Format function added

[danlark1]

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For changelog. Remove if this is non-significant change.

Category (leave one):

• New Feature

Short description (up to few sentences):
format function added

Detailed description (optional):

Formatting constant pattern with the string listed in the arguments. pattern is a simplified Python format pattern. Format string contains "replacement fields" surrounded by curly braces {}. Anything that is not contained in braces is considered literal text, which is copied unchanged to the output. If you need to include a brace character in the literal text, it can be escaped by doubling: {{ and }}. Field names can be numbers (starting from zero) or empty (then they are treated as consequence numbers).

SELECT format('{1} {0} {1}', 'World', 'Hello')

┌─format('{1} {0} {1}', 'World', 'Hello')─┐
│ Hello World Hello                       │
└─────────────────────────────────────────┘

SELECT format('{} {}', 'Hello', 'World')

┌─format('{} {}', 'Hello', 'World')─┐
│ Hello World                       │
└───────────────────────────────────┘

It turned out to be faster than concat function

SELECT count(format('Hello {} World {}', URL, URL))
FROM hits_100m_single 
SETTINGS max_threads = 1

┌─count(format('Hello {} World {}', URL, URL))─┐
│                                    100000000 │
└──────────────────────────────────────────────┘

1 rows in set. Elapsed: 6.684 sec. Processed 100.00 million rows, 9.38 GB (14.96 million rows/s., 1.40 GB/s.) 

vla2-5812-1.qyp-seek-6.vla.yp-c.yandex.net :) select count(concat('Hello ', URL, ' World ', URL)) from hits_100m_single settings max_threads=1;

SELECT count(concat('Hello ', URL, ' World ', URL))
FROM hits_100m_single 
SETTINGS max_threads = 1

┌─count(concat('Hello ', URL, ' World ', URL))─┐
│                                    100000000 │
└──────────────────────────────────────────────┘

1 rows in set. Elapsed: 10.607 sec. Processed 100.00 million rows, 9.38 GB (9.43 million rows/s., 883.98 MB/s.)

SELECT sum(concat('Hello ', URL, ' World ', URL) = format('Hello {} World {}', URL, URL))
FROM hits_100m_single 
SETTINGS max_threads = 1

┌─sum(equals(concat('Hello ', URL, ' World ', URL), format('Hello {} World {}', URL, URL)))─┐
│                                                                                 100000000 │
└───────────────────────────────────────────────────────────────────────────────────────────┘ 

[alexey-milovidov]

(after adding support for const strings)