Hey all.
I ran into an issue recently.  I have a rather large index and in my
application I had defined values for the "pf" parameter, but I had
commented it out years ago not really knowing why I did it.  Obviously the
point of the pf helps rank fields higher if they are in close proximity,
and this is good if you do a text search but want a boost on the "title"
for example.

So I un-commented out the line, to enable it to go against 6 important
fields.  Afterwards through monitoring performance I noticed that my
searches were taking roughly 50% to 100% (2x!) longer, and it started at
the exact time I committed that change, 1:40 pm, qtimes below in a 15
minute average cycle with the start time listed.

What im assuming is happening behind the scenes is solr is doing an
auxiliary search on the defined fields as
field1:"word word word"~n+x
field2:"word word word"~n+x
field3:"word word word"~n+x
where n is the number of words and x is whatever arbitrary number.
 obviously this adds a LOT to the search on the back end if I understand
the functionality correctly.

is there any recommendation to get roughly my old speeds back without a
full re-index to a new "metadata" type field BUT still keep the features of
the pf parameter?  Also using a qf parameter.

set up:
solr 5.x
400gb+ index
16mm docs, 24mm with deletes.
 2TB SSD, 24 cores, 148gb ram, 50gb heap size, about 30,000 searches a day.

Thanks!
-Dave

no pf:

| 2017-03-29 13:00:03 |     355.1961 |
| 2017-03-29 13:15:05 |     277.5479 |
| 2017-03-29 13:30:03 |     235.2263 |
| 2017-03-29 13:45:01 |     398.5000 |
| 2017-03-29 14:00:00 |     371.3048 |
| 2017-03-29 14:15:05 |     373.9901 |
| 2017-03-29 14:30:00 |     401.2474 |
| 2017-03-29 14:45:01 |     358.0344 |
| 2017-03-29 15:00:00 |     404.0234 |


changed pf at 140pm:

| 2017-03-30 13:00:00 |     270.4377 |
| 2017-03-30 13:15:00 |     397.9880 |
| 2017-03-30 13:30:00 |     474.8985 |
| 2017-03-30 13:45:02 |    1082.0114 |
| 2017-03-30 14:00:03 |     821.8152 |
| 2017-03-30 14:15:04 |    1034.8388 |
| 2017-03-30 14:30:00 |    1405.7792 |
| 2017-03-30 14:45:01 |    1200.1488 |
| 2017-03-30 15:00:00 |     694.4559 |

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