mapzen/chef-mapzen_tilestache — pull request #1 by hkrishna (2014-02-18 22:01:29+00:00)
Title: converting string to double precision using TO_NUMBER(height, '999999D99S")

handles height column edge cases:

"163m (535ft)"
"27'6""
"27'6""
"27'6""
"27'6""
"4 m"
"4 m"
"4 stories"