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Opening a file

Columnar supports three ways to open a file.

Click File → Open File… in the native menu bar, or press Ctrl+O (Cmd+O on macOS). A file picker will open — select any .csv or .tsv file.

Click the Open button in the top-right corner of the window. This is equivalent to using the menu.

Drag a .csv or .tsv file from your file manager and drop it anywhere on the Columnar window. The file will load immediately.

Columnar does not load the entire file into memory. Instead it does an index pass — a single scan through the file that records the byte position of every row. During this pass you will see a progress indicator:

Indexing… 1,234 / 14,000 MB (8%)

Once indexing is complete, the grid appears and you can start scrolling immediately. Rows are parsed from disk on demand as you scroll — only the visible rows are ever in memory at one time.

File sizeApproximate time
Under 100 MBUnder 1 second
1 GB2–5 seconds
14 GB20–30 seconds
50 GB+1–2 minutes

Times vary depending on disk speed. SSD is significantly faster than HDD.

Opening a new file while one is already loaded replaces the current file. Columnar supports one file at a time per window. The previous file is closed and the new one is indexed.

Files you open are saved to a recent files list accessible via File → Recent Files. See the recent files guide for details.