How a .csv.gz is read

The wrapper comes off once. The columns stay.

  1. 01 filesales.csv.gzA compressed export in your folder. You do not unzip it.
  2. 02 unwrapGzip is strippedOnce, during the xerj autoindex run. No query reads the archive again.
  3. 03 sniffFirst 8,192 bytesThe family comes from the content, not from the file extension.
  4. 04 indexTyped columnsThe CSV dialect is sniffed. ax_path keeps the .gz name.

Read as text: zgrep, rga

what you getMatching linesThe archive is expanded for every search. A number in a column is a string of characters.
good forOne question, asked onceNo node and no index. Also the right tool for a .tar.gz or a .zip.

Read as data: xerj autoindex

what you getA dataset with named columnsA numeric column takes a range query. A keyword column takes a filter and an aggregation.
good forMany questions, or an agentThe agent asks over HTTP or MCP and reads fields, not lines.
The path a compressed CSV takes through xerj autoindex. The 8,192-byte sniff window is the PREFIX constant in sniff.rs. A .json.gz takes the same path and lands as documents with fields.