PT-1059 tools cannot parse index names containing newlines (#578)

* PT-1059 - Tools can't parse index names containing newlines

Fixed regular expressions in TableParser.
Added test case, including test for new lines in the column name

* PT-1059 - Tools can't parse index names containing newlines

Disabled pt-1637.t until PT-2174 is fixed.
Updated number of tables in b/t/pt-table-checksum/issue_1485195.t

* Patch newlines in table columns (#369)

Will accept this change as part of the fix for PT-1059 - Tools cannot parse index names containing new lines. We will later fix the issue with the patch ourselves.

mysql 5.6.40 allows newlines in column names however the following code:

my @defs = $ddl =~ m/^(\s+`.*?),?$/gm;

breaks due to it detecting newlines as line ends. The 'm' argument at the end does this by auto-detecting lines by newline characters.

To correct this issue I've made use of zero-length assertions known as " positive lookback"

https://www.regular-expressions.info/lookaround.html

what does it do?

m/(?:(?<=,\n)|(?<=\(\n))(\s+`(?:.|\n)+?`.+?),?\n/g;

TLDR:

Treat the string as one long string and don't treat \n as the end of a line.

look for (\s+`(?:.|\n)+?`.+?),?\n

if one of those matches look at what precedes the string

if it's ',\n' or ')\n' the string matches. Only save what's in (\s+`(?:.|\n)+?`.+?),?\n

m/ is declaring this a matching regex.

(?:(?<=,\n)|(?<=(\n)) This is an OR statement including two look-behind clauses. The ?: tells the enclosing parentheses to not store the result as a variable. I've put the two look-behinds in this OR statement below this line:

(?<=,\n) Look behind the matched string for a comma followed by a newline, the comma must be there for this look behind to match.

(?<=(\n) Look behind the matched string for a open parentheses followed by a newline, the open parentheses must be there.

(\s+`(?:.|\n)+?`.+?),?\n This is the actual match. Match newline character followed by one or more spaces followed by back-tick followed by a character which can be any character or a newline one or more times, but don't be greedy and take the rest of the match into consideration. Followed by a back tick and any character one or more times. This match stops where there is a comma or failing that a newline following a back tick and some characters.

,?\n match a comma that may not be there followed by a newline.
/g don't stop if this pattern matches keep looking for more patterns to the end of the string.

* PT-1059 - Tools can't parse index names containing newlines

Placed fix from PR-369 into proper place and created test case for this fix.

---------

Co-authored-by: geneguido <31323560+geneguido@users.noreply.github.com>

t/pt-table-checksum/samples/pt-1059.sql

@@ -0,0 +1,47 @@
+CREATE SCHEMA IF NOT EXISTS pt_1059;
+USE pt_1059;
+DROP TABLE IF EXISTS t1;
+CREATE TABLE `t1` (
+`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
+`c` char(1) DEFAULT NULL,
+PRIMARY KEY (`id`),
+KEY `idx_with_
+newline` (`c`)
+) ENGINE=InnoDB DEFAULT CHARSET=latin1;
+
+INSERT INTO t1 (c) VALUES('a'),('b'),('c');
+
+DROP TABLE IF EXISTS t2;
+CREATE TABLE `t2` (
+`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
+`column_with_
+newline` char(1) DEFAULT NULL,
+PRIMARY KEY (`id`),
+KEY `idx_c` (`column_with_
+newline`)
+) ENGINE=InnoDB DEFAULT CHARSET=latin1;
+
+INSERT INTO t2 (`column_with_
+newline`) VALUES('a'),('b'),('c');
+
+DROP TABLE IF EXISTS t3;
+CREATE TABLE `t3` (
+`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
+`column_with_
+newline` char(1) DEFAULT NULL,
+PRIMARY KEY (`id`),
+KEY `idx_with_
+newline` (`column_with_
+newline`) 
+) ENGINE=InnoDB DEFAULT CHARSET=latin1;
+
+INSERT INTO t3 (`column_with_
+newline`) VALUES('a'),('b'),('c');
+
+DROP TABLE IF EXISTS t4;
+CREATE TABLE `t4` (
+`
+column, starting from new line` char(1)
+) ENGINE=InnoDB DEFAULT CHARSET=latin1;
+
+INSERT INTO t4 VALUES('a'),('b'),('c');