q - Text as Data

q's purpose is to bring SQL expressive power to the Linux command line and to provide easy access to text as actual data.

q allows the following:

Performing SQL-like statements directly on tabular text data, auto-caching the data in order to accelerate additional querying on the same file.
Performing SQL statements directly on multi-file sqlite3 databases, without having to merge them or load them into memory

The following table shows the impact of using caching:

Rows	Columns	File Size	Query time without caching	Query time with caching	Speed Improvement
5,000,000	100	4.8GB	4 minutes, 47 seconds	1.92 seconds	x149
1,000,000	100	983MB	50.9 seconds	0.461 seconds	x110
1,000,000	50	477MB	27.1 seconds	0.272 seconds	x99
100,000	100	99MB	5.2 seconds	0.141 seconds	x36
100,000	50	48MB	2.7 seconds	0.105 seconds	x25

Notice that for the current version, caching is not enabled by default, since the caches take disk space. Use -C readwrite or -C read to enable it for a query, or add caching_mode to .qrc to set a new default.

q's web site is https://harelba.github.io/q/ or https://q.textasdata.wiki It contains everything you need to download and use q immediately.

Usage Examples

q treats ordinary files as database tables, and supports all SQL constructs, such as WHERE, GROUP BY, JOINs, etc. It supports automatic column name and type detection, and provides full support for multiple character encodings.

Here are some example commands to get the idea:

$ q "SELECT COUNT(*) FROM ./clicks_file.csv WHERE c3 > 32.3"

$ ps -ef | q -H "SELECT UID, COUNT(*) cnt FROM - GROUP BY UID ORDER BY cnt DESC LIMIT 3"

$ q "select count(*) from some_db.sqlite3:::albums a left join another_db.sqlite3:::tracks t on (a.album_id = t.album_id)"

Detailed examples are in here