;
 use crate::extension::ColumnsParam;
@@ -67,6 +68,8 @@ struct ReadSheetsParameters {
     file_name_column: Option<String>,
     /// column name for sheet name of record
     sheet_name_column: Option<String>,
+    /// Whether to spread merged cells across merged ranges (default: false)
+    spread_merged_cells: Option<bool>,
 }
 
 impl TryFrom<&BindInfo> for ReadSheetsParameters {
@@ -94,6 +97,7 @@ impl TryFrom<&BindInfo> for ReadSheetsParameters {
             end_at_empty_row: EndAtEmptyRowParam::read(bind)?,
             file_name_column: FileNameColumnParam::read(bind)?,
             sheet_name_column: SheetNameColumnParam::read(bind)?,
+            spread_merged_cells: SpreadMergedCellsParam::read(bind)?,
         })
     }
 }
@@ -109,6 +113,8 @@ pub(crate) struct ReadSheetsBindData {
     file_name_column: Option<usize>,
     /// sheet name column index
     sheet_name_column: Option<usize>,
+    /// Whether to spread merged cells across merged ranges (default: false)
+    spread_merged_cells: bool,
 }
 
 impl TryFrom<&ReadSheetsParameters> for ReadSheetsBindData {
@@ -137,7 +143,7 @@ impl TryFrom<&ReadSheetsParameters> for ReadSheetsBindData {
         let rows_limit = parameters.analyze_rows.or(Some(10));
         let default_preset_columns = vec![];
         let preset = parameters.columns.as_ref().unwrap_or(&default_preset_columns);
-
+        let spread_merged_cells = parameters.spread_merged_cells.unwrap_or(false);
         let mut spreadsheets = Vec::new();
         let mut shared_tables = None::<Vec<Table>>;
         let mut columns = Vec::<Column>::new();
@@ -152,6 +158,7 @@ impl TryFrom<&ReadSheetsParameters> for ReadSheetsBindData {
                 error_as_null,
                 skip_empty_rows,
                 end_at_empty_row,
+                spread_merged_cells: false,
             }, preset)?;
             if tables.is_empty() {
                 continue
@@ -209,6 +216,7 @@ impl TryFrom<&ReadSheetsParameters> for ReadSheetsBindData {
                     error_as_null,
                     skip_empty_rows,
                     end_at_empty_row,
+                    spread_merged_cells: false,
                 }).with_prefix(table.name.as_str()).with_prefix(spreadsheet.name().as_str())?;
                 assert_eq!(actual_sheets.len(), 1);
                 sheets.extend(actual_sheets);
@@ -254,6 +262,7 @@ impl TryFrom<&ReadSheetsParameters> for ReadSheetsBindData {
             columns,
             file_name_column,
             sheet_name_column,
+            spread_merged_cells,
         })
     }
 }
@@ -405,6 +414,7 @@ impl VTab for ReadSheetsTableFunction {
             EndAtEmptyRowParam::definition(),
             FileNameColumnParam::definition(),
             SheetNameColumnParam::definition(),
+            SpreadMergedCellsParam::definition(),
         ])
     }
 }

src/spreadsheet/criteria.rs

@@ -28,6 +28,9 @@ pub(crate) struct Criteria {
 
     /// Stop reading when encountering a completely empty row.
     pub(crate) end_at_empty_row: bool,
+
+    /// Spread data from merged cells across all cells in the merged range.
+    pub(crate) spread_merged_cells: bool,
 }
 
 impl Criteria {

src/spreadsheet/sheet.rs

@@ -155,7 +155,13 @@ impl Sheet {
         if self.col_upper_bound.map(|col_upper_bound| col_upper_bound < col).unwrap_or(true) {
             self.col_upper_bound = Some(col);
         }
-        self.row_upper_bound = Some(row);
+        // Update row_upper_bound to the maximum row seen
+        // Optimize for common case: if row_upper_bound is None or row >= current max, update directly
+        match self.row_upper_bound {
+            None => self.row_upper_bound = Some(row),
+            Some(current_max) if row > current_max => self.row_upper_bound = Some(row),
+            _ => {} // row <= current_max, no update needed
+        }
     }
 
     /// Finalizes chunk creation after all cells have been added.