Query with REGEX expressions is consuming too much memory

[ajnavarro]

The following query:

SELECT f.repository_id, f.blob_hash, f.commit_hash, f.file_path
      FROM (
          SELECT blob_hash, repository_id
          FROM blobs
          WHERE NOT IS_BINARY(blob_content) AND (
              blob_content REGEXP '(?i)facebook.*[\'\\"][0-9a-f]{32}[\'\\"]'
              OR blob_content REGEXP '(?i)twitter.*[\'\\"][0-9a-zA-Z]{35,44}[\'\\"]'
              OR blob_content REGEXP '(?i)github.*[\'\\"][0-9a-zA-Z]{35,40}[\'\\"]'
              OR blob_content REGEXP 'AKIA[0-9A-Z]{16}'
              OR blob_content REGEXP '(?i)heroku.*[0-9A-F]{8}-[0-9A-F]{4}-[0-9A-F]{4}-[0-9A-F]{4}-[0-9A-F]{12}'
              OR blob_content REGEXP '.*-----BEGIN ((RSA|DSA|OPENSSH|SSH2|EC) )?PRIVATE KEY-----.*'
          )
      ) h
      INNER JOIN commit_files f
      ON h.blob_hash = f.blob_hash
          AND h.repository_id = f.repository_id
          AND f.file_path NOT REGEXP '^vendor.*'

Is consuming 9 times more memory than previous v0.19.0 version

We should have a look into that.