Allow to limit labels during query via the new SELECTED_LABELS argument

[danni-m]

No description provided.

[lgtm-com]

This pull request introduces 2 alerts when merging ec1568f into 0eb7248 - view on LGTM.com

new alerts:

• 2 for Missing return statement

[lgtm-com]

This pull request introduces 2 alerts when merging 8b9dcc4 into 1875123 - view on LGTM.com

new alerts:

• 2 for Missing return statement

[codecov]

Codecov Report

Merging #762 (01061af) into master (1ea2113) will increase coverage by 0.24%.
The diff coverage is 97.34%.

@@            Coverage Diff             @@
##           master     #762      +/-   ##
==========================================
+ Coverage   89.10%   89.34%   +0.24%     
==========================================
  Files          23       23              
  Lines        3956     4093     +137     
==========================================
+ Hits         3525     3657     +132     
- Misses        431      436       +5     

Impacted Files	Coverage Δ
src/reply.c	92.95% <83.33%> (-7.05%)	⬇️
src/gears_commands.c	90.71% <100.00%> (+0.20%)	⬆️
src/gears_integration.c	91.30% <100.00%> (+1.34%)	⬆️
src/module.c	93.33% <100.00%> (+0.02%)	⬆️
src/query_language.c	96.90% <100.00%> (+0.62%)	⬆️
src/redisgears.h	42.82% <100.00%> (+1.40%)	⬆️
src/resultset.c	98.44% <100.00%> (+0.01%)	⬆️

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[filipecosta90]

@danni-m @gkorland LVGTM with regards to the overall impact on lastpoint query. Nice work Danni!

Using standalone redis setup:
Overall impact on standalone numbers:

• lastpoint: from 245.87 queries/sec (p50=85.38 ms) to 566.34 queries/sec (p50=34.49 ms)

lastpoint query WITHLABELS

Run complete after 10000 queries with 20 workers (Overall query rate 245.87 queries/sec):
RedisTimeSeries last row per host:
min:    18.26ms, med:    85.38ms, mean:    81.26ms, max:  135.92ms, stddev:    16.79ms, sum: 812.6sec, count: 10000
all queries                      :
min:    18.26ms, med:    85.38ms, mean:    81.26ms, max:  135.92ms, stddev:    16.79ms, sum: 812.6sec, count: 10000

lastpoint query SELECTED_LABELS

Run complete after 10000 queries with 20 workers (Overall query rate 566.34 queries/sec):
RedisTimeSeries last row per host:
min:     5.37ms, med:    34.49ms, mean:    35.27ms, max:   67.07ms, stddev:     7.81ms, sum: 352.7sec, count: 10000
all queries                      :
min:     5.37ms, med:    34.49ms, mean:    35.27ms, max:   67.07ms, stddev:     7.81ms, sum: 352.7sec, count: 10000