perf: don't request the full metadata

[zkochan]

ref #2632

[aparajita]

Well that was simple! What kind of speed improvement are you seeing?

[zkochan]

before

Executed in    5.93 secs   fish           external
   usr time    4.13 secs  494.00 micros    4.13 secs
   sys time    0.91 secs  141.00 micros    0.91 secs

after

Executed in    5.13 secs   fish           external
   usr time    2.34 secs  479.00 micros    2.34 secs
   sys time    0.56 secs  137.00 micros    0.56 secs