Reduce per-row allocations

[indieloki]

Modify several internal functions like a MR for v2 library. Many people are using older versions of pgx and would appreciate a performance boost.

[codecov]

Codecov Report

Attention: Patch coverage is 87.50000% with 5 lines in your changes missing coverage. Please review.

Project coverage is 83.08%. Comparing base (7e6e67b) to head (15cb2ed).
Report is 1 commits behind head on v1.

Files with missing lines	Patch %	Lines
dbscan/dbscan.go	79.16%	4 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##               v1     #149      +/-   ##
==========================================
+ Coverage   82.63%   83.08%   +0.44%     
==========================================
  Files           5        5              
  Lines         432      538     +106     
==========================================
+ Hits          357      447      +90     
- Misses         60       76      +16     
  Partials       15       15              

Flag	Coverage Δ
unittests	83.08% <87.50%> (+0.44%)	⬆️

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[georgysavva]

LGTM! Thanks for adding this

[georgysavva]

Here is the release for it: https://github.com/georgysavva/scany/releases/tag/v1.2.3