[WIP] Add benchmarks

[gouthamve]

➜  tsdb git:(master) ✗ go test -run=XXX -bench=EQS 
goos: linux
goarch: amd64
pkg: github.com/prometheus/tsdb
BenchmarkInMemQueries_Series_1M_EQSelector_1_NoExpansion-8       	       5	 297650662 ns/op	 4653936 B/op	      34 allocs/op
BenchmarkInMemQueries_Series_1M_EQSelector_1_Expansion-8         	       3	 390691429 ns/op	76654000 B/op	 1000036 allocs/op
BenchmarkInMemQueries_Series_1M_EQSelector_2_NoExpansion-8       	     100	  19728340 ns/op	  386016 B/op	      27 allocs/op
BenchmarkInMemQueries_Series_1M_EQSelector_2_Expansion-8         	      50	  27937118 ns/op	 7586080 B/op	  100029 allocs/op
BenchmarkInMemQueries_Series_1M_EQSelector_3_NoExpansion-8       	    2000	   1089713 ns/op	   16240 B/op	      21 allocs/op
BenchmarkInMemQueries_Series_1M_EQSelector_3_Expansion-8         	    1000	   2383873 ns/op	  736304 B/op	   10023 allocs/op
BenchmarkPersistedQueries_Series_1M_EQSelector_1_NoExpansion-8   	  100000	     16793 ns/op	     560 B/op	       9 allocs/op
BenchmarkPersistedQueries_Series_1M_EQSelector_1_Expansion-8     	      10	 136797602 ns/op	92003316 B/op	 1300018 allocs/op
BenchmarkPersistedQueries_Series_1M_EQSelector_2_NoExpansion-8   	   50000	     31750 ns/op	     672 B/op	      12 allocs/op
BenchmarkPersistedQueries_Series_1M_EQSelector_2_Expansion-8     	     100	  15309107 ns/op	 9201015 B/op	  130014 allocs/op
BenchmarkPersistedQueries_Series_1M_EQSelector_3_NoExpansion-8   	   30000	     47446 ns/op	     816 B/op	      15 allocs/op
BenchmarkPersistedQueries_Series_1M_EQSelector_3_Expansion-8     	    1000	   1526049 ns/op	  920906 B/op	   13017 allocs/op
PASS
ok  	github.com/prometheus/tsdb	407.064s

---

This change is 

[gouthamve]

Added benchmarks which stitch together the queries across blocks. Slowed down linearly with the number of blocks.

BenchmarkPersistedQueries_Series_1M_EQSelector_1_NoExpansion-8           	 3000000	     15836 ns/op	     400 B/op	       5 allocs/op
BenchmarkPersistedQueries_Series_1M_EQSelector_1_Expansion-8             	     300	 153037510 ns/op	92025183 B/op	 1300055 allocs/op
BenchmarkPersistedQueries_Series_1M_EQSelector_2_NoExpansion-8           	 1000000	     31488 ns/op	     512 B/op	       8 allocs/op
BenchmarkPersistedQueries_Series_1M_EQSelector_2_Expansion-8             	    3000	  16091378 ns/op	 9203150 B/op	  130014 allocs/op
BenchmarkPersistedQueries_Series_1M_EQSelector_3_NoExpansion-8           	 1000000	     46985 ns/op	     656 B/op	      11 allocs/op
BenchmarkPersistedQueries_Series_1M_EQSelector_3_Expansion-8             	   30000	   1736169 ns/op	  920970 B/op	   13013 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_EQSelector_1_NoExpansion-8   	 1000000	     55631 ns/op	    5036 B/op	      69 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_EQSelector_1_Expansion-8     	     100	 496277503 ns/op	255414319 B/op	 3800431 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_EQSelector_2_NoExpansion-8   	  500000	    110538 ns/op	    5372 B/op	      78 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_EQSelector_2_Expansion-8     	    1000	  51262058 ns/op	25542929 B/op	  380072 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_EQSelector_3_NoExpansion-8   	  300000	    168191 ns/op	    5803 B/op	      87 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_EQSelector_3_Expansion-8     	   10000	   5558311 ns/op	 2556426 B/op	   38045 allocs/op


BenchmarkPersistedQueries_Series_1M_RESelector_1_NoExpansion-8           	 1000000	     49407 ns/op	    3792 B/op	     136 allocs/op
BenchmarkPersistedQueries_Series_1M_RESelector_1_Expansion-8             	     300	 135023707 ns/op	66422086 B/op	 1200173 allocs/op
BenchmarkPersistedQueries_Series_1M_RESelector_2_NoExpansion-8           	  500000	     88186 ns/op	    7376 B/op	     272 allocs/op
BenchmarkPersistedQueries_Series_1M_RESelector_2_Expansion-8             	    3000	  16260850 ns/op	 7313574 B/op	  132278 allocs/op
BenchmarkPersistedQueries_Series_1M_RESelector_3_NoExpansion-8           	  300000	    171849 ns/op	   14400 B/op	     446 allocs/op
BenchmarkPersistedQueries_Series_1M_RESelector_3_Expansion-8             	   10000	   6688048 ns/op	 2651988 B/op	   48101 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_RESelector_1_NoExpansion-8   	  300000	    162830 ns/op	   13940 B/op	     457 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_RESelector_1_Expansion-8     	     100	 424142649 ns/op	178564115 B/op	 3500708 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_RESelector_2_NoExpansion-8   	  200000	    303785 ns/op	   24698 B/op	     865 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_RESelector_2_Expansion-8     	    1000	  56539414 ns/op	19664063 B/op	  385857 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_RESelector_3_NoExpansion-8   	  100000	    738669 ns/op	   45787 B/op	    1387 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_RESelector_3_Expansion-8     	    2000	  24416681 ns/op	 7134001 B/op	  140342 allocs/op

[gouthamve]

Postings lazily expanded:

➜  tsdb git:(bench) ✗ go test -run=XXX -bench="Pers.*RES" -benchtime=30s -timeout 99999s
goos: linux
goarch: amd64
pkg: github.com/prometheus/tsdb
BenchmarkPersistedQueries_Series_1M_RESelector_1_NoExpansion-8           	 1000000	     66759 ns/op	    3792 B/op	     136 allocs/op
BenchmarkPersistedQueries_Series_1M_RESelector_1_Expansion-8             	     300	 183677815 ns/op	66422514 B/op	 1200174 allocs/op
BenchmarkPersistedQueries_Series_1M_RESelector_2_NoExpansion-8           	  500000	    126899 ns/op	    7376 B/op	     272 allocs/op
BenchmarkPersistedQueries_Series_1M_RESelector_2_Expansion-8             	    2000	  23752705 ns/op	 7313527 B/op	  132277 allocs/op
BenchmarkPersistedQueries_Series_1M_RESelector_3_NoExpansion-8           	  200000	    275691 ns/op	   14400 B/op	     446 allocs/op
BenchmarkPersistedQueries_Series_1M_RESelector_3_Expansion-8             	    5000	   9983623 ns/op	 2652012 B/op	   48101 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_RESelector_1_NoExpansion-8   	  200000	    231159 ns/op	   13938 B/op	     457 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_RESelector_1_Expansion-8     	     100	 560997587 ns/op	178561927 B/op	 3500704 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_RESelector_2_NoExpansion-8   	  100000	    444588 ns/op	   24698 B/op	     865 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_RESelector_2_Expansion-8     	    1000	  70224747 ns/op	19663488 B/op	  385856 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_RESelector_3_NoExpansion-8   	   50000	   1120270 ns/op	   45783 B/op	    1387 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_RESelector_3_Expansion-8     	    2000	  24494249 ns/op	 7134136 B/op	  140343 allocs/op
PASS
ok  	github.com/prometheus/tsdb	1742.311s

Postings expanded initially:

➜  tsdb git:(bench) ✗ go test -run=XXX -bench="Pers.*RES" -benchtime=30s -timeout 99999s
goos: linux
goarch: amd64
pkg: github.com/prometheus/tsdb
BenchmarkPersistedQueries_Series_1M_RESelector_1_NoExpansion-8           	   10000	   4179558 ns/op	 4658167 B/op	     167 allocs/op
BenchmarkPersistedQueries_Series_1M_RESelector_1_Expansion-8             	     300	 136080805 ns/op	71083896 B/op	 1200218 allocs/op
BenchmarkPersistedQueries_Series_1M_RESelector_2_NoExpansion-8           	   20000	   2424173 ns/op	  393709 B/op	     293 allocs/op
BenchmarkPersistedQueries_Series_1M_RESelector_2_Expansion-8             	    2000	  20570942 ns/op	 7700142 B/op	  132299 allocs/op
BenchmarkPersistedQueries_Series_1M_RESelector_3_NoExpansion-8           	   20000	   2245289 ns/op	  130399 B/op	     463 allocs/op
BenchmarkPersistedQueries_Series_1M_RESelector_3_Expansion-8             	    5000	   8806588 ns/op	 2768089 B/op	   48118 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_RESelector_1_NoExpansion-8   	    3000	  15657315 ns/op	13980175 B/op	     556 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_RESelector_1_Expansion-8     	     100	 468218545 ns/op	192545348 B/op	 3500836 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_RESelector_2_NoExpansion-8   	    5000	   8052530 ns/op	 1184659 B/op	     929 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_RESelector_2_Expansion-8     	    1000	  54333970 ns/op	20825928 B/op	  385926 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_RESelector_3_NoExpansion-8   	    5000	   7432166 ns/op	  394029 B/op	    1438 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_RESelector_3_Expansion-8     	    2000	  26195864 ns/op	 7482877 B/op	  140395 allocs/op
PASS
ok  	github.com/prometheus/tsdb	1442.792s

Sometimes it's better but in the last case it ended up being worse. @fabxc

[gouthamve]

Update with 10 blocks:

Lazy expansion:

➜  tsdb git:(bench) ✗ go test -run=XXX -bench="Pers.*RES" -benchtime=30s -timeout 99999s
goos: linux
goarch: amd64
pkg: github.com/prometheus/tsdb
BenchmarkPersistedQueries_Series_1M_RESelector_1_Expansion-8            	     300	 129686805 ns/op	66422880 B/op	 1200174 allocs/op
BenchmarkPersistedQueries_Series_1M_RESelector_2_Expansion-8            	    3000	  16975375 ns/op	 7313547 B/op	  132278 allocs/op
BenchmarkPersistedQueries_Series_1M_RESelector_3_Expansion-8            	   10000	   7607723 ns/op	 2651987 B/op	   48101 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_RESelector_1_Expansion-8    	     100	 457491636 ns/op	178563726 B/op	 3500707 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_RESelector_2_Expansion-8    	    1000	  56861207 ns/op	19663910 B/op	  385857 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_RESelector_3_Expansion-8    	    2000	  26012945 ns/op	 7133918 B/op	  140342 allocs/op
BenchmarkPersistedQueries_10Blocks_Series_1M_RESelector_1_Expansion-8   	     100	 461633464 ns/op	178562803 B/op	 3500705 allocs/op
BenchmarkPersistedQueries_10Blocks_Series_1M_RESelector_2_Expansion-8   	    1000	  49650717 ns/op	19663409 B/op	  385856 allocs/op
BenchmarkPersistedQueries_10Blocks_Series_1M_RESelector_3_Expansion-8   	    2000	  21535328 ns/op	 7134296 B/op	  140343 allocs/op
PASS
ok  	github.com/prometheus/tsdb	1130.063s

Postings expanded initially:

➜  tsdb git:(bench) ✗ go test -run=XXX -bench="Pers.*RES" -benchtime=30s -timeout 99999s
goos: linux
goarch: amd64
pkg: github.com/prometheus/tsdb
BenchmarkPersistedQueries_Series_1M_RESelector_1_Expansion-8            	     300	 129024565 ns/op	71083153 B/op	 1200217 allocs/op
BenchmarkPersistedQueries_Series_1M_RESelector_2_Expansion-8            	    3000	  16687652 ns/op	 7700121 B/op	  132299 allocs/op
BenchmarkPersistedQueries_Series_1M_RESelector_3_Expansion-8            	   10000	   6728670 ns/op	 2768045 B/op	   48118 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_RESelector_1_Expansion-8    	     100	 419232545 ns/op	192542643 B/op	 3500830 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_RESelector_2_Expansion-8    	    1000	  49837803 ns/op	20825317 B/op	  385925 allocs/op
BenchmarkPersistedQueries_3Blocks_Series_1M_RESelector_3_Expansion-8    	    2000	  20651045 ns/op	 7482882 B/op	  140395 allocs/op
BenchmarkPersistedQueries_10Blocks_Series_1M_RESelector_1_Expansion-8   	     100	 425725439 ns/op	192539824 B/op	 3500825 allocs/op
BenchmarkPersistedQueries_10Blocks_Series_1M_RESelector_2_Expansion-8   	    1000	  49175584 ns/op	20825426 B/op	  385925 allocs/op
BenchmarkPersistedQueries_10Blocks_Series_1M_RESelector_3_Expansion-8   	    2000	  20114671 ns/op	 7482500 B/op	  140394 allocs/op
PASS
ok  	github.com/prometheus/tsdb	1049.781s

There are mostly gains here, sometimes upto 24%!

[gouthamve]

@fabxc Your thoughts on how I can proceed with this PR?

[krasi-georgiev]

superseded by #467