Pretty

Input	Output	Alias
✗	✔

Description

The Pretty format outputs data as Unicode-art tables, using ANSI-escape sequences for displaying colors in the terminal. A full grid of the table is drawn, and each row occupies two lines in the terminal. Each result block is output as a separate table. This is necessary so that blocks can be output without buffering results (buffering would be necessary to pre-calculate the visible width of all the values). NULL is output as ᴺᵁᴸᴸ.

Example usage

Example (shown for the PrettyCompact format):

Query

SELECT * FROM t_null

Response

┌─x─┬────y─┐
│ 1 │ ᴺᵁᴸᴸ │
└───┴──────┘

Rows are not escaped in any of the Pretty formats. Instead, non-printable control characters (C0 controls 0x00-0x1F and DEL 0x7F) in the values and in the column names are displayed as the corresponding Unicode “Control Pictures” (U+2400-U+2421) by default, so that they stay visible and do not deform the table. For example, a NUL is shown as ␀:

Query

SELECT 'String with a NUL \0 character' AS Escaping_test FORMAT PrettyCompact

Response

┌─Escaping_test─────────────────┐
│ String with a NUL ␀ character │
└───────────────────────────────┘

TAB, the line feed and ESC are exceptions: they are always printed as is, because a terminal interprets them rather than swallowing them - a tab advances to the next tab stop, and an ANSI escape sequence is what lets the data carry a visualization. A line feed keeps breaking the line too: inside a table cell when output_format_pretty_multiline_fields is enabled, and as is otherwise. A column name is the exception to that exception: the header and the footer are a single line, so a line feed in a name is replaced like any other control character. To print control characters verbatim instead, disable output_format_pretty_display_control_characters:

Query

SELECT 'String with a NUL \0 character' AS Escaping_test FORMAT PrettyCompact
SETTINGS output_format_pretty_display_control_characters = 0

The response then contains the raw NUL byte instead. A terminal swallows it, so the character is invisible and the row is one position wider than the border that was measured for it - the deformed table that displaying the Control Picture avoids. To avoid dumping too much data to the terminal, only the first 10,000 rows are printed. If the number of rows is greater than or equal to 10,000, the message “Showed first 10 000” is printed.

This format is only appropriate for outputting a query result, but not for parsing data.

The Pretty format supports outputting total values (when using WITH TOTALS) and extremes (when ‘extremes’ is set to 1). In these cases, total values and extreme values are output after the main data, in separate tables. This is shown in the following example which uses the PrettyCompact format:

Query

SELECT EventDate, count() AS c 
FROM test.hits 
GROUP BY EventDate 
WITH TOTALS 
ORDER BY EventDate 
FORMAT PrettyCompact

Response

┌──EventDate─┬───────c─┐
│ 2014-03-17 │ 1406958 │
│ 2014-03-18 │ 1383658 │
│ 2014-03-19 │ 1405797 │
│ 2014-03-20 │ 1353623 │
│ 2014-03-21 │ 1245779 │
│ 2014-03-22 │ 1031592 │
│ 2014-03-23 │ 1046491 │
└────────────┴─────────┘

Totals:
┌──EventDate─┬───────c─┐
│ 1970-01-01 │ 8873898 │
└────────────┴─────────┘

Extremes:
┌──EventDate─┬───────c─┐
│ 2014-03-17 │ 1031592 │
│ 2014-03-23 │ 1406958 │
└────────────┴─────────┘

Format settings

The following settings are common to all Pretty formats:

Setting	Description	Default
`output_format_pretty_max_rows`	Row limit for Pretty formats.	`10000`
`output_format_pretty_max_column_pad_width`	Maximum width to pad all values in a column in Pretty formats.	`250`
`output_format_pretty_max_value_width`	Maximum width of value to display in Pretty formats. If greater - it will be cut.	`10000`
`output_format_pretty_color`	Use ANSI escape sequences to paint colors in Pretty formats.	`true`
`output_format_pretty_grid_charset`	Charset for printing grid borders. Available charsets: ASCII, UTF-8.	`UTF-8`
`output_format_pretty_row_numbers`	Add row numbers before each row for pretty output format.	`true`
`output_format_pretty_display_footer_column_names`	Display column names in the footer if table contains many rows.	`true`
`output_format_pretty_display_footer_column_names_min_rows`	Sets the minimum number of rows for which a footer will be displayed if `output_format_pretty_display_footer_column_names` is enabled.	`50`

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