xlfilldown

Stream an Excel sheet into SQLite or a new Excel sheet in constant memory. Forward-fill selected columns by header name, preserve original Excel row numbers, and compute a stable SHA-256 row hash.

• Ingests only columns with non-empty headers (from --header-row).
• Stores all non-empty values as TEXT strings (numbers/dates canonicalized to stable text; strings are stripped; whitespace-only cells become NULL).
• Optional excel_row and row_hash columns.
• Streams rows; suitable for large sheets.

---

Install

From PyPI (recommended)

pip install xlfilldown
# or
pipx install xlfilldown

Python ≥ 3.9. Depends on openpyxl.

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CLI

xlfilldown has two subcommands that share the same input options and differ only in the output destination:

• db → write to SQLite
• xlsx → write to Excel

Common input options

• --infile (required): Path to input .xlsx file.

• --insheet (required): Sheet name to read.

• --header-row (required, 1-based): Row number containing the headers.

• --fill-cols: JSON array of header names to forward-fill. Example: '["columnname1","columnname2","anothercolumn,3"]'.

• --fill-cols-letters: Alternative to --fill-cols. Provide Excel column letters (A B C AE etc.). These are resolved to header names using --header-row. If a referenced column’s header cell is empty (None, whitespace, or “nan”), the command errors. Mutually exclusive with --fill-cols.

• --fill-mode (default: hierarchical): Fill strategy.

  • hierarchical → Higher-tier column changes reset lower-tier carries.
  • independent → Pandas-style ffill, each listed column carries independently.

• --drop-blank-rows: Drop rows where all fill columns are empty after filling (treat as spacer rows).

• --require-non-null: JSON array of headers; drop the row if any are null/blank after fill.

• --require-non-null-letters: Excel column letters; resolved to headers and merged with --require-non-null.

• --row-hash: Include a row_hash column. In DB mode this also creates a non-unique index on row_hash.

• --excel-row-numbers: Include original Excel row numbers in column excel_row (1-based).

• --if-exists (default: fail): fail | replace | append.

Header matching: After normalization (trim; case preserved; 'nan' → blank), names must match exactly.

---

db subcommand (SQLite output)

Additional options:

• --db (required): SQLite database file (created if missing).
• --table: SQLite table name (default: derived from input sheet name).
• --batch-size (default: 1000): Rows per executemany() batch.

Create/append semantics

• Table columns are: [row_hash?] [excel_row?] + headers… (all TEXT, including excel_row).
• If --if-exists append, the existing table schema must exactly match the expected column order.
• Helpful indexes are created automatically when enabled: excel_row and row_hash.

Examples

By header names:

xlfilldown db \
  --infile data.xlsx \
  --insheet "Sheet1" \
  --header-row 1 \
  --fill-cols '["columnname1","columnname2","anothercolumn,3"]' \
  --db out.db

By column letters:

xlfilldown db \
  --infile data.xlsx \
  --insheet "Sheet1" \
  --header-row 1 \
  --fill-cols-letters A C AE \
  --db out.db

---

xlsx subcommand (Excel output)

Additional options:

• --outfile (required): Output .xlsx file.
• --outsheet: Output sheet name (default: derived from input sheet name).

Sheet-level --if-exists

• fail: error if target sheet exists.
• replace: recreate target sheet fresh.
• append: append below existing rows; the destination header row must match the expected header list (including excel_row and/or row_hash if enabled).

Examples

By header names:

xlfilldown xlsx \
  --infile data.xlsx \
  --insheet "Sheet1" \
  --header-row 1 \
  --fill-cols '["columnname1","columnname2","anothercolumn,3"]' \
  --outfile out.xlsx \
  --outsheet Processed

By column letters:

xlfilldown xlsx \
  --infile data.xlsx \
  --insheet "Sheet1" \
  --header-row 1 \
  --fill-cols-letters A D \
  --outfile out.xlsx \
  --outsheet Processed

---

Behavior details

Headers

• Only columns with non-empty header cells on --header-row are ingested.
• Empty or duplicate headers after normalization are rejected.

Forward-fill (filling)

• Hierarchical (default): order matters The hierarchy is the order you pass the columns. The leftmost is the highest tier.

  • Names: --fill-cols '["Region","Country","City"]' ⇒ Region > Country > City
  • Letters: --fill-cols-letters A C B ⇒ Column A > Column C > Column B When a higher-tier value appears on a row, all lower-tier carries reset for that row.

• Independent (pandas-style ffill) Each listed column forward-fills independently. Order of columns does not matter. Columns do not reset each other.

• Completely empty rows (all headers blank) are preserved as empty without applying fill; the carry persists past them for later rows.

• Whitespace-only cells are treated as blank.

Illustration

Input:

columnname1   columnname2   anothercolumn,3
apple
       red     sour
potato
       fried   yellow

Hierarchical output:

apple   red    sour
potato  None   None
potato  fried  yellow

Independent output:

apple   red    sour
potato  red    sour
potato  fried  yellow

Dropping rows

• --drop-blank-rows: drops rows where all --fill-cols are blank (often spacer rows).
• --require-non-null [A,B,…] / --require-non-null-letters: drops rows where any of those headers are blank after filling.

Row hash

• --row-hash adds a SHA-256 hex digest over all ingested columns (in header order) after filling for non-empty rows.
• For completely empty rows, the hash reflects all-empty values (no filling is applied by design).
• SQLite mode creates a non-unique index on row_hash for faster lookups.
• Numeric cells are normalized for hashing (e.g., 1, 1.0 → 1; no scientific notation).

Excel row numbers

• --excel-row-numbers includes the original Excel row number (1-based) in column excel_row.

---

Python API

from xlfilldown.api import ingest_excel_to_sqlite, ingest_excel_to_excel

# → SQLite
summary = ingest_excel_to_sqlite(
    file="data.xlsx",
    sheet="Sheet1",
    header_row=1,
    # choose one:
    fill_cols=["columnname1", "columnname2", "anothercolumn,3"],   # by header names
    # fill_cols_letters=["A", "B", "C"],                           # or by Excel letters
    db="out.db",
    table=None,
    drop_blank_rows=True,
    # choose one (or both, merged & de-duped):
    require_non_null=["columnname1", "columnname2"],               # by header names
    # require_non_null_letters=["A", "B"],                         # or by Excel letters
    row_hash=True,
    excel_row_numbers=True,
    if_exists="replace",
    batch_size=1000,
    fill_mode="hierarchical",    # default hierarchical fill
    # fill_mode="independent",   # independent (pandas-style) fill
)

# → Excel
summary = ingest_excel_to_excel(
    file="data.xlsx",
    sheet="Sheet1",
    header_row=1,
    fill_cols=["columnname1", "columnname2", "anothercolumn,3"],
    # or: fill_cols_letters=["A", "B", "C"],
    outfile="out.xlsx",
    outsheet=None,
    drop_blank_rows=True,
    require_non_null=["columnname1", "columnname2"],
    # or: require_non_null_letters=["A", "B"],
    row_hash=True,
    excel_row_numbers=True,
    if_exists="replace",
    fill_mode="independent",     # independent (pandas-style) fill
    # fill_mode="hierarchical",  # hierarchical (default)
)

Return fields

• SQLite: { table, columns, rows_ingested, row_hash, excel_row_numbers }
• Excel: { workbook, sheet, columns, rows_written, row_hash, excel_row_numbers }

---

Raw Ingest Examples

Sometimes you may want to ingest a sheet exactly as-is, without applying any fill-down logic.
This is useful if you just want to load the data into SQLite or Excel with audit columns (row_hash, excel_row) and handle nulls/blanks later.

---

CLI: Raw ingest to SQLite

xlfilldown db \
  --infile data.xlsx --insheet Sheet1 --header-row 1 \
  --db out.db --table raw_ingest \
  --ingest-mode raw \
  --row-hash --excel-row-numbers --if-exists replace

---

CLI: Raw ingest to Excel

xlfilldown xlsx \
  --infile data.xlsx --insheet Sheet1 --header-row 1 \
  --outfile out.xlsx --outsheet RawSheet \
  --ingest-mode raw \
  --row-hash --excel-row-numbers --if-exists replace

---

Python API: Raw ingest to SQLite

from xlfilldown.api import ingest_excel_to_sqlite

summary = ingest_excel_to_sqlite(
    file="data.xlsx", sheet="Sheet1", header_row=1,
    ingest_mode="raw",                      # skip fill-down
    db="out.db", table="raw_ingest",
    row_hash=True, excel_row_numbers=True,
    if_exists="replace",
)
print(summary)

---

Python API: Raw ingest to Excel

from xlfilldown.api import ingest_excel_to_excel

summary = ingest_excel_to_excel(
    file="data.xlsx", sheet="Sheet1", header_row=1,
    ingest_mode="raw",                      # skip fill-down
    outfile="out.xlsx", outsheet="RawSheet",
    row_hash=True, excel_row_numbers=True,
    if_exists="replace",
)
print(summary)

Notes

• All destination columns are written as TEXT (including excel_row). Values are stored as canonical strings; hashing uses the same canonicalization.
• The input workbook is opened with read_only=True, data_only=True (formulas use cached values).

License

MIT © RexBytes

Proof of Ownership

Woof woof!

RexBytes here — author, creator, and maintainer of this project.
I don't know any secret handshakes, so here’s a signed dog tag instead.

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512

woof woof!

RexBytes here - author, creator, and maintainer of project xlfilldown.

In case we ever meet at the same park, I'll show you my signed dog tag to say hello.

Signed on: 2025-10-01

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Donations

This little package started as a way to scratch my own itch. Turns out, it saved me from countless Excel headaches 🧹📊.

If xlfilldown also makes your life easier, and you feel like tossing a treat into the dog bowl,
you can send a few sats my way 🐶🍺.

BTC (Bech32): bc1qk2d5cnn5xlnerxq3fcfrsnutzqmye0fe020rdd

Totally optional. I’ll only use it for beer, toys, maybe even more coding.
Either way, I hope xlfilldown helps flatten your spreadsheets and your stress. 🐾