[wp-trac] [WordPress Trac] #38751: WPDB: get_table_from_query leaves SHOW results LIKE-escaped

[WordPress Trac]

#38751: WPDB: get_table_from_query leaves SHOW results LIKE-escaped
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 Reporter:  andy          |      Owner:
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  Awaiting Review
Component:  Database      |    Version:  trunk
 Severity:  normal        |   Keywords:
  Focuses:                |
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 Consider the statement `SHOW TABLES LIKE 'wp_123_%'`. The percent symbol
 is an unbounded wildcard. What might be less obvious is that the
 underscore is a wildcard matching one character. So this statement matches
 `wp_123_posts` as well as `wp_1234_posts`, `wp_1234`. The underscores in
 that `LIKE` string should be escaped.

 The correct pattern is `SHOW TABLES LIKE 'wp\_123\_%'`.

 However, all `wpdb::get_table_from_query()` gets from that statement is
 `'wp'` since its subpattern stops matching at the first backslash. From
 the unescaped version it gets `'wp_123_'` which is more useful. In fact,
 the latter is what hyperdb has always used to correctly map the table to a
 server when such a query was encountered. The liability of this workaround
 is that unwanted tables might be included in the results, as shown above.

 To be more useful, `wpdb::get_table_from_query()` should unescape
 underscores when the match is being used with `LIKE`.

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Ticket URL: <https://core.trac.wordpress.org/ticket/38751>
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